simple index.html files for folders that contain entry points

pkg/polymer/lib/src/build/index_page_builder.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.
+
+/// Builds an index.html file in each folder containing entry points, if none
+/// already exists. This file simply lists all the entry point files.
+library polymer.src.build.index_page_builder;
+
+import 'dart:async';
+import 'dart:math';
+
+import 'package:barback/barback.dart';
+import 'package:html5lib/dom.dart';

[Siggi Cherem (dart-lang), 2014/09/17 20:32:54]

you might not need this import anymore 

[jakemac, 2014/09/17 22:14:01]

Done.

+import 'package:path/path.dart' as path;
+
+import 'common.dart';
+
+/// Builds an index.html file in each folder containing entry points, if none
+/// already exists. This file simply lists all the entry point files.
+class IndexPageBuilder extends AggregateTransformer {
+  final TransformOptions options;
+
+  IndexPageBuilder(this.options);
+
+  classifyPrimary(AssetId id) {
+    if (!options.isHtmlEntryPoint(id)) return null;
+    // Group all entry points together.
+    return 'all_entry_points';
+  }
+
+  Future apply(AggregateTransform transform) {
+    Map<String, List<String>> dirFilesMap = {};
+
+    return transform.primaryInputs.toList().then((assets) {
+      // Add the asset to its directory, and make sure its directory is included
+      // in all its parents.
+      for (var asset in assets) {
+        var dir = path.url.dirname(asset.id.path);
+        while (dir != '.') {
+          dirFilesMap.putIfAbsent(dir, () => []);
+
+          var relativePath = path.url.relative(asset.id.path, from: dir);
+          var relativeDir = path.url.dirname(relativePath);
+          dirFilesMap[dir].add(relativePath);
+          dir = path.url.dirname(dir);
+        }
+      }
+
+      // Create an output index.html file for each directory, if one doesn't
+      // exist already
+      var futures = [];
+      dirFilesMap.forEach((directory, files) {
+        futures.add(_createOutput(directory, files, transform));
+      });
+      return Future.wait(futures);
+    });
+  }
+
+  Future _createOutput(
+      String directory, List<String> files, AggregateTransform transform) {
+    var indexAsset = new AssetId(
+        transform.package, path.join(directory, 'index.html'));
+
+    return transform.hasInput(indexAsset).then((exists) {
+      // Don't overwrite existing outputs!
+      if (exists) return;
+
+      // Sort alphabetically by recursive path parts.
+      files.sort((String a, String b) {
+        var aParts = path.split(a);
+        var bParts = path.split(b);
+        int diff = 0;
+        int minLength = min(aParts.length, bParts.length);
+        for (int i = 0; i < minLength; i++) {

[Siggi Cherem (dart-lang), 2014/09/17 20:32:54]

now that there is no directory entries, but just paths, it seems that we can
simplify this a bit by using the alphabetic order of the paths themselves.

For example, I believe this will give you the same result:

 var aIsDir = path.dirname(a) != '.';
 var bIsDir = path.dirname(b) != '.';
 if (aIsDir && !bIsDir) return 1;
 if (!aIsDir && bIsDir) return -1;
 return a.compareTo(b);

[jakemac, 2014/09/17 22:14:01]

Talked in person, its more complicated than this though to give what you expect.

On 2014/09/17 20:32:54, Siggi Cherem (dart-lang) wrote:

+          // Directories are sorted below files.
+          var aIsDir = path.url.extension(aParts[i]) == '';
+          var bIsDir = path.url.extension(bParts[i]) == '';
+          if (aIsDir && !bIsDir) {
+            return 1;
+          } else if (!aIsDir && bIsDir) {
+            return -1;
+          }
+
+          // Raw string comparison, if not identical we return.
+          diff = aParts[i].compareTo(bParts[i]);
+          if (diff != 0) return diff;
+        }
+        // Identical files, shouldn't happen in practice.
+        return 0;
+      });
+
+      // Create the document with a list.
+      var doc = new StringBuffer(
+          '<!DOCTYPE html><html><body><h1>Entry points</h1><ul>');
+
+      // Add all the assets to the list.
+      for (var file in files) {
+        doc.write('<li><a href="$file">$file</a></li>');
+      };
+
+      doc.write('</ul></body></html>');
+
+      // Output the index.html file
+      transform.addOutput(new Asset.fromString(indexAsset , doc.toString()));
+    });
+  }
+
+}