Lichen

Annotated deducer.py

1009:3685ed09ef41
1031:aa1826243f0c
1007:ee4709557b91
5 months ago Paul Boddie file changeset files shortlog Avoid creating zero-length temporary arrays.
paul@44 1 
#!/usr/bin/env python
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"""
 
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Deduce types for usage observations.
 
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Copyright (C) 2014-2018, 2023 Paul Boddie <paul@boddie.org.uk>
 
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This program is free software; you can redistribute it and/or modify it under
 
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the terms of the GNU General Public License as published by the Free Software
 
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Foundation; either version 3 of the License, or (at your option) any later
 
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version.
 
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This program is distributed in the hope that it will be useful, but WITHOUT
 
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ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
 
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FOR A PARTICULAR PURPOSE.  See the GNU General Public License for more
 
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details.
 
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You should have received a copy of the GNU General Public License along with
 
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this program.  If not, see <http://www.gnu.org/licenses/>.
 
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"""
 
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from access_plan import AccessPlan
 
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from common import first, get_assigned_attributes, get_attrnames, \
 
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                   get_invoked_attributes, get_name_path, init_item, \
 
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                   order_dependencies_partial, sorted_output, \
 
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                   AccessLocation, CommonOutput, Location
 
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from encoders import encode_access_location, encode_alias_location, \
 
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                     encode_constrained, encode_instruction, encode_location, \
 
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                     encode_usage, get_kinds, \
 
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                     test_label_for_kind, test_label_for_type
 
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from errors import DeduceError
 
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from os.path import join
 
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from referencing import combine_types, is_single_class_type, separate_types, \
 
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                        Reference
 
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class Deducer(CommonOutput):
 
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    "Deduce types in a program."
 
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    root_class_type = "__builtins__.object"
 
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    def __init__(self, importer, output):
 
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        """
 
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        Initialise an instance using the given 'importer' that will perform
 
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        deductions on the program information, writing the results to the given
 
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        'output' directory.
 
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        """
 
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        self.importer = importer
 
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        self.output = output
 
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        # Descendants of classes.
 
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        self.descendants = {}
 
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        self.init_descendants()
 
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        self.init_special_attributes()
 
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        # Map locations to usage in order to determine specific types.
 
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        self.location_index = {}
 
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        # Map access locations to definition locations.
 
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        self.access_index = {}
 
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        # Map definition locations to affected accesses.
 
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        self.access_index_rev = {}
 
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        # Map aliases to accesses that define them.
 
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        self.alias_index = {}
 
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        # Map accesses to aliases whose initial values are influenced by them.
 
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        self.alias_index_rev = {}
 
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        # Map definitions and accesses to initialised names.
 
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        self.initialised_names = {}
 
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        self.initialised_accesses = {}
 
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        # Map constant accesses to redefined accesses.
 
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        self.const_accesses = {}
 
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        self.const_accesses_rev = {}
 
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        # Map usage observations to assigned attributes.
 
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        self.assigned_attrs = {}
 
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        # Map usage observations to objects.
 
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        self.attr_class_types = {}
 
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        self.attr_instance_types = {}
 
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        self.attr_module_types = {}
 
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        # All known attribute names.
 
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        self.all_attrnames = set()
 
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        # Modified attributes from usage observations.
 
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        self.modified_attributes = {}
 
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        # Accesses that are assignments or invocations.
 
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        self.reference_assignments = set()
 
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        self.reference_invocations = {}
 
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        self.reference_invocations_unsuitable = {}
 
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        # Map locations to types, constrained indicators and attributes.
 
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        self.accessor_class_types = {}
 
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        self.accessor_instance_types = {}
 
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        self.accessor_module_types = {}
 
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        self.provider_class_types = {}
 
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        self.provider_instance_types = {}
 
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        self.provider_module_types = {}
 
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        self.accessor_constrained = set()
 
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        self.access_constrained = set()
 
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        self.referenced_attrs = {}
 
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        self.referenced_objects = {}
 
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        # Details of access operations.
 
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        self.access_plans = {}
 
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        # Specific attribute access information.
 
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        self.access_instructions = {}
 
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        self.accessor_kinds = {}
 
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        # Accumulated information about accessors and providers.
 
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        self.accessor_general_class_types = {}
 
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        self.accessor_general_instance_types = {}
 
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        self.accessor_general_module_types = {}
 
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        self.accessor_all_types = {}
 
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        self.accessor_all_general_types = {}
 
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        self.provider_all_types = {}
 
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        self.accessor_guard_tests = {}
 
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        # Accumulated information about accessed attributes and
 
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        # access/attribute-specific accessor tests.
 
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        self.reference_all_attrs = {}
 
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        self.reference_all_providers = {}
 
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        self.reference_all_provider_kinds = {}
 
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        self.reference_all_accessor_types = {}
 
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        self.reference_all_accessor_general_types = {}
 
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        self.reference_test_types = {}
 
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        self.reference_test_accessor_type = {}
 
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        # The processing workflow itself.
 
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        self.init_usage_index()
 
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        self.init_attr_type_indexes()
 
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        self.init_combined_attribute_index()
 
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        self.init_accessors()
 
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        self.init_accesses()
 
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        self.init_aliases()
 
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        self.modify_mutated_attributes()
 
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        self.identify_references()
 
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        self.classify_accessors()
 
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        self.classify_accesses()
 
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        self.initialise_access_plans()
 
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        self.initialise_access_instructions()
 
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        self.identify_dependencies()
 
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    def to_output(self):
 
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        "Write the output files using deduction information."
 
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        self.check_output()
 
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        self.write_mutations()
 
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        self.write_accessors()
 
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        self.write_accesses()
 
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        self.write_access_plans()
 
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    def write_mutations(self):
 
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        """
 
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        Write mutation-related output in the following format:
 
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        qualified name " " original object type
 
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        Object type can be "<class>", "<function>" or "<var>".
 
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        """
 
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        f = open(join(self.output, "mutations"), "w")
 
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        try:
 
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            attrs = self.modified_attributes.items()
 
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            attrs.sort()
 
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            for attr, value in attrs:
 
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                print >>f, attr, value
 
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        finally:
 
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            f.close()
 
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    def write_accessors(self):
 
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        """
 
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        Write reference-related output in the following format for types:
 
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        location " " ( "constrained" | "deduced" ) " " attribute type " " most general type names " " number of specific types
 
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        Note that multiple lines can be given for each location, one for each
 
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        attribute type.
 
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        Locations have the following format:
 
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        qualified name of scope ":" local name ":" name version
 
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        The attribute type can be "<class>", "<instance>", "<module>" or "<>",
 
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        where the latter indicates an absence of suitable references.
 
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        Type names indicate the type providing the attributes, being either a
 
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        class or module qualified name.
 
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        ----
 
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        A summary of accessor types is formatted as follows:
 
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        location " " ( "constrained" | "deduced" ) " " ( "specific" | "common" | "unguarded" ) " " most general type names " " number of specific types
 
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        This summary groups all attribute types (class, instance, module) into a
 
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        single line in order to determine the complexity of identifying an
 
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        accessor.
 
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        ----
 
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        References that cannot be supported by any types are written to a
 
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        warnings file in the following format:
 
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        location
 
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        ----
 
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        For each location where a guard would be asserted to guarantee the
 
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        nature of an object, the following format is employed:
 
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        location " " ( "specific" | "common" ) " " object kind " " object types
 
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        Object kind can be "<class>", "<instance>" or "<module>".
 
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        ----
 
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        A summary of aliases is formatted as follows:
 
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        location " " locations
 
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        """
 
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        f_type_summary = open(join(self.output, "type_summary"), "w")
 
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        f_types = open(join(self.output, "types"), "w")
 
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        f_warnings = open(join(self.output, "type_warnings"), "w")
 
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        f_guards = open(join(self.output, "guards"), "w")
 
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        f_aliases = open(join(self.output, "aliases"), "w")
 
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        try:
 
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            locations = self.accessor_class_types.keys()
 
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            locations.sort()
 
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            for location in locations:
 
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                constrained = location in self.accessor_constrained
 
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                # Accessor information.
 
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                class_types = self.accessor_class_types[location]
 
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                instance_types = self.accessor_instance_types[location]
 
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                module_types = self.accessor_module_types[location]
 
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                general_class_types = self.accessor_general_class_types[location]
 
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                general_instance_types = self.accessor_general_instance_types[location]
 
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                general_module_types = self.accessor_general_module_types[location]
 
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                all_types = self.accessor_all_types[location]
 
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                all_general_types = self.accessor_all_general_types[location]
 
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                if class_types:
 
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                    print >>f_types, encode_location(location), encode_constrained(constrained), "<class>", \
 
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                        sorted_output(general_class_types), len(class_types)
 
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                if instance_types:
 
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                    print >>f_types, encode_location(location), encode_constrained(constrained), "<instance>", \
 
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                        sorted_output(general_instance_types), len(instance_types)
 
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                if module_types:
 
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                    print >>f_types, encode_location(location), encode_constrained(constrained), "<module>", \
 
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                        sorted_output(general_module_types), len(module_types)
 
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                if not all_types:
 
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                    print >>f_types, encode_location(location), "deduced", "<>", 0
 
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                    attrnames = list(self.location_index[location])
 
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                    attrnames.sort()
 
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                    print >>f_warnings, encode_location(location), "; ".join(map(encode_usage, attrnames))
 
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                guard_test = self.accessor_guard_tests.get(location)
 
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                if guard_test:
 
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                    guard_test_type, guard_test_arg = guard_test
 
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                # Write specific type guard details.
 
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                if guard_test and guard_test_type == "specific":
 
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                    print >>f_guards, encode_location(location), "-".join(guard_test), \
 
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                        first(get_kinds(all_types)), \
 
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                        sorted_output(all_types)
 
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                # Write common type guard details.
 
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                elif guard_test and guard_test_type == "common":
 
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                    print >>f_guards, encode_location(location), "-".join(guard_test), \
 
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                        first(get_kinds(all_general_types)), \
 
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                        sorted_output(all_general_types)
 
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                print >>f_type_summary, encode_location(location), encode_constrained(constrained), \
 
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                    guard_test and "-".join(guard_test) or "unguarded", sorted_output(all_general_types), len(all_types)
 
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            # Aliases are visited separately from accessors, even though they
 
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            # are often the same thing.
 
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            locations = self.alias_index.keys()
 
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            locations.sort()
 
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            for location in locations:
 
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                accesses = []
 
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                for access_location in self.alias_index[location]:
 
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                    invocation = access_location in self.reference_invocations
 
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                    accesses.append(encode_alias_location(access_location, invocation))
 
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                invocation = location in self.reference_invocations
 
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                print >>f_aliases, encode_alias_location(location, invocation), ", ".join(accesses)
 
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        finally:
 
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            f_type_summary.close()
 
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            f_types.close()
 
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            f_warnings.close()
 
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            f_guards.close()
 
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            f_aliases.close()
 
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    def write_accesses(self):
 
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        """
 
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        Specific attribute output is produced in the following format:
 
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        location " " ( "constrained" | "deduced" ) " " attribute type " " attribute references
 
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        Note that multiple lines can be given for each location and attribute
 
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        name, one for each attribute type.
 
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        Locations have the following format:
 
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        qualified name of scope ":" local name ":" attribute name ":" access number
 
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        The attribute type can be "<class>", "<instance>", "<module>" or "<>",
 
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        where the latter indicates an absence of suitable references.
 
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        Attribute references have the following format:
 
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        object type ":" qualified name
 
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        Object type can be "<class>", "<function>" or "<var>".
 
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        ----
 
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        A summary of attributes is formatted as follows:
 
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        location " " attribute name " " ( "constrained" | "deduced" ) " " test " " attribute references
 
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        This summary groups all attribute types (class, instance, module) into a
 
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        single line in order to determine the complexity of each access.
 
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        Tests can be "validate", "specific", "untested", "guarded-validate" or "guarded-specific".
 
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        ----
 
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        For each access where a test would be asserted to guarantee the
 
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        nature of an attribute, the following formats are employed:
 
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        location " " attribute name " " "validate"
 
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        location " " attribute name " " "specific" " " attribute type " " object type
 
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        ----
 
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        References that cannot be supported by any types are written to a
 
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        warnings file in the following format:
 
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        location
 
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        """
 
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        f_attr_summary = open(join(self.output, "attribute_summary"), "w")
 
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        f_attrs = open(join(self.output, "attributes"), "w")
 
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        f_tests = open(join(self.output, "tests"), "w")
 
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        f_warnings = open(join(self.output, "attribute_warnings"), "w")
 
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        f_unsuitable = open(join(self.output, "invocation_warnings"), "w")
 
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        try:
 
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            locations = self.referenced_attrs.keys()
 
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            locations.sort()
 
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            for location in locations:
 
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                constrained = location in self.access_constrained
 
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                # Attribute information, both name-based and anonymous.
 
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                referenced_attrs = self.referenced_attrs[location]
 
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                if referenced_attrs:
 
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                    attrname = location.get_attrname()
 
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                    all_accessed_attrs = list(set(self.reference_all_attrs[location]))
 
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                    all_accessed_attrs.sort()
 
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                    for attrtype, attrs in self.get_referenced_attrs(location):
 
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                        print >>f_attrs, encode_access_location(location), encode_constrained(constrained), attrtype, sorted_output(attrs)
 
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                    test_type = self.reference_test_types.get(location)
 
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                    # Write the need to test at run time.
 
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                    if test_type[0] == "validate":
 
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                        print >>f_tests, encode_access_location(location), "-".join(test_type)
 
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                    # Write any type checks for anonymous accesses.
 
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                    elif test_type and self.reference_test_accessor_type.get(location):
 
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                        print >>f_tests, encode_access_location(location), "-".join(test_type), \
 
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                            sorted_output(all_accessed_attrs), \
 
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                            self.reference_test_accessor_type[location]
 
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                    print >>f_attr_summary, encode_access_location(location), encode_constrained(constrained), \
 
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                        test_type and "-".join(test_type) or "untested", sorted_output(all_accessed_attrs)
 
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                    # Write details of potentially unsuitable invocation
 
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                    # occurrences.
 
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                    unsuitable = self.reference_invocations_unsuitable.get(location)
 
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                    if unsuitable:
 
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                        unsuitable = map(str, unsuitable)
 
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                        unsuitable.sort()
 
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                        print >>f_unsuitable, encode_access_location(location), ", ".join(unsuitable)
 
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                else:
 
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                    print >>f_warnings, encode_access_location(location)
 
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        finally:
 
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            f_attr_summary.close()
 
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            f_attrs.close()
 
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            f_tests.close()
 
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            f_warnings.close()
 
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            f_unsuitable.close()
 
 paul@44    453 
 
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    def write_access_plans(self):
 
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        """
 
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        Write access and instruction plans.
 
 paul@653    458 
 
 paul@91    459 
        Each attribute access is written out as a plan of the following form:
 
 paul@91    460 
 
 paul@91    461 
        location " " name " " test " " test type " " base " " traversed attributes
 
 paul@653    462 
                 " " traversal access modes " " attributes to traverse
 
 paul@653    463 
                 " " context " " context test " " first access method
 
 paul@653    464 
                 " " final access method " " static attribute " " accessor kinds
 
 paul@653    465 
 
 paul@653    466 
        Locations have the following format:
 
 paul@653    467 
 
 paul@653    468 
        qualified name of scope "." local name ":" name version
 
 paul@653    469 
 
 paul@653    470 
        Traversal access modes are either "class" (obtain accessor class to
 
 paul@653    471 
        access attribute) or "object" (obtain attribute directly from accessor).
 
 paul@91    472 
        """
 
 paul@67    473 
 
 paul@67    474 
        f_attrs = open(join(self.output, "attribute_plans"), "w")
 
 paul@67    475 
 
 paul@67    476 
        try:
 
 paul@67    477 
            locations = self.access_plans.keys()
 
 paul@67    478 
            locations.sort()
 
 paul@67    479 
 
 paul@67    480 
            for location in locations:
 
 paul@1006    481 
                self.access_plans[location].write(f_attrs, location)
 
 paul@67    482 
 
 paul@67    483 
        finally:
 
 paul@67    484 
            f_attrs.close()
 
 paul@67    485 
 
 paul@653    486 
        f = open(join(self.output, "instruction_plans"), "w")
 
 paul@653    487 
        try:
 
 paul@653    488 
            access_instructions = self.access_instructions.items()
 
 paul@653    489 
            access_instructions.sort()
 
 paul@653    490 
 
 paul@653    491 
            for location, instructions in access_instructions:
 
 paul@653    492 
                print >>f, encode_access_location(location), "..."
 
 paul@653    493 
                for instruction in instructions:
 
 paul@653    494 
                    print >>f, encode_instruction(instruction)
 
 paul@653    495 
                print >>f
 
 paul@653    496 
 
 paul@653    497 
        finally:
 
 paul@653    498 
            f.close()
 
 paul@653    499 
 
 paul@44    500 
    def classify_accessors(self):
 
 paul@44    501 
 
 paul@44    502 
        "For each program location, classify accessors."
 
