Adding some asset-related utilities to code_transformers

pkg/polymer/lib/src/build/common.dart

 // Copyright (c) 2013, 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.
 
 /// Common methods used by transfomers.
 library polymer.src.build.common;
 
 import 'dart:async';
 import 'dart:math' show min, max;
 
@@ skipping 118 matching lines @@
   var primaryId = transform.primaryInput.id;
   bool samePackage = id.package == primaryId.package;
   return samePackage ? id.path
       : assetUrlFor(id, primaryId, transform.logger, allowAssetUrl: true);
 }
 
 /// Transformer phases which should be applied to the Polymer package.
 List<List<Transformer>> get phasesForPolymer =>
     [[new ObservableTransformer(['lib/src/instance.dart'])]];
 
-/// Create an [AssetId] for a [url] seen in the [source] asset. By default this
-/// is used to resolve relative urls that occur in HTML assets, including
-/// cross-package urls of the form "packages/foo/bar.html". Dart "package:"
-/// urls are not resolved unless [source] is Dart file (has a .dart extension).
-// TODO(sigmund): delete once this is part of barback (dartbug.com/12610)
-AssetId resolve(AssetId source, String url, TransformLogger logger, Span span,
-    {bool allowAbsolute: false}) {
-  if (url == null || url == '') return null;
-  var uri = Uri.parse(url);
-  var urlBuilder = path.url;
-  if (uri.host != '' || uri.scheme != '' || urlBuilder.isAbsolute(url)) {
-    if (source.extension == '.dart' && uri.scheme == 'package') {
-      var index = uri.path.indexOf('/');
-      if (index != -1) {
-        return new AssetId(uri.path.substring(0, index),
-            'lib${uri.path.substring(index)}');
-      }
-    }
-
-    if (!allowAbsolute) {
-      logger.error('absolute paths not allowed: "$url"', span: span);
-    }
-    return null;
-  }
-
-  var targetPath = urlBuilder.normalize(
-      urlBuilder.join(urlBuilder.dirname(source.path), url));
-  var segments = urlBuilder.split(targetPath);
-  var sourceSegments = urlBuilder.split(source.path);
-  assert (sourceSegments.length > 0);
-  var topFolder = sourceSegments[0];
-  var entryFolder = topFolder != 'lib' && topFolder != 'asset';
-
-  // Find the first 'packages/'  or 'assets/' segment:
-  var packagesIndex = segments.indexOf('packages');
-  var assetsIndex = segments.indexOf('assets');
-  var index = (packagesIndex >= 0 && assetsIndex >= 0)
-      ? min(packagesIndex, assetsIndex)
-      : max(packagesIndex, assetsIndex);
-  if (index > -1) {
-    if (entryFolder) {
-      // URLs of the form "packages/foo/bar" seen under entry folders (like
-      // web/, test/, example/, etc) are resolved as an asset in another
-      // package. 'packages' can be used anywhere, there is no need to walk up
-      // where the entrypoint file was.
-      return _extractOtherPackageId(index, segments, logger, span);
-    } else if (index == 1 && segments[0] == '..') {
-      // Relative URLs of the form "../../packages/foo/bar" in an asset under
-      // lib/ or asset/ are also resolved as an asset in another package, but we
-      // check that the relative path goes all the way out where the packages
-      // folder lives (otherwise the app would not work in Dartium). Since
-      // [targetPath] has been normalized, "packages" or "assets" should be at
-      // index 1.
-      return _extractOtherPackageId(1, segments, logger, span);
-    } else {
-      var prefix = segments[index];
-      var fixedSegments = [];
-      fixedSegments.addAll(sourceSegments.map((_) => '..'));
-      fixedSegments.addAll(segments.sublist(index));
-      var fixedUrl = urlBuilder.joinAll(fixedSegments);
-      logger.error('Invalid url to reach to another package: $url. Path '
-          'reaching to other packages must first reach up all the '
-          'way to the $prefix folder. For example, try changing the url above '
-          'to: $fixedUrl', span: span);
-      return null;
-    }
-  }
-
-  // Otherwise, resolve as a path in the same package.
-  return new AssetId(source.package, targetPath);
-}
-
-AssetId _extractOtherPackageId(int index, List segments,
-    TransformLogger logger, Span span) {
-  if (index >= segments.length) return null;
-  var prefix = segments[index];
-  if (prefix != 'packages' && prefix != 'assets') return null;
-  var folder = prefix == 'packages' ? 'lib' : 'asset';
-  if (segments.length < index + 3) {
-    logger.error("incomplete $prefix/ path. It should have at least 3 "
-        "segments $prefix/name/path-from-name's-$folder-dir", span: span);
-    return null;
-  }
-  return new AssetId(segments[index + 1],
-      path.url.join(folder, path.url.joinAll(segments.sublist(index + 2))));
-}
-
 /// Generate the import url for a file described by [id], referenced by a file
 /// with [sourceId].
 // TODO(sigmund): this should also be in barback (dartbug.com/12610)
 String assetUrlFor(AssetId id, AssetId sourceId, TransformLogger logger,
     {bool allowAssetUrl: false}) {
   // use package: and asset: urls if possible
   if (id.path.startsWith('lib/')) {
     return 'package:${id.package}/${id.path.substring(4)}';
   }
 
@@ skipping 32 matching lines @@
   var scanner = new Scanner(null, reader, errorListener);
   var token = scanner.tokenize();
   var parser = new Parser(null, errorListener);
   return parser.parseCompilationUnit(token);
 }
 
 class _ErrorCollector extends AnalysisErrorListener {
   final errors = <AnalysisError>[];
   onError(error) => errors.add(error);
 }