Paul Berry
ba241c0c8d
This carries a number of benefits: - It allows the front end to trivially support schemes other than "file:" (e.g. "http:") by allowing the client to supply a FileSystem implementation that handles them. - It is more consistent with the functionality of the ".packages" file (which allows packages to map to any kind of URI). - It allows the "bazel root" feature to be rewritten to use a magic scheme rather than a magic path. (This eliminates concerns about the magic path overlapping with a user's use case). Note that this feature has been renamed to "multi root" since it is sufficiently generic to be applicable to build systems other than Bazel. - It reduces the risk of forgetting to use the front end's FileSystem abstraction to access the file system, since the native file system interfaces do not accept URIs. R=danrubel@google.com Review-Url: https://codereview.chromium.org/2614063007 .
104 lines
2.9 KiB
Dart
104 lines
2.9 KiB
Dart
// Copyright (c) 2016, the Dart project authors. Please see the AUTHORS file
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// for details. All rights reserved. Use of this source code is governed by a
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// BSD-style license that can be found in the LICENSE file.
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library front_end.memory_file_system;
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import 'dart:async';
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import 'dart:convert';
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import 'dart:typed_data';
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import 'package:path/path.dart' as p;
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import 'file_system.dart';
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/// Concrete implementation of [FileSystem] which performs its operations on an
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/// in-memory virtual file system.
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///
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/// Not intended to be implemented or extended by clients.
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class MemoryFileSystem implements FileSystem {
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@override
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final p.Context context;
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final Map<Uri, Uint8List> _files = {};
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/// The "current directory" in the in-memory virtual file system.
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///
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/// This is used to convert relative URIs to absolute URIs.
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///
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/// Always ends in a trailing '/'.
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Uri currentDirectory;
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MemoryFileSystem(this.context, Uri currentDirectory)
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: currentDirectory = _addTrailingSlash(currentDirectory);
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@override
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MemoryFileSystemEntity entityForUri(Uri uri) {
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return new MemoryFileSystemEntity._(
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this, currentDirectory.resolveUri(uri).normalizePath());
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}
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static Uri _addTrailingSlash(Uri uri) {
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if (!uri.path.endsWith('/')) {
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uri = uri.replace(path: uri.path + '/');
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}
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return uri;
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}
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}
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/// Concrete implementation of [FileSystemEntity] for use by
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/// [MemoryFileSystem].
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class MemoryFileSystemEntity implements FileSystemEntity {
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final MemoryFileSystem _fileSystem;
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@override
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final Uri uri;
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MemoryFileSystemEntity._(this._fileSystem, this.uri);
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@override
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int get hashCode => uri.hashCode;
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@override
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bool operator ==(Object other) =>
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other is MemoryFileSystemEntity &&
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other.uri == uri &&
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identical(other._fileSystem, _fileSystem);
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@override
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Future<List<int>> readAsBytes() async {
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List<int> contents = _fileSystem._files[uri];
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if (contents != null) {
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return contents.toList();
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}
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throw new Exception('File does not exist');
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}
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@override
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Future<String> readAsString() async {
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List<int> contents = await readAsBytes();
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return UTF8.decode(contents);
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}
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/// Writes the given raw bytes to this file system entity.
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///
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/// If no file exists, one is created. If a file exists already, it is
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/// overwritten.
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void writeAsBytesSync(List<int> bytes) {
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_fileSystem._files[uri] = new Uint8List.fromList(bytes);
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}
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/// Writes the given string to this file system entity.
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///
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/// The string is encoded as UTF-8.
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///
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/// If no file exists, one is created. If a file exists already, it is
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/// overwritten.
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void writeAsStringSync(String s) {
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// Note: the return type of UTF8.encode is List<int>, but in practice it
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// always returns Uint8List. We rely on that for efficiency, so that we
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// don't have to make an extra copy.
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_fileSystem._files[uri] = UTF8.encode(s) as Uint8List;
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}
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}
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