 paul@44    503 
 
 paul@44    504 
        # Where instance and module types are defined, class types are also
 
 paul@44    505 
        # defined. See: init_definition_details
 
 paul@44    506 
 
 paul@44    507 
        locations = self.accessor_class_types.keys()
 
 paul@44    508 
 
 paul@44    509 
        for location in locations:
 
 paul@67    510 
            constrained = location in self.accessor_constrained
 
 paul@44    511 
 
 paul@44    512 
            # Provider information.
 
 paul@44    513 
 
 paul@44    514 
            class_types = self.provider_class_types[location]
 
 paul@44    515 
            instance_types = self.provider_instance_types[location]
 
 paul@44    516 
            module_types = self.provider_module_types[location]
 
 paul@44    517 
 
 paul@44    518 
            # Collect specific and general type information.
 
 paul@44    519 
 
 paul@69    520 
            self.provider_all_types[location] = \
 
 paul@57    521 
                combine_types(class_types, instance_types, module_types)
 
 paul@44    522 
 
 paul@44    523 
            # Accessor information.
 
 paul@44    524 
 
 paul@44    525 
            class_types = self.accessor_class_types[location]
 
 paul@44    526 
            self.accessor_general_class_types[location] = \
 
 paul@69    527 
                general_class_types = self.get_most_general_class_types(class_types)
 
 paul@44    528 
 
 paul@44    529 
            instance_types = self.accessor_instance_types[location]
 
 paul@44    530 
            self.accessor_general_instance_types[location] = \
 
 paul@69    531 
                general_instance_types = self.get_most_general_class_types(instance_types)
 
 paul@44    532 
 
 paul@44    533 
            module_types = self.accessor_module_types[location]
 
 paul@44    534 
            self.accessor_general_module_types[location] = \
 
 paul@44    535 
                general_module_types = self.get_most_general_module_types(module_types)
 
 paul@44    536 
 
 paul@44    537 
            # Collect specific and general type information.
 
 paul@44    538 
 
 paul@44    539 
            self.accessor_all_types[location] = all_types = \
 
 paul@57    540 
                combine_types(class_types, instance_types, module_types)
 
 paul@44    541 
 
 paul@44    542 
            self.accessor_all_general_types[location] = all_general_types = \
 
 paul@57    543 
                combine_types(general_class_types, general_instance_types, general_module_types)
 
 paul@44    544 
 
 paul@742    545 
            # Record guard information but only for accessors employed by
 
 paul@742    546 
            # accesses. There are no attribute accesses to guard, otherwise.
 
 paul@742    547 
 
 paul@742    548 
            if not constrained and self.access_index_rev.get(location):
 
 paul@44    549 
 
 paul@816    550 
                # Test for self parameters in methods that could not be
 
 paul@816    551 
                # constrained, potentially due to usage unsupported by the class
 
 paul@816    552 
                # defining the method (such as in mix-in classes).
 
 paul@816    553 
 
 paul@816    554 
                if location.name != "self" or self.in_method(location.path):
 
 paul@816    555 
                    self.record_guard(location, all_types, all_general_types)
 
 paul@816    556 
 
 paul@816    557 
    def record_guard(self, location, all_types, all_general_types):
 
 paul@816    558 
 
 paul@816    559 
        """
 
 paul@816    560 
        For the accessor 'location', record a guard if 'all_types' or
 
 paul@816    561 
        'all_general_types' are appropriate. Where no guard is recorded, access
 
 paul@816    562 
        tests will need to be applied.
 
 paul@816    563 
        """
 
 paul@816    564 
 
 paul@816    565 
        # Record specific type guard details.
 
 paul@816    566 
 
 paul@816    567 
        if len(all_types) == 1:
 
 paul@816    568 
            self.accessor_guard_tests[location] = ("specific", test_label_for_type(first(all_types)))
 
 paul@816    569 
        elif is_single_class_type(all_types):
 
 paul@816    570 
            self.accessor_guard_tests[location] = ("specific", "object")
 
 paul@816    571 
 
 paul@816    572 
        # Record common type guard details.
 
 paul@816    573 
 
 paul@816    574 
        elif len(all_general_types) == 1:
 
 paul@816    575 
            self.accessor_guard_tests[location] = ("common", test_label_for_type(first(all_types)))
 
 paul@816    576 
        elif is_single_class_type(all_general_types):
 
 paul@816    577 
            self.accessor_guard_tests[location] = ("common", "object")
 
 paul@816    578 
 
 paul@816    579 
        # Otherwise, no convenient guard can be defined.
 
 paul@44    580 
 
 paul@44    581 
    def classify_accesses(self):
 
 paul@44    582 
 
 paul@44    583 
        "For each program location, classify accesses."
 
 paul@44    584 
 
 paul@44    585 
        # Attribute accesses use potentially different locations to those of
 
 paul@44    586 
        # accessors.
 
 paul@44    587 
 
 paul@44    588 
        locations = self.referenced_attrs.keys()
 
 paul@44    589 
 
 paul@44    590 
        for location in locations:
 
 paul@44    591 
            constrained = location in self.access_constrained
 
 paul@44    592 
 
 paul@69    593 
            # Combine type information from all accessors supplying the access.
 
 paul@44    594 
 
 paul@44    595 
            accessor_locations = self.get_accessors_for_access(location)
 
 paul@44    596 
 
 paul@44    597 
            all_provider_types = set()
 
 paul@44    598 
            all_accessor_types = set()
 
 paul@44    599 
            all_accessor_general_types = set()
 
 paul@44    600 
 
 paul@44    601 
            for accessor_location in accessor_locations:
 
 paul@44    602 
 
 paul@44    603 
                # Obtain the provider types for guard-related attribute access
 
 paul@44    604 
                # checks.
 
 paul@44    605 
 
 paul@67    606 
                all_provider_types.update(self.provider_all_types.get(accessor_location))
 
 paul@67    607 
 
 paul@67    608 
                # Obtain the accessor guard types (specific and general).
 
 paul@67    609 
 
 paul@67    610 
                all_accessor_types.update(self.accessor_all_types.get(accessor_location))
 
 paul@67    611 
                all_accessor_general_types.update(self.accessor_all_general_types.get(accessor_location))
 
 paul@44    612 
 
 paul@70    613 
            # Obtain basic properties of the types involved in the access.
 
 paul@70    614 
 
 paul@70    615 
            single_accessor_type = len(all_accessor_types) == 1
 
 paul@70    616 
            single_accessor_class_type = is_single_class_type(all_accessor_types)
 
 paul@70    617 
            single_accessor_general_type = len(all_accessor_general_types) == 1
 
 paul@70    618 
            single_accessor_general_class_type = is_single_class_type(all_accessor_general_types)
 
 paul@70    619 
 
 paul@69    620 
            # Determine whether the attribute access is guarded or not.
 
 paul@44    621 
 
 paul@44    622 
            guarded = (
 
 paul@70    623 
                single_accessor_type or single_accessor_class_type or
 
 paul@70    624 
                single_accessor_general_type or single_accessor_general_class_type
 
 paul@44    625 
                )
 
 paul@44    626 
 
 paul@44    627 
            if guarded:
 
 paul@44    628 
                (guard_class_types, guard_instance_types, guard_module_types,
 
 paul@57    629 
                    _function_types, _var_types) = separate_types(all_provider_types)
 
 paul@44    630 
 
 paul@67    631 
            self.reference_all_accessor_types[location] = all_accessor_types
 
 paul@67    632 
            self.reference_all_accessor_general_types[location] = all_accessor_general_types
 
 paul@63    633 
 
 paul@44    634 
            # Attribute information, both name-based and anonymous.
 
 paul@44    635 
 
 paul@44    636 
            referenced_attrs = self.referenced_attrs[location]
 
 paul@44    637 
 
 paul@71    638 
            if not referenced_attrs:
 
 paul@839    639 
                raise DeduceError("In %s, access via %s to attribute %s (occurrence %d) cannot be identified." %
 
 paul@839    640 
                    (location.path, location.name, location.get_attrname(), location.access_number))
 
 paul@71    641 
 
 paul@71    642 
            # Record attribute information for each name used on the
 
 paul@71    643 
            # accessor.
 
 paul@71    644 
 
 paul@791    645 
            attrname = location.get_attrname()
 
 paul@71    646 
 
 paul@843    647 
            self.reference_all_attrs[location] = all_accessed_attrs = set()
 
 paul@843    648 
            self.reference_all_providers[location] = all_providers = set()
 
 paul@687    649 
            self.reference_all_provider_kinds[location] = all_provider_kinds = set()
 
 paul@71    650 
 
 paul@71    651 
            # Obtain provider and attribute details for this kind of
 
 paul@71    652 
            # object.
 
 paul@71    653 
 
 paul@71    654 
            for attrtype, object_type, attr in referenced_attrs:
 
 paul@843    655 
                all_accessed_attrs.add(attr)
 
 paul@843    656 
                all_providers.add(object_type)
 
 paul@687    657 
                all_provider_kinds.add(attrtype)
 
 paul@687    658 
 
 paul@687    659 
            # Obtain reference and provider information as sets for the
 
 paul@687    660 
            # operations below, retaining the list forms for use with
 
 paul@687    661 
            # instruction plan preparation.
 
 paul@687    662 
 
 paul@71    663 
            all_general_providers = self.get_most_general_types(all_providers)
 
 paul@71    664 
 
 paul@71    665 
            # Determine which attributes would be provided by the
 
 paul@71    666 
            # accessor types upheld by a guard.
 
 paul@71    667 
 
 paul@71    668 
            if guarded:
 
 paul@71    669 
                guard_attrs = set()
 
 paul@555    670 
 
 paul@71    671 
                for _attrtype, object_type, attr in \
 
 paul@555    672 
                    self._identify_reference_attribute(location, attrname, guard_class_types, guard_instance_types, guard_module_types):
 
 paul@555    673 
 
 paul@71    674 
                    guard_attrs.add(attr)
 
 paul@71    675 
            else:
 
 paul@71    676 
                guard_attrs = None
 
 paul@71    677 
 
 paul@71    678 
            # Constrained accesses guarantee the nature of the accessor.
 
 paul@71    679 
            # However, there may still be many types involved.
 
 paul@71    680 
 
 paul@71    681 
            if constrained:
 
 paul@71    682 
                if single_accessor_type:
 
 paul@237    683 
                    self.reference_test_types[location] = ("constrained", "specific", test_label_for_type(first(all_accessor_types)))
 
 paul@71    684 
                elif single_accessor_class_type:
 
 paul@237    685 
                    self.reference_test_types[location] = ("constrained", "specific", "object")
 
 paul@71    686 
                elif single_accessor_general_type:
 
 paul@237    687 
                    self.reference_test_types[location] = ("constrained", "common", test_label_for_type(first(all_accessor_general_types)))
 
 paul@71    688 
                elif single_accessor_general_class_type:
 
 paul@237    689 
                    self.reference_test_types[location] = ("constrained", "common", "object")
 
 paul@44    690 
                else:
 
 paul@237    691 
                    self.reference_test_types[location] = ("constrained", "many")
 
 paul@71    692 
 
 paul@71    693 
            # Suitably guarded accesses, where the nature of the
 
 paul@71    694 
            # accessor can be guaranteed, do not require the attribute
 
 paul@71    695 
            # involved to be validated. Otherwise, for unguarded
 
 paul@71    696 
            # accesses, access-level tests are required.
 
 paul@71    697 
 
 paul@71    698 
            elif guarded and all_accessed_attrs.issubset(guard_attrs):
 
 paul@71    699 
                if single_accessor_type:
 
 paul@237    700 
                    self.reference_test_types[location] = ("guarded", "specific", test_label_for_type(first(all_accessor_types)))
 
 paul@71    701 
                elif single_accessor_class_type:
 
 paul@237    702 
                    self.reference_test_types[location] = ("guarded", "specific", "object")
 
 paul@71    703 
                elif single_accessor_general_type:
 
 paul@237    704 
                    self.reference_test_types[location] = ("guarded", "common", test_label_for_type(first(all_accessor_general_types)))
 
 paul@71    705 
                elif single_accessor_general_class_type:
 
 paul@237    706 
                    self.reference_test_types[location] = ("guarded", "common", "object")
 
 paul@71    707 
 
 paul@71    708 
            # Record the need to test the type of anonymous and
 
 paul@71    709 
            # unconstrained accessors.
 
 paul@71    710 
 
 paul@71    711 
            elif len(all_providers) == 1:
 
 paul@71    712 
                provider = first(all_providers)
 
 paul@654    713 
                if provider != self.root_class_type:
 
 paul@71    714 
                    all_accessor_kinds = set(get_kinds(all_accessor_types))
 
 paul@71    715 
                    if len(all_accessor_kinds) == 1:
 
 paul@385    716 
                        test_type = ("test", "specific", test_label_for_kind(first(all_accessor_kinds)))
 
 paul@70    717 
                    else:
 
 paul@237    718 
                        test_type = ("test", "specific", "object")
 
 paul@71    719 
                    self.reference_test_types[location] = test_type
 
 paul@77    720 
                    self.reference_test_accessor_type[location] = provider
 
 paul@71    721 
 
 paul@71    722 
            elif len(all_general_providers) == 1:
 
 paul@71    723 
                provider = first(all_general_providers)
 
 paul@654    724 
                if provider != self.root_class_type:
 
 paul@71    725 
                    all_accessor_kinds = set(get_kinds(all_accessor_general_types))
 
 paul@71    726 
                    if len(all_accessor_kinds) == 1:
 
 paul@385    727 
                        test_type = ("test", "common", test_label_for_kind(first(all_accessor_kinds)))
 
 paul@71    728 
                    else:
 
 paul@237    729 
                        test_type = ("test", "common", "object")
 
 paul@71    730 
                    self.reference_test_types[location] = test_type
 
 paul@77    731 
                    self.reference_test_accessor_type[location] = provider
 
 paul@71    732 
 
 paul@71    733 
            # Record the need to test the identity of the attribute.
 
 paul@71    734 
 
 paul@71    735 
            else:
 
 paul@237    736 
                self.reference_test_types[location] = ("validate",)
 
 paul@44    737 
 
 paul@67    738 
    def initialise_access_plans(self):
 
 paul@67    739 
 
 paul@67    740 
        "Define attribute access plans."
 
 paul@67    741 
 
 paul@67    742 
        for location in self.referenced_attrs.keys():
 
 paul@76    743 
            original_location = self.const_accesses_rev.get(location)
 
 paul@76    744 
            self.access_plans[original_location or location] = self.get_access_plan(location)
 
 paul@67    745 
 
 paul@411    746 
    def identify_dependencies(self):
 
 paul@411    747 
 
 paul@411    748 
        "Introduce more module dependencies to the importer."
 
 paul@411    749 
 
 paul@411    750 
        for location, referenced_attrs in self.referenced_attrs.items():
 
 paul@411    751 
 
 paul@418    752 
            # Identify references providing dependencies.
 
 paul@411    753 
 
 paul@411    754 
            for attrtype, objtype, attr in referenced_attrs:
 
 paul@791    755 
                self.importer.add_dependency(location.path, attr.get_origin())
 
 paul@411    756 
 
 paul@44    757 
    def get_referenced_attrs(self, location):
 
 paul@44    758 
 
 paul@44    759 
        """
 
 paul@44    760 
        Return attributes referenced at the given access 'location' by the given
 
 paul@44    761 
        'attrname' as a list of (attribute type, attribute set) tuples.
 
 paul@44    762 
        """
 
 paul@44    763 
 
 paul@69    764 
        d = {}
 
 paul@69    765 
        for attrtype, objtype, attr in self.referenced_attrs[location]:
 
 paul@69    766 
            init_item(d, attrtype, set)
 
 paul@246    767 
            d[attrtype].add(attr.unaliased())
 
 paul@69    768 
        l = d.items()
 
 paul@69    769 
        l.sort() # class, module, instance
 
 paul@44    770 
        return l
 
 paul@44    771 
 
 paul@44    772 
    # Initialisation methods.
 
 paul@44    773 
 
 paul@44    774 
    def init_descendants(self):
 
 paul@44    775 
 
 paul@44    776 
        "Identify descendants of each class."
 
 paul@44    777 
 
 paul@44    778 
        for name in self.importer.classes.keys():
 
 paul@44    779 
            self.get_descendants_for_class(name)
 
 paul@44    780 
 
 paul@44    781 
    def get_descendants_for_class(self, name):
 
 paul@44    782 
 
 paul@44    783 
        """
 
 paul@44    784 
        Use subclass information to deduce the descendants for the class of the
 
 paul@44    785 
        given 'name'.
 
 paul@44    786 
        """
 
 paul@44    787 
 
 paul@44    788 
        if not self.descendants.has_key(name):
 
 paul@44    789 
            descendants = set()
 
 paul@44    790 
 
 paul@44    791 
            for subclass in self.importer.subclasses[name]:
 
 paul@44    792 
                descendants.update(self.get_descendants_for_class(subclass))
 
 paul@44    793 
                descendants.add(subclass)
 
 paul@44    794 
 
 paul@44    795 
            self.descendants[name] = descendants
 
 paul@44    796 
 
 paul@44    797 
        return self.descendants[name]
 
 paul@44    798 
 
 paul@44    799 
    def init_special_attributes(self):
 
 paul@44    800 
 
 paul@44    801 
        "Add special attributes to the classes for inheritance-related tests."
 
