Add BazelPackageUriResolver with resolveAbsolute().

pkg/analyzer/lib/src/generated/bazel.dart

 // Copyright (c) 2016, 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 analyzer.src.generated.bazel;
 
+import 'dart:collection';
 import 'dart:core';
 
 import 'package:analyzer/file_system/file_system.dart';
 import 'package:analyzer/src/generated/source.dart';
 import 'package:analyzer/src/generated/source_io.dart';
 import 'package:path/path.dart';
 
 /**
  * Instances of the class `BazelFileUriResolver` resolve `file` URI's by first
  * resolving file uri's in the expected way, and then by looking in the
@@ skipping 14 matching lines @@
     String path = provider.pathContext.fromUri(uri);
     File file = workspace.findFile(path);
     if (file != null) {
       return file.createSource(actualUri ?? uri);
     }
     return null;
   }
 }
 
 /**
+ * The [UriResolver] that can resolve `package` URIs in [BazelWorkspace].
+ */
+class BazelPackageUriResolver extends UriResolver {
+  final BazelWorkspace _workspace;
+  final Context _context;
+
+  /**
+   * The cache of absolute [Uri]s to [Source]s mappings.
+   */
+  final Map<Uri, Source> _sourceCache = new HashMap<Uri, Source>();
+
+  BazelPackageUriResolver(BazelWorkspace workspace)
+      : _workspace = workspace,
+        _context = workspace.provider.pathContext;
+
+  @override
+  Source resolveAbsolute(Uri uri, [Uri actualUri]) {
+    return _sourceCache.putIfAbsent(uri, () {
+      if (uri.scheme != 'package') {
+        return null;
+      }
+      String uriPath = uri.path;
+      int slash = uriPath.indexOf('/');
+
+      // If the path either starts with a slash or has no slash, it is invalid.
+      if (slash < 1) {
+        return null;
+      }
+
+      String packageName = uriPath.substring(0, slash);
+      String fileUriPart = uriPath.substring(slash + 1);
+      String filePath = fileUriPart.replaceAll('/', _context.separator);
+
+      if (packageName.indexOf('.') == -1) {
+        String path =
+            _context.join('third_party', 'dart', packageName, 'lib', filePath);
+        File file = _workspace.getFile(path);
+        return file?.createSource(uri);
+      } else {
+        String packagePath = packageName.replaceAll('.', _context.separator);
+        String path =
+            _context.join(_workspace.root, packagePath, 'lib', filePath);
+        File file = _workspace.findFile(path);
+        return file?.createSource(uri);
+      }
+    });
+  }
+}
+
+/**
  * Information about a Bazel workspace.
  */
 class BazelWorkspace {
   static const String _WORKSPACE = 'WORKSPACE';
   static const String _READONLY = 'READONLY';
 
   final ResourceProvider provider;
 
   /**
    * The absolute workspace root path.
@@ skipping 71 matching lines @@
         return new BazelWorkspace._(provider, path, null, null, null);
       }
     }
   }
 
   BazelWorkspace._(
       this.provider, this.root, this.readonly, this.bin, this.genfiles);
 
   /**
    * Return the file with the given [absolutePath], looking first into
-   * directories for generated files: `bazel-bin` and `bazel-genfiles`, and
+   * directories for generated files: `bazel-genfiles` and `bazel-bin`, and
    * then into the workspace root. The file in the workspace root is returned
    * even if it does not exist. Return `null` if the given [absolutePath] is
    * not in the workspace [root].
    */
   File findFile(String absolutePath) {
     Context context = provider.pathContext;
     try {
       String relative = context.relative(absolutePath, from: root);
       // genfiles
       if (genfiles != null) {
@@ skipping 15 matching lines @@
         if (file.exists) {
           return file;
         }
       }
       // Not generated, return the default one.
       return provider.getFile(absolutePath);
     } catch (_) {
       return null;
     }
   }
+
+  /**
+   * Return the file for the given [pathInWorkspace]. The file is returned even
+   * if it does not exist.
+   */
+  File getFile(String pathInWorkspace) {
+    return provider.getFile(provider.pathContext.join(root, pathInWorkspace));
+  }
 }