Rename TranslateUri to UriTranslator, rename files, extract Impl.

pkg/front_end/lib/src/fasta/translate_uri.dart

Index: pkg/front_end/lib/src/fasta/translate_uri.dart
diff --git a/pkg/front_end/lib/src/fasta/translate_uri.dart b/pkg/front_end/lib/src/fasta/translate_uri.dart
deleted file mode 100644
index 74543888c0732d3c30be45ab847a7a7246af8f91..0000000000000000000000000000000000000000
--- a/pkg/front_end/lib/src/fasta/translate_uri.dart
+++ /dev/null
@@ -1,131 +0,0 @@
-// Copyright (c) 2016, 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 fasta.translate_uri;
-
-import 'dart:async' show Future;
-import 'dart:convert' show JSON;
-
-import 'package:front_end/file_system.dart'
-    show FileSystem, FileSystemException;
-import 'package:package_config/packages_file.dart' as packages_file show parse;
-
-import 'deprecated_problems.dart' show deprecated_inputError;
-
-/// Instances of [TranslateUri] translate absolute `dart` and `package` URIs
-/// into corresponding file URIs in a [FileSystem]. Translated URIs are
-/// typically `file:` URIs, but may use a different scheme if the compiler is
-/// invoked with the `multiRoot` option or in unit tests that use a custom file
-/// system.
-class TranslateUri {
-  /// Mapping from Dart library names (e.g. `math`) to file URIs.
-  final Map<String, Uri> dartLibraries;
-
-  // TODO(ahe): We probably want this to be `Map<String, Uri>`, that is, just
-  // one patch library (with parts).
-  /// Mapping from Dart library names to the file URIs of patches to apply.
-  final Map<String, List<Uri>> dartPatches;
-
-  /// Mapping from package names (e.g. `angular`) to the file URIs.
-  final Map<String, Uri> packages;
-
-  TranslateUri(this.dartLibraries, this.dartPatches, this.packages);
-
-  /// If the given [uri] is a `dart` or `package` URI, return the corresponding
-  /// file URI (possibly `null` if there is no corresponding file URI);
-  /// otherwise (e.g. when the [uri] is already a file URI) return `null`.
-  ///
-  /// This is the URIs only transformation, there is no guarantee that the
-  /// corresponding file exists in the file system.
-  Uri translate(Uri uri) {
-    if (uri.scheme == "dart") return _translateDartUri(uri);
-    if (uri.scheme == "package") return _translatePackageUri(uri);
-    return null;
-  }
-
-  /// Return the file URI that corresponds to the given `dart` URI, or `null`
-  /// if there is no corresponding Dart library registered.
-  Uri _translateDartUri(Uri uri) {
-    if (!uri.isScheme('dart')) return null;
-    String path = uri.path;
-
-    int index = path.indexOf('/');
-    if (index == -1) return dartLibraries[path];
-
-    String libraryName = path.substring(0, index);
-    String relativePath = path.substring(index + 1);
-    Uri libraryFileUri = dartLibraries[libraryName];
-    return libraryFileUri?.resolve(relativePath);
-  }
-
-  /// Return the file URI that corresponds to the given `package` URI, or
-  /// `null` if the `package` [uri] format is invalid, or there is no
-  /// corresponding package registered.
-  Uri _translatePackageUri(Uri uri) {
-    int index = uri.path.indexOf("/");
-    if (index == -1) return null;
-    String name = uri.path.substring(0, index);
-    String path = uri.path.substring(index + 1);
-    Uri root = packages[name];
-    if (root == null) return null;
-    return root.resolve(path);
-  }
-
-  /// Returns `true` if [uri] is private to the platform libraries (and thus
-  /// not accessible from user code).
-  bool isPlatformImplementation(Uri uri) {
-    if (uri.scheme != "dart") return false;
-    String path = uri.path;
-    return dartLibraries[path] == null || path.startsWith("_");
-  }
-
-  static Future<TranslateUri> parse(FileSystem fileSystem, Uri sdk,
-      {Uri packages}) async {
-    Uri librariesJson = sdk?.resolve("lib/libraries.json");
-
-    // TODO(ahe): Provide a value for this file.
-    Uri patches = null;
-
-    packages ??= Uri.base.resolve(".packages");
-
-    List<int> bytes;
-    try {
-      bytes = await fileSystem.entityForUri(packages).readAsBytes();
-    } on FileSystemException catch (e) {
-      deprecated_inputError(packages, -1, e.message);
-    }
-
-    Map<String, Uri> parsedPackages;
-    try {
-      parsedPackages = packages_file.parse(bytes, packages);
-    } on FormatException catch (e) {
-      return deprecated_inputError(packages, e.offset, e.message);
-    }
-
-    var dartLibraries = await computeDartLibraries(fileSystem, librariesJson);
-    return new TranslateUri(dartLibraries,
-        await computeDartPatches(fileSystem, patches), parsedPackages);
-  }
-}
-
-/// Read the JSON file with defined SDK libraries from the given [uri] in the
-/// [fileSystem] and return the mapping from parsed Dart library names (e.g.
-/// `math`) to file URIs.
-Future<Map<String, Uri>> computeDartLibraries(
-    FileSystem fileSystem, Uri uri) async {
-  if (uri == null) return const <String, Uri>{};
-  Map<String, String> libraries = JSON
-      .decode(await fileSystem.entityForUri(uri).readAsString())["libraries"];
-  Map<String, Uri> result = <String, Uri>{};
-  libraries.forEach((String name, String path) {
-    result[name] = uri.resolveUri(new Uri.file(path));
-  });
-  return result;
-}
-
-Future<Map<String, List<Uri>>> computeDartPatches(
-    FileSystem fileSystem, Uri uri) async {
-  // TODO(ahe): Read patch information.
-  return const <String, List<Uri>>{};
-}