Resource/File/Folder interfaces and implementations for dart:io and memory.

pkg/analysis_server/lib/src/resource.dart

+// Copyright (c) 2014, 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 resource;
+
+import 'dart:io' as io;
+
+import 'package:analyzer/src/generated/engine.dart' show TimestampedData;
+import 'package:analyzer/src/generated/java_io.dart';
+import 'package:analyzer/src/generated/source_io.dart';
+import 'package:path/path.dart';
+
+
+/**
+ * [File]s are leaf [Resource]s which contain data.
+ */
+abstract class File extends Resource {
+  /**
+   * Create a new [Source] instance that serves this file.
+   */
+  Source createSource(UriKind uriKind);
+}
+
+
+/**
+ * [Folder]s are [Resource]s which may contain files and/or other folders.
+ */
+abstract class Folder extends Resource {
+  /**
+   * Return an existing child [Resource] with the given [relPath].
+   * Return a not existing [File] if no such child exist.
+   */
+  Resource getChild(String relPath);
+
+  /**
+   * Return a list of existing direct children [Resource]s (folders and files)
+   * in this folder, in no particular order.
+   */
+  List<Resource> getChildren();
+}
+
+
+/**
+ * The abstract class [Resource] is an abstraction of file or folder.
+ */
+abstract class Resource {
+  /**
+   * Return `true` if this resource exists.
+   */
+  bool get exists;
+
+  /**
+   * Return the full (long) version of the name that can be displayed to the
+   * user to denote this resource.
+   */
+  String get fullName;
+
+  /**
+   * Return a short version of the name that can be displayed to the user to
+   * denote this resource.
+   */
+  String get shortName;
+}
+
+
+/**
+ * Instances of the class [ResourceProvider] convert [String] paths into
+ * [Resource]s.
+ */
+abstract class ResourceProvider {
+  /**
+   * Return the [Resource] that corresponds to the given [path].
+   */
+  Resource getResource(String path);
+}
+
+
+/**
+ * An in-memory implementation of [Resource].
+ */
+abstract class _MemoryResource implements Resource {
+  final MemoryResourceProvider _provider;
+  final String _path;
+
+  _MemoryResource(this._provider, this._path);
+
+  @override
+  bool operator ==(o) {

[Brian Wilkerson, 2014/05/25 15:29:58]

I really dislike single character variable names for anything other than loop
variables because I believe that names should carry semantic meaning. Even the
overridden method uses "other".

[scheglov, 2014/05/25 16:16:38]

Done.

+    return identical(this, o);
+  }
+
+  @override
+  bool get exists => _provider._pathToResource.containsKey(_path);
+
+  @override
+  String get fullName => _path;
+
+  @override
+  get hashCode => _path.hashCode;
+
+  @override
+  String get shortName => basename(_path);
+
+  @override
+  String toString() => fullName;
+}
+
+
+/**
+ * An in-memory implementation of [File].
+ */
+class _MemoryFile extends _MemoryResource implements File {
+  _MemoryFile(MemoryResourceProvider provider, String path) :
+      super(provider, path);
+
+  @override
+  Source createSource(UriKind uriKind) {
+    return new _MemoryFileSource(this, uriKind);
+  }
+
+  String get _content => _provider._pathToContent[_path];
+
+  int get _timestamp => _provider._pathToTimestamp[_path];
+}
+
+
+/**
+ * An in-memory implementation of [Source].
+ */
+class _MemoryFileSource implements Source {
+  final _MemoryFile _file;
+
+  final UriKind uriKind;
+
+  _MemoryFileSource(this._file, this.uriKind);
+
+  @override
+  TimestampedData<String> get contents {
+    return new TimestampedData<String>(modificationStamp, _file._content);
+  }
+
+  @override
+  String get encoding {
+    return '${new String.fromCharCode(uriKind.encoding)}${_file.fullName}';
+  }
+
+  @override
+  bool exists() => _file.exists;
+
+  @override
+  String get fullName => _file.fullName;
+
+  @override
+  bool get isInSystemLibrary => false;
+
+  @override
+  int get modificationStamp => _file._timestamp;
+
+  @override
+  Source resolveRelative(Uri relativeUri) {
+    String relativePath = fromUri(relativeUri);
+    String folderPath = dirname(_file._path);
+    String path = join(folderPath, relativePath);
+    path = normalize(path);
+    _MemoryFile file = new _MemoryFile(_file._provider, path);
+    return new _MemoryFileSource(file, uriKind);
+  }
+
+  @override
+  String get shortName => _file.shortName;
+}
+
+
+/**
+ * An in-memory implementation of [Folder].
+ */
+class _MemoryFolder extends _MemoryResource implements Folder {
+  _MemoryFolder(MemoryResourceProvider provider, String path) :
+      super(provider, path);
+  @override
+  Resource getChild(String relPath) {
+    relPath = normalize(relPath);
+    String childPath = join(_path, relPath);
+    childPath = normalize(childPath);
+    _MemoryResource resource = _provider._pathToResource[childPath];
+    if (resource == null) {
+      resource = new _MemoryFile(_provider, childPath);
+    }
+    return resource;
+  }
+
+  @override
+  List<Resource> getChildren() {
+    List<Resource> children = [];

