dwds/lib/src/utilities/dart_uri.dart

// Copyright (c) 2019, 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.

import 'package:path/path.dart' as p;

/// The URI for a particular Dart file, able to canonicalize from various
/// different representations.
class DartUri {
  /// The canonical web server path part of the URI.
  ///
  /// This is a relative path, which can be used to fetch the corresponding file
  /// from the server. For example, 'hello_world/main.dart' or
  /// 'packages/path/src/utils.dart'.
  final String serverPath;

  /// Accepts various forms of URI and can convert between forms.
  ///
  /// The accepted forms are:
  ///
  ///  - package:packageName/pathUnderLib/file.dart
  ///  - org-dartlang-app:///prefix/path/file.dart, where prefix is ignored.
  ///    e.g. org-dartlang-app:example/hello_world/main.dart,
  ///  - /packages/packageName/foo.dart, the web server form of a package URI,
  ///    e.g. /packages/path/src/utils.dart
  ///  - /path/foo.dart or path/foo.dart, e.g. /hello_world/web/main.dart, where
  ///    path is a web server path and so relative to the directory being
  ///    served, not to the package.
  ///
  /// The optional [serverUri] is a temporary workaround for a bug with construction.
  /// Older SDKs (before D24) gave us a path that didn't include the full path,
  /// e.g. main.dart rather than hello_world/main.dart and src/path.dart rather than
  /// packages/path/src/path.dart. The optional [serverUri] is the full URI of the
  /// JS script. The dirname of that path should give us the missing prefix.
  factory DartUri(String uri, [String serverUri]) {
    // TODO(401): Remove serverUri after D24 is stable.
    if (uri.startsWith('package:')) return DartUri._fromPackageUri(uri);
    if (uri.startsWith('org-dartlang-app:')) return DartUri._fromAppUri(uri);
    if (uri.startsWith('/packages/')) return DartUri._fromServerPath(uri);
    if (uri.startsWith('/')) return DartUri._fromServerPath(uri);
    if (uri.startsWith('http:') || uri.startsWith('https:')) {
      return DartUri(Uri.parse(uri).path);
    }
    // Work around short paths if we have been provided the context.
    if (serverUri != null) {
      var path = Uri.parse(serverUri).path;
      var dir = p.dirname(path);
      return DartUri._fromServerPath(p.join(dir, uri));
    }
    throw FormatException('Unsupported URI form', uri);
  }

  /// Construct from a package: URI
  factory DartUri._fromPackageUri(String uri) {
    return DartUri._('packages/${uri.substring("package:".length)}');
  }

  /// Construct from an org-dartlang-app: URI.
  factory DartUri._fromAppUri(String uri) {
    // We ignore the first segment of the path, which is the root
    // from which we're serving.
    // TODO: To be able to convert to an org-dartlang-app: URI we will
    // need to know the root - possibly keep it as a static?
    return DartUri._(Uri.parse(uri).pathSegments.skip(1).join('/').toString());
  }

  DartUri._(this.serverPath);

  /// Construct from a path, relative to the directory being served.
  factory DartUri._fromServerPath(String uri) {
    uri = uri[0] == '.' ? uri.substring(1) : uri;
    uri = uri[0] == '/' ? uri.substring(1) : uri;
    return DartUri._(uri);
  }
}