 paul@44    802 
 
 paul@44    803 
        all_class_attrs = self.importer.all_class_attrs
 
 paul@44    804 
 
 paul@44    805 
        for name, descendants in self.descendants.items():
 
 paul@44    806 
            for descendant in descendants:
 
 paul@44    807 
                all_class_attrs[descendant]["#%s" % name] = name
 
 paul@44    808 
 
 paul@44    809 
        for name in all_class_attrs.keys():
 
 paul@44    810 
            all_class_attrs[name]["#%s" % name] = name
 
 paul@44    811 
 
 paul@44    812 
    def init_usage_index(self):
 
 paul@44    813 
 
 paul@44    814 
        """
 
 paul@44    815 
        Create indexes for module and function attribute usage and for anonymous
 
 paul@44    816 
        accesses.
 
 paul@44    817 
        """
 
 paul@44    818 
 
 paul@44    819 
        for module in self.importer.get_modules():
 
 paul@44    820 
            for path, assignments in module.attr_usage.items():
 
 paul@44    821 
                self.add_usage(assignments, path)
 
 paul@44    822 
 
 paul@791    823 
        for path, all_attrnames in self.importer.all_attr_accesses.items():
 
 paul@44    824 
            for attrnames in all_attrnames:
 
 paul@44    825 
                attrname = get_attrnames(attrnames)[-1]
 
 paul@791    826 
                access_location = AccessLocation(path, None, attrnames, 0)
 
 paul@107    827 
                self.add_usage_term(access_location, ((attrname, False, False),))
 
 paul@44    828 
 
 paul@44    829 
    def add_usage(self, assignments, path):
 
 paul@44    830 
 
 paul@44    831 
        """
 
 paul@44    832 
        Collect usage from the given 'assignments', adding 'path' details to
 
 paul@44    833 
        each record if specified. Add the usage to an index mapping to location
 
 paul@44    834 
        information, as well as to an index mapping locations to usages.
 
 paul@44    835 
        """
 
 paul@44    836 
 
 paul@44    837 
        for name, versions in assignments.items():
 
 paul@44    838 
            for i, usages in enumerate(versions):
 
 paul@791    839 
                location = Location(path, name, None, i)
 
 paul@44    840 
 
 paul@88    841 
                for usage in usages:
 
 paul@88    842 
                    self.add_usage_term(location, usage)
 
 paul@88    843 
 
 paul@88    844 
    def add_usage_term(self, location, usage):
 
 paul@44    845 
 
 paul@44    846 
        """
 
 paul@88    847 
        For 'location' and using 'usage' as a description of usage, record
 
 paul@44    848 
        in the usage index a mapping from the usage to 'location', and record in
 
 paul@44    849 
        the location index a mapping from 'location' to the usage.
 
 paul@44    850 
        """
 
 paul@44    851 
 
 paul@44    852 
        init_item(self.location_index, location, set)
 
 paul@88    853 
        self.location_index[location].add(usage)
 
 paul@44    854 
 
 paul@44    855 
    def init_accessors(self):
 
 paul@44    856 
 
 paul@44    857 
        "Create indexes for module and function accessor information."
 
 paul@44    858 
 
 paul@44    859 
        for module in self.importer.get_modules():
 
 paul@44    860 
            for path, all_accesses in module.attr_accessors.items():
 
 paul@44    861 
                self.add_accessors(all_accesses, path)
 
 paul@44    862 
 
 paul@44    863 
    def add_accessors(self, all_accesses, path):
 
 paul@44    864 
 
 paul@44    865 
        """
 
 paul@44    866 
        For attribute accesses described by the mapping of 'all_accesses' from
 
 paul@44    867 
        name details to accessor details, record the locations of the accessors
 
 paul@44    868 
        for each access.
 
 paul@44    869 
        """
 
 paul@44    870 
 
 paul@44    871 
        # Get details for each access combining the given name and attribute.
 
 paul@44    872 
 
 paul@44    873 
        for (name, attrnames), accesses in all_accesses.items():
 
 paul@44    874 
 
 paul@44    875 
            # Obtain the usage details using the access information.
 
 paul@44    876 
 
 paul@44    877 
            for access_number, versions in enumerate(accesses):
 
 paul@791    878 
                access_location = AccessLocation(path, name, attrnames, access_number)
 
 paul@44    879 
                locations = []
 
 paul@44    880 
 
 paul@44    881 
                for version in versions:
 
 paul@791    882 
                    location = Location(path, name, None, version)
 
 paul@44    883 
                    locations.append(location)
 
 paul@44    884 
 
 paul@742    885 
                    # Map accessors to affected accesses.
 
 paul@742    886 
 
 paul@742    887 
                    l = init_item(self.access_index_rev, location, set)
 
 paul@742    888 
                    l.add(access_location)
 
 paul@742    889 
 
 paul@742    890 
                # Map accesses to supplying accessors.
 
 paul@742    891 
 
 paul@44    892 
                self.access_index[access_location] = locations
 
 paul@44    893 
 
 paul@44    894 
    def get_accessors_for_access(self, access_location):
 
 paul@44    895 
 
 paul@44    896 
        "Find a definition providing accessor details, if necessary."
 
 paul@44    897 
 
 paul@44    898 
        try:
 
 paul@44    899 
            return self.access_index[access_location]
 
 paul@44    900 
        except KeyError:
 
 paul@44    901 
            return [access_location]
 
 paul@44    902 
 
 paul@44    903 
    def init_accesses(self):
 
 paul@44    904 
 
 paul@44    905 
        """
 
 paul@501    906 
        Check that attributes used in accesses are actually defined on some
 
 paul@501    907 
        object. This can be overlooked if unknown attributes are employed in
 
 paul@501    908 
        attribute chains.
 
 paul@501    909 
 
 paul@44    910 
        Initialise collections for accesses involving assignments.
 
 paul@44    911 
        """
 
 paul@44    912 
 
 paul@44    913 
        # For each scope, obtain access details.
 
 paul@44    914 
 
 paul@44    915 
        for path, all_accesses in self.importer.all_attr_access_modifiers.items():
 
 paul@44    916 
 
 paul@44    917 
            # For each combination of name and attribute names, obtain
 
 paul@44    918 
            # applicable modifiers.
 
 paul@44    919 
 
 paul@112    920 
            for (name, attrname_str), modifiers in all_accesses.items():
 
 paul@44    921 
 
 paul@44    922 
                # For each access, determine the name versions affected by
 
 paul@44    923 
                # assignments.
 
 paul@44    924 
 
 paul@117    925 
                for access_number, (assignment, invocation) in enumerate(modifiers):
 
 paul@112    926 
 
 paul@44    927 
                    if name:
 
 paul@791    928 
                        access_location = AccessLocation(path, name, attrname_str, access_number)
 
 paul@44    929 
                    else:
 
 paul@791    930 
                        access_location = AccessLocation(path, None, attrname_str, 0)
 
 paul@112    931 
 
 paul@501    932 
                    # Plain name accesses do not employ attributes and are
 
 paul@717    933 
                    # ignored. Whether they are invoked is of interest, however.
 
 paul@501    934 
 
 paul@502    935 
                    if not attrname_str:
 
 paul@717    936 
                        if invocation:
 
 paul@717    937 
                            self.reference_invocations[access_location] = invocation
 
 paul@501    938 
                        continue
 
 paul@501    939 
 
 paul@501    940 
                    attrnames = get_attrnames(attrname_str)
 
 paul@501    941 
 
 paul@501    942 
                    # Check the attribute names.
 
 paul@501    943 
 
 paul@501    944 
                    for attrname in attrnames:
 
 paul@501    945 
                        if not attrname in self.all_attrnames:
 
 paul@501    946 
                            raise DeduceError("In %s, attribute %s is not defined in the program." % (path, attrname))
 
 paul@501    947 
 
 paul@501    948 
                    # Now only process assignments and invocations.
 
 paul@501    949 
 
 paul@117    950 
                    if invocation:
 
 paul@553    951 
                        self.reference_invocations[access_location] = invocation
 
 paul@117    952 
                        continue
 
 paul@501    953 
                    elif not assignment:
 
 paul@501    954 
                        continue
 
 paul@501    955 
 
 paul@501    956 
                    # Associate assignments with usage.
 
 paul@117    957 
 
 paul@112    958 
                    self.reference_assignments.add(access_location)
 
 paul@71    959 
 
 paul@112    960 
                    # Assignment occurs for the only attribute.
 
 paul@112    961 
 
 paul@112    962 
                    if len(attrnames) == 1:
 
 paul@112    963 
                        accessor_locations = self.get_accessors_for_access(access_location)
 
 paul@112    964 
 
 paul@112    965 
                        for location in accessor_locations:
 
 paul@112    966 
                            for usage in self.location_index[location]:
 
 paul@88    967 
                                init_item(self.assigned_attrs, usage, set)
 
 paul@112    968 
                                self.assigned_attrs[usage].add((path, name, attrnames[0]))
 
 paul@112    969 
 
 paul@112    970 
                    # Assignment occurs for the final attribute.
 
 paul@112    971 
 
 paul@112    972 
                    else:
 
 paul@112    973 
                        usage = ((attrnames[-1], False, False),)
 
 paul@112    974 
                        init_item(self.assigned_attrs, usage, set)
 
 paul@112    975 
                        self.assigned_attrs[usage].add((path, name, attrnames[-1]))
 
 paul@44    976 
 
 paul@44    977 
    def init_aliases(self):
 
 paul@44    978 
 
 paul@44    979 
        "Expand aliases so that alias-based accesses can be resolved."
 
 paul@44    980 
 
 paul@44    981 
        # Get aliased names with details of their accesses.
 
 paul@44    982 
 
 paul@681    983 
        for (path, name), all_aliases in self.importer.all_aliased_names.items():
 
 paul@44    984 
 
 paul@742    985 
            # For each version of the name, obtain the access locations.
 
 paul@742    986 
 
 paul@742    987 
            for version, aliases in all_aliases.items():
 
 paul@742    988 
                for (original_path, original_name, attrnames, access_number) in aliases:
 
 paul@791    989 
                    accessor_location = Location(path, name, None, version)
 
 paul@791    990 
                    access_location = AccessLocation(original_path, original_name, attrnames, access_number)
 
 paul@742    991 
                    init_item(self.alias_index, accessor_location, list)
 
 paul@742    992 
                    self.alias_index[accessor_location].append(access_location)
 
 paul@44    993 
 
 paul@791    994 
        # Get initialised name information for accessors and accesses.
 
 paul@791    995 
 
 paul@791    996 
        for (path, name), versions in self.importer.all_initialised_names.items():
 
 paul@791    997 
            for version, ref in versions.items():
 
 paul@791    998 
                location = Location(path, name, None, version)
 
 paul@791    999 
 
 paul@791   1000 
                self.initialised_names[location] = ref
 
 paul@791   1001 
 
 paul@791   1002 
                access_locations = self.access_index_rev.get(location)
 
 paul@791   1003 
                if access_locations:
 
 paul@791   1004 
                    for access_location in access_locations:
 
 paul@791   1005 
                        init_item(self.initialised_accesses, access_location, set)
 
 paul@791   1006 
                        self.initialised_accesses[access_location].add(ref)
 
 paul@44   1007 
 
 paul@742   1008 
        # Get a mapping from accesses to affected aliases.
 
 paul@735   1009 
 
 paul@735   1010 
        for accessor_location, access_locations in self.alias_index.items():
 
 paul@735   1011 
            for access_location in access_locations:
 
 paul@735   1012 
                init_item(self.alias_index_rev, access_location, set)
 
 paul@735   1013 
                self.alias_index_rev[access_location].add(accessor_location)
 
 paul@735   1014 
 
 paul@44   1015 
    # Attribute mutation for types.
 
 paul@44   1016 
 
 paul@44   1017 
    def modify_mutated_attributes(self):
 
 paul@44   1018 
 
 paul@44   1019 
        "Identify known, mutated attributes and change their state."
 
 paul@44   1020 
 
 paul@44   1021 
        # Usage-based accesses.
 
 paul@44   1022 
 
 paul@44   1023 
        for usage, all_attrnames in self.assigned_attrs.items():
 
 paul@44   1024 
            if not usage:
 
 paul@44   1025 
                continue
 
 paul@44   1026 
 
 paul@112   1027 
            for path, name, attrname in all_attrnames:
 
 paul@44   1028 
                class_types = self.get_class_types_for_usage(usage)
 
 paul@44   1029 
                only_instance_types = set(self.get_instance_types_for_usage(usage)).difference(class_types)
 
 paul@44   1030 
                module_types = self.get_module_types_for_usage(usage)
 
 paul@44   1031 
 
 paul@44   1032 
                # Detect self usage within methods in order to narrow the scope
 
 paul@44   1033 
                # of the mutation.
 
 paul@44   1034 
 
 paul@44   1035 
                t = name == "self" and self.constrain_self_reference(path, class_types, only_instance_types)
 
 paul@44   1036 
                if t:
 
 paul@44   1037 
                    class_types, only_instance_types, module_types, constrained = t
 
 paul@44   1038 
                objects = set(class_types).union(only_instance_types).union(module_types)
 
 paul@44   1039 
 
 paul@112   1040 
                self.mutate_attribute(objects, attrname)
 
 paul@112   1041 
 
 paul@112   1042 
    def mutate_attribute(self, objects, attrname):
 
 paul@112   1043 
 
 paul@112   1044 
        "Mutate static 'objects' with the given 'attrname'."
 
 paul@44   1045 
 
 paul@44   1046 
        for name in objects:
 
 paul@112   1047 
            attr = "%s.%s" % (name, attrname)
 
 paul@44   1048 
            value = self.importer.get_object(attr)
 
 paul@44   1049 
 
 paul@44   1050 
            # If the value is None, the attribute is
 
 paul@44   1051 
            # inherited and need not be set explicitly on
 
 paul@44   1052 
            # the class concerned.
 
 paul@44   1053 
 
 paul@44   1054 
            if value:
 
 paul@44   1055 
                self.modified_attributes[attr] = value
 
 paul@44   1056 
                self.importer.set_object(attr, value.as_var())
 
 paul@44   1057 
 
 paul@44   1058 
    # Simplification of types.
 
 paul@44   1059 
 
 paul@69   1060 
    def get_most_general_types(self, types):
 
 paul@69   1061 
 
 paul@69   1062 
        "Return the most general types for the given 'types'."
 
 paul@69   1063 
 
 paul@69   1064 
        module_types = set()
 
 paul@69   1065 
        class_types = set()
 
 paul@69   1066 
 
 paul@69   1067 
        for type in types:
 
 paul@69   1068 
            ref = self.importer.identify(type)
 
 paul@69   1069 
            if ref.has_kind("<module>"):
 
 paul@69   1070 
                module_types.add(type)
 
 paul@69   1071 
            else:
 
 paul@69   1072 
                class_types.add(type)
 
 paul@69   1073 
 
 paul@69   1074 
        types = set(self.get_most_general_module_types(module_types))
 
 paul@69   1075 
        types.update(self.get_most_general_class_types(class_types))
 
 paul@69   1076 
        return types
 
 paul@69   1077 
 
 paul@69   1078 
    def get_most_general_class_types(self, class_types):
 
 paul@44   1079 
 
 paul@44   1080 
        "Return the most general types for the given 'class_types'."
 
 paul@44   1081 
 
 paul@44   1082 
        class_types = set(class_types)
 
 paul@44   1083 
        to_remove = set()
 
 paul@44   1084 
 
 paul@44   1085 
        for class_type in class_types:
 
 paul@44   1086 
            for base in self.importer.classes[class_type]:
 
 paul@44   1087 
                base = base.get_origin()
 
 paul@44   1088 
                descendants = self.descendants[base]
 
 paul@44   1089 
                if base in class_types and descendants.issubset(class_types):
 
 paul@44   1090 
                    to_remove.update(descendants)
 
 paul@44   1091 
 
 paul@44   1092 
        class_types.difference_update(to_remove)
 
 paul@44   1093 
        return class_types
 
 paul@44   1094 
 
 paul@44   1095 
    def get_most_general_module_types(self, module_types):
 
 paul@44   1096 
 
 paul@44   1097 
        "Return the most general type for the given 'module_types'."
 
 paul@44   1098 
 
 paul@44   1099 
        # Where all modules are provided, an object would provide the same
 
 paul@44   1100 
        # attributes.
 
 paul@44   1101 
 
 paul@44   1102 
        if len(module_types) == len(self.importer.modules):
 
 paul@654   1103 
            return [self.root_class_type]
 
 paul@44   1104 
        else:
 
 paul@44   1105 
            return module_types
 
 paul@44   1106 
 
 paul@44   1107 
    # More efficient usage-to-type indexing and retrieval.
 
 paul@44   1108 
 
 paul@44   1109 
    def init_attr_type_indexes(self):
 
 paul@44   1110 
 
 paul@44   1111 
        "Identify the types that can support each attribute name."
 
