Re add large sample (#3661)

* Revert "Revert "Mega gallery (#3647)" (#3659)"

This reverts commit ea62d31fde20ab109d51aa9d0104583c414b13a4.

* fix the dev/dartdoc.dart script
diff --git a/dev/tools/mega_gallery.dart b/dev/tools/mega_gallery.dart
new file mode 100644
index 0000000..7ce1faa
--- /dev/null
+++ b/dev/tools/mega_gallery.dart
@@ -0,0 +1,191 @@
+// Copyright 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+/// Make `n` copies of material_gallery.
+
+import 'dart:io';
+
+import 'package:args/args.dart';
+import 'package:path/path.dart' as path;
+
+/// If no `copies` param is passed in, we scale the generated app up to 60k lines.
+const int kTargetLineCount = 60 * 1024;
+
+void main(List<String> args) {
+  // If we're run from the `tools` dir, set the cwd to the repo root.
+  if (path.basename(Directory.current.path) == 'tools')
+    Directory.current = Directory.current.parent.parent;
+
+  ArgParser argParser = new ArgParser();
+  // ../mega_gallery? dev/benchmarks/mega_gallery?
+  argParser.addOption('out', defaultsTo: _normalize('dev/benchmarks/mega_gallery'));
+  argParser.addOption('copies');
+  argParser.addFlag('delete', negatable: false);
+  argParser.addFlag('help', abbr: 'h', negatable: false);
+
+  ArgResults results = argParser.parse(args);
+
+  if (results['help']) {
+    print('Generate n copies of material_gallery.\n');
+    print('usage: dart mega_gallery.dart <options>');
+    print(argParser.usage);
+    exit(0);
+  }
+
+  Directory source = new Directory(_normalize('examples/material_gallery'));
+  Directory out = new Directory(_normalize(results['out']));
+
+  if (results['delete']) {
+    if (out.existsSync()) {
+      print('Deleting ${out.path}');
+      out.deleteSync(recursive: true);
+    }
+
+    exit(0);
+  }
+
+  int copies;
+  if (!results.wasParsed('copies')) {
+    SourceStats stats = getStatsFor(_dir(source, 'lib'));
+    copies = (kTargetLineCount / stats.lines).round();
+  } else {
+    copies = int.parse(results['copies']);
+  }
+
+  print('Stats:');
+  print('  packages/flutter           : ${getStatsFor(new Directory("packages/flutter"))}');
+  print('  examples/material_gallery  : ${getStatsFor(new Directory("examples/material_gallery"))}');
+  print('');
+
+  print('Making $copies copies of material_gallery:');
+
+  Directory lib = _dir(out, 'lib');
+  if (lib.existsSync())
+    lib.deleteSync(recursive: true);
+
+  // Copy everything that's not a symlink, dot directory, or build/.
+  _copy(source, out);
+
+  // Make n - 1 copies.
+  for (int i = 1; i < copies; i++)
+    _copyGallery(out, i);
+
+  // Create a new entry-point.
+  _createEntry(_file(out, 'lib/main.dart'), copies);
+
+  // Update the pubspec.
+  String pubspec = _file(out, 'pubspec.yaml').readAsStringSync();
+  pubspec = pubspec.replaceAll('../../packages/flutter', '../../../packages/flutter');
+  _file(out, 'pubspec.yaml').writeAsStringSync(pubspec);
+
+  _file(out, '.dartignore').writeAsStringSync('');
+
+  // Count source lines and number of files; tell how to run it.
+  print('  ${path.relative(results["out"])}: ${getStatsFor(out)}');
+}
+
+// TODO(devoncarew): Create an entry-point that builds a UI with all `n` copies.
+void _createEntry(File mainFile, int copies) {
+  StringBuffer imports = new StringBuffer();
+  StringBuffer importRefs = new StringBuffer();
+
+  for (int i = 1; i < copies; i++) {
+    imports.writeln("import 'gallery_$i/main.dart' as main_$i;");
+    importRefs.writeln("  main_$i.main;");
+  }
+
+  String contents = '''
+// Copyright 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'package:flutter/widgets.dart';
+
+import 'gallery/app.dart';
+${imports.toString().trim()}
+
+void main() {
+  // Make sure the imports are not marked as unused.
+  ${importRefs.toString().trim()}
+
+  runApp(new GalleryApp());
+}
+''';
+
+  mainFile.writeAsStringSync(contents);
+}
+
+void _copyGallery(Directory galleryDir, int index) {
+  Directory lib = _dir(galleryDir, 'lib');
+  Directory dest = _dir(lib, 'gallery_$index');
+  dest.createSync();
+
+  // Copy demo/, gallery/, and main.dart.
+  _copy(_dir(lib, 'demo'), _dir(dest, 'demo'));
+  _copy(_dir(lib, 'gallery'), _dir(dest, 'gallery'));
+  _file(dest, 'main.dart').writeAsBytesSync(_file(lib, 'main.dart').readAsBytesSync());
+}
+
+void _copy(Directory source, Directory target) {
+  if (!target.existsSync())
+    target.createSync();
+
+  for (FileSystemEntity entity in source.listSync(followLinks: false)) {
+    String name = path.basename(entity.path);
+
+    if (entity is Directory) {
+      if (name == 'build' || name.startsWith('.'))
+        continue;
+      _copy(entity, new Directory(path.join(target.path, name)));
+    } else if (entity is File) {
+      if (name == '.packages' || name == 'pubspec.lock')
+        continue;
+      File dest = new File(path.join(target.path, name));
+      dest.writeAsBytesSync(entity.readAsBytesSync());
+    }
+  }
+}
+
+Directory _dir(Directory parent, String name) => new Directory(path.join(parent.path, name));
+File _file(Directory parent, String name) => new File(path.join(parent.path, name));
+String _normalize(String filePath) => path.normalize(path.absolute(filePath));
+
+class SourceStats {
+  int files = 0;
+  int lines = 0;
+
+  String toString() => '${_comma(files)} files, ${_comma(lines)} lines';
+}
+
+SourceStats getStatsFor(Directory dir, [SourceStats stats]) {
+  stats ??= new SourceStats();
+
+  for (FileSystemEntity entity in dir.listSync(recursive: false, followLinks: false)) {
+    String name = path.basename(entity.path);
+    if (entity is File && name.endsWith('.dart')) {
+      stats.files += 1;
+      stats.lines += _lineCount(entity);
+    } else if (entity is Directory && !name.startsWith('.')) {
+      getStatsFor(entity, stats);
+    }
+  }
+
+  return stats;
+}
+
+int _lineCount(File file) {
+  return file.readAsLinesSync().where((String line) {
+    line = line.trim();
+    if (line.isEmpty || line.startsWith('//'))
+      return false;
+    return true;
+  }).length;
+}
+
+String _comma(int count) {
+  String str = count.toString();
+  if (str.length > 3)
+    return str.substring(0, str.length - 3) + ',' + str.substring(str.length - 3);
+  return str;
+}