Roll Observatory packages and add a roll script

analyzer/lib/source/package_map_resolver.dart

-// Copyright (c) 2014, 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 source.package_map_resolver;
-
-import 'dart:core' hide Resource;
-
-import 'package:analyzer/file_system/file_system.dart';
-import 'package:analyzer/src/generated/source.dart';
-import 'package:analyzer/src/util/asserts.dart' as asserts;
-import 'package:path/path.dart' as pathos;
-
-/**
- * A [UriResolver] implementation for the `package:` scheme that uses a map of
- * package names to their directories.
- */
-class PackageMapUriResolver extends UriResolver {
-  /**
-   * The name of the `package` scheme.
-   */
-  static const String PACKAGE_SCHEME = "package";
-
-  /**
-   * A table mapping package names to the path of the directories containing
-   * the package.
-   */
-  final Map<String, List<Folder>> packageMap;
-
-  /**
-   * The [ResourceProvider] for this resolver.
-   */
-  final ResourceProvider resourceProvider;
-
-  /**
-   * Create a new [PackageMapUriResolver].
-   *
-   * [packageMap] is a table mapping package names to the paths of the
-   * directories containing the package
-   */
-  PackageMapUriResolver(this.resourceProvider, this.packageMap) {
-    asserts.notNull(resourceProvider);
-    asserts.notNull(packageMap);
-  }
-
-  @override
-  Source resolveAbsolute(Uri uri) {
-    if (!isPackageUri(uri)) {
-      return null;
-    }
-    // Prepare path.
-    String path = uri.path;
-    // Prepare path components.
-    int index = path.indexOf('/');
-    if (index == -1 || index == 0) {
-      return null;
-    }
-    // <pkgName>/<relPath>
-    String pkgName = path.substring(0, index);
-    String relPath = path.substring(index + 1);
-    // Try to find an existing file.
-    List<Folder> packageDirs = packageMap[pkgName];
-    if (packageDirs != null) {
-      for (Folder packageDir in packageDirs) {
-        if (packageDir.exists) {
-          Resource result = packageDir.getChild(relPath);
-          if (result is File && result.exists) {
-            return result.createSource(uri);
-          }
-        }
-      }
-    }
-    // Return a NonExistingSource instance.
-    // This helps provide more meaningful error messages to users
-    // (a missing file error, as opposed to an invalid URI error).
-    String fullPath = packageDirs != null && packageDirs.isNotEmpty
-        ? packageDirs.first.canonicalizePath(relPath)
-        : relPath;
-    return new NonExistingSource(fullPath, uri, UriKind.PACKAGE_URI);
-  }
-
-  @override
-  Uri restoreAbsolute(Source source) {
-    String sourcePath = source.fullName;
-    Uri bestMatch;
-    int bestMatchLength = -1;
-    pathos.Context pathContext = resourceProvider.pathContext;
-    for (String pkgName in packageMap.keys) {
-      List<Folder> pkgFolders = packageMap[pkgName];
-      for (int i = 0; i < pkgFolders.length; i++) {
-        Folder pkgFolder = pkgFolders[i];
-        String pkgFolderPath = pkgFolder.path;
-        if (pkgFolderPath.length > bestMatchLength &&
-            sourcePath.startsWith(pkgFolderPath + pathContext.separator)) {
-          String relPath = sourcePath.substring(pkgFolderPath.length + 1);
-          if (_isReversibleTranslation(pkgFolders, i, relPath)) {
-            List<String> relPathComponents = pathContext.split(relPath);
-            String relUriPath = pathos.posix.joinAll(relPathComponents);
-            bestMatch = Uri.parse('$PACKAGE_SCHEME:$pkgName/$relUriPath');
-            bestMatchLength = pkgFolderPath.length;
-          }
-        }
-      }
-    }
-    return bestMatch;
-  }
-
-  /**
-   * A translation from file path to package URI has just been found for
-   * using the [packageDirIndex]th element of [packageDirs], and appending the
-   * relative path [relPath].  Determine whether the translation is reversible;
-   * that is, whether translating the package URI pack to a file path will
-   * produce the file path we started with.
-   */
-  bool _isReversibleTranslation(
-      List<Folder> packageDirs, int packageDirIndex, String relPath) {
-    // The translation is reversible provided there is no prior element of
-    // [packageDirs] containing a file matching [relPath].
-    for (int i = 0; i < packageDirIndex; i++) {
-      Folder packageDir = packageDirs[i];
-      if (packageDir.exists) {
-        Resource result = packageDir.getChild(relPath);
-        if (result is File && result.exists) {
-          return false;
-        }
-      }
-    }
-    return true;
-  }
-
-  /**
-   * Returns `true` if [uri] is a `package` URI.
-   */
-  static bool isPackageUri(Uri uri) {
-    return uri.scheme == PACKAGE_SCHEME;
-  }
-}