 paul@44   1112 
 
 paul@44   1113 
        self._init_attr_type_index(self.attr_class_types, self.importer.all_class_attrs)
 
 paul@107   1114 
        self._init_attr_type_index(self.attr_instance_types, self.importer.all_instance_attrs, True)
 
 paul@107   1115 
        self._init_attr_type_index(self.attr_instance_types, self.importer.all_combined_attrs, False)
 
 paul@44   1116 
        self._init_attr_type_index(self.attr_module_types, self.importer.all_module_attrs)
 
 paul@44   1117 
 
 paul@107   1118 
    def _init_attr_type_index(self, attr_types, attrs, assignment=None):
 
 paul@44   1119 
 
 paul@44   1120 
        """
 
 paul@44   1121 
        Initialise the 'attr_types' attribute-to-types mapping using the given
 
 paul@44   1122 
        'attrs' type-to-attributes mapping.
 
 paul@44   1123 
        """
 
 paul@44   1124 
 
 paul@44   1125 
        for name, attrnames in attrs.items():
 
 paul@44   1126 
            for attrname in attrnames:
 
 paul@107   1127 
 
 paul@107   1128 
                # Permit general access for certain kinds of object.
 
 paul@107   1129 
 
 paul@107   1130 
                if assignment is None:
 
 paul@107   1131 
                    init_item(attr_types, (attrname, False), set)
 
 paul@107   1132 
                    init_item(attr_types, (attrname, True), set)
 
 paul@107   1133 
                    attr_types[(attrname, False)].add(name)
 
 paul@107   1134 
                    attr_types[(attrname, True)].add(name)
 
 paul@107   1135 
 
 paul@107   1136 
                # Restrict attribute assignment for instances.
 
 paul@107   1137 
 
 paul@107   1138 
                else:
 
 paul@107   1139 
                    init_item(attr_types, (attrname, assignment), set)
 
 paul@107   1140 
                    attr_types[(attrname, assignment)].add(name)
 
 paul@44   1141 
 
 paul@88   1142 
    def get_class_types_for_usage(self, usage):
 
 paul@88   1143 
 
 paul@88   1144 
        "Return names of classes supporting the given 'usage'."
 
 paul@88   1145 
 
 paul@88   1146 
        return self._get_types_for_usage(usage, self.attr_class_types, self.importer.all_class_attrs)
 
 paul@88   1147 
 
 paul@88   1148 
    def get_instance_types_for_usage(self, usage):
 
 paul@44   1149 
 
 paul@44   1150 
        """
 
 paul@88   1151 
        Return names of classes whose instances support the given 'usage'
 
 paul@44   1152 
        (as either class or instance attributes).
 
 paul@44   1153 
        """
 
 paul@44   1154 
 
 paul@88   1155 
        return self._get_types_for_usage(usage, self.attr_instance_types, self.importer.all_combined_attrs)
 
 paul@88   1156 
 
 paul@88   1157 
    def get_module_types_for_usage(self, usage):
 
 paul@88   1158 
 
 paul@88   1159 
        "Return names of modules supporting the given 'usage'."
 
 paul@88   1160 
 
 paul@88   1161 
        return self._get_types_for_usage(usage, self.attr_module_types, self.importer.all_module_attrs)
 
 paul@88   1162 
 
 paul@88   1163 
    def _get_types_for_usage(self, usage, attr_types, attrs):
 
 paul@44   1164 
 
 paul@44   1165 
        """
 
 paul@88   1166 
        For the given 'usage' representing attribute usage, return types
 
 paul@44   1167 
        recorded in the 'attr_types' attribute-to-types mapping that support
 
 paul@44   1168 
        such usage, with the given 'attrs' type-to-attributes mapping used to
 
 paul@44   1169 
        quickly assess whether a type supports all of the stated attributes.
 
 paul@44   1170 
        """
 
 paul@44   1171 
 
 paul@44   1172 
        # Where no attributes are used, any type would be acceptable.
 
 paul@44   1173 
 
 paul@88   1174 
        if not usage:
 
 paul@44   1175 
            return attrs.keys()
 
 paul@44   1176 
 
 paul@107   1177 
        keys = []
 
 paul@107   1178 
        for attrname, invocation, assignment in usage:
 
 paul@107   1179 
            keys.append((attrname, assignment))
 
 paul@107   1180 
 
 paul@107   1181 
        # Obtain types supporting the first (attribute name, assignment) key...
 
 paul@107   1182 
 
 paul@107   1183 
        types = set(attr_types.get(keys[0]) or [])
 
 paul@107   1184 
 
 paul@107   1185 
        for key in keys[1:]:
 
 paul@107   1186 
            
 
 paul@44   1187 
            # Record types that support all of the other attributes as well.
 
 paul@44   1188 
 
 paul@107   1189 
            types.intersection_update(attr_types.get(key) or [])
 
 paul@44   1190 
 
 paul@44   1191 
        return types
 
 paul@44   1192 
 
 paul@501   1193 
    def init_combined_attribute_index(self):
 
 paul@501   1194 
 
 paul@501   1195 
        "Initialise a combined index for the detection of invalid attributes."
 
 paul@501   1196 
 
 paul@501   1197 
        self.all_attrnames = set()
 
 paul@501   1198 
        for attrs in (self.importer.all_combined_attrs, self.importer.all_module_attrs):
 
 paul@501   1199 
            for name, attrnames in attrs.items():
 
 paul@501   1200 
                self.all_attrnames.update(attrnames)
 
 paul@501   1201 
 
 paul@44   1202 
    # Reference identification.
 
 paul@44   1203 
 
 paul@44   1204 
    def identify_references(self):
 
 paul@44   1205 
 
 paul@44   1206 
        "Identify references using usage and name reference information."
 
 paul@44   1207 
 
 paul@44   1208 
        # Names with associated attribute usage.
 
 paul@44   1209 
 
 paul@44   1210 
        for location, usages in self.location_index.items():
 
 paul@44   1211 
 
 paul@44   1212 
            # Obtain attribute usage associated with a name, deducing the nature
 
 paul@44   1213 
            # of the name. Obtain types only for branches involving attribute
 
 paul@44   1214 
            # usage. (In the absence of usage, any type could be involved, but
 
 paul@44   1215 
            # then no accesses exist to require knowledge of the type.)
 
 paul@44   1216 
 
 paul@44   1217 
            have_usage = False
 
 paul@44   1218 
            have_no_usage_branch = False
 
 paul@44   1219 
 
 paul@44   1220 
            for usage in usages:
 
 paul@44   1221 
                if not usage:
 
 paul@44   1222 
                    have_no_usage_branch = True
 
 paul@44   1223 
                    continue
 
 paul@44   1224 
                elif not have_usage:
 
 paul@44   1225 
                    self.init_definition_details(location)
 
 paul@44   1226 
                    have_usage = True
 
 paul@44   1227 
                self.record_types_for_usage(location, usage)
 
 paul@44   1228 
 
 paul@44   1229 
            # Where some usage occurs, but where branches without usage also
 
 paul@44   1230 
            # occur, record the types for those branches anyway.
 
 paul@44   1231 
 
 paul@44   1232 
            if have_usage and have_no_usage_branch:
 
 paul@44   1233 
                self.init_definition_details(location)
 
 paul@44   1234 
                self.record_types_for_usage(location, None)
 
 paul@44   1235 
 
 paul@44   1236 
        # Specific name-based attribute accesses.
 
 paul@44   1237 
 
 paul@44   1238 
        for access_location, accessor_locations in self.access_index.items():
 
 paul@742   1239 
            self.record_types_for_access(access_location, accessor_locations)
 
 paul@44   1240 
 
 paul@44   1241 
        # Anonymous references with attribute chains.
 
 paul@44   1242 
 
 paul@791   1243 
        for path, accesses in self.importer.all_attr_accesses.items():
 
 paul@44   1244 
 
 paul@44   1245 
            # Get distinct attribute names.
 
 paul@44   1246 
 
 paul@44   1247 
            all_attrnames = set()
 
 paul@44   1248 
 
 paul@44   1249 
            for attrnames in accesses:
 
 paul@44   1250 
                all_attrnames.update(get_attrnames(attrnames))
 
 paul@44   1251 
 
 paul@44   1252 
            # Get attribute and accessor details for each attribute name.
 
 paul@44   1253 
 
 paul@44   1254 
            for attrname in all_attrnames:
 
 paul@791   1255 
                access_location = AccessLocation(path, None, attrname, 0)
 
 paul@44   1256 
                self.record_types_for_attribute(access_location, attrname)
 
 paul@44   1257 
 
 paul@44   1258 
        # References via constant/identified objects.
 
 paul@44   1259 
 
 paul@791   1260 
        for path, name_accesses in self.importer.all_const_accesses.items():
 
 paul@44   1261 
 
 paul@44   1262 
            # A mapping from the original name and attributes to resolved access
 
 paul@44   1263 
            # details.
 
 paul@44   1264 
 
 paul@44   1265 
            for original_access, access in name_accesses.items():
 
 paul@44   1266 
                original_name, original_attrnames = original_access
 
 paul@44   1267 
                objpath, ref, attrnames = access
 
 paul@44   1268 
 
 paul@44   1269 
                # Build an accessor combining the name and attribute names used.
 
 paul@44   1270 
 
 paul@44   1271 
                original_accessor = tuple([original_name] + original_attrnames.split("."))
 
 paul@44   1272 
 
 paul@44   1273 
                # Direct accesses to attributes.
 
 paul@44   1274 
 
 paul@44   1275 
                if not attrnames:
 
 paul@44   1276 
 
 paul@44   1277 
                    # Build a descriptive location based on the original
 
 paul@44   1278 
                    # details, exposing the final attribute name.
 
 paul@44   1279 
 
 paul@44   1280 
                    oa, attrname = original_accessor[:-1], original_accessor[-1]
 
 paul@44   1281 
                    oa = ".".join(oa)
 
 paul@44   1282 
 
 paul@791   1283 
                    access_location = AccessLocation(path, oa, attrname, 0)
 
 paul@791   1284 
                    accessor_location = Location(path, oa, None, 0)
 
 paul@44   1285 
                    self.access_index[access_location] = [accessor_location]
 
 paul@44   1286 
 
 paul@44   1287 
                    self.init_access_details(access_location)
 
 paul@44   1288 
                    self.init_definition_details(accessor_location)
 
 paul@44   1289 
 
 paul@44   1290 
                    # Obtain a reference for the accessor in order to properly
 
 paul@44   1291 
                    # determine its type.
 
 paul@44   1292 
 
 paul@44   1293 
                    if ref.get_kind() != "<instance>":
 
 paul@44   1294 
                        objpath = ref.get_origin()
 
 paul@44   1295 
 
 paul@44   1296 
                    objpath = objpath.rsplit(".", 1)[0]
 
 paul@44   1297 
 
 paul@44   1298 
                    # Where the object name conflicts with the module
 
 paul@44   1299 
                    # providing it, obtain the module details.
 
 paul@44   1300 
 
 paul@44   1301 
                    if objpath in self.importer.modules:
 
 paul@44   1302 
                        accessor = Reference("<module>", objpath)
 
 paul@44   1303 
                    else:
 
 paul@44   1304 
                        accessor = self.importer.get_object(objpath)
 
 paul@44   1305 
 
 paul@44   1306 
                    self.referenced_attrs[access_location] = [(accessor.get_kind(), accessor.get_origin(), ref)]
 
 paul@44   1307 
                    self.access_constrained.add(access_location)
 
 paul@44   1308 
 
 paul@57   1309 
                    class_types, instance_types, module_types = accessor.get_types()
 
 paul@44   1310 
                    self.record_reference_types(accessor_location, class_types, instance_types, module_types, True, True)
 
 paul@64   1311 
 
 paul@64   1312 
                else:
 
 paul@44   1313 
 
 paul@64   1314 
                    # Build a descriptive location based on the original
 
 paul@64   1315 
                    # details, employing the first remaining attribute name.
 
 paul@64   1316 
 
 paul@64   1317 
                    l = get_attrnames(attrnames)
 
 paul@64   1318 
                    attrname = l[0]
 
 paul@44   1319 
 
 paul@64   1320 
                    oa = original_accessor[:-len(l)]
 
 paul@64   1321 
                    oa = ".".join(oa)
 
 paul@44   1322 
 
 paul@791   1323 
                    access_location = AccessLocation(path, oa, attrnames, 0)
 
 paul@791   1324 
                    accessor_location = Location(path, oa, None, 0)
 
 paul@64   1325 
                    self.access_index[access_location] = [accessor_location]
 
 paul@64   1326 
 
 paul@64   1327 
                    self.init_access_details(access_location)
 
 paul@64   1328 
                    self.init_definition_details(accessor_location)
 
 paul@44   1329 
 
 paul@64   1330 
                    class_types, instance_types, module_types = ref.get_types()
 
 paul@64   1331 
 
 paul@64   1332 
                    self.identify_reference_attributes(access_location, attrname, class_types, instance_types, module_types, True)
 
 paul@64   1333 
                    self.record_reference_types(accessor_location, class_types, instance_types, module_types, True, True)
 
 paul@64   1334 
 
 paul@679   1335 
                # Define mappings between the original and access locations
 
 paul@679   1336 
                # so that translation can work from the source details.
 
 paul@679   1337 
 
 paul@791   1338 
                original_location = AccessLocation(path, original_name, original_attrnames, 0)
 
 paul@64   1339 
 
 paul@64   1340 
                if original_location != access_location:
 
 paul@64   1341 
                    self.const_accesses[original_location] = access_location
 
 paul@67   1342 
                    self.const_accesses_rev[access_location] = original_location
 
 paul@44   1343 
 
 paul@735   1344 
        # Propagate alias-related information.
 
 paul@735   1345 
 
 paul@735   1346 
        affected_aliases = set(self.alias_index.keys())
 
 paul@735   1347 
 
 paul@735   1348 
        while True:
 
 paul@735   1349 
 
 paul@735   1350 
            # Aliased name definitions. All aliases with usage will have been
 
 paul@735   1351 
            # defined, but they may be refined according to referenced accesses.
 
 paul@735   1352 
 
 paul@735   1353 
            updated_aliases = set()
 
 paul@735   1354 
 
 paul@735   1355 
            for location in affected_aliases:
 
 paul@735   1356 
                if self.record_types_for_alias(location):
 
 paul@735   1357 
                    updated_aliases.add(location)
 
 paul@735   1358 
 
 paul@742   1359 
            # Define accesses employing aliases.
 
 paul@742   1360 
 
 paul@742   1361 
            alias_accesses = set()
 
 paul@742   1362 
            affected_aliases = set()
 
 paul@742   1363 
 
 paul@742   1364 
            for alias in updated_aliases:
 
 paul@742   1365 
 
 paul@742   1366 
                # Access affected by the alias.
 
 paul@742   1367 
 
 paul@742   1368 
                if self.access_index_rev.has_key(alias):
 
 paul@742   1369 
                    alias_accesses.update(self.access_index_rev[alias])
 
 paul@742   1370 
 
 paul@742   1371 
                # Another alias affected by the alias.
 
 paul@742   1372 
 
 paul@742   1373 
                elif self.alias_index_rev.has_key(alias):
 
 paul@742   1374 
                    affected_aliases.update(self.alias_index_rev[alias])
 
 paul@742   1375 
 
 paul@735   1376 
            # Update accesses employing aliases.
 
 paul@735   1377 
 
 paul@735   1378 
            updated_accesses = set()
 
 paul@735   1379 
 
 paul@735   1380 
            for access_location in alias_accesses:
 
 paul@735   1381 
                if self.record_types_for_access(access_location, self.access_index[access_location]):
 
 paul@735   1382 
                    updated_accesses.add(access_location)
 
 paul@735   1383 
 
 paul@742   1384 
            # Determine which aliases are affected by the updated accesses.
 
 paul@735   1385 
 
 paul@735   1386 
            for access_location in updated_accesses:
 
 paul@735   1387 
                if self.alias_index_rev.has_key(access_location):
 
 paul@735   1388 
                    affected_aliases.update(self.alias_index_rev[access_location])
 
 paul@735   1389 
 
 paul@735   1390 
            if not affected_aliases:
 
 paul@735   1391 
                break
 
 paul@44   1392 
 
 paul@44   1393 
    def constrain_types(self, path, class_types, instance_types, module_types):
 
 paul@44   1394 
 
 paul@44   1395 
        """
 
 paul@44   1396 
        Using the given 'path' to an object, constrain the given 'class_types',
 
 paul@44   1397 
        'instance_types' and 'module_types'.
 
 paul@44   1398 
 
 paul@44   1399 
        Return the class, instance, module types plus whether the types are
 
 paul@44   1400 
        constrained to a specific kind of type.
 
 paul@44   1401 
        """
 
 paul@44   1402 
 
 paul@44   1403 
        ref = self.importer.identify(path)
 
 paul@44   1404 
        if ref:
 
 paul@44   1405 
 
 paul@44   1406 
            # Constrain usage suggestions using the identified object.
 
