| // Copyright (c) 2015, 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 package_config.packages; |
| |
| import "dart:async" show Future; |
| import "discovery.dart" show findPackages; |
| import "src/packages_impl.dart"; |
| |
| /// A package resolution strategy. |
| /// |
| /// Allows converting a `package:` URI to a different kind of URI. |
| /// |
| /// May also allow listing the available packages and converting |
| /// to a `Map<String, Uri>` that gives the base location of each available |
| /// package. In some cases there is no way to find the available packages, |
| /// in which case [packages] and [asMap] will throw if used. |
| /// One such case is if the packages are resolved relative to a |
| /// `packages/` directory available over HTTP. |
| abstract class Packages { |
| |
| /// A [Packages] resolver containing no packages. |
| /// |
| /// This constant object is returned by [find] above if no |
| /// package resolution strategy is found. |
| static const Packages noPackages = const NoPackages(); |
| |
| /// Create a `Packages` object based on a map from package name to base URI. |
| /// |
| /// The resulting `Packages` object will resolve package URIs by using this |
| /// map. |
| /// There is no validation of the map containing only valid package names, |
| factory Packages(Map<String, Uri> packageMapping) => |
| new MapPackages(packageMapping); |
| |
| /// Attempts to find a package resolution strategy for a Dart script. |
| /// |
| /// The [baseLocation] should point to a Dart script or to its directory. |
| /// The function goes through the following steps in order to search for |
| /// a packages resolution strategy: |
| /// |
| /// * First check if a `.packages` file in the script's directory. |
| /// If a file is found, its content is loaded and interpreted as a map |
| /// from package names to package location URIs. |
| /// If loading or parsing of the file fails, so does this function. |
| /// * Then if `baseLocation` is not a `file:` URI, |
| /// assume that a `packages/` directory exists in the script's directory, |
| /// and return a `Packages` object that resolves package URIs as |
| /// paths into that directory. |
| /// * If `baseLocation` is a `file:` URI, instead *check* whether |
| /// a `packages/` directory exists in the script directory. |
| /// If it does, return a `Packages` object that resolves package URIs |
| /// as paths into that directory. This `Packages` object is able to |
| /// read the directory and see which packages are available. |
| /// * Otherwise, check each directory in the parent path of `baseLocation` |
| /// for the existence of a `.packages` file. If one is found, it is loaded |
| /// just as in the first step. |
| /// * If no file is found before reaching the file system root, |
| /// the constant [noPacakages] is returned. It's a `Packages` object |
| /// with no available packages. |
| /// |
| static Future<Packages> find(Uri baseLocation) => findPackages(baseLocation); |
| |
| /// Resolve a package URI into a non-package URI. |
| /// |
| /// Translates a `package:` URI, according to the package resolution |
| /// strategy, into a URI that can be loaded. |
| /// By default, only `file`, `http` and `https` URIs are returned. |
| /// Custom `Packages` objects may return other URIs. |
| /// |
| /// If resolution fails because a package with the requested package name |
| /// is not available, the [notFound] function is called. |
| /// If no `notFound` function is provided, it defaults to throwing an error. |
| /// |
| /// The [packageUri] must be a valid package URI. |
| Uri resolve(Uri packageUri, {Uri notFound(Uri packageUri)}); |
| |
| /// Return the names of the available packages. |
| /// |
| /// Returns an iterable that allows iterating the names of available packages. |
| /// |
| /// Some `Packages` objects are unable to find the package names, |
| /// and getting `packages` from such a `Packages` object will throw. |
| Iterable<String> get packages; |
| |
| /// Return the names-to-base-URI mapping of the available packages. |
| /// |
| /// Returns a map from package name to a base URI. |
| /// The [resolve] method will resolve a package URI with a specific package |
| /// name to a path extending the base URI that this map gives for that |
| /// package name. |
| /// |
| /// Some `Packages` objects are unable to find the package names, |
| /// and calling `asMap` on such a `Packages` object will throw. |
| Map<String, Uri> asMap(); |
| } |