simplify computing of runtime file locations

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;
@@ skipping 12 matching lines @@
 import 'package:analyzer/src/generated/constant.dart' show DartObjectImpl;
 import 'package:analyzer/src/generated/element.dart';
 import 'package:analyzer/src/generated/engine.dart'
     show ParseDartTask, AnalysisContext;
 import 'package:analyzer/src/generated/error.dart' show ErrorCode;
 import 'package:analyzer/src/generated/resolver.dart' show TypeProvider;
 import 'package:analyzer/src/generated/source.dart' show LineInfo, Source;
 import 'package:analyzer/analyzer.dart' show parseDirectives;
 import 'package:crypto/crypto.dart' show CryptoUtils, MD5;
 import 'package:source_span/source_span.dart';
-import 'package:yaml/yaml.dart';
 
 import 'codegen/js_names.dart' show invalidVariableName;
 
 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
@@ skipping 260 matching lines @@
   if (contents == null || contents == '') return null;
   return CryptoUtils.bytesToHex((new MD5()..add(contents.codeUnits)).close());
 }
 
 /// Computes a hash for the given file path (reads the contents in binary form).
 String computeHashFromFile(String filepath) {
   var bytes = new File(filepath).readAsBytesSync();
   return CryptoUtils.bytesToHex((new MD5()..add(bytes)).close());
 }
 
-String resourceOutputPath(Uri resourceUri, Uri entryUri) {
+String resourceOutputPath(Uri resourceUri, Uri entryUri, String runtimeDir) {
   if (resourceUri.scheme == 'package') return resourceUri.path;
 
   if (resourceUri.scheme != 'file') return null;
-  var filepath = resourceUri.path;
-  var relativePath = path.relative(filepath, from: path.dirname(entryUri.path));
 
-  // File:/// urls can be for resources in the same project or resources from
-  // the dev_compiler package. For now we only support relative paths going
-  // further inside the folder where the entrypoint is located, otherwise we
-  // assume this is a runtime resource from the dev_compiler.
-  if (!relativePath.startsWith('..')) return relativePath;
+  var entryDir = path.dirname(entryUri.path);
+  var filepath = path.normalize(path.join(entryDir, resourceUri.path));
+  if (path.isWithin(runtimeDir, filepath)) {
+    filepath = path.relative(filepath, from: runtimeDir);
+    return path.join('dev_compiler', 'runtime', filepath);
+  }
 
-  // Since this is a URI path we can assume forward slash and use lastIndexOf.
-  var runtimePath = '/lib/runtime/';
-  var pos = filepath.lastIndexOf(runtimePath);
-  if (pos == -1) return null;
-
-  var filename = filepath.substring(pos + runtimePath.length);
-  var dir = filepath.substring(0, pos);
-
-  // TODO(jmesserly): can we implement this without repeatedly reading pubspec?
-  // It seems like we should know our package's root directory without needing
-  // to search like this.
-  var pubspec =
-      loadYaml(new File(path.join(dir, 'pubspec.yaml')).readAsStringSync());
-
-  // Ensure this is loaded from the dev_compiler package.
-  if (pubspec['name'] != 'dev_compiler') return null;
-  return path.join('dev_compiler', 'runtime', filename);
+  return path.relative(resourceUri.path, from: entryDir);
 }
 
 /// Given an annotated [node] and a [test] function, returns the first matching
 /// constant valued annotation.
 ///
 /// For example if we had the ClassDeclaration node for `FontElement`:
 ///
 ///    @JsName('HTMLFontElement')
 ///    @deprecated
 ///    class FontElement { ... }
@@ skipping 109 matching lines @@
   } else {
     // TODO(jmesserly): this is for backwards compat, but not sure it's very
     // useful to log this.
     return 'AnalyzerMessage';
   }
 }
 
 bool isInlineJS(Element e) => e is FunctionElement &&
     e.library.source.uri.toString() == 'dart:_foreign_helper' &&
     e.name == 'JS';