 paul@44   1407 
 
 paul@44   1408 
            if ref.has_kind("<class>"):
 
 paul@44   1409 
                return (
 
 paul@44   1410 
                    set(class_types).intersection([ref.get_origin()]), [], [], True
 
 paul@44   1411 
                    )
 
 paul@44   1412 
            elif ref.has_kind("<module>"):
 
 paul@44   1413 
                return (
 
 paul@44   1414 
                    [], [], set(module_types).intersection([ref.get_origin()]), True
 
 paul@44   1415 
                    )
 
 paul@44   1416 
 
 paul@44   1417 
        return class_types, instance_types, module_types, False
 
 paul@44   1418 
 
 paul@44   1419 
    def get_target_types(self, location, usage):
 
 paul@44   1420 
 
 paul@44   1421 
        """
 
 paul@44   1422 
        Return the class, instance and module types constrained for the name at
 
 paul@44   1423 
        the given 'location' exhibiting the given 'usage'. Whether the types
 
 paul@44   1424 
        have been constrained using contextual information is also indicated,
 
 paul@44   1425 
        plus whether the types have been constrained to a specific kind of type.
 
 paul@44   1426 
        """
 
 paul@44   1427 
 
 paul@107   1428 
        have_assignments = get_assigned_attributes(usage)
 
 paul@44   1429 
 
 paul@44   1430 
        # Detect any initialised name for the location.
 
 paul@44   1431 
 
 paul@791   1432 
        if location.name:
 
 paul@742   1433 
            refs = self.get_initialised_name(location)
 
 paul@742   1434 
            if refs:
 
 paul@44   1435 
                (class_types, only_instance_types, module_types,
 
 paul@742   1436 
                    _function_types, _var_types) = separate_types(refs)
 
 paul@107   1437 
                return class_types, only_instance_types, module_types, True, have_assignments
 
 paul@44   1438 
 
 paul@44   1439 
        # Retrieve the recorded types for the usage.
 
 paul@44   1440 
 
 paul@44   1441 
        class_types = self.get_class_types_for_usage(usage)
 
 paul@44   1442 
        only_instance_types = set(self.get_instance_types_for_usage(usage)).difference(class_types)
 
 paul@44   1443 
        module_types = self.get_module_types_for_usage(usage)
 
 paul@44   1444 
 
 paul@44   1445 
        # Merge usage deductions with observations to obtain reference types
 
 paul@44   1446 
        # for names involved with attribute accesses.
 
 paul@44   1447 
 
 paul@791   1448 
        if not location.name:
 
 paul@107   1449 
            return class_types, only_instance_types, module_types, False, have_assignments
 
 paul@44   1450 
 
 paul@44   1451 
        # Obtain references to known objects.
 
 paul@44   1452 
 
 paul@791   1453 
        path = get_name_path(location.path, location.name)
 
 paul@44   1454 
 
 paul@44   1455 
        class_types, only_instance_types, module_types, constrained_specific = \
 
 paul@44   1456 
            self.constrain_types(path, class_types, only_instance_types, module_types)
 
 paul@44   1457 
 
 paul@44   1458 
        if constrained_specific:
 
 paul@107   1459 
            return class_types, only_instance_types, module_types, constrained_specific, \
 
 paul@107   1460 
                constrained_specific or have_assignments
 
 paul@44   1461 
 
 paul@44   1462 
        # Constrain "self" references.
 
 paul@44   1463 
 
 paul@816   1464 
        class_name = self.in_method(location.path)
 
 paul@816   1465 
        constrained = False
 
 paul@816   1466 
 
 paul@816   1467 
        if class_name and location.name == "self":
 
 paul@816   1468 
 
 paul@816   1469 
            # Constrain the types to the class's hierarchy.
 
 paul@816   1470 
 
 paul@816   1471 
            class_types, only_instance_types, module_types, constrained = \
 
 paul@816   1472 
                self.constrain_to_class(class_name, class_types, only_instance_types)
 
 paul@816   1473 
 
 paul@816   1474 
            # Without any deduced types, produce an error.
 
 paul@816   1475 
 
 paul@816   1476 
            if not class_types and not only_instance_types:
 
 paul@350   1477 
                raise DeduceError("In %s, usage {%s} is not directly supported by class %s or its instances." %
 
 paul@791   1478 
                                  (location.path, encode_usage(usage), class_name))
 
 paul@350   1479 
 
 paul@816   1480 
            # If the class defining the method does not appear amongst the
 
 paul@816   1481 
            # types supporting the usage, remove the constrained status of the
 
 paul@816   1482 
            # name.
 
 paul@816   1483 
 
 paul@816   1484 
            constrained = constrained and (class_name in class_types or class_name in only_instance_types)
 
 paul@816   1485 
 
 paul@816   1486 
        return class_types, only_instance_types, module_types, constrained, have_assignments
 
 paul@44   1487 
 
 paul@44   1488 
    def constrain_self_reference(self, unit_path, class_types, only_instance_types):
 
 paul@44   1489 
 
 paul@44   1490 
        """
 
 paul@44   1491 
        Where the name "self" appears in a method, attempt to constrain the
 
 paul@44   1492 
        classes involved.
 
 paul@44   1493 
 
 paul@44   1494 
        Return the class, instance, module types plus whether the types are
 
 paul@44   1495 
        constrained.
 
 paul@44   1496 
        """
 
 paul@44   1497 
 
 paul@44   1498 
        class_name = self.in_method(unit_path)
 
 paul@44   1499 
 
 paul@44   1500 
        if not class_name:
 
 paul@44   1501 
            return None
 
 paul@44   1502 
 
 paul@816   1503 
        return self.constrain_to_class(class_name, class_types, only_instance_types)
 
 paul@816   1504 
 
 paul@816   1505 
    def constrain_to_class(self, class_name, class_types, only_instance_types):
 
 paul@816   1506 
 
 paul@816   1507 
        """
 
 paul@816   1508 
        Constrain to 'class_name' and its descendants, the given 'class_types'
 
 paul@816   1509 
        and 'only_instance_types'.
 
 paul@816   1510 
 
 paul@816   1511 
        Return the class, instance, module types plus whether the types are
 
 paul@816   1512 
        constrained.
 
 paul@816   1513 
        """
 
 paul@816   1514 
 
 paul@44   1515 
        classes = set([class_name])
 
 paul@44   1516 
        classes.update(self.get_descendants_for_class(class_name))
 
 paul@44   1517 
 
 paul@44   1518 
        # Note that only instances will be expected for these references but
 
 paul@44   1519 
        # either classes or instances may provide the attributes.
 
 paul@44   1520 
 
 paul@44   1521 
        return (
 
 paul@44   1522 
            set(class_types).intersection(classes),
 
 paul@44   1523 
            set(only_instance_types).intersection(classes),
 
 paul@44   1524 
            [], True
 
 paul@44   1525 
            )
 
 paul@44   1526 
 
 paul@44   1527 
    def in_method(self, path):
 
 paul@44   1528 
 
 paul@44   1529 
        "Return whether 'path' refers to a method."
 
 paul@44   1530 
 
 paul@816   1531 
        t = path.rsplit(".", 1)
 
 paul@816   1532 
        if len(t) == 1:
 
 paul@816   1533 
            return False
 
 paul@816   1534 
 
 paul@816   1535 
        class_name, method_name = t
 
 paul@274   1536 
        return class_name != "__builtins__.core.type" and self.importer.classes.has_key(class_name) and class_name
 
 paul@44   1537 
 
 paul@44   1538 
    def init_reference_details(self, location):
 
 paul@44   1539 
 
 paul@44   1540 
        "Initialise reference-related details for 'location'."
 
 paul@44   1541 
 
 paul@44   1542 
        self.init_definition_details(location)
 
 paul@44   1543 
        self.init_access_details(location)
 
 paul@44   1544 
 
 paul@44   1545 
    def init_definition_details(self, location):
 
 paul@44   1546 
 
 paul@44   1547 
        "Initialise name definition details for 'location'."
 
 paul@44   1548 
 
 paul@44   1549 
        self.accessor_class_types[location] = set()
 
 paul@44   1550 
        self.accessor_instance_types[location] = set()
 
 paul@44   1551 
        self.accessor_module_types[location] = set()
 
 paul@44   1552 
        self.provider_class_types[location] = set()
 
 paul@44   1553 
        self.provider_instance_types[location] = set()
 
 paul@44   1554 
        self.provider_module_types[location] = set()
 
 paul@44   1555 
 
 paul@44   1556 
    def init_access_details(self, location):
 
 paul@44   1557 
 
 paul@44   1558 
        "Initialise access details at 'location'."
 
 paul@44   1559 
 
 paul@44   1560 
        self.referenced_attrs[location] = {}
 
 paul@44   1561 
 
 paul@742   1562 
    def record_types_for_access(self, access_location, accessor_locations):
 
 paul@44   1563 
 
 paul@44   1564 
        """
 
 paul@44   1565 
        Define types for the 'access_location' associated with the given
 
 paul@735   1566 
        'accessor_locations'. Return whether referenced attributes were updated.
 
 paul@44   1567 
        """
 
 paul@44   1568 
 
 paul@791   1569 
        attrname = access_location.get_attrname()
 
 paul@91   1570 
        if not attrname:
 
 paul@735   1571 
            return False
 
 paul@44   1572 
 
 paul@720   1573 
        invocation = access_location in self.reference_invocations
 
 paul@720   1574 
        assignment = access_location in self.reference_assignments
 
 paul@720   1575 
 
 paul@44   1576 
        # Collect all suggested types for the accessors. Accesses may
 
 paul@44   1577 
        # require accessors from of a subset of the complete set of types.
 
 paul@44   1578 
 
 paul@44   1579 
        class_types = set()
 
 paul@44   1580 
        module_types = set()
 
 paul@44   1581 
        instance_types = set()
 
 paul@44   1582 
 
 paul@44   1583 
        constrained = True
 
 paul@44   1584 
 
 paul@735   1585 
        old_referenced_attrs = self.referenced_attrs.get(access_location)
 
 paul@735   1586 
 
 paul@44   1587 
        for location in accessor_locations:
 
 paul@44   1588 
 
 paul@44   1589 
            # Use the type information deduced for names from above.
 
 paul@44   1590 
 
 paul@44   1591 
            if self.accessor_class_types.has_key(location):
 
 paul@44   1592 
                class_types.update(self.accessor_class_types[location])
 
 paul@44   1593 
                module_types.update(self.accessor_module_types[location])
 
 paul@44   1594 
                instance_types.update(self.accessor_instance_types[location])
 
 paul@44   1595 
 
 paul@44   1596 
            # Where accesses are associated with assignments but where no
 
 paul@44   1597 
            # attribute usage observations have caused such an association,
 
 paul@44   1598 
            # the attribute name is considered by itself.
 
 paul@44   1599 
 
 paul@44   1600 
            else:
 
 paul@44   1601 
                self.init_definition_details(location)
 
 paul@720   1602 
                self.record_types_for_usage(location, [(attrname, invocation, assignment)])
 
 paul@44   1603 
 
 paul@67   1604 
            constrained = location in self.accessor_constrained and constrained
 
 paul@44   1605 
 
 paul@44   1606 
        self.init_access_details(access_location)
 
 paul@44   1607 
        self.identify_reference_attributes(access_location, attrname, class_types, instance_types, module_types, constrained)
 
 paul@44   1608 
 
 paul@735   1609 
        # Return whether the referenced attributes have changed.
 
 paul@735   1610 
 
 paul@735   1611 
        return old_referenced_attrs != self.referenced_attrs.get(access_location)
 
 paul@735   1612 
 
 paul@44   1613 
    def record_types_for_usage(self, accessor_location, usage):
 
 paul@44   1614 
 
 paul@44   1615 
        """
 
 paul@44   1616 
        Record types for the given 'accessor_location' according to the given
 
 paul@44   1617 
        'usage' observations which may be None to indicate an absence of usage.
 
 paul@44   1618 
        """
 
 paul@44   1619 
 
 paul@44   1620 
        (class_types,
 
 paul@44   1621 
         instance_types,
 
 paul@44   1622 
         module_types,
 
 paul@44   1623 
         constrained,
 
 paul@44   1624 
         constrained_specific) = self.get_target_types(accessor_location, usage)
 
 paul@44   1625 
 
 paul@90   1626 
        invocations = get_invoked_attributes(usage)
 
 paul@90   1627 
 
 paul@107   1628 
        self.record_reference_types(accessor_location, class_types, instance_types,
 
 paul@107   1629 
            module_types, constrained, constrained_specific, invocations)
 
 paul@44   1630 
 
 paul@44   1631 
    def record_types_for_attribute(self, access_location, attrname):
 
 paul@44   1632 
 
 paul@44   1633 
        """
 
 paul@44   1634 
        Record types for the 'access_location' employing only the given
 
 paul@44   1635 
        'attrname' for type deduction.
 
 paul@44   1636 
        """
 
 paul@44   1637 
 
 paul@102   1638 
        (class_types,
 
 paul@102   1639 
         only_instance_types,
 
 paul@102   1640 
         module_types) = self.get_types_for_attribute(attrname)
 
 paul@102   1641 
 
 paul@102   1642 
        self.init_reference_details(access_location)
 
 paul@102   1643 
 
 paul@102   1644 
        self.identify_reference_attributes(access_location, attrname, class_types, only_instance_types, module_types, False)
 
 paul@102   1645 
        self.record_reference_types(access_location, class_types, only_instance_types, module_types, False)
 
 paul@102   1646 
 
 paul@102   1647 
    def get_types_for_attribute(self, attrname):
 
 paul@102   1648 
 
 paul@102   1649 
        "Return class, instance-only and module types supporting 'attrname'."
 
 paul@102   1650 
 
 paul@107   1651 
        usage = ((attrname, False, False),)
 
 paul@44   1652 
 
 paul@44   1653 
        class_types = self.get_class_types_for_usage(usage)
 
 paul@44   1654 
        only_instance_types = set(self.get_instance_types_for_usage(usage)).difference(class_types)
 
 paul@44   1655 
        module_types = self.get_module_types_for_usage(usage)
 
 paul@44   1656 
 
 paul@102   1657 
        return class_types, only_instance_types, module_types
 
 paul@44   1658 
 
 paul@44   1659 
    def record_types_for_alias(self, accessor_location):
 
 paul@44   1660 
 
 paul@44   1661 
        """
 
 paul@44   1662 
        Define types for the 'accessor_location' not having associated usage.
 
 paul@735   1663 
        Return whether the types were updated.
 
 paul@44   1664 
        """
 
 paul@44   1665 
 
 paul@44   1666 
        have_access = self.provider_class_types.has_key(accessor_location)
 
 paul@44   1667 
 
 paul@44   1668 
        # With an access, attempt to narrow the existing selection of provider
 
 paul@709   1669 
        # types. Invocations attempt to find return value information, with
 
 paul@709   1670 
        # instance return values also yielding class providers (since attributes
 
 paul@709   1671 
        # on instances could be provided by classes).
 
 paul@44   1672 
 
 paul@44   1673 
        if have_access:
 
 paul@44   1674 
            provider_class_types = self.provider_class_types[accessor_location]
 
 paul@44   1675 
            provider_instance_types = self.provider_instance_types[accessor_location]
 
 paul@44   1676 
            provider_module_types = self.provider_module_types[accessor_location]
 
 paul@44   1677 
 
 paul@721   1678 
            accessor_class_types = self.accessor_class_types[accessor_location]
 
 paul@721   1679 
            accessor_instance_types = self.accessor_instance_types[accessor_location]
 
 paul@721   1680 
            accessor_module_types = self.accessor_module_types[accessor_location]
 
 paul@721   1681 
 
 paul@44   1682 
            # Find details for any corresponding access.
 
 paul@44   1683 
 
 paul@721   1684 
            new_provider_class_types = set()
 
 paul@721   1685 
            new_provider_instance_types = set()
 
 paul@721   1686 
            new_provider_module_types = set()
 
 paul@721   1687 
 
 paul@721   1688 
            new_accessor_class_types = set()
 
 paul@721   1689 
            new_accessor_instance_types = set()
 
 paul@721   1690 
            new_accessor_module_types = set()
 
 paul@44   1691 
 
 paul@742   1692 
            refs = set()
 
 paul@742   1693 
 
 paul@44   1694 
            for access_location in self.alias_index[accessor_location]:
 
 paul@791   1695 
                attrnames = access_location.attrnames
 
 paul@791   1696 
                invocation = self.reference_invocations.has_key(access_location)
 
 paul@44   1697 
 
 paul@715   1698 
                attrnames = attrnames and attrnames.split(".")
 
 paul@715   1699 
                remaining = attrnames and len(attrnames) > 1
 
 paul@715   1700 
 
 paul@715   1701 
                # Alias has remaining attributes: reference details do not
 
 paul@715   1702 
                # correspond to the accessor; the remaining attributes would
 
 paul@715   1703 
                # need to be traversed first.
 
 paul@715   1704 
 
 paul@715   1705 
                if remaining:
 
 paul@735   1706 
                    return False
 
 paul@715   1707 
 
 paul@44   1708 
                # Alias references an attribute access.
 
 paul@44   1709 
 
 paul@44   1710 
                if attrnames:
 
 paul@44   1711 
 
 paul@709   1712 
                    # Obtain references and attribute types for the access.
 
 paul@44   1713 
 
 paul@708   1714 
                    attrs = self.get_references_for_access(access_location)
 
 paul@721   1715 
 
 paul@744   1716 
                    if attrs:
 
 paul@744   1717 
 
 paul@744   1718 
                        # Invocations converting class accessors to instances do
 
 paul@744   1719 
                        # not change the nature of class providers.
 
