Reland r45669:

runtime/bin/builtin.dart

Index: runtime/bin/builtin.dart
===================================================================
--- runtime/bin/builtin.dart	(revision 45696)
+++ runtime/bin/builtin.dart	(working copy)
@@ -4,68 +4,99 @@
 
 library builtin;
 // NOTE: Do not import 'dart:io' in builtin.
-import 'dart:async';
-import 'dart:convert';
 import 'dart:isolate';
+import 'dart:typed_data';
 
+// import 'root_library'; happens here from C Code
 
-/* See Dart_LibraryTag in dart_api.h */
-const Dart_kScriptTag = null;
-const Dart_kImportTag = 0;
-const Dart_kSourceTag = 1;
-const Dart_kCanonicalizeUrl = 2;
+// Build time flag to enable debug logging of loading code.
+const _logLoading = false;
 
-// Dart native extension scheme.
-const _DART_EXT = 'dart-ext:';
 
-// import 'root_library'; happens here from C Code
-
 // The root library (aka the script) is imported into this library. The
 // standalone embedder uses this to lookup the main entrypoint in the
 // root library's namespace.
 Function _getMainClosure() => main;
 
-// A port for communicating with the service isolate for I/O.
-SendPort _loadPort;
 
-const _logBuiltin = false;
+// 'print' implementation.
+// The standalone embedder registers the closurized _print function with the
+// dart:core library.
+void _printString(String s) native "Builtin_PrintString";
 
-// Corelib 'print' implementation.
+
 void _print(arg) {
-  _Logger._printString(arg.toString());
+  _printString(arg.toString());
 }
 
-class _Logger {
-  static void _printString(String s) native "Logger_PrintString";
-}
 
 _getPrintClosure() => _print;
 
+
+// Corelib 'Uri.base' implementation.
+// Uri.base is susceptible to changes in the current working directory.
 _getCurrentDirectoryPath() native "Builtin_GetCurrentDirectory";
 
-// Corelib 'Uri.base' implementation.
+
 Uri _uriBase() {
   // We are not using Dircetory.current here to limit the dependency
   // on dart:io. This code is the same as:
   //   return new Uri.file(Directory.current.path + "/");
   var result = _getCurrentDirectoryPath();
-  return new Uri.file(result + "/");
+  return new Uri.file("$result/");
 }
 
+
 _getUriBaseClosure() => _uriBase;
 
 
-// Are we running on Windows?
-var _isWindows;
-var _workingWindowsDrivePrefix;
-// The current working directory
+// Asynchronous loading of resources.
+// The embedder forwards most loading requests to this library.
+
+// See Dart_LibraryTag in dart_api.h
+const Dart_kScriptTag = null;
+const Dart_kImportTag = 0;
+const Dart_kSourceTag = 1;
+const Dart_kCanonicalizeUrl = 2;
+
+// A port for communicating with the service isolate for I/O.
+SendPort _loadPort;
+// Maintain a number of outstanding load requests. Current loading request is
+// finished once there are no outstanding requests.
+int _numOutstandingLoadRequests = 0;
+
+// The current working directory when the embedder was launched.
 var _workingDirectoryUri;
 // The URI that the entry point script was loaded from. Remembered so that
 // package imports can be resolved relative to it.
 var _entryPointScript;
-// The directory to look in to resolve "package:" scheme URIs.
-var _packageRoot;
+// The directory to look in to resolve "package:" scheme URIs. By detault it is
+// the 'packages' directory right next to the script.
+var _packageRoot = _entryPointScript.resolve('packages/');
 
+// Special handling for Windows paths so that they are compatible with URI
+// handling.
+// Embedder sets whether we are running on Windows.
+var _isWindows;
+
+
+// A class wrapping the load error message in an Error object.
+class LoadError extends Error {
+  final String message;
+  LoadError(this.message);
+
+  String toString() => 'Load Error: $message';
+}
+
+
+// Native calls provided by the embedder.
+void _signalDoneLoading() native "Builtin_DoneLoading";
+void _loadScriptCallback(int tag, String uri, String libraryUri, Uint8List data)
+    native "Builtin_LoadSource";
+void _asyncLoadErrorCallback(uri, libraryUri, error)
+    native "Builtin_AsyncLoadError";
+
+
 _sanitizeWindowsPath(path) {
   // For Windows we need to massage the paths a bit according to
   // http://blogs.msdn.com/b/ie/archive/2006/12/06/file-uris-in-windows.aspx
@@ -90,6 +121,7 @@
   return fixedPath;
 }
 
