First shot at source maps generation in dart2js.

lib/compiler/implementation/dart2js.dart

Index: lib/compiler/implementation/dart2js.dart
diff --git a/lib/compiler/implementation/dart2js.dart b/lib/compiler/implementation/dart2js.dart
index e463a62ec3b58d9b12481d75fa0e3a9eabf051ef..f184553252ac6fa12a5cc3e5e36bb9530f579a33 100644
--- a/lib/compiler/implementation/dart2js.dart
+++ b/lib/compiler/implementation/dart2js.dart
@@ -71,6 +71,7 @@ void compile(List<String> argv) {
   bool verbose = false;
   Uri libraryRoot = cwd;
   Uri out = cwd.resolve('out.js');
+  Uri sourceMapOut = null;
   Uri packageRoot = null;
   List<String> options = new List<String>();
   bool explicitOut = false;
@@ -91,6 +92,10 @@ void compile(List<String> argv) {
     out = cwd.resolve(nativeToUriPath(extractParameter(argument)));
   }
 
+  setSourceMapOutput(String argument) {
+    sourceMapOut = cwd.resolve(nativeToUriPath(extractParameter(argument)));
+  }
+
   handleShortOptions(String argument) {
     var shortOptions = argument.substring(1).splitChars();
     for (var shortOption in shortOptions) {
@@ -120,9 +125,11 @@ void compile(List<String> argv) {
     new OptionHandler('--verbose', (_) => verbose = true),
     new OptionHandler('--library-root=.+', setLibraryRoot),
     new OptionHandler('--out=.+|-o.+', setOutput),
+    new OptionHandler('--source-map-out=.+', setSourceMapOutput),
     new OptionHandler('--allow-mock-compilation', passThrough),
     new OptionHandler('--unparse-validation', passThrough),
     new OptionHandler('--no-colors', (_) => colors.enabled = false),

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

I think you accidentally copied a line here.

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

Done.

+    new OptionHandler('--no-colors', (_) => colors.enabled = false),
     new OptionHandler('--enable[_-]checked[_-]mode|--checked',
                       (_) => passThrough('--enable-checked-mode')),
     new OptionHandler(@'--help|/\?|/h', (_) => wantHelp = true),
@@ -202,11 +209,16 @@ void compile(List<String> argv) {
 
   // TODO(ahe): We expect the future to be complete and call value
   // directly. In effect, we don't support truly asynchronous API.
-  String code = api.compile(uri, libraryRoot, packageRoot, provider, handler,
-                            options).value;
+  api.CompiledScript script = api.compile(
+      uri, libraryRoot, packageRoot, provider, handler, options).value;
+  String code = script.code;
   if (code === null) {
     fail('Error: Compilation failed.');
   }
+  if (sourceMapOut !== null) {
+    writeString(sourceMapOut, script.sourceMap);
+    code = '$code\n//@ sourceMappingURL=$sourceMapOut';
+  }
   writeString(out, code);
   int jsBytesWritten = code.length;
   info('compiled $dartBytesRead bytes Dart -> $jsBytesWritten bytes JS '