 paul@744   1720 
 
 paul@744   1721 
                        provider_attrs = self.convert_invocation_providers(attrs, invocation)
 
 paul@744   1722 
 
 paul@744   1723 
                        # Accessors are updated separately, employing invocation
 
 paul@744   1724 
                        # result details.
 
 paul@744   1725 
 
 paul@744   1726 
                        accessor_attrs = self.convert_invocations(attrs, invocation)
 
 paul@742   1727 
 
 paul@44   1728 
                # Alias references a name, not an access.
 
 paul@44   1729 
 
 paul@44   1730 
                else:
 
 paul@742   1731 
                    # Attempt to refine the types using initialised names or
 
 paul@742   1732 
                    # accessors.
 
 paul@742   1733 
 
 paul@791   1734 
                    attrs = self.get_initialised_access(access_location)
 
 paul@742   1735 
 
 paul@742   1736 
                    if attrs:
 
 paul@721   1737 
                        provider_attrs = self.convert_invocation_providers(attrs, invocation)
 
 paul@721   1738 
                        accessor_attrs = self.convert_invocations(attrs, invocation)
 
 paul@742   1739 
                    else:
 
 paul@742   1740 
                        provider_attrs = self.get_provider_references(access_location)
 
 paul@742   1741 
                        attrs = accessor_attrs = self.get_accessor_references(access_location)
 
 paul@44   1742 
 
 paul@744   1743 
                # Where no specific attributes are defined, do not attempt
 
 paul@744   1744 
                # to refine the alias's types.
 
 paul@744   1745 
 
 paul@744   1746 
                if not attrs:
 
 paul@744   1747 
                    return False
 
 paul@744   1748 
 
 paul@744   1749 
                (class_types, instance_types, module_types, function_types,
 
 paul@744   1750 
                    var_types) = separate_types(provider_attrs)
 
 paul@744   1751 
 
 paul@744   1752 
                # Where non-accessor types are found, do not attempt to refine
 
 paul@744   1753 
                # the defined accessor types.
 
 paul@744   1754 
 
 paul@744   1755 
                if function_types or var_types:
 
 paul@744   1756 
                    return False
 
 paul@744   1757 
 
 paul@744   1758 
                class_types = set(provider_class_types).intersection(class_types)
 
 paul@744   1759 
                instance_types = set(provider_instance_types).intersection(instance_types)
 
 paul@744   1760 
                module_types = set(provider_module_types).intersection(module_types)
 
 paul@744   1761 
 
 paul@744   1762 
                new_provider_class_types.update(class_types)
 
 paul@744   1763 
                new_provider_instance_types.update(instance_types)
 
 paul@744   1764 
                new_provider_module_types.update(module_types)
 
 paul@744   1765 
 
 paul@744   1766 
                (class_types, instance_types, module_types, function_types,
 
 paul@744   1767 
                    var_types) = separate_types(accessor_attrs)
 
 paul@744   1768 
 
 paul@744   1769 
                class_types = set(accessor_class_types).intersection(class_types)
 
 paul@744   1770 
                instance_types = set(accessor_instance_types).intersection(instance_types)
 
 paul@744   1771 
                module_types = set(accessor_module_types).intersection(module_types)
 
 paul@744   1772 
 
 paul@744   1773 
                new_accessor_class_types.update(class_types)
 
 paul@744   1774 
                new_accessor_instance_types.update(instance_types)
 
 paul@744   1775 
                new_accessor_module_types.update(module_types)
 
 paul@744   1776 
 
 paul@744   1777 
                refs.update(accessor_attrs)
 
 paul@742   1778 
 
 paul@742   1779 
                # Update the alias relationships for invocations.
 
 paul@742   1780 
 
 paul@742   1781 
                self.update_alias_accesses(access_location, attrs)
 
 paul@742   1782 
 
 paul@44   1783 
            # Record refined type details for the alias as an accessor.
 
 paul@44   1784 
 
 paul@44   1785 
            self.init_definition_details(accessor_location)
 
 paul@721   1786 
            self.update_provider_types(accessor_location, new_provider_class_types, new_provider_instance_types, new_provider_module_types)
 
 paul@721   1787 
            self.update_accessor_types(accessor_location, new_accessor_class_types, new_accessor_instance_types, new_accessor_module_types)
 
 paul@44   1788 
 
 paul@742   1789 
            # Record reference details for the alias separately from accessors.
 
 paul@742   1790 
 
 paul@742   1791 
            self.referenced_objects[accessor_location] = refs
 
 paul@742   1792 
 
 paul@735   1793 
            return new_accessor_class_types != accessor_class_types or \
 
 paul@735   1794 
                   new_accessor_instance_types != accessor_instance_types or \
 
 paul@735   1795 
                   new_accessor_module_types != accessor_module_types
 
 paul@735   1796 
 
 paul@44   1797 
        # Without an access, attempt to identify references for the alias.
 
 paul@709   1798 
        # Invocations convert classes to instances and also attempt to find
 
 paul@709   1799 
        # return value information.
 
 paul@44   1800 
 
 paul@44   1801 
        else:
 
 paul@44   1802 
            refs = set()
 
 paul@44   1803 
 
 paul@44   1804 
            for access_location in self.alias_index[accessor_location]:
 
 paul@791   1805 
                attrnames = access_location.attrnames
 
 paul@791   1806 
                invocation = self.reference_invocations.has_key(access_location)
 
 paul@709   1807 
 
 paul@683   1808 
                attrnames = attrnames and attrnames.split(".")
 
 paul@683   1809 
                remaining = attrnames and len(attrnames) > 1
 
 paul@683   1810 
 
 paul@683   1811 
                # Alias has remaining attributes: reference details do not
 
 paul@683   1812 
                # correspond to the accessor; the remaining attributes would
 
 paul@683   1813 
                # need to be traversed first.
 
 paul@683   1814 
 
 paul@683   1815 
                if remaining:
 
 paul@735   1816 
                    return False
 
 paul@44   1817 
 
 paul@44   1818 
                # Alias references an attribute access.
 
 paul@44   1819 
 
 paul@721   1820 
                if attrnames:
 
 paul@709   1821 
 
 paul@709   1822 
                    # Obtain references and attribute types for the access.
 
 paul@709   1823 
 
 paul@708   1824 
                    attrs = self.get_references_for_access(access_location)
 
 paul@742   1825 
 
 paul@44   1826 
                # Alias references a name, not an access.
 
 paul@44   1827 
 
 paul@44   1828 
                else:
 
 paul@709   1829 
 
 paul@709   1830 
                    # Obtain initialiser information.
 
 paul@709   1831 
 
 paul@791   1832 
                    attrs = self.get_initialised_access(access_location)
 
 paul@742   1833 
 
 paul@742   1834 
                    if attrs:
 
 paul@742   1835 
                        provider_attrs = self.convert_invocation_providers(attrs, invocation)
 
 paul@742   1836 
                        accessor_attrs = self.convert_invocations(attrs, invocation)
 
 paul@742   1837 
                    else:
 
 paul@742   1838 
                        provider_attrs = self.get_provider_references(access_location)
 
 paul@742   1839 
                        attrs = accessor_attrs = self.get_accessor_references(access_location)
 
 paul@742   1840 
 
 paul@744   1841 
                # Where no further information is found, do not attempt to
 
 paul@744   1842 
                # refine the defined accessor types.
 
 paul@744   1843 
 
 paul@744   1844 
                if not attrs:
 
 paul@744   1845 
                    return False
 
 paul@744   1846 
 
 paul@744   1847 
                refs.update(self.convert_invocations(attrs, invocation))
 
 paul@742   1848 
 
 paul@742   1849 
                # Update the alias relationships for invocations.
 
 paul@742   1850 
 
 paul@742   1851 
                self.update_alias_accesses(access_location, attrs)
 
 paul@742   1852 
 
 paul@742   1853 
            # Record refined type details for the alias as an accessor.
 
 paul@742   1854 
 
 paul@742   1855 
            (class_types, instance_types, module_types, function_types,
 
 paul@742   1856 
                var_types) = separate_types(refs)
 
 paul@742   1857 
 
 paul@742   1858 
            # Where non-accessor types are found, do not attempt to refine
 
 paul@742   1859 
            # the defined accessor types.
 
 paul@742   1860 
 
 paul@742   1861 
            if not function_types and not var_types:
 
 paul@742   1862 
                self.init_definition_details(accessor_location)
 
 paul@742   1863 
                self.update_provider_types(accessor_location, class_types + instance_types, class_types + instance_types, module_types)
 
 paul@742   1864 
                self.update_accessor_types(accessor_location, class_types, instance_types, module_types)
 
 paul@709   1865 
 
 paul@44   1866 
            # Record reference details for the alias separately from accessors.
 
 paul@44   1867 
 
 paul@44   1868 
            self.referenced_objects[accessor_location] = refs
 
 paul@44   1869 
 
 paul@742   1870 
            return True
 
 paul@742   1871 
 
 paul@742   1872 
    def update_alias_accesses(self, access_location, refs):
 
 paul@742   1873 
 
 paul@742   1874 
        """
 
 paul@742   1875 
        Record 'access_location' as a location affected by the return values of
 
 paul@742   1876 
        'refs' if an invocation is involved.
 
 paul@742   1877 
        """
 
 paul@742   1878 
 
 paul@742   1879 
        if not self.reference_invocations.has_key(access_location):
 
 paul@742   1880 
            return
 
 paul@742   1881 
 
 paul@742   1882 
        for ref in refs:
 
 paul@742   1883 
 
 paul@742   1884 
            # Initialising accesses originate from the return values.
 
 paul@742   1885 
 
 paul@742   1886 
            key = (ref.get_origin(), "$return")
 
 paul@742   1887 
            self._update_alias_accesses(access_location, key, self.importer.all_initialised_names)
 
 paul@742   1888 
            self._update_alias_accesses(access_location, key, self.importer.all_aliased_names)
 
 paul@742   1889 
 
 paul@742   1890 
    def _update_alias_accesses(self, access_location, key, names):
 
 paul@742   1891 
 
 paul@742   1892 
        """
 
 paul@742   1893 
        Make each return value provide information to the given
 
 paul@742   1894 
        'access_location', using 'key' to reference the return value and 'names'
 
 paul@742   1895 
        as the collection of definitions.
 
 paul@742   1896 
        """
 
 paul@742   1897 
 
 paul@742   1898 
        versions = names.get(key)
 
 paul@742   1899 
        if not versions:
 
 paul@742   1900 
            return
 
 paul@742   1901 
 
 paul@791   1902 
        path, name = key
 
 paul@791   1903 
 
 paul@742   1904 
        for version in versions.keys():
 
 paul@791   1905 
            location = Location(path, name, None, version)
 
 paul@742   1906 
            l = init_item(self.alias_index_rev, location, set)
 
 paul@742   1907 
            l.add(access_location)
 
 paul@742   1908 
 
 paul@742   1909 
            l = init_item(self.alias_index, access_location, set)
 
 paul@742   1910 
            l.add(location)
 
 paul@735   1911 
 
 paul@708   1912 
    def get_references_for_access(self, access_location):
 
 paul@708   1913 
 
 paul@708   1914 
        "Return the references identified for 'access_location'."
 
 paul@708   1915 
 
 paul@843   1916 
        attrs = set()
 
 paul@708   1917 
        for attrtype, object_type, attr in self.referenced_attrs[access_location]:
 
 paul@843   1918 
            attrs.add(attr)
 
 paul@708   1919 
        return attrs
 
 paul@708   1920 
 
 paul@709   1921 
    def convert_invocation_providers(self, refs, invocation):
 
 paul@709   1922 
 
 paul@709   1923 
        """
 
 paul@709   1924 
        Convert 'refs' to providers corresponding to the results of invoking
 
 paul@709   1925 
        each of the given references, if 'invocation' is set to a true value.
 
 paul@709   1926 
        """
 
 paul@709   1927 
 
 paul@709   1928 
        if not invocation:
 
 paul@709   1929 
            return refs
 
 paul@709   1930 
 
 paul@709   1931 
        providers = set()
 
 paul@709   1932 
 
 paul@709   1933 
        for ref in refs:
 
 paul@742   1934 
            invocation_providers = self.convert_accessors_to_providers(self.convert_invocation_provider(ref))
 
 paul@742   1935 
            providers.update(invocation_providers)
 
 paul@742   1936 
 
 paul@742   1937 
        return self.references_or_var(providers)
 
 paul@742   1938 
 
 paul@742   1939 
    def convert_accessors_to_providers(self, refs):
 
 paul@742   1940 
 
 paul@742   1941 
        "Convert accessor 'refs' to provider references."
 
 paul@742   1942 
 
 paul@742   1943 
        providers = set()
 
 paul@742   1944 
        for ref in refs:
 
 paul@742   1945 
            if ref.has_kind("<instance>"):
 
 paul@742   1946 
                providers.add(Reference("<class>", ref.get_origin()))
 
 paul@742   1947 
            providers.add(ref)
 
 paul@709   1948 
        return providers
 
 paul@709   1949 
 
 paul@709   1950 
    def convert_invocation_provider(self, ref):
 
 paul@709   1951 
 
 paul@709   1952 
        "Convert 'ref' to a provider appropriate to its invocation result."
 
 paul@709   1953 
 
 paul@712   1954 
        if ref:
 
 paul@712   1955 
            if ref.has_kind("<class>"):
 
 paul@742   1956 
                return [ref]
 
 paul@712   1957 
            elif ref.has_kind("<function>"):
 
 paul@731   1958 
                return self.convert_function_invocation(ref)
 
 paul@709   1959 
 
 paul@742   1960 
        return [Reference("<var>")]
 
 paul@709   1961 
 
 paul@709   1962 
    def convert_invocations(self, refs, invocation):
 
 paul@709   1963 
 
 paul@709   1964 
        """
 
 paul@709   1965 
        Convert 'refs' to invocation results if 'invocation' is set to a true
 
 paul@709   1966 
        value.
 
 paul@709   1967 
        """
 
 paul@709   1968 
 
 paul@739   1969 
        if not invocation:
 
 paul@739   1970 
            return refs
 
 paul@739   1971 
 
 paul@739   1972 
        invocation_refs = set()
 
 paul@739   1973 
 
 paul@739   1974 
        for ref in refs:
 
 paul@739   1975 
            invocation_refs.update(self.convert_invocation(ref))
 
 paul@739   1976 
 
 paul@742   1977 
        return self.references_or_var(invocation_refs)
 
 paul@709   1978 
 
 paul@709   1979 
    def convert_invocation(self, ref):
 
 paul@709   1980 
 
 paul@709   1981 
        "Convert 'ref' to its invocation result."
 
 paul@709   1982 
 
 paul@712   1983 
        if ref:
 
 paul@712   1984 
            if ref.has_kind("<class>"):
 
 paul@739   1985 
                return [ref.instance_of()]
 
 paul@712   1986 
            elif ref.has_kind("<function>"):
 
 paul@731   1987 
                return self.convert_function_invocation(ref)
 
 paul@731   1988 
 
 paul@739   1989 
        return [Reference("<var>")]
 
 paul@731   1990 
 
 paul@731   1991 
    def convert_function_invocation(self, ref):
 
 paul@731   1992 
 
 paul@731   1993 
        "Convert the function 'ref' to its return value reference."
 
 paul@731   1994 
 
 paul@742   1995 
        initialisers = self.importer.all_initialised_names.get((ref.get_origin(), "$return"))
 
 paul@742   1996 
        aliases = self.importer.all_aliased_names.get((ref.get_origin(), "$return"))
 
 paul@742   1997 
 
 paul@742   1998 
        if initialisers and not aliases:
 
 paul@742   1999 
            return set(initialisers.values())
 
 paul@739   2000 
 
 paul@739   2001 
        return [Reference("<var>")]
 
 paul@709   2002 
 
 paul@742   2003 
    def references_or_var(self, refs):
 
 paul@742   2004 
 
 paul@742   2005 
        var = Reference("<var>")
 
 paul@742   2006 
 
 paul@742   2007 
        if var in refs:
 
 paul@742   2008 
            return set([var])
 
 paul@742   2009 
        else:
 
 paul@742   2010 
            return refs
 
 paul@742   2011 
 
 paul@791   2012 
    def get_initialised_name(self, location):
 
 paul@44   2013 
 
 paul@44   2014 
        """
 
 paul@791   2015 
        Return references for any initialised names at 'location', or None if no
 
 paul@791   2016 
        such references exist.
 
 paul@44   2017 
        """
 
 paul@44   2018 
 
 paul@791   2019 
        ref = self.initialised_names.get(location)
 
 paul@791   2020 
        return ref and [ref] or None
 
 paul@791   2021 
 
 paul@791   2022 
    def get_initialised_access(self, location):
 
 paul@791   2023 
 
 paul@791   2024 
        """
 
 paul@791   2025 
        Return references for any initialised names supplying the given access
 
 paul@791   2026 
        'location', or None if no such references exist.
 
 paul@791   2027 
        """
 
 paul@791   2028 
 
 paul@791   2029 
        if location.access_number is not None:
 
 paul@791   2030 
            return self.initialised_accesses.get(location)
 
 paul@742   2031 
        else:
 
 paul@791   2032 
            return self.get_initialised_name(location)
 
 paul@742   2033 
 
 paul@742   2034 
    def get_accessor_references(self, access_location):
 
 paul@742   2035 
 
 paul@742   2036 
        """
 
 paul@742   2037 
        Return references corresponding to accessor details at the given
 
 paul@742   2038 
        'access_location'.
 
