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| 1 // Copyright (c) 2013, the Dart project authors. Please see the AUTHORS file |
| 2 // for details. All rights reserved. Use of this source code is governed by a |
| 3 // BSD-style license that can be found in the LICENSE file. |
| 4 |
| 5 /** Transfomer that combines multiple dart script tags into a single one. */ |
| 6 library polymer.src.transform.script_compactor; |
| 7 |
| 8 import 'dart:async'; |
| 9 |
| 10 import 'package:barback/barback.dart'; |
| 11 import 'package:html5lib/parser.dart' show parseFragment; |
| 12 import 'package:path/path.dart' as path; |
| 13 |
| 14 import 'code_extractor.dart'; // import just for documentation. |
| 15 import 'common.dart'; |
| 16 |
| 17 /** |
| 18 * Combines Dart script tags into a single script tag, and creates a new Dart |
| 19 * file that calls the main function of each of the original script tags. |
| 20 * |
| 21 * This transformer assumes that all script tags point to external files. To |
| 22 * support script tags with inlined code, use this transformer after running |
| 23 * [InlineCodeExtractor] on an earlier phase. |
| 24 * |
| 25 * Internally, this transformer will convert each script tag into an import |
| 26 * statement to a library, and then uses `initPolymer` (see polymer.dart) to |
| 27 * invoke the main method on each of these libraries and register any polymer |
| 28 * elements annotated with `@CustomTag`. |
| 29 */ |
| 30 class ScriptCompactor extends Transformer { |
| 31 Future<bool> isPrimary(Asset input) => |
| 32 new Future.value(input.id.extension == ".html"); |
| 33 |
| 34 Future apply(Transform transform) { |
| 35 var id = transform.primaryId; |
| 36 var logger = transform.logger; |
| 37 return getPrimaryContent(transform).then((content) { |
| 38 var document = parseHtml(content, id.path, logger); |
| 39 var libraries = []; |
| 40 bool changed = false; |
| 41 for (var tag in document.queryAll('script')) { |
| 42 if (tag.attributes['type'] != 'application/dart') continue; |
| 43 tag.remove(); |
| 44 changed = true; |
| 45 var src = tag.attributes['src']; |
| 46 if (src == null) { |
| 47 logger.warning('unexpected script without a src url. The ' |
| 48 'ScriptCompactor transformer should run after running the ' |
| 49 'InlineCodeExtractor', tag.sourceSpan); |
| 50 continue; |
| 51 } |
| 52 var libraryId = resolve(id, src, logger, tag.sourceSpan); |
| 53 |
| 54 // TODO(sigmund): should we detect/remove duplicates? |
| 55 if (libraryId == null) continue; |
| 56 libraries.add(libraryId); |
| 57 } |
| 58 |
| 59 if (!changed) { |
| 60 transform.addOutput(new Asset.fromString(id, content)); |
| 61 return; |
| 62 } |
| 63 |
| 64 var bootstrapId = id.addExtension('_bootstrap.dart'); |
| 65 var filename = path.basename(bootstrapId.path); |
| 66 document.body.nodes.add(parseFragment( |
| 67 '<script type="application/dart" src="$filename"></script>')); |
| 68 |
| 69 var urls = libraries.map((id) => importUrlFor(id, bootstrapId, logger)) |
| 70 .where((url) => url != null).toList(); |
| 71 var buffer = new StringBuffer()..write(_header); |
| 72 for (int i = 0; i < urls.length; i++) { |
| 73 buffer.writeln("import '${urls[i]}' as i$i;"); |
| 74 } |
| 75 buffer..write(_mainPrefix) |
| 76 ..writeAll(urls.map((url) => " '$url',\n")) |
| 77 ..write(_mainSuffix); |
| 78 |
| 79 transform.addOutput(new Asset.fromString(bootstrapId, buffer.toString())); |
| 80 transform.addOutput(new Asset.fromString(id, document.outerHtml)); |
| 81 }); |
| 82 } |
| 83 |
| 84 /** |
| 85 * Generate the import url for a file described by [id], referenced by a file |
| 86 * with [sourceId]. |
| 87 */ |
| 88 String importUrlFor(AssetId id, AssetId sourceId, TransformLogger logger) { |
| 89 // use package: urls if possible |
| 90 if (id.path.startsWith('lib/')) { |
| 91 return 'package:${id.package}/${id.path.substring(4)}'; |
| 92 } |
| 93 |
| 94 // Use relative urls only if it's possible. |
| 95 if (id.package != sourceId.package) { |
| 96 logger.error("don't know how to import $id from $sourceId"); |
| 97 return null; |
| 98 } |
| 99 |
| 100 var upPath = path.joinAll(path.split(sourceId.path).map((_) => '..')); |
| 101 return path.normalize(path.join(sourceId.path, upPath, id.path)); |
| 102 } |
| 103 } |
| 104 |
| 105 const _header = """ |
| 106 library app_bootstrap; |
| 107 |
| 108 import 'package:polymer/polymer.dart'; |
| 109 import 'dart:mirrors' show currentMirrorSystem; |
| 110 |
| 111 """; |
| 112 |
| 113 const _mainPrefix = """ |
| 114 |
| 115 void main() { |
| 116 initPolymer([ |
| 117 """; |
| 118 |
| 119 // TODO(sigmund): investigate alternative to get the baseUri (dartbug.com/12612) |
| 120 const _mainSuffix = """ |
| 121 ], |
| 122 currentMirrorSystem().findLibrary(const Symbol('app_bootstrap')) |
| 123 .first.uri.toString()); |
| 124 } |
| 125 """; |
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