Support source maps in server mode

lib/src/codegen/js_printer.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.js_printer;
 
 import 'dart:convert' show JSON, JsonEncoder;
 import 'dart:io' show Directory, File, Platform, Process;
 
 import 'package:analyzer/src/generated/ast.dart';
 import 'package:path/path.dart' as path;
 import 'package:source_maps/source_maps.dart' as srcmaps show Printer;
 import 'package:source_maps/source_maps.dart' show SourceMapSpan;
 import 'package:source_span/source_span.dart' show SourceLocation;
 
 import '../js/js_ast.dart' as JS;
 import '../utils.dart' show computeHash, locationForOffset;
 
 import 'js_names.dart' show TemporaryNamer;
 
-String writeJsLibrary(JS.Program jsTree, String outputPath,
+String writeJsLibrary(JS.Program jsTree, String outputPath, String inputDir,
+    String serverUrl,
     {bool emitSourceMaps: false, bool arrowFnBindThisWorkaround: false}) {
   var outFilename = path.basename(outputPath);
   var outDir = path.dirname(outputPath);
   new Directory(outDir).createSync(recursive: true);
 
   JS.JavaScriptPrintingContext context;
   if (emitSourceMaps) {
     var printer = new srcmaps.Printer(outFilename);
-    context = new SourceMapPrintingContext(printer, outDir);
+    context = new SourceMapPrintingContext(printer, outDir, inputDir, serverUrl);
   } else {
     context = new JS.SimpleJavaScriptPrintingContext();
   }
 
   var opts = new JS.JavaScriptPrintingOptions(
       allowKeywordsInProperties: true,
       arrowFnBindThisWorkaround: arrowFnBindThisWorkaround);
   var jsNamer = new TemporaryNamer(jsTree);
   jsTree.accept(new JS.Printer(opts, context, localNamer: jsNamer));
 
@@ skipping 24 matching lines @@
     // TODO(jmesserly): should only do this if the input file was executable?
     if (!Platform.isWindows) Process.runSync('chmod', ['+x', outputPath]);
   }
 
   return computeHash(text);
 }
 
 class SourceMapPrintingContext extends JS.JavaScriptPrintingContext {
   final srcmaps.Printer printer;
   final String outputDir;
+  final String inputDir;
+  final String serverUrl;
 
   CompilationUnit unit;
   Uri uri;
 
-  SourceMapPrintingContext(this.printer, this.outputDir);
+  SourceMapPrintingContext(this.printer, this.outputDir, this.inputDir, this.serverUrl);

[Jennifer Messerly, 2015/12/16 18:40:07]

slight factoring thing, I wonder if we should pass in something that can do URI
mapping for us (AbstractCompiler?), rather than have SourceMapPrintingContext
know about server details?

I've been slowly trying to disentangle server from the rest of the code base, in
the hopes that we can remove it in favor of a file watcher as the primary dev
experience.

[vsm, 2016/01/07 21:22:03]

added a todo

 
   void emit(String string) {
     printer.add(string);
   }
 
   AstNode _currentTopLevelDeclaration;
 
   void enterNode(JS.Node jsNode) {
     AstNode node = jsNode.sourceInformation;
     if (node == null || node.offset == -1) return;
     if (unit == null) {
       // This is a top-level declaration.  Note: consecutive top-level
       // declarations may come from different compilation units due to
       // parts.
       _currentTopLevelDeclaration = node;
       unit = node.getAncestor((n) => n is CompilationUnit);
       uri = _makeRelativeUri(unit.element.source.uri);
     }
+    if (unit == null) return;
 
     assert(unit != null);
     var loc = _location(node.offset);
     var name = _getIdentifier(node);
     if (name != null) {
       // TODO(jmesserly): mark only uses the beginning of the span, but
       // we're required to pass this as a valid span.
       var end = _location(node.end);
       printer.mark(new SourceMapSpan(loc, end, name, isIdentifier: true));
     } else {
       printer.mark(loc);
     }
   }
 
   SourceLocation _location(int offset) =>
       locationForOffset(unit.lineInfo, uri, offset);
 
   Uri _makeRelativeUri(Uri src) {
-    return new Uri(path: path.relative(src.path, from: outputDir));
+    if (serverUrl == null) {
+      return new Uri(path: path.relative(src.path, from: outputDir));
+    } else {
+      if (src.path.startsWith('/')) {
+        return new Uri(path: serverUrl + path.relative(src.path, from: inputDir));

[Jennifer Messerly, 2015/12/16 18:40:07]

the name here's a little confusing, if this was a full "serverUrl" I don't think
it would make sense to put it in the "path" part of the Uri. I guess it's the
"servePath", e.g. if server Url is http://localhost:8080/foo/bar, this is the
"foo/bar/" part?

[vsm, 2016/01/07 21:22:03]

i think i was abusing the path argument to the Uri constructor.  redid this more
cleanly.

+      } else {
+        return new Uri(path: serverUrl + 'packages/' + src.path);
+      }
+    }
   }
 
   void exitNode(JS.Node jsNode) {
     AstNode node = jsNode.sourceInformation;
     if (unit == null || node == null || node.offset == -1) return;
 
     // TODO(jmesserly): in many cases marking the end will be unnecessary.
     printer.mark(_location(node.end));
 
     if (_currentTopLevelDeclaration == node) {
       unit = null;
       uri = null;
       _currentTopLevelDeclaration == null;
       return;
     }
   }
 
   String _getIdentifier(AstNode node) {
     if (node is SimpleIdentifier) return node.name;
     return null;
   }
 }