Add a --pkg-importer flag (#2169)

See sass/sass#2739

CHANGELOG.md

@@ -5,6 +5,13 @@ announcement][pkg-importers] on the Sass blog.
 
 [pkg-importers]: https://sass-lang.com/blog/announcing-pkg-importers
 
+### Command-Line Interface
+
+* Add a `--pkg-importer` flag to enable built-in `pkg:` importers. Currently
+  this only supports the Node.js package resolution algorithm, via
+  `--pkg-importer=node`. For example, `@use "pkg:bootstrap"` will load
+  `node_modules/bootstrap/scss/bootstrap.scss`.
+
 ### JavaScript API
 
 * Add a `NodePackageImporter` importer that can be passed to the `importers`

bin/sass.dart

@@ -45,6 +45,7 @@ Future<void> main(List<String> args) async {
     }
 
     var graph = StylesheetGraph(ImportCache(
+        importers: options.pkgImporters,
         loadPaths: options.loadPaths,
         // This logger is only used for handling fatal/future deprecations
         // during parsing, and is re-used across parses, so we don't want to

lib/src/executable/compile_stylesheet.dart

@@ -95,7 +95,9 @@ Future<void> _compileStylesheetWithoutErrorHandling(ExecutableOptions options,
   try {
     if (options.asynchronous) {
       var importCache = AsyncImportCache(
-          loadPaths: options.loadPaths, logger: options.logger);
+          importers: options.pkgImporters,
+          loadPaths: options.loadPaths,
+          logger: options.logger);
 
       result = source == null
           ? await compileStringAsync(await readStdin(),

lib/src/executable/options.dart

@@ -10,6 +10,7 @@ import 'package:pub_semver/pub_semver.dart';
 import 'package:term_glyph/term_glyph.dart' as term_glyph;
 
 import '../../sass.dart';
+import '../importer/node_package.dart';
 import '../io.dart';
 import '../util/character.dart';
 
@@ -47,6 +48,12 @@ final class ExecutableOptions {
           help: 'A path to use when resolving imports.\n'
               'May be passed multiple times.',
           splitCommas: false)
+      ..addMultiOption('pkg-importer',
+          abbr: 'p',
+          valueHelp: 'TYPE',
+          allowed: ['node'],
+          help: 'Built-in importer(s) to use for pkg: URLs.',
+          allowedHelp: {'node': 'Load files like Node.js package resolution.'})
       ..addOption('style',
           abbr: 's',
           valueHelp: 'NAME',
@@ -218,6 +225,12 @@ final class ExecutableOptions {
   /// The set of paths Sass in which should look for imported files.
   List<String> get loadPaths => _options['load-path'] as List<String>;
 
+  /// The list of built-in importers to use to load `pkg:` URLs.
+  List<Importer> get pkgImporters => [
+        for (var _ in _options['pkg-importer'] as List<String>)
+          NodePackageImporter('.')
+      ];
+
   /// Whether to run the evaluator in asynchronous mode, for debugging purposes.
   bool get asynchronous => _options['async'] as bool;
 

lib/src/executable/repl.dart

@@ -23,7 +23,10 @@ Future<void> repl(ExecutableOptions options) async {
   var logger = TrackingLogger(options.logger);
   var evaluator = Evaluator(
       importer: FilesystemImporter.cwd,
-      importCache: ImportCache(loadPaths: options.loadPaths, logger: logger),
+      importCache: ImportCache(
+          importers: options.pkgImporters,
+          loadPaths: options.loadPaths,
+          logger: logger),
       logger: logger);
   await for (String line in repl.runAsync()) {
     if (line.trim().isEmpty) continue;

pkg/sass_api/CHANGELOG.md

@@ -1,3 +1,7 @@
+## 9.4.0
+
+* No user-visible changes.
+
 ## 9.3.0
 
 * No user-visible changes.

pkg/sass_api/pubspec.yaml

@@ -2,15 +2,15 @@ name: sass_api
 # Note: Every time we add a new Sass AST node, we need to bump the *major*
 # version because it's a breaking change for anyone who's implementing the
 # visitor interface(s).
-version: 9.3.0
+version: 9.4.0
 description: Additional APIs for Dart Sass.
 homepage: https://github.com/sass/dart-sass
 
 environment:
   sdk: ">=3.0.0 <4.0.0"
 
 dependencies:
-  sass: 1.70.0
+  sass: 1.71.0
 
 dev_dependencies:
   dartdoc: ^6.0.0

pubspec.yaml

@@ -1,5 +1,5 @@
 name: sass
-version: 1.71.0-dev
+version: 1.71.0
 description: A Sass implementation in Dart.
 homepage: https://github.com/sass/dart-sass