+
 _trimWindowsPath(path) {
   // Convert /X:/ to X:/.
   if (_isWindows == false) {
@@ -107,8 +139,9 @@
   return path;
 }
 
+
+// Ensure we have a trailing slash character.
 _enforceTrailingSlash(uri) {
-  // Ensure we have a trailing slash character.
   if (!uri.endsWith('/')) {
     return '$uri/';
   }
@@ -116,28 +149,21 @@
 }
 
 
-_extractDriveLetterPrefix(cwd) {
-  if (!_isWindows) {
-    return null;
+// Embedder Entrypoint:
+// The embedder calls this method with the current working directory.
+void _setWorkingDirectory(cwd) {
+  if (_logLoading) {
+    _print('# Setting working directory: $cwd');
   }
-  if (cwd.length > 1 && cwd[1] == ':') {
-    return '/${cwd[0]}:';
+  _workingDirectoryUri = new Uri.directory(cwd);
+  if (_logLoading) {
+    _print('# Working directory URI: $_workingDirectoryUri');
   }
-  return null;
 }
 
 
-void _setWorkingDirectory(cwd) {
-  _workingWindowsDrivePrefix = _extractDriveLetterPrefix(cwd);
-  cwd = _sanitizeWindowsPath(cwd);
-  cwd = _enforceTrailingSlash(cwd);
-  _workingDirectoryUri = new Uri(scheme: 'file', path: cwd);
-  if (_logBuiltin) {
-    _print('# Working Directory: $cwd');
-  }
-}
-
-
+// Embedder Entrypoint:
+// The embedder calls this method with a custom package root.
 _setPackageRoot(String packageRoot) {
   packageRoot = _enforceTrailingSlash(packageRoot);
   if (packageRoot.startsWith('file:') ||
@@ -149,7 +175,7 @@
     packageRoot = _trimWindowsPath(packageRoot);
     _packageRoot = _workingDirectoryUri.resolveUri(new Uri.file(packageRoot));
   }
-  if (_logBuiltin) {
+  if (_logLoading) {
     _print('# Package root: $packageRoot -> $_packageRoot');
   }
 }
@@ -167,76 +193,44 @@
           "'$right', not '$wrong'.";
   }
 
-  var packageRoot = _packageRoot == null ?
-                    _entryPointScript.resolve('packages/') :
-                    _packageRoot;
-  return packageRoot.resolve(uri.path);
+  if (_logLoading) {
+    _print('# Package root: $_packageRoot');
+    _print('# uri path: ${uri.path}');
+  }
+  return _packageRoot.resolve(uri.path);
 }
 
 
-
-String _resolveScriptUri(String scriptName) {
+// Resolves the script uri in the current working directory iff the given uri
+// did not specify a scheme (e.g. a path to a script file on the command line).
+Uri _resolveScriptUri(String scriptName) {
   if (_workingDirectoryUri == null) {
     throw 'No current working directory set.';
   }
   scriptName = _sanitizeWindowsPath(scriptName);
 
   var scriptUri = Uri.parse(scriptName);
-  if (scriptUri.scheme != '') {
-    // Script has a scheme, assume that it is fully formed.
-    _entryPointScript = scriptUri;
-  } else {
+  if (scriptUri.scheme == '') {
     // Script does not have a scheme, assume that it is a path,
     // resolve it against the working directory.
-    _entryPointScript = _workingDirectoryUri.resolve(scriptName);
+    scriptUri = _workingDirectoryUri.resolveUri(scriptUri);
   }
-  if (_logBuiltin) {
-    _print('# Resolved entry point to: $_entryPointScript');
-  }
-  return _entryPointScript.toString();
-}
 
+  // Remember the entry point script URI so that we can resolve packages
+  // based on this location.
+  _entryPointScript = scriptUri;
 
-// Function called by standalone embedder to resolve uris.
-String _resolveUri(String base, String userString) {
-  if (_logBuiltin) {
-    _print('# Resolving: $userString from $base');
+  if (_logLoading) {
+    _print('# Resolved entry point to: $_entryPointScript');
   }
-  var baseUri = Uri.parse(base);
-  if (userString.startsWith(_DART_EXT)) {
-    var uri = userString.substring(_DART_EXT.length);
-    return '$_DART_EXT${baseUri.resolve(uri)}';
-  } else {
-    return baseUri.resolve(userString).toString();
-  }
+  return scriptUri;
 }
 
