blob: a30e75fd764fbee73a477b6e513361d0caf841a6 [file] [log] [blame]
// Copyright (c) 2017, 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.
/// A file system that implements [CopilerOptions.multiRoots].
library front_end.src.multi_roots_file_system;
import 'dart:async';
import 'package:front_end/src/api_prototype/file_system.dart';
/// Wraps a file system to create an overlay of files from multiple roots.
/// Regular `file:` URIs are resolved directly in the underlying file system,
/// but URIs that use a special [markerScheme] are resolved by searching
/// under a set of given roots in order.
/// For example, consider the following inputs:
/// - markerScheme is `multi-root`
/// - the set of roots are `file:///a/` and `file:///b/`
/// - the underlying file system contains files:
/// a/c/a1.dart
/// a/c/a2.dart
/// b/c/b1.dart
/// b/c/a2.dart
/// c/c1.dart
/// Then:
/// - file:///c/c1.dart is resolved as file:///c/c1.dart
/// - multi-root:///c/a1.dart is resolved as file:///a/c/a1.dart
/// - multi-root:///c/b1.dart is resolved as file:///b/c/b1.dart
/// - multi-root:///c/a2.dart is resolved as file:///a/c/b2.dart
class MultiRootFileSystem implements FileSystem {
final String markerScheme;
final List<Uri> roots;
final FileSystem original;
MultiRootFileSystem(this.markerScheme, List roots, this.original)
: roots =;
FileSystemEntity entityForUri(Uri uri) =>
new MultiRootFileSystemEntity(this, uri);
/// Entity that searches the multiple roots and resolve a, possibly multi-root,
/// entity to a plain entity under `multiRootFileSystem.original`.
class MultiRootFileSystemEntity implements FileSystemEntity {
final MultiRootFileSystem multiRootFileSystem;
final Uri uri;
FileSystemEntity _delegate;
Future<FileSystemEntity> get delegate async =>
_delegate ??= await _resolveEntity();
Future<FileSystemEntity> _resolveEntity() async {
if (uri.scheme == multiRootFileSystem.markerScheme && uri.isAbsolute) {
var original = multiRootFileSystem.original;
var path = uri.path.substring(1);
for (var root in multiRootFileSystem.roots) {
var candidate = original.entityForUri(root.resolve(path));
if (await candidate.exists()) return candidate;
return multiRootFileSystem.original.entityForUri(uri);
MultiRootFileSystemEntity(this.multiRootFileSystem, this.uri);
Future<bool> exists() async => (await delegate).exists();
Future<List<int>> readAsBytes() async => (await delegate).readAsBytes();
Future<String> readAsString() async => (await delegate).readAsString();
_normalize(root) {
Uri uri = root;
return uri.path.endsWith('/') ? uri : uri.replace(path: '${uri.path}/');