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Unified Diff: utils/pub/cache.dart

Issue 10091014: Start implementing pub object model. Rudimentary package cache class, and a simple pub command to l… (Closed) Base URL: https://dart.googlecode.com/svn/branches/bleeding_edge/dart
Patch Set: Platform is static now. Created 8 years, 8 months ago
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Index: utils/pub/cache.dart
diff --git a/utils/pub/cache.dart b/utils/pub/cache.dart
new file mode 100644
index 0000000000000000000000000000000000000000..4c599e02c5800976b444b3d4778bcbed9576e42a
--- /dev/null
+++ b/utils/pub/cache.dart
@@ -0,0 +1,104 @@
+// Copyright (c) 2012, 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 local cache of previously installed packages.
+ */
+class PackageCache {
+ /**
+ * The root directory where this package cache is located.
+ */
+ final String rootDir;
+
+ // TODO(rnystrom): When packages are versioned, String here and elsewhere will
+ // become a name/version/(source?) tuple.
+ final Map<String, Package> _loadedPackages;
+
+ /**
+ * Packages which are currently being asynchronously loaded.
+ */
+ final Map<String, Future<Package>> _pendingPackages;
+
+ /**
+ * Creates a new package cache which is backed by the given directory on the
+ * user's file system.
+ */
+ PackageCache(this.rootDir)
+ : _loadedPackages = <Package>{},
+ _pendingPackages = <Future<Package>>{};
+
+ /**
+ * Loads all of the packages in the cache and returns them.
+ */
+ Future<List<Package>> listAll() {
+ return listDir(rootDir).chain((paths) {
+ final packages = paths.map((path) => find(basename(path)));
+ return Futures.wait(packages);
+ });
+ }
+
+ /**
+ * Loads the package named [name] from this cache, if present.
+ */
+ // TODO(rnystrom): What happens if the package isn't cached?
+ Future<Package> find(String name) {
+ // Use the previously loaded one.
+ final package = _loadedPackages[name];
+ if (package != null) {
+ return new Future.immediate(package);
+ }
+
+ // If we are already in-progress loading it, re-use that one.
+ final pending = _pendingPackages[name];
+ if (pending != null) {
+ return pending;
+ }
+
+ return _loadPackage(name);
+ }
+
+ /**
+ * Start loading the package.
+ */
+ Future<Package> _loadPackage(String name) {
+ final future = _parsePubspec(name).transform((dependencies) {
+ final package = new Package._(this, name, dependencies);
+
+ _pendingPackages.remove(name);
+ _loadedPackages[name] = package;
+ return package;
+ });
+
+ _pendingPackages[name] = future;
+ return future;
+ }
+
+ Future<List<String>> _parsePubspec(String name) {
+ final completer = new Completer<List<String>>();
+ final pubspecPath = join(rootDir, name, 'pubspec');
+
+ // TODO(rnystrom): Handle the directory not existing.
+ // TODO(rnystrom): Error-handling.
+ final readFuture = readTextFile(pubspecPath);
+ readFuture.handleException((error) {
+ // If there is no pubspec, we implicitly treat that as a package with no
+ // dependencies.
+ // TODO(rnystrom): Distinguish file not found from other real errors.
+ completer.complete(<String>[]);
+ return true;
+ });
+
+ readFuture.then((pubspec) {
+ // TODO(rnystrom): Use YAML parser when ready. For now, it's just a flat
+ // list of newline-separated strings.
+ final dependencyNames = pubspec.split('\n').
+ map((name) => name.trim()).
+ filter((name) => (name != null) && (name != ''));
+
+ completer.complete(dependencyNames);
+ });
+
+ return completer.future;
+ }
+}
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