implement null aware ops, fixes #249

lib/src/codegen/ast_builder.dart

 // Copyright (c) 2015, 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.
 
 library dev_compiler.src.codegen.ast_builder;
 
 import 'package:analyzer/src/generated/ast.dart';
 import 'package:analyzer/src/generated/scanner.dart';
 import 'package:analyzer/src/generated/utilities_dart.dart';
 import 'package:logging/logging.dart' as logger;
@@ skipping 82 matching lines @@
   }
 
   static Expression parenthesize(Expression exp) {
     if (exp is Identifier ||
         exp is ParenthesizedExpression ||
         exp is FunctionExpressionInvocation ||
         exp is MethodInvocation) return exp;
     return parenthesizedExpression(exp);
   }
 
+  static PropertyAccess propertyAccess(
+      Expression target, SimpleIdentifier name) {
+    var p = new Token(TokenType.PERIOD, 0);
+    return new PropertyAccess(target, p, name);
+  }
+
+  static MethodInvocation methodInvoke(
+      Expression target, SimpleIdentifier name, NodeList<Expression> args) {
+    var p = new Token(TokenType.PERIOD, 0);
+    return new MethodInvocation(target, p, name, null, argumentList(args));
+  }
+
   static TokenType getTokenType(String lexeme) {
     switch (lexeme) {
       case "&":
         return TokenType.AMPERSAND;
       case "&&":
         return TokenType.AMPERSAND_AMPERSAND;
       case "&=":
         return TokenType.AMPERSAND_EQ;
       case "@":
         return TokenType.AT;
@@ skipping 98 matching lines @@
       case "~/":
         return TokenType.TILDE_SLASH;
       case "~/=":
         return TokenType.TILDE_SLASH_EQ;
       case "`":
         return TokenType.BACKPING;
       case "\\":
         return TokenType.BACKSLASH;
       case "...":
         return TokenType.PERIOD_PERIOD_PERIOD;
+      case "??":
+        return TokenType.QUESTION_QUESTION;
+      case "??=":
+        return TokenType.QUESTION_QUESTION_EQ;
       default:
         return null;
     }
   }
 
   static Token _binaryOperation(String oper) {
     var type = getTokenType(oper);
     assert(type != null);
     return new Token(type, 0);
   }
@@ skipping 339 matching lines @@
     Label l = new Label(s, new Token(TokenType.COLON, 0));
     return new NamedExpression(l, e);
   }
 
   static VariableDeclarationStatement variableDeclarationStatement(
       VariableDeclarationList varDecl) {
     var semi = new Token(TokenType.SEMICOLON, 0);
     return new VariableDeclarationStatement(varDecl, semi);
   }
 }