Edit pruneCss flag to allow printing pruned css instead of overwriting.

README.md

@@ -121,7 +121,7 @@ Examples: see [example/angular1](https://github.com/google/dart-scissors/tree/ma
   ```
 
 Valid settings:
-- `pruneCss` (boolean): by default, `true` in `release` only
+- `pruneCss` (`skip` or `print` or `overwrite`): by default, `overwrite` in `release` only
 - `imageInlining`: default is `linkInlinedImages` in `debug`, `inlineInlinedImages` in `release`
     - `inlineAllUrls`: treats `url` as `inline-image`
     - `inlineInlinedImages`: simply honours `inline-image`

example/angular1/pubspec.yaml

@@ -15,7 +15,7 @@ transformers:
     cssJanusPath: ${PWD}/../../.dependencies/cssjanus/cssjanus.py
     release:
         imageInlining: inlineAllUrls
-    # pruneCss: false
+    # pruningScheme: skip
     # optimizeSvg: false
     # optimizePng: false
     compiledCssExtension: replace

example/angular2/pubspec.yaml

@@ -11,7 +11,7 @@ transformers:
 # - scissors/eager_transformer
 - scissors:
     verbose: true
-    # pruneCss: false
+    # pruningScheme: skip
     # optimizeSvg: false
     # optimizePng: false
 - angular2/transform/codegen

lib/eager_transformer.dart

@@ -16,6 +16,7 @@ library scissors.scissors_transformer;
 import 'package:barback/barback.dart';
 
 import 'src/css_mirroring/transformer.dart';
+import 'src/css_pruning/css_utils.dart' show PruningScheme;
 import 'src/css_pruning/transformer.dart';
 import 'src/image_inlining/transformer.dart';
 import 'src/png_optimization/transformer.dart';
@@ -46,7 +47,11 @@ List<List<Transformer>> _createPhases(_ScissorsSettings settings) {
           : null,
       settings.compileSass.value ? new SassCTransformer(settings) : null
     ],
-    [settings.pruneCss.value ? new CssPruningTransformer(settings) : null],
+    [
+      settings.pruningScheme.value != PruningScheme.skip
+          ? new CssPruningTransformer(settings)
+          : null
+    ],
     [
       settings.imageInlining.value != ImageInliningMode.disablePass
           ? new ImageInliningTransformer(settings)

lib/src/css_pruning/css_pruning.dart

@@ -32,6 +32,7 @@ import 'rule_set_index.dart';
 import 'template_extractor.dart' show extractTemplates;
 import 'usage_collector.dart';
 import 'transformer.dart' show CssPruningSettings;
+import 'css_utils.dart' show PruningScheme;
 
 Future<String> findHtmlTemplate(Transform transform, AssetId cssAssetId) async {
   try {
@@ -69,7 +70,6 @@ dropUnusedCssRules(
     SourceFile cssSourceFile,
     String htmlTemplate) {
   hacks.useCssLib();
-
   final StyleSheet cssTree =
       new css_parser.Parser(cssSourceFile, transaction.original).parse();
   final List<dom.Node> htmlTrees =
@@ -89,15 +89,18 @@ dropUnusedCssRules(
 
   final fileLength = transaction.file.length;
   topLevelsToDropWithIndex.forEach((TreeNode topLevel, int i) {
-    if (settings.verbose.value) {
+    if (settings.verbose.value ||
+        settings.pruningScheme.value == PruningScheme.print) {
       transform.logger.info("Dropping unused CSS rule: "
           "${_printCss(new StyleSheet([topLevel], null))}");
     }
-    final start = topLevel.span.start.offset;
-    final end = i == topLevels.length - 1
-        ? fileLength
-        : topLevels[i + 1].span.start.offset;
-    transaction.edit(start, end, '');
+    if (settings.pruningScheme.value == PruningScheme.overwrite) {
+      final start = topLevel.span.start.offset;
+      final end = i == topLevels.length - 1
+          ? fileLength
+          : topLevels[i + 1].span.start.offset;
+      transaction.edit(start, end, '');
+    }
   });
 }
 

lib/src/css_pruning/css_utils.dart

@@ -0,0 +1,3 @@
+library scissors.src.css_pruning.css_utils;
+
+enum PruningScheme { skip, print, overwrite }

lib/src/css_pruning/settings.dart

@@ -16,8 +16,10 @@ part of scissors.src.css_pruning.transformer;
 abstract class CssPruningSettings {
   Setting<bool> get verbose;
 
-  final pruneCss =
-      new Setting<bool>('pruneCss', debugDefault: false, releaseDefault: true);
+  final pruningScheme = new Setting<PruningScheme>('pruningScheme',
+      debugDefault: PruningScheme.skip,
+      releaseDefault: PruningScheme.overwrite,
+      parser: new EnumParser<PruningScheme>(PruningScheme.values).parse);
 
   // final bidiCss = new Setting<bool>('bidiCss',
   //     comment:

lib/src/css_pruning/transformer.dart

@@ -19,11 +19,13 @@ import 'package:barback/barback.dart';
 import 'package:source_maps/refactor.dart';
 import 'package:source_span/source_span.dart';
 
+import '../utils/enum_parser.dart';
 import '../utils/path_utils.dart';
 import '../utils/settings_base.dart';
 import '../utils/file_skipping.dart';
 import '../utils/delta_format.dart';
 import 'css_pruning.dart';
+import 'css_utils.dart';
 
 part 'settings.dart';
 
@@ -39,7 +41,8 @@ class CssPruningTransformer extends Transformer
   final String allowedExtensions = ".css .css.map";
 
   @override
-  bool isPrimary(AssetId id) => _settings.pruneCss.value && super.isPrimary(id);
+  bool isPrimary(AssetId id) =>
+      _settings.pruningScheme != PruningScheme.skip && super.isPrimary(id);
 
   @override
   declareOutputs(DeclaringTransform transform) {