-Uri _createUri(String userUri) {
-  var uri = Uri.parse(userUri);
-  switch (uri.scheme) {
-    case '':
-    case 'data':
-    case 'file':
-    case 'http':
-    case 'https':
-      return uri;
-    case 'package':
-      return _resolvePackageUri(uri);
-    default:
-      // Only handling file, http[s], and package URIs
-      // in standalone binary.
-      if (_logBuiltin) {
-        _print('# Unknown scheme (${uri.scheme}) in $uri.');
-      }
-      throw 'Not a known scheme: $uri';
-  }
-}
 
-int _numOutstandingLoadRequests = 0;
-void _finishedOneLoadRequest(String uri) {
+void _finishLoadRequest(String uri) {
   assert(_numOutstandingLoadRequests > 0);
   _numOutstandingLoadRequests--;
-  if (_logBuiltin) {
+  if (_logLoading) {
     _print("Loading of $uri finished, "
            "${_numOutstandingLoadRequests} requests remaining");
   }
@@ -245,38 +239,28 @@
   }
 }
 
-void _startingOneLoadRequest(String uri) {
+
+void _startLoadRequest(String uri, Uri resourceUri) {
   assert(_numOutstandingLoadRequests >= 0);
   _numOutstandingLoadRequests++;
-  if (_logBuiltin) {
-    _print("Loading of $uri started, "
+  if (_logLoading) {
+    _print("Loading of $resourceUri for $uri started, "
            "${_numOutstandingLoadRequests} requests outstanding");
   }
 }
 
-class LoadError extends Error {
-  final String message;
-  LoadError(this.message);
 
-  String toString() => 'Load Error: $message';
-}
-
-void _signalDoneLoading() native "Builtin_DoneLoading";
-void _loadScriptCallback(int tag, String uri, String libraryUri, List<int> data)
-    native "Builtin_LoadScript";
-void _asyncLoadErrorCallback(uri, libraryUri, error)
-    native "Builtin_AsyncLoadError";
-
-void _loadScript(int tag, String uri, String libraryUri, List<int> data) {
+void _loadScript(int tag, String uri, String libraryUri, Uint8List data) {
   // TODO: Currently a compilation error while loading the script is
   // fatal for the isolate. _loadScriptCallback() does not return and
   // the _numOutstandingLoadRequests counter remains out of sync.
   _loadScriptCallback(tag, uri, libraryUri, data);
-  _finishedOneLoadRequest(uri);
+  _finishLoadRequest(uri);
 }
 
+
 void _asyncLoadError(int tag, String uri, String libraryUri, LoadError error) {
-  if (_logBuiltin) {
+  if (_logLoading) {
     _print("_asyncLoadError($uri), error: $error");
   }
   if (tag == Dart_kImportTag) {
@@ -285,18 +269,18 @@
     libraryUri = uri;
   }
   _asyncLoadErrorCallback(uri, libraryUri, error);
-  _finishedOneLoadRequest(uri);
+  _finishLoadRequest(uri);
 }
 
 
-_loadDataAsyncLoadPort(int tag,
-                       String uri,
-                       String libraryUri,
-                       Uri resourceUri) {
+_loadDataFromLoadPort(int tag,
+                      String uri,
+                      String libraryUri,
+                      Uri resourceUri) {
   var receivePort = new ReceivePort();
   receivePort.first.then((dataOrError) {
     receivePort.close();
-    if (dataOrError is List<int>) {
+    if (dataOrError is Uint8List) {
       _loadScript(tag, uri, libraryUri, dataOrError);
     } else {
       assert(dataOrError is String);
@@ -314,9 +298,9 @@
   try {
     var msg = [receivePort.sendPort, resourceUri.toString()];
     _loadPort.send(msg);
-    _startingOneLoadRequest(uri);
+    _startLoadRequest(uri, resourceUri);
   } catch (e) {
-    if (_logBuiltin) {
+    if (_logLoading) {
       _print("Exception when communicating with service isolate: $e");
     }
     // Wrap inside a LoadError unless we are already propagating a previously
@@ -327,21 +311,92 @@
   }
 }
 
+
+// Embedder Entrypoint:
 // Asynchronously loads script data through a http[s] or file uri.
 _loadDataAsync(int tag, String uri, String libraryUri) {
+  var resourceUri;
   if (tag == Dart_kScriptTag) {
-    uri = _resolveScriptUri(uri);
+    resourceUri = _resolveScriptUri(uri);
+    uri = resourceUri.toString();
+  } else {
+    resourceUri = Uri.parse(uri);
   }
 