[Brian Wilkerson, 2014/05/25 15:29:58]

I think we should include a type annotation with literal lists and maps because
it has meaning in checked mode (that is "[]" --> "<Resource>[]"). (Also in other
places.)

[scheglov, 2014/05/25 16:16:38]

Done.

+    _provider._pathToResource.forEach((path, resource) {
+      if (dirname(path) == _path) {
+        children.add(resource);
+      }
+    });
+    return children;
+  }
+}
+
+
+/**
+ * An in-memory implementation of [ResourceProvider].
+ * Use `/` as a path separator.
+ */
+class MemoryResourceProvider implements ResourceProvider {
+  final Map<String, _MemoryResource> _pathToResource = {};
+  final Map<String, String> _pathToContent = {};
+  final Map<String, int> _pathToTimestamp = {};
+  int nextStamp = 0;
+
+  @override
+  Resource getResource(String path) {
+    path = normalize(path);
+    Resource resource = _pathToResource[path];
+    if (resource == null) {
+      resource = new _MemoryFile(this, path);
+    }
+    return resource;
+  }
+
+  Folder newFolder(String path) {
+    path = normalize(path);
+    if (path.isEmpty) {
+      throw new ArgumentError('Empty paths are not supported');
+    }
+    if (!path.startsWith('/')) {
+      throw new ArgumentError('Path must start with \'/\'');

[Brian Wilkerson, 2014/05/25 15:29:58]

It would be better to use double quotes so that you don't need to escape the
embedded single quotes.

[scheglov, 2014/05/25 16:16:38]

Done.

+    }
+    _MemoryFolder folder = null;
+    String partialPath = "";

[Brian Wilkerson, 2014/05/25 15:29:58]

It's probably more efficient to use a StringBuffer to build up the string.

[scheglov, 2014/05/25 16:16:38]

It is surprising, but no, it is not faster.
Actually with StringBuffer.write() works 10 times (!) slower than String+.

main() {
  var sw = new Stopwatch();
  var totalLength = 0;
  for (int j = 0; j < 1000000; j++) {
    sw.start();
    {
      String s = 'aaa';
      s += 'bbb';
      s += 'ccc';
      s += 'ddd';
      s += 'eee';
      totalLength += s.length;
    }
    // StringBuffer.write() is 10x slower
//    {
//      var sb = new StringBuffer();
//      // writeAll() is even slower
//      sb.writeAll(['aaa', 'bbb', 'ccc', 'ddd', 'eee']);
//      sb.write('aaa');
//      sb.write('bbb');
//      sb.write('ccc');
//      sb.write('ddd');
//      sb.write('eee');
//      totalLength += sb.toString().length;
//    }
    sw.stop();
  }
  print(sw.elapsedMilliseconds);
  print(totalLength);
}

