Index: lib/discovery.dart |
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+// 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.discovery; |
+ |
+import "dart:async"; |
+import "dart:io" show Directory, File, FileSystemEntity; |
+import "package:path/path.dart" as path; |
+import "package:http/http.dart" as http; |
+import "packages.dart"; |
+import "packages_file.dart" as pkgfile show parse; |
+import "src/packages_impl.dart"; |
+ |
+/// Discover the package configuration for a Dart script. |
+/// |
+/// The [baseUri] points to either the Dart script or its directory. |
+/// A package resolution strategy is found by going through the following steps, |
+/// and stopping when something is found. |
+/// |
+/// * Check if a `.packages` file exists in the same directory. |
+/// * If `baseUri`'s scheme is not `file`, then assume a `packages` directory |
+/// in the same directory, and resolve packages relative to that. |
+/// * If `baseUri`'s scheme *is* `file`: |
+/// * Check if a `packages` directory exists. |
+/// * Otherwise check each successive parent directory of `baseUri` for a |
+/// `.packages` file. |
+/// |
+/// If any of these tests succeed, a `Packages` class is returned. |
+/// Returns the constant [noPackages] if no resolution strategy is found. |
+/// |
+/// This function currently only supports `file`, `http` and `https` URIs. |
+/// It needs to be able to load a `.packages` file from the URI, so only |
+/// recognized schemes are accepted. |
+/// |
+/// To support other schemes, an optional [loader] function can be supplied. |
+/// It's called to load the `.packages` file for any unsupported scheme. |
+/// It must return the *contents* of the file identified by the URI it's given, |
+/// which should be a UTF-8 encoded `.packages` file, and must return an |
+/// error future if loading fails for any reason. |
+Future<Packages> findPackages( |
+ Uri baseUri, |
+ {Future<List<int>> loader(Uri unsupportedUri)}) { |
+ if (baseUri.scheme == "file") { |
+ return new Future<Packages>.sync(() => findPackagesFromFile(baseUri)); |
+ } else if (baseUri.scheme == "http" || baseUri.scheme == "https") { |
+ return findPackagesFromNonFile(baseUri, _httpGet); |
+ } else if (loader != null) { |
+ return findPackagesFromNonFile(baseUri, loader); |
+ } else { |
+ return new Future<Packages>.value(Packages.noPackages); |
+ } |
+} |
+ |
+/// Find the location of the package resolution file/directory for a Dart file. |
+/// |
+/// Checks for a `.packages` file in the [workingDirectory]. |
+/// If not found, checks for a `packages` directory in the same directory. |
+/// If still not found, starts checking parent directories for |
+/// `.packages` until reaching the root directory. |
+/// |
+/// Returns a [File] object of a `.packages` file if one is found, or a |
+/// [Directory] object for the `packages/` directory if that is found. |
+FileSystemEntity _findPackagesFile(String workingDirectory) { |
+ var dir = new Directory(workingDirectory); |
+ if (!dir.isAbsolute) dir = dir.absolute; |
+ if (!dir.existsSync()) { |
+ throw new ArgumentError.value( |
+ workingDirectory, "workingDirectory", "Directory does not exist."); |
+ } |
+ File checkForConfigFile(Directory directory) { |
+ assert(directory.isAbsolute); |
+ var file = new File(path.join(directory.path, ".packages")); |
+ if (file.existsSync()) return file; |
+ return null; |
+ } |
+ // Check for $cwd/.packages |
+ var packagesCfgFile = checkForConfigFile(dir); |
+ if (packagesCfgFile != null) return packagesCfgFile; |
+ // Check for $cwd/packages/ |
+ var packagesDir = new Directory(path.join(dir.path, "packages")); |
+ if (packagesDir.existsSync()) return packagesDir; |
+ // Check for cwd(/..)+/.packages |
+ var parentDir = dir.parent; |
+ while (parentDir.path != dir.path) { |
+ packagesCfgFile = checkForConfigFile(parentDir); |
+ if (packagesCfgFile != null) break; |
+ dir = parentDir; |
+ parentDir = dir.parent; |
+ } |
+ return packagesCfgFile; |
+} |
+ |
+/// Finds a package resolution strategy for a local Dart script. |
+/// |
+/// The [fileBaseUri] points to either a Dart script or the directory of the |
+/// script. The `fileBaseUri` must be a `file:` URI. |
+/// |
+/// This function first tries to locate a `.packages` file in the `fileBaseUri` |
+/// directory. If that is not found, it instead checks for the presence of |
+/// a `packages/` directory in the same place. |
+/// If that also fails, it starts checking parent directories for a `.packages` |
+/// file, and stops if it finds it. |
+/// Otherwise it gives up and returns [Pacakges.noPackages]. |
+Packages findPackagesFromFile(Uri fileBaseUri) { |
+ Uri baseDirectoryUri = fileBaseUri; |
+ if (!fileBaseUri.path.endsWith('/')) { |
+ baseDirectoryUri = baseDirectoryUri.resolve("."); |
+ } |
+ String baseDirectoryPath = baseDirectoryUri.toFilePath(); |
+ FileSystemEntity location = _findPackagesFile(baseDirectoryPath); |
+ if (location == null) return Packages.noPackages; |
+ if (location is File) { |
+ List<int> fileBytes = location.readAsBytesSync(); |
+ Map<String, Uri> map = pkgfile.parse(fileBytes, |
+ new Uri.file(location.path)); |
+ return new MapPackages(map); |
+ } |
+ assert(location is Directory); |
+ return new FilePackagesDirectoryPackages(location); |
+} |
+ |
+/// Finds a package resolution strategy for a Dart script. |
+/// |
+/// The [nonFileUri] points to either a Dart script or the directory of the |
+/// script. |
+/// The [nonFileUri] should not be a `file:` URI since the algorithm for |
+/// finding a package resolution strategy is more elaborate for `file:` URIs. |
+/// In that case, use [findPackagesFile]. |
+/// |
+/// This function first tries to locate a `.packages` file in the [nonFileUri] |
+/// directory. If that is not found, it instead assumes a `packages/` directory |
+/// in the same place. |
+/// |
+/// By default, this function only works for `http:` and `https:` URIs. |
+/// To support other schemes, a loader must be provided, which is used to |
+/// try to load the `.packages` file. The loader should return the contents |
+/// of the requestsed `.packages` file as bytes, which will be assumed to be |
+/// UTF-8 encoded. |
+Future<Packages> findPackagesFromNonFile(Uri nonFileUri, |
+ [Future<List<int>> loader(Uri name)]) { |
+ if (loader == null) loader = _httpGet; |
+ Uri packagesFileUri = nonFileUri.resolve(".packages"); |
+ return loader(packagesFileUri).then((List<int> fileBytes) { |
+ Map<String, Uri> map = pkgfile.parse(fileBytes, packagesFileUri); |
+ return new MapPackages(map); |
+ }, onError: (_) { |
+ // Didn't manage to load ".packages". Assume a "packages/" directory. |
+ Uri packagesDirectoryUri = nonFileUri.resolve("packages/"); |
+ return new NonFilePackagesDirectoryPackages(packagesDirectoryUri); |
+ }); |
+} |
+ |
+/// Fetches a file using the http library. |
+Future<List<int>> _httpGet(Uri uri) { |
+ return http.get(uri).then((http.Response response) { |
+ if (response.statusCode == 200) return response.bodyBytes; |
+ throw 0; // The error message isn't being used for anything. |
+ }); |
+} |