[VM generic function reification] Support generic functions in Invocation class.

runtime/lib/invocation_mirror_patch.dart

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 // NOTE: When making changes to this class, please also update
 // `VmTarget.instantiateInvocation` and `VmTarget._invocationType` in
 // `pkg/kernel/lib/target/vm.dart`.
+// TODO(regis): See above NOTE.
 class _InvocationMirror implements Invocation {
   // Constants describing the invocation type.
   // _FIELD cannot be generated by regular invocation mirrors.
   static const int _METHOD = 0;
   static const int _GETTER = 1;
   static const int _SETTER = 2;
   static const int _FIELD = 3;
   static const int _LOCAL_VAR = 4;
   static const int _TYPE_SHIFT = 0;
   static const int _TYPE_BITS = 3;
@@ skipping 18 matching lines @@
 
   // Internal representation of the invocation mirror.
   final String _functionName;
   final List _argumentsDescriptor;
   final List _arguments;
   final bool _isSuperInvocation;
 
   // External representation of the invocation mirror; populated on demand.
   Symbol _memberName;
   int _type;
+  List _typeArguments;
   List _positionalArguments;
   Map<Symbol, dynamic> _namedArguments;
 
   void _setMemberNameAndType() {
     if (_functionName.startsWith("get:")) {
       _type = _GETTER;
       _memberName = new internal.Symbol.unvalidated(_functionName.substring(4));
     } else if (_functionName.startsWith("set:")) {
       _type = _SETTER;
       _memberName =
           new internal.Symbol.unvalidated(_functionName.substring(4) + "=");
     } else {
       _type = _isSuperInvocation ? (_SUPER << _CALL_SHIFT) | _METHOD : _METHOD;
       _memberName = new internal.Symbol.unvalidated(_functionName);
     }
   }
 
   Symbol get memberName {
     if (_memberName == null) {
       _setMemberNameAndType();
     }
     return _memberName;
   }
 
+  List get typeArguments {
+    if (_typeArguments == null) {
+      int typeArgsLen = _argumentsDescriptor[_TYPE_ARGS_LEN];
+      if (typeArgsLen == 0) {
+        return _typeArguments = const [];
+      }
+      // A TypeArguments object does not have a corresponding Dart class and
+      // cannot be accessed as an array in Dart. Therefore, we need a native
+      // call to unpack the individual types into a list.
+      _typeArguments = _unpackTypeArguments(_arguments[0]);
+    }
+    return _typeArguments;
+  }
+
+  // Unpack the given TypeArguments object into a new list of individual types.
+  static List _unpackTypeArguments(typeArguments)
+      native "InvocationMirror_unpackTypeArguments";
+
   List get positionalArguments {
     if (_positionalArguments == null) {
-      int numPositionalArguments = _argumentsDescriptor[_POSITIONAL_COUNT];
-      // Don't count receiver.
-      if (numPositionalArguments == 1) {
+      // The argument descriptor counts the receiver, but not the type arguments
+      // as positional arguments.
+      int numPositionalArguments = _argumentsDescriptor[_POSITIONAL_COUNT] - 1;
+      if (numPositionalArguments == 0) {
         return _positionalArguments = const [];
       }
-      // Exclude receiver.
-      _positionalArguments =
-          new _ImmutableList._from(_arguments, 1, numPositionalArguments - 1);
+      // Exclude receiver and type args in the returned list.
+      int receiverIndex = _argumentsDescriptor[_TYPE_ARGS_LEN] > 0 ? 1 : 0;
+      _positionalArguments = new _ImmutableList._from(
+          _arguments, receiverIndex + 1, numPositionalArguments);
     }
     return _positionalArguments;
   }
 
   Map<Symbol, dynamic> get namedArguments {
     if (_namedArguments == null) {
       int numArguments = _argumentsDescriptor[_COUNT] - 1; // Exclude receiver.
       int numPositionalArguments = _argumentsDescriptor[_POSITIONAL_COUNT] - 1;
       int numNamedArguments = numArguments - numPositionalArguments;
       if (numNamedArguments == 0) {
         return _namedArguments = const {};
       }
+      int receiverIndex = _argumentsDescriptor[_TYPE_ARGS_LEN] > 0 ? 1 : 0;
       _namedArguments = new Map<Symbol, dynamic>();
       for (int i = 0; i < numNamedArguments; i++) {
         int namedEntryIndex = _FIRST_NAMED_ENTRY + 2 * i;
         String arg_name = _argumentsDescriptor[namedEntryIndex];
-        var arg_value = _arguments[_argumentsDescriptor[namedEntryIndex + 1]];
+        var arg_value = _arguments[
+            receiverIndex + _argumentsDescriptor[namedEntryIndex + 1]];
         _namedArguments[new internal.Symbol.unvalidated(arg_name)] = arg_value;
       }
       _namedArguments = new Map.unmodifiable(_namedArguments);
     }
     return _namedArguments;
   }
 
   bool get isMethod {
     if (_type == null) {
       _setMemberNameAndType();
@@ skipping 24 matching lines @@
 
   _InvocationMirror(this._functionName, this._argumentsDescriptor,
       this._arguments, this._isSuperInvocation);
 
   static _allocateInvocationMirror(String functionName,
       List argumentsDescriptor, List arguments, bool isSuperInvocation) {
     return new _InvocationMirror(
         functionName, argumentsDescriptor, arguments, isSuperInvocation);
   }
 }