 paul@742   2039 
        """
 
 paul@742   2040 
 
 paul@742   2041 
        if self.accessor_class_types.has_key(access_location):
 
 paul@742   2042 
            class_types = self.accessor_class_types[access_location]
 
 paul@742   2043 
            instance_types = self.accessor_instance_types[access_location]
 
 paul@742   2044 
            module_types = self.accessor_module_types[access_location]
 
 paul@742   2045 
            return combine_types(class_types, instance_types, module_types)
 
 paul@742   2046 
        else:
 
 paul@742   2047 
            return None
 
 paul@742   2048 
 
 paul@742   2049 
    def get_provider_references(self, access_location):
 
 paul@742   2050 
 
 paul@742   2051 
        """
 
 paul@742   2052 
        Return references corresponding to provider details at the given
 
 paul@742   2053 
        'access_location'.
 
 paul@742   2054 
        """
 
 paul@742   2055 
 
 paul@742   2056 
        if self.provider_class_types.has_key(access_location):
 
 paul@742   2057 
            class_types = self.provider_class_types[access_location]
 
 paul@742   2058 
            instance_types = self.provider_instance_types[access_location]
 
 paul@742   2059 
            module_types = self.provider_module_types[access_location]
 
 paul@742   2060 
            return combine_types(class_types, instance_types, module_types)
 
 paul@44   2061 
        else:
 
 paul@44   2062 
            return None
 
 paul@44   2063 
 
 paul@44   2064 
    def record_reference_types(self, location, class_types, instance_types,
 
 paul@90   2065 
        module_types, constrained, constrained_specific=False, invocations=None):
 
 paul@44   2066 
 
 paul@44   2067 
        """
 
 paul@44   2068 
        Associate attribute provider types with the given 'location', consisting
 
 paul@44   2069 
        of the given 'class_types', 'instance_types' and 'module_types'.
 
 paul@44   2070 
 
 paul@44   2071 
        If 'constrained' is indicated, the constrained nature of the accessor is
 
 paul@44   2072 
        recorded for the location.
 
 paul@44   2073 
 
 paul@44   2074 
        If 'constrained_specific' is indicated using a true value, instance types
 
 paul@44   2075 
        will not be added to class types to permit access via instances at the
 
 paul@44   2076 
        given location. This is only useful where a specific accessor is known
 
 paul@44   2077 
        to be a class.
 
 paul@44   2078 
 
 paul@105   2079 
        If 'invocations' is given, the given attribute names indicate those
 
 paul@105   2080 
        which are involved in invocations. Such invocations, if involving
 
 paul@105   2081 
        functions, will employ those functions as bound methods and will
 
 paul@105   2082 
        therefore not support classes as accessors, only instances of such
 
 paul@105   2083 
        classes.
 
 paul@105   2084 
 
 paul@44   2085 
        Note that the specified types only indicate the provider types for
 
 paul@44   2086 
        attributes, whereas the recorded accessor types indicate the possible
 
 paul@44   2087 
        types of the actual objects used to access attributes.
 
 paul@44   2088 
        """
 
 paul@44   2089 
 
 paul@44   2090 
        # Update the type details for the location.
 
 paul@44   2091 
 
 paul@721   2092 
        self.update_provider_types(location, class_types, instance_types, module_types)
 
 paul@44   2093 
 
 paul@44   2094 
        # Class types support classes and instances as accessors.
 
 paul@44   2095 
        # Instance-only and module types support only their own kinds as
 
 paul@44   2096 
        # accessors.
 
 paul@44   2097 
 
 paul@791   2098 
        path, name = location.path, location.name
 
 paul@90   2099 
 
 paul@90   2100 
        if invocations:
 
 paul@90   2101 
            class_only_types = self.filter_for_invocations(class_types, invocations)
 
 paul@90   2102 
        else:
 
 paul@90   2103 
            class_only_types = class_types
 
 paul@90   2104 
 
 paul@44   2105 
        # However, the nature of accessors can be further determined.
 
 paul@44   2106 
        # Any self variable may only refer to an instance.
 
 paul@44   2107 
 
 paul@44   2108 
        if name != "self" or not self.in_method(path):
 
 paul@90   2109 
            self.accessor_class_types[location].update(class_only_types)
 
 paul@44   2110 
 
 paul@44   2111 
        if not constrained_specific:
 
 paul@44   2112 
            self.accessor_instance_types[location].update(class_types)
 
 paul@44   2113 
 
 paul@44   2114 
        self.accessor_instance_types[location].update(instance_types)
 
 paul@44   2115 
 
 paul@44   2116 
        if name != "self" or not self.in_method(path):
 
 paul@44   2117 
            self.accessor_module_types[location].update(module_types)
 
 paul@44   2118 
 
 paul@44   2119 
        if constrained:
 
 paul@67   2120 
            self.accessor_constrained.add(location)
 
 paul@44   2121 
 
 paul@840   2122 
        # Complain about situations where no types are valid but where a
 
 paul@840   2123 
        # specific, known accessor type has been indicated. This absence of
 
 paul@840   2124 
        # suitable types is likely to occur when the presence of invocations
 
 paul@840   2125 
        # filters out the accessor type.
 
 paul@840   2126 
 
 paul@840   2127 
        if not class_only_types and not instance_types and not module_types and \
 
 paul@840   2128 
           invocations and constrained_specific:
 
 paul@840   2129 
 
 paul@840   2130 
            raise DeduceError("In %s, methods of class %s cannot be called directly." %
 
 paul@840   2131 
                (path, name))
 
 paul@840   2132 
 
 paul@721   2133 
    def update_provider_types(self, location, class_types, instance_types, module_types):
 
 paul@721   2134 
 
 paul@721   2135 
        """
 
 paul@721   2136 
        Update provider types for the given 'location', adding 'class_types',
 
 paul@721   2137 
        'instance_types' and 'module_types' to those already stored.
 
 paul@721   2138 
        """
 
 paul@721   2139 
 
 paul@721   2140 
        self.provider_class_types[location].update(class_types)
 
 paul@721   2141 
        self.provider_instance_types[location].update(instance_types)
 
 paul@721   2142 
        self.provider_module_types[location].update(module_types)
 
 paul@721   2143 
 
 paul@721   2144 
    def update_accessor_types(self, location, class_types, instance_types, module_types):
 
 paul@721   2145 
 
 paul@721   2146 
        """
 
 paul@721   2147 
        Update accessor types for the given 'location', adding 'class_types',
 
 paul@721   2148 
        'instance_types' and 'module_types' to those already stored.
 
 paul@721   2149 
        """
 
 paul@721   2150 
 
 paul@721   2151 
        self.accessor_class_types[location].update(class_types)
 
 paul@721   2152 
        self.accessor_instance_types[location].update(instance_types)
 
 paul@721   2153 
        self.accessor_module_types[location].update(module_types)
 
 paul@721   2154 
 
 paul@90   2155 
    def filter_for_invocations(self, class_types, attrnames):
 
 paul@90   2156 
 
 paul@90   2157 
        """
 
 paul@90   2158 
        From the given 'class_types', identify methods for the given
 
 paul@90   2159 
        'attrnames' that are being invoked, returning a filtered collection of
 
 paul@90   2160 
        class types.
 
 paul@553   2161 
 
 paul@553   2162 
        This method may be used to remove class types from consideration where
 
 paul@553   2163 
        their attributes are methods that are directly invoked: method
 
 paul@553   2164 
        invocations must involve instance accessors.
 
 paul@90   2165 
        """
 
 paul@90   2166 
 
 paul@90   2167 
        to_filter = set()
 
 paul@90   2168 
 
 paul@90   2169 
        for class_type in class_types:
 
 paul@90   2170 
            for attrname in attrnames:
 
 paul@553   2171 
 
 paul@553   2172 
                # Attempt to obtain a class attribute of the given name. This
 
 paul@553   2173 
                # may return an attribute provided by an ancestor class.
 
 paul@553   2174 
 
 paul@90   2175 
                ref = self.importer.get_class_attribute(class_type, attrname)
 
 paul@90   2176 
                parent_class = ref and ref.parent()
 
 paul@90   2177 
 
 paul@553   2178 
                # If such an attribute is a method and would be available on
 
 paul@553   2179 
                # the given class, record the class for filtering.
 
 paul@553   2180 
 
 paul@90   2181 
                if ref and ref.has_kind("<function>") and (
 
 paul@90   2182 
                   parent_class == class_type or
 
 paul@90   2183 
                   class_type in self.descendants[parent_class]):
 
 paul@90   2184 
 
 paul@90   2185 
                    to_filter.add(class_type)
 
 paul@90   2186 
                    break
 
 paul@90   2187 
 
 paul@90   2188 
        return set(class_types).difference(to_filter)
 
 paul@90   2189 
 
 paul@44   2190 
    def identify_reference_attributes(self, location, attrname, class_types, instance_types, module_types, constrained):
 
 paul@44   2191 
 
 paul@44   2192 
        """
 
 paul@44   2193 
        Identify reference attributes, associating them with the given
 
 paul@44   2194 
        'location', identifying the given 'attrname', employing the given
 
 paul@44   2195 
        'class_types', 'instance_types' and 'module_types'.
 
 paul@44   2196 
 
 paul@44   2197 
        If 'constrained' is indicated, the constrained nature of the access is
 
 paul@44   2198 
        recorded for the location.
 
 paul@44   2199 
        """
 
 paul@44   2200 
 
 paul@44   2201 
        # Record the referenced objects.
 
 paul@44   2202 
 
 paul@44   2203 
        self.referenced_attrs[location] = \
 
 paul@555   2204 
            self._identify_reference_attribute(location, attrname, class_types, instance_types, module_types)
 
 paul@44   2205 
 
 paul@44   2206 
        if constrained:
 
 paul@44   2207 
            self.access_constrained.add(location)
 
 paul@44   2208 
 
 paul@555   2209 
    def _identify_reference_attribute(self, location, attrname, class_types, instance_types, module_types):
 
 paul@44   2210 
 
 paul@44   2211 
        """
 
 paul@555   2212 
        Identify the reference attribute at the given access 'location', using
 
 paul@555   2213 
        the given 'attrname', and employing the given 'class_types',
 
 paul@555   2214 
        'instance_types' and 'module_types'.
 
 paul@44   2215 
        """
 
 paul@44   2216 
 
 paul@44   2217 
        attrs = set()
 
 paul@44   2218 
 
 paul@44   2219 
        # The class types expose class attributes either directly or via
 
 paul@44   2220 
        # instances.
 
 paul@44   2221 
 
 paul@44   2222 
        for object_type in class_types:
 
 paul@44   2223 
            ref = self.importer.get_class_attribute(object_type, attrname)
 
 paul@555   2224 
            if ref and self.is_compatible_callable(location, object_type, ref):
 
 paul@44   2225 
                attrs.add(("<class>", object_type, ref))
 
 paul@44   2226 
 
 paul@44   2227 
            # Add any distinct instance attributes that would be provided
 
 paul@44   2228 
            # by instances also providing indirect class attribute access.
 
 paul@44   2229 
 
 paul@44   2230 
            for ref in self.importer.get_instance_attributes(object_type, attrname):
 
 paul@555   2231 
                if self.is_compatible_callable(location, object_type, ref):
 
 paul@555   2232 
                    attrs.add(("<instance>", object_type, ref))
 
 paul@44   2233 
 
 paul@44   2234 
        # The instance-only types expose instance attributes, but although
 
 paul@44   2235 
        # classes are excluded as potential accessors (since they do not provide
 
 paul@44   2236 
        # the instance attributes), the class types may still provide some
 
 paul@44   2237 
        # attributes.
 
 paul@44   2238 
 
 paul@44   2239 
        for object_type in instance_types:
 
 paul@44   2240 
            instance_attrs = self.importer.get_instance_attributes(object_type, attrname)
 
 paul@44   2241 
 
 paul@44   2242 
            if instance_attrs:
 
 paul@44   2243 
                for ref in instance_attrs:
 
 paul@555   2244 
                    if self.is_compatible_callable(location, object_type, ref):
 
 paul@555   2245 
                        attrs.add(("<instance>", object_type, ref))
 
 paul@44   2246 
            else:
 
 paul@44   2247 
                ref = self.importer.get_class_attribute(object_type, attrname)
 
 paul@555   2248 
                if ref and self.is_compatible_callable(location, object_type, ref):
 
 paul@44   2249 
                    attrs.add(("<class>", object_type, ref))
 
 paul@44   2250 
 
 paul@44   2251 
        # Module types expose module attributes for module accessors.
 
 paul@44   2252 
 
 paul@44   2253 
        for object_type in module_types:
 
 paul@44   2254 
            ref = self.importer.get_module_attribute(object_type, attrname)
 
 paul@555   2255 
            if ref and self.is_compatible_callable(location, object_type, ref):
 
 paul@44   2256 
                attrs.add(("<module>", object_type, ref))
 
 paul@44   2257 
 
 paul@44   2258 
        return attrs
 
 paul@44   2259 
 
 paul@555   2260 
    def is_compatible_callable(self, location, object_type, ref):
 
 paul@555   2261 
 
 paul@555   2262 
        """
 
 paul@555   2263 
        Return whether any invocation at 'location' involving an attribute of
 
 paul@555   2264 
        'object_type' identified by 'ref' is compatible with any arguments used.
 
 paul@555   2265 
        """
 
 paul@555   2266 
 
 paul@557   2267 
        invocation = self.reference_invocations.get(location)
 
 paul@557   2268 
        if invocation is None:
 
 paul@555   2269 
            return True
 
 paul@555   2270 
 
 paul@555   2271 
        objpath = ref.get_origin()
 
 paul@555   2272 
        if not objpath:
 
 paul@555   2273 
            return True
 
 paul@555   2274 
 
 paul@555   2275 
        parameters = self.importer.function_parameters.get(objpath)
 
 paul@555   2276 
        if not parameters:
 
 paul@555   2277 
            return True
 
 paul@555   2278 
 
 paul@555   2279 
        defaults = self.importer.function_defaults.get(objpath)
 
 paul@557   2280 
        arguments, keywords = invocation
 
 paul@557   2281 
        names = set(parameters)
 
 paul@555   2282 
 
 paul@555   2283 
        # Determine whether the specified arguments are
 
 paul@555   2284 
        # compatible with the callable signature.
 
 paul@555   2285 
 
 paul@555   2286 
        if arguments >= len(parameters) - len(defaults) and \
 
 paul@557   2287 
           arguments <= len(parameters) and \
 
 paul@557   2288 
           names.issuperset(keywords):
 
 paul@555   2289 
 
 paul@555   2290 
            return True
 
 paul@555   2291 
        else:
 
 paul@555   2292 
            init_item(self.reference_invocations_unsuitable, location, set)
 
 paul@555   2293 
            self.reference_invocations_unsuitable[location].add(ref)
 
 paul@555   2294 
            return False
 
 paul@555   2295 
 
 paul@553   2296 
    # Attribute access plan formulation.
 
 paul@553   2297 
 
 paul@67   2298 
    class_tests = (
 
 paul@237   2299 
        ("guarded", "specific", "type"),
 
 paul@237   2300 
        ("guarded", "common", "type"),
 
 paul@237   2301 
        ("test", "specific", "type"),
 
 paul@237   2302 
        ("test", "common", "type"),
 
 paul@67   2303 
        )
 
 paul@67   2304 
 
 paul@67   2305 
    def get_access_plan(self, location):
 
 paul@65   2306 
 
 paul@77   2307 
        """
 
 paul@77   2308 
        Return details of the access at the given 'location'. The details are as
 
 paul@77   2309 
        follows:
 
 paul@77   2310 
 
 paul@77   2311 
         * the initial accessor (from which accesses will be performed if no
 
 paul@77   2312 
           computed static accessor is found)
 
 paul@77   2313 
         * details of any test required on the initial accessor
 
 paul@77   2314 
         * details of any type employed by the test
 
 paul@77   2315 
         * any static accessor (from which accesses will be performed in
 
 paul@77   2316 
           preference to the initial accessor)
 
 paul@77   2317 
         * attributes needing to be traversed from the base that yield
 
 paul@77   2318 
           unambiguous objects
 
 paul@98   2319 
         * access modes for each of the unambiguously-traversed attributes
 
 paul@77   2320 
         * remaining attributes needing to be tested and traversed
 
 paul@77   2321 
         * details of the context
 
 paul@102   2322 
         * any test to apply to the context
 
 paul@653   2323 
         * the method of obtaining the first attribute
 
 paul@77   2324 
         * the method of obtaining the final attribute
 
 paul@77   2325 
         * any static final attribute
 
 paul@325   2326 
         * the kinds of objects providing the final attribute
 
 paul@77   2327 
        """
 
 paul@65   2328 
 
 paul@256   2329 
        const_access = self.const_accesses_rev.get(location)
 
 paul@65   2330 
 
 paul@791   2331 
        path, name, attrnames = location.path, location.name, location.attrnames
 
 paul@75   2332 
        remaining = attrnames.split(".")
 
