Implement InvocationMirror.invokeOn method in the vm (issue 7227).

runtime/lib/invocation_mirror_patch.dart

Index: runtime/lib/invocation_mirror_patch.dart
===================================================================
--- runtime/lib/invocation_mirror_patch.dart	(revision 16186)
+++ runtime/lib/invocation_mirror_patch.dart	(working copy)
@@ -3,64 +3,112 @@
 // BSD-style license that can be found in the LICENSE file.
 
 class _InvocationMirror implements InvocationMirror {
-  static final int METHOD = 0;
-  static final int GETTER = 1;
-  static final int SETTER = 2;
+  // Constants describing the invocation type.
+  static final int _METHOD = 0;
+  static final int _GETTER = 1;
+  static final int _SETTER = 2;
 
-  // TODO(regis): Compute lazily the value of these fields, and save the
-  // arguments passed into _allocateInvocationMirror.
+  // Internal representation of the invocation mirror.
+  final String _functionName;
+  final List _argumentsDescriptor;
+  final List _arguments;
 
-  final String memberName;
-  final List positionalArguments;
-  final Map<String, dynamic> namedArguments;
+  // External representation of the invocation mirror; populated on demand.
+  String _memberName;
+  int _type;
+  List _positionalArguments;
+  Map<String, dynamic> _namedArguments;
 
-  final int _type;
+  void _setMemberNameAndType() {
+    if (_functionName.startsWith("get:")) {
+      _type = _GETTER;
+      _memberName = _functionName.substring(4);
+    } else if (_functionName.startsWith("set:")) {
+      _type = _SETTER;
+      _memberName = _functionName.substring(4).concat("=");
+    } else {
+      _type = _METHOD;
+      _memberName = _functionName;
+    }
+  }
 
-  _InvocationMirror(this.memberName,
-                    this._type,
-                    this.positionalArguments,
-                    this.namedArguments);
+  String get memberName {
+    if (_memberName == null) {
+      _setMemberNameAndType();
+    }
+    return _memberName;
+  }
 
-  static _allocateInvocationMirror(String name,
-                                   List argumentsDescriptor,
-                                   List arguments) {
-    var memberName;
-    var type;
-    if (name.startsWith("get:")) {
-      type = GETTER;
-      memberName = name.substring(4);
-    } else if (name.startsWith("set:")) {
-      type = SETTER;
-      memberName = name.substring(4).concat("=");
-    } else {
-      type = METHOD;
-      memberName = name;
+  List get positionalArguments {
+    if (_positionalArguments == null) {
+      // Exclude receiver.
+      int numPositionalArguments = _argumentsDescriptor[1] - 1;
+      _positionalArguments = _arguments.getRange(1, numPositionalArguments);
     }
-    // Exclude receiver.
-    int numArguments = argumentsDescriptor[0] - 1;
-    int numPositionalArguments = argumentsDescriptor[1] - 1;
-    int numNamedArguments = numArguments - numPositionalArguments;
-    List positionalArguments = arguments.getRange(1, numPositionalArguments);
-    Map<String, dynamic> namedArguments;
-    if (numNamedArguments > 0) {
-      namedArguments = new Map<String, dynamic>();
+    return _positionalArguments;
+  }
+
+  Map<String, dynamic> get namedArguments {
+    if (_namedArguments == null) {
+      _namedArguments = new Map<String, dynamic>();
+      int numArguments = _argumentsDescriptor[0] - 1;  // Exclude receiver.
+      int numPositionalArguments = _argumentsDescriptor[1] - 1;
+      int numNamedArguments = numArguments - numPositionalArguments;
       for (int i = 0; i < numNamedArguments; i++) {
-        String arg_name = argumentsDescriptor[2 + 2*i];
-        var arg_value = arguments[argumentsDescriptor[3 + 2*i]];
-        namedArguments[arg_name] = arg_value;
+        String arg_name = _argumentsDescriptor[2 + 2*i];
+        var arg_value = _arguments[_argumentsDescriptor[3 + 2*i]];
+        _namedArguments[arg_name] = arg_value;
       }
     }
-    return new _InvocationMirror(memberName, type,
-                                 positionalArguments, namedArguments);
+    return _namedArguments;
   }
 
-  bool get isMethod => _type == METHOD;
-  bool get isAccessor => _type != METHOD;
-  bool get isGetter => _type == GETTER;
-  bool get isSetter => _type == SETTER;
+  bool get isMethod {
+    if (_memberName == null) {
+      _setMemberNameAndType();
+    }
+    return _type == _METHOD;
+  }
 
+  bool get isAccessor {
+    if (_memberName == null) {
+      _setMemberNameAndType();
+    }
+    return _type != _METHOD;
+  }
+
+  bool get isGetter {
+    if (_memberName == null) {
+      _setMemberNameAndType();
+    }
+    return _type == _GETTER;
+  }
+
+  bool get isSetter {
+    if (_memberName == null) {
+      _setMemberNameAndType();
+    }
+    return _type == _SETTER;
+  }
+
+  _InvocationMirror(this._functionName,
+                    this._argumentsDescriptor,
+                    this._arguments);
+
+  static _allocateInvocationMirror(String functionName,
+                                   List argumentsDescriptor,
+                                   List arguments) {
+    return new _InvocationMirror(functionName, argumentsDescriptor, arguments);
+  }
+
+  static _invoke(Object receiver,
+                 String functionName,
+                 List argumentsDescriptor,
+                 List arguments)
+      native "InvocationMirror_invoke";
+
   invokeOn(Object receiver) {
-    throw new UnsupportedError("invokeOn not implemented yet");
+    _invoke(receiver, _functionName, _argumentsDescriptor, _arguments);
   }
 }