First shot at source maps generation in dart2js.

lib/compiler/implementation/emitter.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.
 
 /**
  * A function element that represents a closure call. The signature is copied
  * from the given element.
  */
 class ClosureInvocationElement extends FunctionElement {
   ClosureInvocationElement(SourceString name,
@@ skipping 20 matching lines @@
   /** Shorter access to [isolatePropertiesName]. Both here in the code, as
       well as in the generated code. */
   String isolateProperties;
   final Map<int, String> boundClosureCache;
 
   CodeEmitterTask(Compiler compiler)
       : namer = compiler.namer,
         boundClosureBuffer = new StringBuffer(),
         mainBuffer = new StringBuffer(),
         boundClosureCache = new Map<int, String>(),
+        sourceMappings = new List<SourceMappingEntry>(),
         super(compiler) {
     nativeEmitter = new NativeEmitter(this);
   }
 
   String get name() => 'CodeEmitter';
 
   String get defineClassName()
       => '${namer.ISOLATE}.\$defineClass';
   String get finishClassesName()
       => '${namer.ISOLATE}.\$finishClasses';
@@ skipping 539 matching lines @@
   void emitFinishClassesInvocationIfNecessary(StringBuffer buffer) {
     if (needsDefineClass) buffer.add("$finishClassesName();\n");
   }
 
   void emitStaticFunctionsWithNamer(StringBuffer buffer,
                                     Map<Element, String> generatedCode,
                                     String functionNamer(Element element)) {
     generatedCode.forEach((Element element, String codeBlock) {
       if (!element.isInstanceMember()) {
         String functionName = functionNamer(element);
-        buffer.add('$isolateProperties.$functionName = $codeBlock;\n\n');
+        buffer.add('$isolateProperties.$functionName = ');
+        int beginPosition = buffer.length;
+        buffer.add(codeBlock);
+        int endPosition = buffer.length;
+        buffer.add(';\n\n');
+        addSourceMapping(element, beginPosition, endPosition);
       }
     });
   }
 
   void emitStaticFunctions(StringBuffer buffer) {
     emitStaticFunctionsWithNamer(buffer,
                                  compiler.codegenWorld.generatedCode,
                                  namer.getName);
     emitStaticFunctionsWithNamer(buffer,
                                  compiler.codegenWorld.generatedBailoutCode,
@@ skipping 388 matching lines @@
       emitMain(mainBuffer);
       mainBuffer.add('function init() {\n');
       mainBuffer.add('  $isolateProperties = {};\n');
       addDefineClassAndFinishClassFunctionsIfNecessary(mainBuffer);
       emitFinishIsolateConstructor(mainBuffer);
       mainBuffer.add('}\n');
       compiler.assembledCode = mainBuffer.toString();
     });
     return compiler.assembledCode;
   }
+
+  void addSourceMapping(FunctionElement element, int emittedBeginPosition, int emittedEndPosition) {

[podivilov, 2012/06/19 16:37:54]

This should probably be a method of SourceMapListener interface.

[ahe, 2012/06/19 17:00:41]

Long lines.

[podivilov, 2012/06/20 09:37:14]

Done.

+    SourceFile sourceFile = element.getCompilationUnit().script.file;
+    FunctionExpression expression = element.cachedNode;
+    sourceMappings.add(new SourceMappingEntry(sourceFile, expression.getBeginToken().charOffset, emittedBeginPosition));
+    sourceMappings.add(new SourceMappingEntry(sourceFile, expression.getEndToken().charOffset, emittedEndPosition));
+  }
+
+  final List<SourceMappingEntry> sourceMappings;
 }