Roll Observatory packages and add a roll script

package_config/lib/discovery_analysis.dart

-// 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.
-
-/// Analyse a directory structure and find packages resolvers for each
-/// sub-directory.
-///
-/// The resolvers are generally the same that would be found by using
-/// the `discovery.dart` library on each sub-directory in turn,
-/// but more efficiently and with some heuristics for directories that
-/// wouldn't otherwise have a package resolution strategy, or that are
-/// determined to be "package directories" themselves.
-library package_config.discovery_analysis;
-
-import "dart:io" show File, Directory;
-import "dart:collection" show HashMap;
-
-import "package:path/path.dart" as path;
-
-import "packages.dart";
-import "packages_file.dart" as pkgfile;
-import "src/packages_impl.dart";
-import "src/packages_io_impl.dart";
-
-/// Associates a [Packages] package resolution strategy with a directory.
-///
-/// The package resolution applies to the directory and any sub-directory
-/// that doesn't have its own overriding child [PackageContext].
-abstract class PackageContext {
-  /// The directory that introduced the [packages] resolver.
-  Directory get directory;
-
-  /// A [Packages] resolver that applies to the directory.
-  ///
-  /// Introduced either by a `.packages` file or a `packages/` directory.
-  Packages get packages;
-
-  /// Child contexts that apply to sub-directories of [directory].
-  List<PackageContext> get children;
-
-  /// Look up the [PackageContext] that applies to a specific directory.
-  ///
-  /// The directory must be inside [directory].
-  PackageContext operator[](Directory directory);
-
-  /// A map from directory to package resolver.
-  ///
-  /// Has an entry for this package context and for each child context
-  /// contained in this one.
-  Map<Directory, Packages> asMap();
-
-  /// Analyze [directory] and sub-directories for package resolution strategies.
-  ///
-  /// Returns a mapping from sub-directories to [Packages] objects.
-  ///
-  /// The analysis assumes that there are no `.packages` files in a parent
-  /// directory of `directory`. If there is, its corresponding `Packages` object
-  /// should be provided as `root`.
-  static PackageContext findAll(Directory directory,
-                                {Packages root: Packages.noPackages}) {
-    if (!directory.existsSync()) {
-      throw new ArgumentError("Directory not found: $directory");
-    }
-    List contexts = [];
-    void findRoots(Directory directory) {
-      Packages packages;
-      List oldContexts;
-      File packagesFile = new File(path.join(directory.path, ".packages"));
-      if (packagesFile.existsSync()) {
-        packages = _loadPackagesFile(packagesFile);
-        oldContexts = contexts;
-        contexts = [];
-      } else {
-        Directory packagesDir =
-            new Directory(path.join(directory.path, "packages"));
-        if (packagesDir.existsSync()) {
-          packages = new FilePackagesDirectoryPackages(packagesDir);
-          oldContexts = contexts;
-          contexts = [];
-        }
-      }
-      for (var entry in directory.listSync()) {
-        if (entry is Directory) {
-          if (packages == null || !entry.path.endsWith("/packages")) {
-            findRoots(entry);
-          }
-        }
-      }
-      if (packages != null) {
-        oldContexts.add(new _PackageContext(directory, packages, contexts));
-        contexts = oldContexts;
-      }
-    }
-    findRoots(directory);
-    // If the root is not itself context root, add a the wrapper context.
-    if (contexts.length == 1 &&
-        contexts[0].directory == directory) {
-      return contexts[0];
-    }
-    return new _PackageContext(directory, root, contexts);
-  }
-}
-
-class _PackageContext implements PackageContext {
-  final Directory directory;
-  final Packages packages;
-  final List<PackageContext> children;
-  _PackageContext(this.directory, this.packages, List<PackageContext> children)
-      : children = new List<PackageContext>.unmodifiable(children);
-
-  Map<Directory, Packages> asMap() {
-    var result = new HashMap<Directory, Packages>();
-    recurse(_PackageContext current) {
-      result[current.directory] = current.packages;
-      for (var child in current.children) {
-        recurse(child);
-      }
-    }
-    recurse(this);
-    return result;
-  }
-
-  PackageContext operator[](Directory directory) {
-    String path = directory.path;
-    if (!path.startsWith(this.directory.path)) {
-      throw new ArgumentError("Not inside $path: $directory");
-    }
-    _PackageContext current = this;
-    // The current path is know to agree with directory until deltaIndex.
-    int deltaIndex = current.directory.path.length;
-    List children = current.children;
-    int i = 0;
-    while (i < children.length) {
-      // TODO(lrn): Sort children and use binary search.
-      _PackageContext child = children[i];
-      String childPath = child.directory.path;
-      if (_stringsAgree(path, childPath, deltaIndex, childPath.length)) {
-        deltaIndex = childPath.length;
-        if (deltaIndex == path.length) {
-          return child;
-        }
-        current = child;
-        children = current.children;
-        i = 0;
-        continue;
-      }
-      i++;
-    }
-    return current;
-  }
-
-  static bool _stringsAgree(String a, String b, int start, int end) {
-    if (a.length < end || b.length < end) return false;
-    for (int i = start; i < end; i++) {
-      if (a.codeUnitAt(i) != b.codeUnitAt(i)) return false;
-    }
-    return true;
-  }
-}
-
-Packages _loadPackagesFile(File file) {
-  var uri = new Uri.file(file.path);
-  var bytes = file.readAsBytesSync();
-  var map = pkgfile.parse(bytes, uri);
-  return new MapPackages(map);
-}