| // 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. |
| |
| /// The class `UriResolver` implements the rules for resolving "dart:" and |
| /// "package:" URIs. |
| class UriResolver { |
| /// The URI scheme used for "package" URIs. |
| static const PACKAGE_SCHEME = 'package'; |
| |
| /// The URI scheme used for "dart" URIs. |
| static const DART_SCHEME = 'dart'; |
| |
| /// A map from package name to the file URI of the "lib" directory of the |
| /// corresponding package. This is equivalent to the format returned by |
| /// the "package_config" package's parse() function. |
| final Map<String, Uri> packages; |
| |
| /// A map from SDK library name (e.g. `core` for `dart:core`) to the file URI |
| /// of the defining compilation unit of the SDK library. |
| final Map<String, Uri> sdkLibraries; |
| |
| UriResolver(this.packages, this.sdkLibraries); |
| |
| /// Converts "package:" and "dart:" URIs to the locations of the corresponding |
| /// files. |
| /// |
| /// If the given URI is a "package:" or "dart:" URI, is well formed, and names |
| /// a package or dart library that is recognized, returns the URI it resolves |
| /// to. If the given URI is a "package:" or "dart:" URI, and is ill-formed |
| /// or names a package or dart library that is not recognized, returns `null`. |
| /// |
| /// If the given URI has any scheme other than "package:" or "dart:", it is |
| /// returned unchanged. |
| /// |
| /// It is not necessary for the URI to be absolute (relative URIs will be |
| /// passed through unchanged). |
| /// |
| /// Note that no I/O is performed; the URI that is returned will be |
| /// independent of whether or not any particular file exists on the file |
| /// system. |
| Uri resolve(Uri uri) { |
| if (uri.scheme == DART_SCHEME || uri.scheme == PACKAGE_SCHEME) { |
| var path = uri.path; |
| var slashIndex = path.indexOf('/'); |
| String prefix; |
| String rest; |
| if (slashIndex >= 0) { |
| prefix = path.substring(0, slashIndex); |
| rest = path.substring(slashIndex + 1); |
| } else { |
| prefix = path; |
| rest = ''; |
| } |
| Uri libUri; |
| if (uri.scheme == PACKAGE_SCHEME) { |
| if (slashIndex < 0) return null; |
| libUri = packages[prefix]; |
| } else if (uri.scheme == DART_SCHEME) { |
| libUri = sdkLibraries[prefix]; |
| } |
| if (libUri == null) return null; |
| return libUri.resolve(rest); |
| } else { |
| return uri; |
| } |
| } |
| } |