Qualify library names in packages

lib/src/analyzer/multi_package_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.
 
 import 'dart:io';
 
 import 'package:analyzer/src/generated/java_io.dart';
 import 'package:analyzer/src/generated/source.dart';
 import 'package:analyzer/src/generated/source_io.dart';
-import 'package:path/path.dart' show join;
+import 'package:path/path.dart' as path;
 
 /// A package resolver that supports a non-standard package layout, where
 /// packages with dotted names are expanded to a hierarchy of directories, and
 /// packages can be found on one or more locations.
 class MultiPackageResolver extends UriResolver {
   final List<String> searchPaths;
   MultiPackageResolver(this.searchPaths);
 
   @override
   Source resolveAbsolute(Uri uri, [Uri actualUri]) {
     var candidates = _expandPath(uri);
     if (candidates == null) return null;
 
     for (var path in candidates) {
       var resolvedPath = _resolve(path);
       if (resolvedPath != null) {
         return new FileBasedSource(
             new JavaFile(resolvedPath), actualUri != null ? actualUri : uri);
       }
     }
     return null;
   }
 
-  /// Resolve [path] by looking at each prefix in [searchPaths] and returning
-  /// the first location where `prefix + path` exists.
-  String _resolve(String path) {
+  @override
+  Uri restoreAbsolute(Source source) {

[Paul Berry, 2016/04/27 19:19:57]

FYI, technically this breaks the interface contract of
UriResolver.restoreAbsolute, which says "The computation should be based solely
on [source.fullName]".

The rationale is: some callers of restoreAbsolute start with a path in the file
system and nothing else, and then they create a Source object whose .fullName
points to that path and whose other properties (.uri, .etc.) are likely to be
bogus.  Then they pass this bogus Source object to restoreAbsolute(), get back a
Uri, and then pass it to resolveAbsolute() to get a non-bogus Source object.

I think this would be easy to fix; simply drop the uri.scheme checks at the top
of the function, and set filePath = path.absolute(source.fullName).

Having said that, restoreAbsolute() is used in such limited circumstances that
if you want to chance it, you probably won't run into any trouble.

+    var uri = source.uri;
+    if (uri.scheme == 'package' || uri.scheme == 'dart') {
+      return uri;
+    }
+    if (uri.scheme == '' || uri.scheme == 'file') {
+      var filePath = path.absolute(uri.path);

[Paul Berry, 2016/04/27 19:19:57]

This won't work on Windows, since uri.path uses '/', and path.absolute() assumes
the conventions of the host OS.

My suggestion above (set filePath = path.absolute(source.fullName) would address
this.

+      for (var searchPath in searchPaths) {
+        if (path.isWithin(searchPath, filePath)) {
+          var relativePath = path.relative(filePath, from: searchPath);
+          var segments = path.split(relativePath);
+          var libIndex = segments.lastIndexOf('lib');

[vsm, 2016/04/27 18:24:35]

This is not yet tested and seems brittle...

+          var packageName = segments.sublist(0, libIndex).join('.');
+          var packageRelativePath = segments.sublist(libIndex + 1).join('/');
+          return Uri.parse('package:$packageName/$packageRelativePath');
+        }
+      }
+    }
+    return null;
+  }
+
+  /// Resolve [packagePath] by looking at each prefix in [searchPaths] and returning

[Jennifer Messerly, 2016/04/27 18:30:05]

long line

+  /// the first location where `prefix + packagePath` exists.
+  String _resolve(String packagePath) {
     for (var prefix in searchPaths) {
-      var resolvedPath = join(prefix, path);
+      var resolvedPath = path.join(prefix, packagePath);
       if (new File(resolvedPath).existsSync()) return resolvedPath;
     }
     return null;
   }
 
   /// Expand `uri.path`, replacing dots in the package name with slashes.
   List<String> _expandPath(Uri uri) {
     if (uri.scheme != 'package') return null;
     var path = uri.path;
     var slashPos = path.indexOf('/');
     var packagePath = path.substring(0, slashPos).replaceAll(".", "/");
     var filePath = path.substring(slashPos + 1);
     return ['$packagePath/lib/$filePath', '$packagePath/$filePath'];
   }
 }