+    for (String pathPart in path.split('/')) {
+      if (pathPart.isEmpty) {
+        continue;
+      }
+      partialPath += '/' + pathPart;
+      _MemoryResource resource = _pathToResource[partialPath];
+      if (resource == null) {
+        folder = new _MemoryFolder(this, partialPath);
+        _pathToResource[partialPath] = folder;
+        _pathToTimestamp[partialPath] = nextStamp++;
+      } else if (resource is _MemoryFolder) {
+        folder = resource;
+      } else {
+        String message = 'Folder expected at ';
+        message += "'$partialPath'";
+        message += 'but ${resource.runtimeType} found';

[Brian Wilkerson, 2014/05/25 15:29:58]

It looks really strange to have a mixture of "+" and string interpolation to
build the same string. Is there a reason for this?

[scheglov, 2014/05/25 16:16:38]

Mostly because it does not fit one 80 characters line.
But yes, it can be made better by using AdjacentStrings.

+        throw new ArgumentError(message);
+      }
+    }
+    return folder;
+  }
+
+  File newFile(String path, String content) {
+    path = normalize(path);
+    newFolder(dirname(path));
+    _MemoryFile file = new _MemoryFile(this, path);
+    _pathToResource[path] = file;
+    _pathToContent[path] = content;
+    _pathToTimestamp[path] = nextStamp++;
+    return file;
+  }
+}
+
+
+/**
+ * A `dart:io` based implementation of [File].
+ */
+class _PhysicalFile extends _PhysicalResource implements File {
+  _PhysicalFile(io.File file) : super(file);
+
+  @override
+  Source createSource(UriKind uriKind) {
+    io.File file = _entry as io.File;
+    JavaFile javaFile = new JavaFile(file.absolute.path);
+    return new FileBasedSource.con2(javaFile, uriKind);
+  }
+}
+
+
+/**
+ * A `dart:io` based implementation of [Folder].
+ */
+class _PhysicalFolder extends _PhysicalResource implements Folder {
+  _PhysicalFolder(io.Directory directory) : super(directory);
+
+  @override
+  Resource getChild(String relPath) {
+    String childPath = join(_entry.absolute.path, relPath);
+    return PhysicalResourceProvider.INSTANCE.getResource(childPath);
+  }
+
+  @override
+  List<Resource> getChildren() {
+    List<Resource> children = [];
+    io.Directory directory = _entry as io.Directory;
+    List<io.FileSystemEntity> entries = directory.listSync(recursive: false);
+    int numEntries = entries.length;
+    for (int i = 0; i < numEntries; i++) {
+      io.FileSystemEntity entity = entries[i];
+      if (entity is io.Directory) {
+        children.add(new _PhysicalFolder(entity));
+      } else if (entity is io.File) {
+        children.add(new _PhysicalFile(entity));
+      }
+    }
+    return children;
+  }
+}
+
+
+/**
+ * A `dart:io` based implementation of [Resource].
+ */
+abstract class _PhysicalResource implements Resource {
+  final io.FileSystemEntity _entry;
+
+  _PhysicalResource(this._entry);
+
+  @override
+  bool get exists => _entry.existsSync();
+
+  @override
+  String get fullName => _entry.absolute.path;
+
+  @override
+  get hashCode => _entry.hashCode;
+
+  @override
+  String get shortName => basename(fullName);
+
+  @override
+  String toString() => fullName;
+}
+
+
+/**
+ * A `dart:io` based implementation of [ResourceProvider].
+ */
+class PhysicalResourceProvider implements ResourceProvider {
+  static final PhysicalResourceProvider INSTANCE = new PhysicalResourceProvider._();
+
+  PhysicalResourceProvider._();
+
+  @override
+  Resource getResource(String path) {
+    if (io.FileSystemEntity.isDirectorySync(path)) {
+      io.Directory directory = new io.Directory(path);
+      return new _PhysicalFolder(directory);
+    } else {
+      io.File file = new io.File(path);
+      return new _PhysicalFile(file);
+    }
+  }
+}