Sigmund Cherem
8f4c9bcf15
A file-system that we'll use to generate machine agnostic dill files. Bug: https://github.com/dart-lang/sdk/issues/32633 Change-Id: I05b25940764f4af0bc86c5304e8ba4a6650fb362 Reviewed-on: https://dart-review.googlesource.com/56280 Reviewed-by: Peter von der Ahé <ahe@google.com>
77 lines
2.8 KiB
Dart
77 lines
2.8 KiB
Dart
// Copyright (c) 2018, 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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import 'dart:async';
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import 'package:front_end/src/api_unstable/build_integration.dart';
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/// A [FileSystem] that resolves custom URIs to entities under a specified root
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/// folder on an underlying [FileSystem].
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///
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/// This abstraction lets packages like `package:front_end` use absolute URIs
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/// freely, while hiding machine-specific or user-specific details. In
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/// particular, this file-system is used to create a machine-independent .dill
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/// files in distributed build systems.
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///
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/// The resolution rules are as follows: if a given URI uses a special
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/// [markerScheme] it gets resolved under the given [root], while a given URI
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/// with any other scheme will produce an error.
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///
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/// For example, if [markerScheme] is `single-root`, and [root] is
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/// `file:///a/b/c/`, then, calling [entityForUri] will:
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///
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/// * resolve `single-root:///f1.dart` to `file:///a/b/c/f1.dart`.
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/// * resolve `single-root:///d/f2.dart` to `file:///a/b/c/d/f2.dart`.
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/// * throw on `other-custom-scheme:///d/f2.dart`.
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/// * throw on `file:///d/f2.dart`.
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class SingleRootFileSystem implements FileSystem {
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final String markerScheme;
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final Uri root;
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final FileSystem original;
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SingleRootFileSystem(this.markerScheme, Uri root, this.original)
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: root = _normalize(root);
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@override
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FileSystemEntity entityForUri(Uri uri) {
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if (uri.scheme != markerScheme) {
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throw new FileSystemException(
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uri,
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"This SingleRootFileSystem only handles URIs with the '$markerScheme'"
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" scheme and cannot handle URIs with scheme '${uri.scheme}': $uri");
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}
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if (!uri.path.startsWith('/')) {
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throw new FileSystemException(
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uri, "This SingleRootFileSystem only handles absolutes URIs: $uri");
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}
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var path = uri.path.substring(1);
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return new SingleRootFileSystemEntity(
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uri, original.entityForUri(root.resolve(path)));
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}
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}
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/// [FileSystemEntity] with a URI of the `SingleRootFileSystem.markerScheme`,
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/// that delegates all operations to an underlying entity in the original
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/// `SingleRootFileSystem.filesystem`.
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class SingleRootFileSystemEntity implements FileSystemEntity {
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final Uri uri;
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final FileSystemEntity delegate;
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SingleRootFileSystemEntity(this.uri, this.delegate);
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@override
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Future<bool> exists() async => delegate.exists();
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@override
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Future<List<int>> readAsBytes() async => delegate.readAsBytes();
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@override
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Future<String> readAsString() async => delegate.readAsString();
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}
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_normalize(root) {
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Uri uri = root;
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return uri.path.endsWith('/') ? uri : uri.replace(path: '${uri.path}/');
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}
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