Add shallowCompare option

passing {shallowCompare: 2} would match a manifest entry:
	{/var/www/css/style.css: css/style-12345.css}
to a file reference:
	href="../css/style.css"

README.md

@@ -103,6 +103,12 @@ Type: `Stream` (e.g., `gulp.src()`)
 Read JSON manifests written out by `rev`. Allows replacing filenames that were
 `rev`ed prior to the current task.
 
+#### options.shallowCompare
+Type: `int`
+
+Only match manifest paths using the rightmost `shallowCompare` levels.
+e.g. `shallowCompare: 2` would match `../css/unicorn.css` to `/var/www/css/unicorn.css`
+
 ## Contributors
 
 - Chad Jablonski

index.js

@@ -59,8 +59,8 @@ function plugin(options) {
         var manifest = JSON.parse(file.contents.toString());
         Object.keys(manifest).forEach(function (srcFile) {
           renames.push({
-            unreved: canonicalizeUri(srcFile),
-            reved: options.prefix + canonicalizeUri(manifest[srcFile])
+            unreved: canonicalizeUri(shallowify(srcFile)),
+            reved: options.prefix + canonicalizeUri(shallowify(manifest[srcFile]))
           });
         });
       });
@@ -99,6 +99,19 @@ function plugin(options) {
     return canonicalizeUri(newPath);
   }
 
+  // Only look at the last few parts of a path
+  function shallowify(filePath) {
+    if (options.shallowCompare) {
+
+      var separator = utils.getPathSeparator(filePath);
+
+      return filePath.split(separator)
+        .slice(-options.shallowCompare)
+        .join(separator);
+    }
+    return filePath;
+  }
+
   function canonicalizeUri(filePath) {
     if (path.sep !== '/' && options.canonicalUris) {
       filePath = filePath.split(path.sep).join('/');

test.js

@@ -330,6 +330,59 @@ describe('manifest option', function () {
 
     stream.end();
   });
+
+  it('should only check top shallowCompare levels', function (cb) {
+    var manifest = es.readArray([
+      new gutil.File({
+        path: '/project/rev-manifest.json',
+        contents: new Buffer(JSON.stringify({
+          '/var/www/project/css/style.css': '/css/style-12345.css'
+        }))
+      })
+    ]);
+
+    var stream = revReplace({manifest: manifest, shallowCompare: 2});
+
+    var replacedCSSFilePattern = /"\/css\/style-12345\.css"/;
+    stream.on('data', function(file) {
+      var contents = file.contents.toString();
+
+      var extension = path.extname(file.path);
+      if (extension === '.html') {
+        assert(
+          replacedCSSFilePattern.test(contents),
+          'The renamed CSS file\'s name should be replaced'
+        );
+      }
+    });
+    stream.on('end', function() {
+      cb();
+    });
+
+    stream.write(new gutil.File({
+      path: 'index.html',
+      contents: new Buffer(htmlFileBody)
+    }));
+
+    stream.end();
+  });
+});
+
+describe('utils.getPathSeparator', function() {
+  it('should return \\ for backslashy paths', function() {
+    assert('\\' === utils.getPathSeparator('c:\\wamp\\www\\css\\style.css'),
+      'Backslash path should be detected');
+  });
+
+  it('should return / for foreslashy paths', function() {
+    assert('/' === utils.getPathSeparator('/css/style.css'),
+      'forwardslash paths should be detected');
+  });
+
+  it('should return a reasonable default if separator cannot be determined', function() {
+    assert('/' === utils.getPathSeparator('style.css'),
+      'Default value should be returned');
+  });
 });
 
 describe('utils.byLongestUnreved', function() {

utils.js

@@ -4,6 +4,15 @@ function byLongestUnreved(a, b) {
   return b.unreved.length - a.unreved.length;
 }
 
+function getPathSeparator(filePath) {
+	if ((filePath.match(/\\/g) || []).length > (filePath.match(/\//g) || []).length) {
+		return '\\';
+	}
+
+	return '/';
+}
+
 module.exports = {
-  byLongestUnreved: byLongestUnreved
+  byLongestUnreved: byLongestUnreved,
+  getPathSeparator: getPathSeparator
 };