Sanitize library names generated from file paths

pkg/polymer/lib/src/build/import_inliner.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.
 
 /// Transfomer that inlines polymer-element definitions from html imports.
 library polymer.src.build.import_inliner;
 
 import 'dart:async';
 import 'dart:convert';
 
@@ skipping 228 matching lines @@
 /// Transform AssetId into a library name. For example:
 ///
 ///     myPkgName|lib/foo/bar.html -> myPkgName.foo.bar_html
 ///     myPkgName|web/foo/bar.html -> myPkgName.web.foo.bar_html
 ///
 /// This should roughly match the recommended library name conventions.
 String _libraryNameFor(AssetId id, int suffix) {
   var name = '${path.withoutExtension(id.path)}_'
       '${path.extension(id.path).substring(1)}';
   if (name.startsWith('lib/')) name = name.substring(4);
-  name = name.replaceAll('/', '.').replaceAll('-', '_');
+  name = name.split('/').map((part) {
+    part = part.replaceAll(INVALID_LIB_CHARS_REGEX, '_');
+    if (part.startsWith(NUM_REGEX)) part = '_${part}';
+    return part;
+  }).join(".");
   return '${id.package}.${name}_$suffix';
 }
 
 /// Parse [code] and determine whether it has a library directive.
 bool _hasLibraryDirective(String code) =>
     parseDirectives(code, suppressErrors: true)
         .directives.any((d) => d is LibraryDirective);
 
 
 /// Recursively inlines the contents of HTML imports. Produces as output a
@@ skipping 26 matching lines @@
 
 /// Internally adjusts urls in the html that we are about to inline.
 class _UrlNormalizer extends TreeVisitor {
   final Transform transform;
 
   /// Asset where the original content (and original url) was found.
   final AssetId sourceId;
 
   /// Counter used to ensure that every library name we inject is unique.
   int _count = 0;
-  
+
   /// Path to the top level folder relative to the transform primaryInput.
   /// This should just be some arbitrary # of ../'s.
   final String topLevelPath;
 
   _UrlNormalizer(transform, this.sourceId)
       : transform = transform,
-        topLevelPath = 
+        topLevelPath =
           '../' * (transform.primaryInput.id.path.split('/').length - 2);
 
   visitElement(Element node) {
     // TODO(jakemac): Support custom elements that extend html elements which
     // have url-like attributes. This probably means keeping a list of which
     // html elements support each url-like attribute.
     if (!isCustomTagName(node.localName)) {
       node.attributes.forEach((name, value) {
         if (_urlAttributes.contains(name)) {
           if (value != '' && !value.trim().startsWith('{{')) {
@@ skipping 118 matching lines @@
   'href',       // in a, area, link, base, command
   'icon',       // in command
   'manifest',   // in html
   'poster',     // in video
   'src',        // in audio, embed, iframe, img, input, script, source, track,
                 //    video
 ];
 
 /// When inlining <link rel="stylesheet"> tags copy over all attributes to the
 /// style tag except these ones.
-const IGNORED_LINKED_STYLE_ATTRS = 
+const IGNORED_LINKED_STYLE_ATTRS =
     const ['charset', 'href', 'href-lang', 'rel', 'rev'];
 
+/// Global RegExp objects for validating generated library names.
+final INVALID_LIB_CHARS_REGEX = new RegExp('[^a-z0-9_]');
+final NUM_REGEX = new RegExp('[0-9]');
+
 _getSpan(SourceFile file, AstNode node) => file.span(node.offset, node.end);