Rev package version as the extended source map format is a new feature.

lib/parser.dart

Index: lib/parser.dart
diff --git a/lib/parser.dart b/lib/parser.dart
index 492e6cf65030792b5062594ace3b748553f2305b..ca872fad325802e5eb8826b10c1fdcfea0f6ca83 100644
--- a/lib/parser.dart
+++ b/lib/parser.dart
@@ -8,7 +8,6 @@ library source_maps.parser;
 import 'dart:collection';
 import 'dart:convert';
 
-import 'package:path/path.dart' as path;
 import 'package:source_span/source_span.dart';
 
 import 'builder.dart' as builder;
@@ -205,13 +204,50 @@ class MappingBundle extends Mapping {
     if (uri == null) {
       throw new ArgumentError.notNull('uri');
     }
-    if (_mappings.containsKey(uri)) {
-      return _mappings[uri].spanFor(line, column, files: files, uri: uri);
-    }
-    // Fall back to looking up the source map on just the basename.
-    var name = path.basename(uri.toString());
-    if (_mappings.containsKey(name)) {
-      return _mappings[name].spanFor(line, column, files: files, uri: name);
+
+    // Find the longest suffix of the uri that matches the sourcemap
+    // where the suffix starts after a path segment boundary.
+    // We consider ":", "/", and "\" as path segment boundaries so that
+    // "package:" uris, windows paths, and linux paths can all be handled
+    // properly with minimal special casing. Having a few false positive
+    // path segment boundaries is not a significant issue as we prefer the
+    // longest matching prefix.
+    // Using package:path `path.split` to find path segment boundaries would
+    // not generate all of the path segment boundaries we want for package:
+    // urls as "package:package_name" would be one path segment when we want
+    // "package" and "package_name" to be sepearate path segments.
+
+    bool onBoundary = true;
+    var separatorCodeUnits = [
+      '/'.codeUnitAt(0),
+      '\\'.codeUnitAt(0),

[Siggi Cherem (dart-lang), 2016/12/14 19:10:34]

we discussed this offline: let's get rid of the handling of backslashes here and
add ensure that the input is normalized, so that what we look up here has to
match what was given to us in MappingBundle.fromJson(...);

[Jacob, 2016/12/14 19:17:00]

Done.

+      ':'.codeUnitAt(0)
+    ];
+    for (var i = 0; i < uri.length; ++i) {
+      if (onBoundary) {
+        var candidate = uri.substring(i);
+        if (_mappings.containsKey(candidate)) {
+          return _mappings[candidate]
+              .spanFor(line, column, files: files, uri: candidate);
+        }
+        // The following two cases are needed to handle cases where the uri
+        // may use different path separator conventions that the source map
+        // bundle as is seasonable if we are using the source map bundle on
+        // the server while the files being considered are on the client.
+
+        var webCandidate = candidate.replaceAll('\\', '/');
+        if (_mappings.containsKey(webCandidate)) {
+          return _mappings[webCandidate]
+              .spanFor(line, column, files: files, uri: webCandidate);
+        }
+
+        var windowsCandidate = candidate.replaceAll('/', '\\');
+        if (_mappings.containsKey(windowsCandidate)) {
+          return _mappings[windowsCandidate]
+              .spanFor(line, column, files: files, uri: windowsCandidate);
+        }
+      }
+      onBoundary = separatorCodeUnits.contains(uri.codeUnitAt(i));
     }
 
     // Note: when there is no source map for an uri, this behaves like an