# HG changeset patch
# User Paul Boddie <paul@boddie.org.uk>
# Date 1530826853 -7200
# Node ID d305986d05c873a86f06471ec962e69de543b7c7
# Parent  3b243cd23b58d6251a35e5ab633b57eb9d1c0842
Employed sets for attributes and providers referenced by accesses. This causes
various attributes to be identified definitively in the access plans and
instruction sequences.

diff -r 3b243cd23b58 -r d305986d05c8 deducer.py
--- a/deducer.py	Thu Jul 05 19:34:04 2018 +0200
+++ b/deducer.py	Thu Jul 05 23:40:53 2018 +0200
@@ -659,24 +659,22 @@
 
             attrname = location.get_attrname()
 
-            self.reference_all_attrs[location] = all_accessed_attrs = []
-            self.reference_all_providers[location] = all_providers = []
+            self.reference_all_attrs[location] = all_accessed_attrs = set()
+            self.reference_all_providers[location] = all_providers = set()
             self.reference_all_provider_kinds[location] = all_provider_kinds = set()
 
             # Obtain provider and attribute details for this kind of
             # object.
 
             for attrtype, object_type, attr in referenced_attrs:
-                all_accessed_attrs.append(attr)
-                all_providers.append(object_type)
+                all_accessed_attrs.add(attr)
+                all_providers.add(object_type)
                 all_provider_kinds.add(attrtype)
 
             # Obtain reference and provider information as sets for the
             # operations below, retaining the list forms for use with
             # instruction plan preparation.
 
-            all_accessed_attrs = set(all_accessed_attrs)
-            all_providers = set(all_providers)
             all_general_providers = self.get_most_general_types(all_providers)
 
             # Determine which attributes would be provided by the
@@ -1930,9 +1928,9 @@
 
         "Return the references identified for 'access_location'."
 
-        attrs = []
+        attrs = set()
         for attrtype, object_type, attr in self.referenced_attrs[access_location]:
-            attrs.append(attr)
+            attrs.add(attr)
         return attrs
 
     def convert_invocation_providers(self, refs, invocation):
diff -r 3b243cd23b58 -r d305986d05c8 translator.py
--- a/translator.py	Thu Jul 05 19:34:04 2018 +0200
+++ b/translator.py	Thu Jul 05 23:40:53 2018 +0200
@@ -601,8 +601,7 @@
         # Get full final identity details.
 
         if final_identity and not refs:
-            ref = self.importer.identify(final_identity)
-            refs = [ref]
+            refs = set([self.importer.identify(final_identity)])
 
         del self.attrs[0]
         return AttrResult(output, refs, location, context_identity, context_identity_verified, accessor_test)
@@ -661,14 +660,9 @@
         access_location = self.deducer.const_accesses.get(location)
 
         if remaining and not access_location:
-            return []
-
-        refs = []
-        l = self.deducer.referenced_attrs.get(access_location or location)
-        if l:
-            for attrtype, objpath, attr in l:
-                refs.append(attr)
-        return refs
+            return set()
+
+        return self.deducer.get_references_for_access(access_location or location)
 
     def get_referenced_attribute_invocations(self, location):