Support browser caching using hashes in serverMode (fixes #93, fixes #92)

lib/src/utils.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.
 
 /// Holds a couple utility functions used at various places in the system.
 library dev_compiler.src.utils;
 
 import 'dart:io';
 
 import 'package:path/path.dart' as path;
 import 'package:analyzer/src/generated/ast.dart'
     show
         ImportDirective,
         ExportDirective,
         PartDirective,
         CompilationUnit,
         Identifier,
         AnnotatedNode,
         AstNode;
 import 'package:analyzer/src/generated/engine.dart'
     show ParseDartTask, AnalysisContext;
 import 'package:analyzer/src/generated/source.dart' show Source;
 import 'package:analyzer/src/generated/element.dart';
 import 'package:analyzer/analyzer.dart' show parseDirectives;
+import 'package:crypto/crypto.dart' show CryptoUtils, MD5;
 import 'package:source_span/source_span.dart';
 
 bool isDartPrivateLibrary(LibraryElement library) {
   var uri = library.source.uri;
   if (uri.scheme != "dart") return false;
   return Identifier.isPrivateName(uri.path);
 }
 
 /// Choose a canonical name from the library element. This is safe to use as a
 /// namespace in JS and Dart code generation.  This never uses the library's
@@ skipping 141 matching lines @@
     return _RED_COLOR;
   }
   if (levelName == 'warning') return _MAGENTA_COLOR;
   if (levelName == 'info') return _CYAN_COLOR;
   return null;
 }
 
 const String _RED_COLOR = '\u001b[31m';
 const String _MAGENTA_COLOR = '\u001b[35m';
 const String _CYAN_COLOR = '\u001b[36m';
+const String GREEN_COLOR = '\u001b[32m';
+const String NO_COLOR = '\u001b[0m';
 
 class OutWriter {
   final String _path;
   final StringBuffer _sb = new StringBuffer();
   int _indent = 0;
   String _prefix = "";
   bool _needsIndent = true;
 
   OutWriter(this._path);
 
@@ skipping 53 matching lines @@
   var currentToken = node is AnnotatedNode
       ? node.firstTokenAfterCommentAndMetadata
       : node.beginToken;
   var begin = currentToken.offset;
   var end = node.end;
   var text = source.contents.data.substring(begin, end);
   var uri = source.uri;
   return new SourceSpan(locationForOffset(unit, uri, begin),
       locationForOffset(unit, uri, end), '$text');
 }
+
+/// Computes a hash for the given contents.
+String computeHash(String contents) {
+  if (contents == null || contents == '') return null;
+  return CryptoUtils.bytesToHex((new MD5()..add(contents.codeUnits)).close());
+}
+
+String resourceOutputPath(Uri resourceUri) => resourceUri.path;