-  Uri resourceUri = _createUri(uri);
+  // package based uris need to be resolved to the correct loadable location.
+  if (resourceUri.scheme == 'package') {
+    resourceUri = _resolvePackageUri(resourceUri);
+  }
 
-  _loadDataAsyncLoadPort(tag, uri, libraryUri, resourceUri);
+  _loadDataFromLoadPort(tag, uri, libraryUri, resourceUri);
 }
 
+
+// Embedder Entrypoint:
+// Function called by standalone embedder to resolve uris when the VM requests
+// Dart_kCanonicalizeUrl from the tag handler.
+String _resolveUri(String base, String userString) {
+  if (_logLoading) {
+    _print('# Resolving: $userString from $base');
+  }
+  var baseUri = Uri.parse(base);
+  var result;
+  if (userString.startsWith(_DART_EXT)) {
+    var uri = userString.substring(_DART_EXT.length);
+    result = '$_DART_EXT${baseUri.resolve(uri)}';
+  } else {
+    result = baseUri.resolve(userString).toString();
+  }
+  if (_logLoading) {
+    _print('Resolved $userString in $base to $result');
+  }
+  return result;
+}
+
+
+// Embedder Entrypoint (gen_snapshot):
+// Resolve relative paths relative to working directory.
+String _resolveInWorkingDirectory(String fileName) {
+  if (_workingDirectoryUri == null) {
+    throw 'No current working directory set.';
+  }
+  var name = _sanitizeWindowsPath(fileName);
+
+  var uri = Uri.parse(name);
+  if (uri.scheme != '') {
+    throw 'Schemes are not supported when resolving filenames.';
+  }
+  uri = _workingDirectoryUri.resolveUri(uri);
+
+  if (_logLoading) {
+    _print('# Resolved in working directory: $fileName -> $uri');
+  }
+  return uri.toString();
+}
+
+
+// Handling of dart-ext loading.
+// Dart native extension scheme.
+const _DART_EXT = 'dart-ext:';
+
+String _nativeLibraryExtension() native "Builtin_NativeLibraryExtension";
+
+
+String _platformExtensionFileName(String name) {
+  var extension = _nativeLibraryExtension();
+
+  if (_isWindows) {
+    return '$name.$extension';
+  } else {
+    return 'lib$name.$extension';
+  }
+}
+
+
 // Returns either a file path or a URI starting with http[s]:, as a String.
 String _filePathFromUri(String userUri) {
   var uri = Uri.parse(userUri);
-  if (_logBuiltin) {
+  if (_logLoading) {
     _print('# Getting file path from: $uri');
   }
 
@@ -349,35 +404,27 @@
   switch (uri.scheme) {
     case '':
     case 'file':
-      return uri.toFilePath();
+    return uri.toFilePath();
     case 'package':
-      return _filePathFromUri(_resolvePackageUri(uri).toString());
+    return _filePathFromUri(_resolvePackageUri(uri).toString());
     case 'data':
     case 'http':
     case 'https':
-      return uri.toString();
+    return uri.toString();
     default:
-      // Only handling file, http, and package URIs
-      // in standalone binary.
-      if (_logBuiltin) {
-        _print('# Unknown scheme (${uri.scheme}) in $uri.');
-      }
-      throw 'Not a known scheme: $uri';
+    // Only handling file, http, and package URIs
+    // in standalone binary.
+    if (_logLoading) {
+      _print('# Unknown scheme (${uri.scheme}) in $uri.');
+    }
+    throw 'Not a known scheme: $uri';
   }
 }
 
-String _nativeLibraryExtension() native "Builtin_NativeLibraryExtension";
 
-String _platformExtensionFileName(String name) {
-  var extension = _nativeLibraryExtension();
-
-  if (_isWindows) {
-    return '$name.$extension';
-  } else {
-    return 'lib$name.$extension';
-  }
-}
-
+// Embedder Entrypoint:
+// When loading an extension the embedder calls this method to get the
+// different components.
 // Returns the directory part, the filename part, and the name
 // of a native extension URL as a list [directory, filename, name].
 // The directory part is either a file system path or an HTTP(S) URL.
@@ -393,7 +440,6 @@
     throw 'Unexpected internal error: Extension URI $userUri contains \\';
   }
 
-
   String name;
   String path;  // Will end in '/'.
   int index = userUri.lastIndexOf('/');