# HG changeset patch
# User Paul Boddie <paul@boddie.org.uk>
# Date 1207509966 -7200
# Node ID 24df65a47aa8ef4220e7fe70697e972661dd0898
# Parent  0ed30aeb2ef92a70830b17ad7f3a02d67b26acc7
Made optimised attribute access via self optional.
Renamed an example.

diff -r 0ed30aeb2ef9 -r 24df65a47aa8 micropython/ast.py
--- a/micropython/ast.py	Sun Apr 06 03:04:36 2008 +0200
+++ b/micropython/ast.py	Sun Apr 06 21:26:06 2008 +0200
@@ -48,7 +48,7 @@
 
     "A translated module."
 
-    supported_optimisations = ["constant_storage", "known_target"]
+    supported_optimisations = ["constant_storage", "known_target", "self_access"]
 
     def __init__(self, module, objtable, paramtable, builtins=None, optimisations=None):
 
@@ -238,14 +238,11 @@
             self.replace_op(AttrInstruction(pos))
 
         # Where the last operation involves the special 'self' name, check to
-        # see if the attribute is acceptably positioned.
+        # see if the attribute is acceptably positioned and produce a direct
+        # access to the attribute.
 
-        elif isinstance(self.unit, micropython.inspect.Function) and \
-            self.unit.is_method() and isinstance(last, LoadName) and \
-            last.attr.name == "self" and not self.unit.is_relocated(attrname):
-
-            attr = self.unit.parent.all_attributes()[attrname]
-            self.new_op(AttrInstruction(attr))
+        elif self._optimise_self_access(attrname, AttrInstruction):
+            pass
 
         # Otherwise, perform a normal operation.
 
@@ -471,6 +468,9 @@
     def _should_optimise_known_target(self):
         return "known_target" in self.optimisations
 
+    def _should_optimise_self_access(self):
+        return "self_access" in self.optimisations
+
     def _have_constant_input(self, n):
         last = self.last_ops(n+1)
         return len(last) > n and (isinstance(last[n], LoadAttr) and last[n].attr.assignments == 1 or
@@ -479,17 +479,26 @@
     def _have_known_target(self):
         return self._have_constant_input(0)
 
+    def _have_self_input(self):
+        last = self.last_op()
+        return isinstance(self.unit, micropython.inspect.Function) and \
+            self.unit.is_method() and isinstance(last, LoadName) and \
+            last.attr.name == "self"
+
     # Optimisation methods. See the supported_optimisations class attribute.
 
-    def _optimise_constant_storage(self, cls, n):
+    def _optimise_constant_storage(self, instruction, n):
 
         """
         Where this operation should store a constant into a target which is
         also constant, optimise away both operations.
         """
 
-        if self._should_optimise_constant_storage() and cls in (StoreAttr, StoreName) and \
-            self._have_constant_input(n) and (n == 0 or self._have_constant_input(n-1)):
+        if self._should_optimise_constant_storage() and \
+            instruction in (StoreAttr, StoreName) and \
+            self._have_constant_input(n) and \
+            (n == 0 or self._have_constant_input(n-1)):
+
             self.remove_ops(n+1)
             return 1
         else:
@@ -523,6 +532,23 @@
 
         return target, context
 
+    def _optimise_self_access(self, attrname, instruction):
+
+        """
+        Where the provided 'attrname' accesses an attribute which occupies the
+        same position in all possible objects which can be accessed, generate an
+        'instruction' accessing the attribute directly.
+        """
+
+        if self._should_optimise_self_access() and self._have_self_input() and \
+            not self.unit.is_relocated(attrname):
+
+            attr = self.unit.parent.all_attributes()[attrname]
+            self.new_op(instruction(attr))
+            return 1
+        else:
+            return 0
+
     # Visitor methods.
 
     def default(self, node, *args):
diff -r 0ed30aeb2ef9 -r 24df65a47aa8 tests/attributes.py
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/tests/attributes.py	Sun Apr 06 21:26:06 2008 +0200
@@ -0,0 +1,9 @@
+#!/usr/bin/env python
+
+class C:
+    clsattr = 123
+
+    def __init__(self, value):
+        self.instattr = value
+
+# vim: tabstop=4 expandtab shiftwidth=4
diff -r 0ed30aeb2ef9 -r 24df65a47aa8 tests/sealing.py
--- a/tests/sealing.py	Sun Apr 06 03:04:36 2008 +0200
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,9 +0,0 @@
-#!/usr/bin/env python
-
-class C:
-    clsattr = 123
-
-    def __init__(self, value):
-        self.instattr = value
-
-# vim: tabstop=4 expandtab shiftwidth=4