 paul@75   2333 
        attrname = remaining[0]
 
 paul@65   2334 
 
 paul@890   2335 
        # Special case for the ubiquitous __class__ attribute.
 
 paul@890   2336 
 
 paul@890   2337 
        ubiquitous = attrname == "__class__"
 
 paul@890   2338 
 
 paul@687   2339 
        # Obtain reference, provider and provider kind information.
 
 paul@687   2340 
 
 paul@687   2341 
        attrs = self.reference_all_attrs[location]
 
 paul@687   2342 
        provider_types = self.reference_all_providers[location]
 
 paul@687   2343 
        provider_kinds = self.reference_all_provider_kinds[location]
 
 paul@67   2344 
 
 paul@67   2345 
        # Obtain accessor type and kind information.
 
 paul@67   2346 
 
 paul@67   2347 
        accessor_types = self.reference_all_accessor_types[location]
 
 paul@67   2348 
        accessor_general_types = self.reference_all_accessor_general_types[location]
 
 paul@824   2349 
        accessor_kinds = set(get_kinds(accessor_general_types))
 
 paul@67   2350 
 
 paul@67   2351 
        # Determine any guard or test requirements.
 
 paul@67   2352 
 
 paul@67   2353 
        constrained = location in self.access_constrained
 
 paul@70   2354 
        test = self.reference_test_types[location]
 
 paul@77   2355 
        test_type = self.reference_test_accessor_type.get(location)
 
 paul@67   2356 
 
 paul@67   2357 
        # Determine the accessor and provider properties.
 
 paul@67   2358 
 
 paul@67   2359 
        class_accessor = "<class>" in accessor_kinds
 
 paul@67   2360 
        module_accessor = "<module>" in accessor_kinds
 
 paul@67   2361 
        instance_accessor = "<instance>" in accessor_kinds
 
 paul@67   2362 
        provided_by_class = "<class>" in provider_kinds
 
 paul@67   2363 
        provided_by_instance = "<instance>" in provider_kinds
 
 paul@67   2364 
 
 paul@74   2365 
        # Determine how attributes may be accessed relative to the accessor.
 
 paul@74   2366 
 
 paul@890   2367 
        object_relative = ubiquitous or class_accessor or module_accessor or provided_by_instance
 
 paul@890   2368 
        class_relative = not ubiquitous and instance_accessor and provided_by_class
 
 paul@74   2369 
 
 paul@67   2370 
        # Identify the last static attribute for context acquisition.
 
 paul@67   2371 
 
 paul@67   2372 
        base = None
 
 paul@67   2373 
        dynamic_base = None
 
 paul@67   2374 
 
 paul@687   2375 
        # Constant accesses have static providers.
 
 paul@65   2376 
 
 paul@65   2377 
        if const_access:
 
 paul@687   2378 
            base = len(provider_types) == 1 and first(provider_types)
 
 paul@67   2379 
 
 paul@263   2380 
        # Name-based accesses.
 
 paul@67   2381 
 
 paul@213   2382 
        elif name:
 
 paul@65   2383 
            ref = self.importer.identify("%s.%s" % (path, name))
 
 paul@263   2384 
 
 paul@263   2385 
            # Constant accessors are static.
 
 paul@263   2386 
 
 paul@263   2387 
            if ref and ref.static():
 
 paul@65   2388 
                base = ref.get_origin()
 
 paul@65   2389 
 
 paul@70   2390 
            # Usage of previously-generated guard and test details.
 
 paul@70   2391 
 
 paul@237   2392 
            elif test[:2] == ("constrained", "specific"):
 
 paul@67   2393 
                ref = first(accessor_types)
 
 paul@67   2394 
 
 paul@237   2395 
            elif test[:2] == ("constrained", "common"):
 
 paul@67   2396 
                ref = first(accessor_general_types)
 
 paul@67   2397 
 
 paul@237   2398 
            elif test[:2] == ("guarded", "specific"):
 
 paul@67   2399 
                ref = first(accessor_types)
 
 paul@67   2400 
 
 paul@237   2401 
            elif test[:2] == ("guarded", "common"):
 
 paul@67   2402 
                ref = first(accessor_general_types)
 
 paul@67   2403 
 
 paul@70   2404 
            # For attribute-based tests, tentatively identify a dynamic base.
 
 paul@70   2405 
            # Such tests allow single or multiple kinds of a type.
 
 paul@70   2406 
 
 paul@237   2407 
            elif test[0] == "test" and test[1] in ("common", "specific"):
 
 paul@77   2408 
                dynamic_base = test_type
 
 paul@67   2409 
 
 paul@67   2410 
            # Static accessors.
 
 paul@67   2411 
 
 paul@70   2412 
            if not base and test in self.class_tests:
 
 paul@70   2413 
                base = ref and ref.get_origin() or dynamic_base
 
 paul@70   2414 
 
 paul@70   2415 
            # Accessors that are not static but whose nature is determined.
 
 paul@70   2416 
 
 paul@70   2417 
            elif not base and ref:
 
 paul@67   2418 
                dynamic_base = ref.get_origin()
 
 paul@67   2419 
 
 paul@102   2420 
        # Determine initial accessor details.
 
 paul@102   2421 
 
 paul@102   2422 
        accessor = base or dynamic_base
 
 paul@102   2423 
        accessor_kind = len(accessor_kinds) == 1 and first(accessor_kinds) or None
 
 paul@102   2424 
        provider_kind = len(provider_kinds) == 1 and first(provider_kinds) or None
 
 paul@102   2425 
 
 paul@102   2426 
        # Traverse remaining attributes.
 
 paul@102   2427 
 
 paul@65   2428 
        traversed = []
 
 paul@96   2429 
        traversal_modes = []
 
 paul@65   2430 
 
 paul@108   2431 
        while len(attrs) == 1 and not first(attrs).has_kind("<var>"):
 
 paul@65   2432 
            attr = first(attrs)
 
 paul@65   2433 
 
 paul@65   2434 
            traversed.append(attrname)
 
 paul@96   2435 
            traversal_modes.append(accessor_kind == provider_kind and "object" or "class")
 
 paul@96   2436 
 
 paul@102   2437 
            # Consume attribute names providing unambiguous attributes.
 
 paul@102   2438 
 
 paul@75   2439 
            del remaining[0]
 
 paul@75   2440 
 
 paul@75   2441 
            if not remaining:
 
 paul@65   2442 
                break
 
 paul@65   2443 
 
 paul@67   2444 
            # Update the last static attribute.
 
 paul@67   2445 
 
 paul@65   2446 
            if attr.static():
 
 paul@65   2447 
                base = attr.get_origin()
 
 paul@65   2448 
                traversed = []
 
 paul@96   2449 
                traversal_modes = []
 
 paul@65   2450 
 
 paul@102   2451 
            # Get the access details.
 
 paul@67   2452 
 
 paul@75   2453 
            attrname = remaining[0]
 
 paul@102   2454 
            accessor = attr.get_origin()
 
 paul@102   2455 
            accessor_kind = attr.get_kind()
 
 paul@102   2456 
            provider_kind = self.importer.get_attribute_provider(attr, attrname)
 
 paul@102   2457 
            accessor_kinds = [accessor_kind]
 
 paul@102   2458 
            provider_kinds = [provider_kind]
 
 paul@102   2459 
 
 paul@102   2460 
            # Get the next attribute.
 
 paul@102   2461 
 
 paul@65   2462 
            attrs = self.importer.get_attributes(attr, attrname)
 
 paul@67   2463 
 
 paul@67   2464 
        # Where many attributes are suggested, no single attribute identity can
 
 paul@67   2465 
        # be loaded.
 
 paul@67   2466 
 
 paul@65   2467 
        else:
 
 paul@65   2468 
            attr = None
 
 paul@65   2469 
 
 paul@67   2470 
        # Determine the method of access.
 
 paul@67   2471 
 
 paul@256   2472 
        is_assignment = location in self.reference_assignments or const_access in self.reference_assignments
 
 paul@256   2473 
        is_invocation = location in self.reference_invocations or const_access in self.reference_invocations
 
 paul@98   2474 
 
 paul@71   2475 
        # Identified attribute that must be accessed via its parent.
 
 paul@71   2476 
 
 paul@98   2477 
        if attr and attr.get_name() and is_assignment:
 
 paul@98   2478 
            final_method = "static-assign"; origin = attr.get_name()
 
 paul@71   2479 
 
 paul@67   2480 
        # Static, identified attribute.
 
 paul@67   2481 
 
 paul@71   2482 
        elif attr and attr.static():
 
 paul@117   2483 
            final_method = is_assignment and "static-assign" or \
 
 paul@117   2484 
                           is_invocation and "static-invoke" or \
 
 paul@117   2485 
                           "static"
 
 paul@98   2486 
            origin = attr.final()
 
 paul@94   2487 
 
 paul@94   2488 
        # All other methods of access involve traversal.
 
 paul@94   2489 
 
 paul@94   2490 
        else:
 
 paul@587   2491 
            final_method = is_assignment and "assign" or \
 
 paul@587   2492 
                           is_invocation and "access-invoke" or \
 
 paul@587   2493 
                           "access"
 
 paul@98   2494 
            origin = None
 
 paul@67   2495 
 
 paul@93   2496 
        # First attribute accessed at a known position via the accessor.
 
 paul@67   2497 
 
 paul@495   2498 
        # Static bases support object-relative accesses only.
 
 paul@495   2499 
 
 paul@495   2500 
        if base:
 
 paul@495   2501 
            first_method = "relative-object"
 
 paul@495   2502 
 
 paul@495   2503 
        # Dynamic bases support either object- or class-relative accesses.
 
 paul@495   2504 
 
 paul@495   2505 
        elif dynamic_base:
 
 paul@94   2506 
            first_method = "relative" + (object_relative and "-object" or "") + \
 
 paul@94   2507 
                                        (class_relative and "-class" or "")
 
 paul@67   2508 
 
 paul@890   2509 
        # Special case for the ubiquitous __class__ attribute.
 
 paul@890   2510 
 
 paul@890   2511 
        elif ubiquitous:
 
 paul@890   2512 
            first_method = "relative-object"
 
 paul@890   2513 
 
 paul@67   2514 
        # The fallback case is always run-time testing and access.
 
 paul@67   2515 
 
 paul@67   2516 
        else:
 
 paul@94   2517 
            first_method = "check" + (object_relative and "-object" or "") + \
 
 paul@94   2518 
                                     (class_relative and "-class" or "")
 
 paul@67   2519 
 
 paul@102   2520 
        # Determine whether an unbound method is being accessed via an instance,
 
 paul@102   2521 
        # requiring a context test.
 
 paul@102   2522 
 
 paul@102   2523 
        context_test = "ignore"
 
 paul@102   2524 
 
 paul@102   2525 
        # Assignments do not employ the context.
 
 paul@102   2526 
 
 paul@102   2527 
        if is_assignment:
 
 paul@102   2528 
            pass
 
 paul@102   2529 
 
 paul@102   2530 
        # Obtain a selection of possible attributes if no unambiguous attribute
 
 paul@102   2531 
        # was identified.
 
 paul@102   2532 
 
 paul@102   2533 
        elif not attr:
 
 paul@102   2534 
 
 paul@102   2535 
            # Use previously-deduced attributes for a simple ambiguous access.
 
 paul@102   2536 
            # Otherwise, use the final attribute name to obtain possible
 
 paul@102   2537 
            # attributes.
 
 paul@102   2538 
 
 paul@102   2539 
            if len(remaining) > 1:
 
 paul@102   2540 
                attrname = remaining[-1]
 
 paul@102   2541 
 
 paul@102   2542 
                (class_types,
 
 paul@102   2543 
                 only_instance_types,
 
 paul@102   2544 
                 module_types) = self.get_types_for_attribute(attrname)
 
 paul@102   2545 
 
 paul@212   2546 
                accessor_kinds = set()
 
 paul@212   2547 
                provider_kinds = set()
 
 paul@102   2548 
 
 paul@102   2549 
                if class_types:
 
 paul@212   2550 
                    accessor_kinds.add("<class>")
 
 paul@212   2551 
                    accessor_kinds.add("<instance>")
 
 paul@212   2552 
                    provider_kinds.add("<class>")
 
 paul@102   2553 
                if only_instance_types:
 
 paul@212   2554 
                    accessor_kinds.add("<instance>")
 
 paul@212   2555 
                    provider_kinds.add("<instance>")
 
 paul@102   2556 
                if module_types:
 
 paul@212   2557 
                    accessor_kinds.add("<module>")
 
 paul@212   2558 
                    provider_kinds.add("<module>")
 
 paul@102   2559 
 
 paul@102   2560 
                attrs = set()
 
 paul@102   2561 
                for type in combine_types(class_types, only_instance_types, module_types):
 
 paul@102   2562 
                    attrs.update(self.importer.get_attributes(type, attrname))
 
 paul@102   2563 
 
 paul@102   2564 
            always_unbound = True
 
 paul@102   2565 
            have_function = False
 
 paul@102   2566 
            have_var = False
 
 paul@102   2567 
 
 paul@102   2568 
            # Determine whether all attributes are unbound methods and whether
 
 paul@102   2569 
            # functions or unidentified attributes occur.
 
 paul@102   2570 
 
 paul@102   2571 
            for attr in attrs:
 
 paul@102   2572 
                always_unbound = always_unbound and attr.has_kind("<function>") and attr.name_parent() == attr.parent()
 
 paul@102   2573 
                have_function = have_function or attr.has_kind("<function>")
 
 paul@102   2574 
                have_var = have_var or attr.has_kind("<var>")
 
 paul@102   2575 
 
 paul@102   2576 
            # Test for class-via-instance accesses.
 
 paul@102   2577 
 
 paul@102   2578 
            if accessor_kind == "<instance>" and \
 
 paul@102   2579 
               provider_kind == "<class>":
 
 paul@102   2580 
 
 paul@102   2581 
                if always_unbound:
 
 paul@102   2582 
                    context_test = "replace"
 
 paul@102   2583 
                else:
 
 paul@102   2584 
                    context_test = "test"
 
 paul@102   2585 
 
 paul@102   2586 
            # Test for the presence of class-via-instance accesses.
 
 paul@102   2587 
 
 paul@102   2588 
            elif "<instance>" in accessor_kinds and \
 
 paul@102   2589 
                 "<class>" in provider_kinds and \
 
 paul@102   2590 
                 (have_function or have_var):
 
 paul@102   2591 
 
 paul@102   2592 
                context_test = "test"
 
 paul@102   2593 
 
 paul@102   2594 
        # With an unambiguous attribute, determine whether a test is needed.
 
 paul@102   2595 
 
 paul@102   2596 
        elif accessor_kind == "<instance>" and \
 
 paul@102   2597 
             provider_kind == "<class>" and \
 
 paul@102   2598 
             (attr.has_kind("<var>") or
 
 paul@102   2599 
              attr.has_kind("<function>") and
 
 paul@102   2600 
              attr.name_parent() == attr.parent()):
 
 paul@102   2601 
 
 paul@102   2602 
            if attr.has_kind("<var>"):
 
 paul@102   2603 
                context_test = "test"
 
 paul@102   2604 
            else:
 
 paul@102   2605 
                context_test = "replace"
 
 paul@102   2606 
 
 paul@102   2607 
        # With an unambiguous attribute with ambiguity in the access method,
 
 paul@102   2608 
        # generate a test.
 
 paul@102   2609 
 
 paul@102   2610 
        elif "<instance>" in accessor_kinds and \
 
 paul@102   2611 
             "<class>" in provider_kinds and \
 
 paul@102   2612 
             (attr.has_kind("<var>") or
 
 paul@102   2613 
              attr.has_kind("<function>") and
 
 paul@102   2614 
              attr.name_parent() == attr.parent()):
 
 paul@102   2615 
 
 paul@102   2616 
            context_test = "test"
 
 paul@102   2617 
 
 paul@75   2618 
        # Determine the nature of the context.
 
 paul@75   2619 
 
 paul@102   2620 
        context = context_test == "ignore" and "unset" or \
 
 paul@100   2621 
                  len(traversed + remaining) == 1 and \
 
 paul@100   2622 
                      (base and "base" or "original-accessor") or \
 
 paul@100   2623 
                  "final-accessor"
 
 paul@77   2624 
 
 paul@1006   2625 
        return AccessPlan(name, test, test_type, base,
 
 paul@1006   2626 
                          traversed, traversal_modes, remaining,
 
 paul@1006   2627 
                          context, context_test,
 
 paul@1006   2628 
                          first_method, final_method,
 
 paul@1006   2629 
                          origin, accessor_kinds)
 
 paul@65   2630 
 
 paul@653   2631 
    def initialise_access_instructions(self):
 
 paul@653   2632 
 
 paul@653   2633 
        "Expand access plans into instruction sequences."
 
 paul@653   2634 
 
 paul@1007   2635 
        for access_location, access_plan in self.access_plans.items():
 
 paul@1007   2636 
            self.access_instructions[access_location] = access_plan.get_instructions()
 
 paul@1007   2637 
            self.accessor_kinds[access_location] = access_plan.accessor_kinds
 
 paul@653   2638 
 
 paul@44   2639 
# vim: tabstop=4 expandtab shiftwidth=4