Constrain type annotations with deferred types.

sdk/lib/_internal/compiler/implementation/js/builder.dart

 // Copyright (c) 2013, 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.
 
 // Utilities for building JS ASTs at runtime.  Contains a builder class
 // and a parser that parses part of the language.
 
 part of js;
 
 class JsBuilder {
@@ skipping 27 matching lines @@
   Expression parseForeignJS(String source, [var expression]) {
     // We can parse simple JS with the mini parser.  At the moment we can't
     // handle JSON literals and function literals, both of which contain "{".
     if (source.contains("{") || source.startsWith("throw ")) {
       assert(expression == null);
       return new LiteralExpression(source);
     }
     return call(source, expression);
   }
 
+  /// Creates a litteral js string from [value].
+  LiteralString escapedString(String value) {
+    // Do not escape unicode characters and ' because they are allowed in the
+    // string literal anyway.
+    String escaped =
+        value.replaceAllMapped(new RegExp('\n|"|\\|\0|\b|\t|\v'), (match) {
+      switch (match.group(0)) {
+        case "\n" : return r"\n";
+        case "\\" : return r"\\";
+        case "\"" : return r'\"';
+        case "\0" : return r"\0";
+        case "\b" : return r"\b";
+        case "\t" : return r"\t";
+        case "\f" : return r"\f";
+        case "\v" : return r"\v";
+      }
+    });
+    LiteralString result = string(escaped);
+    // We don't escape ' under the assumption that the string is wrapped
+    // into ". Verify that assumption.
+    assert(result.value.codeUnitAt(0) == '"'.codeUnitAt(0));

[floitsch, 2014/03/06 15:25:02]

since this is an assert.
assert(result.value[0] == '"');

This is actually optimized by the VM.

+    return result;
+  }
+
+  /// Creates a litteral js string from [value].
+  ///
+  /// Note that this function only puts quotes around [value]. It does not do
+  /// any escaping, so use only when you can guarantee that [value] does not
+  /// contain newlines or backslashes. For escaping the string use
+  /// [escapedString].
   LiteralString string(String value) => new LiteralString('"$value"');
 
   LiteralNumber number(num value) => new LiteralNumber('$value');
 
   If if_(condition, thenPart, [elsePart]) {
     condition = toExpression(condition);
     return (elsePart == null)
         ? new If.noElse(condition, toStatement(thenPart))
         : new If(condition, toStatement(thenPart), toStatement(elsePart));
   }
@@ skipping 735 matching lines @@
   }
 
   Node visitLiteralNull(LiteralNull node) {
     return node;
   }
 
   Node visitLiteralBool(LiteralBool node) {
     return node;
   }
 }