Add support for plain CSS imports (#436)

Closes #424

Author: nex3

CHANGELOG.md

@@ -1,5 +1,12 @@
 ## 1.11.0
 
+* Add support for importing plain CSS files. They can only be imported *without*
+  an extension—for example, `@import "style"` will import `style.css`. Plain CSS
+  files imported this way only support standard CSS features, not Sass
+  extensions.
+
+  See [the proposal][css-import] for details.
+
 * Add support for CSS's `min()` and `max()` [math functions][]. A `min()` and
   `max()` call will continue to be parsed as a Sass function if it involves any
   Sass-specific features like variables or function calls, but if it's valid
@@ -15,6 +22,7 @@
   [the proposal][identifier-escapes] for details.
 
 [math functions]: https://drafts.csswg.org/css-values/#math-function
+[css-import]: https://github.com/sass/language/blob/master/accepted/css-imports.md
 [css-min-max]: https://github.com/sass/language/blob/master/accepted/min-max.md
 [media-ranges]: https://github.com/sass/language/blob/master/accepted/media-ranges.md
 [identifier-escapes]: https://github.com/sass/language/blob/master/accepted/identifier-escapes.md
@@ -24,6 +32,23 @@
 * The `--watch` command now continues to recompile a file after a syntax error
   has been detected.
 
+### Dart API
+
+* Added a `Syntax` enum to indicate syntaxes for Sass source files.
+
+* The `compile()` and `compileAsync()` functions now parse files with the `.css`
+  extension as plain CSS.
+
+* Added a `syntax` parameter to `compileString()` and `compileStringAsync()`.
+
+* Deprecated the `indented` parameter to `compileString()` and `compileStringAsync()`.
+
+* Added a `syntax` parameter to `new ImporterResult()` and a
+  `ImporterResult.syntax` getter to set the syntax of the source file.
+
+* Deprecated the `indented` parameter to `new ImporterResult()` and the
+  `ImporterResult.indented` getter in favor of `syntax`.
+
 ## 1.10.4
 
 ### Command-Line Interface

lib/sass.dart

@@ -15,11 +15,13 @@ import 'src/exception.dart';
 import 'src/importer.dart';
 import 'src/logger.dart';
 import 'src/sync_package_resolver.dart';
+import 'src/syntax.dart';
 import 'src/visitor/serialize.dart';
 
 export 'src/callable.dart' show Callable, AsyncCallable;
 export 'src/importer.dart';
 export 'src/logger.dart';
+export 'src/syntax.dart';
 export 'src/value.dart' show ListSeparator;
 export 'src/value/external/value.dart';
 export 'src/visitor/serialize.dart' show OutputStyle;
@@ -94,8 +96,7 @@ String compile(String path,
 
 /// Compiles [source] to CSS and returns the result.
 ///
-/// If [indented] is `true`, this parses [source] using indented syntax;
-/// otherwise (and by default) it uses SCSS.
+/// This parses the stylesheet as [syntax], which defaults to [Syntax.scss].
 ///
 /// If [color] is `true`, this will use terminal colors in warnings. It's
 /// ignored if [logger] is passed.
@@ -147,7 +148,7 @@ String compile(String path,
 ///
 /// Throws a [SassException] if conversion fails.
 String compileString(String source,
-    {bool indented: false,
+    {Syntax syntax,
     bool color: false,
     Logger logger,
     Iterable<Importer> importers,
@@ -157,9 +158,10 @@ String compileString(String source,
     OutputStyle style,
     Importer importer,
     url,
-    void sourceMap(SingleMapping map)}) {
+    void sourceMap(SingleMapping map),
+    @Deprecated("Use syntax instead.") bool indented: false}) {
   var result = c.compileString(source,
-      indented: indented,
+      syntax: syntax ?? (indented ? Syntax.sass : Syntax.scss),
       logger: logger ?? new Logger.stderr(color: color),
       importers: importers,
       packageResolver: packageResolver,
@@ -205,7 +207,7 @@ Future<String> compileAsync(String path,
 /// synchronous [Importer]s. However, running asynchronously is also somewhat
 /// slower, so [compileString] should be preferred if possible.
 Future<String> compileStringAsync(String source,
-    {bool indented: false,
+    {Syntax syntax,
     bool color: false,
     Logger logger,
     Iterable<AsyncImporter> importers,
@@ -215,9 +217,10 @@ Future<String> compileStringAsync(String source,
     OutputStyle style,
     AsyncImporter importer,
     url,
-    void sourceMap(SingleMapping map)}) async {
+    void sourceMap(SingleMapping map),
+    @Deprecated("Use syntax instead.") bool indented: false}) async {
   var result = await c.compileStringAsync(source,
-      indented: indented,
+      syntax: syntax ?? (indented ? Syntax.sass : Syntax.scss),
       logger: logger ?? new Logger.stderr(color: color),
       importers: importers,
       packageResolver: packageResolver,

lib/src/ast/sass/statement/stylesheet.dart

@@ -6,8 +6,10 @@ import 'package:source_span/source_span.dart';
 
 import '../../../visitor/interface/statement.dart';
 import '../../../logger.dart';
+import '../../../parse/css.dart';
 import '../../../parse/sass.dart';
 import '../../../parse/scss.dart';
+import '../../../syntax.dart';
 import '../statement.dart';
 import 'parent.dart';
 
@@ -17,9 +19,31 @@ import 'parent.dart';
 class Stylesheet extends ParentStatement {
   final FileSpan span;
 
-  Stylesheet(Iterable<Statement> children, this.span)
+  /// Whether this was parsed from a plain CSS stylesheet.
+  final bool plainCss;
+
+  Stylesheet(Iterable<Statement> children, this.span, {this.plainCss: false})
       : super(new List.unmodifiable(children));
 
+  /// Parses a stylesheet from [contents] according to [syntax].
+  ///
+  /// If passed, [url] is the name of the file from which [contents] comes.
+  ///
+  /// Throws a [SassFormatException] if parsing fails.
+  factory Stylesheet.parse(String contents, Syntax syntax,
+      {url, Logger logger}) {
+    switch (syntax) {
+      case Syntax.sass:
+        return new Stylesheet.parseSass(contents, url: url, logger: logger);
+      case Syntax.scss:
+        return new Stylesheet.parseScss(contents, url: url, logger: logger);
+      case Syntax.css:
+        return new Stylesheet.parseCss(contents, url: url, logger: logger);
+      default:
+        throw new ArgumentError("Unknown syntax $syntax.");
+    }
+  }
+
   /// Parses an indented-syntax stylesheet from [contents].
   ///
   /// If passed, [url] is the name of the file from which [contents] comes.
@@ -36,6 +60,14 @@ class Stylesheet extends ParentStatement {
   factory Stylesheet.parseScss(String contents, {url, Logger logger}) =>
       new ScssParser(contents, url: url, logger: logger).parse();
 
+  /// Parses a plain CSS stylesheet from [contents].
+  ///
+  /// If passed, [url] is the name of the file from which [contents] comes.
+  ///
+  /// Throws a [SassFormatException] if parsing fails.
+  factory Stylesheet.parseCss(String contents, {url, Logger logger}) =>
+      new CssParser(contents, url: url, logger: logger).parse();
+
   T accept<T>(StatementVisitor<T> visitor) => visitor.visitStylesheet(this);
 
   String toString() => children.join(" ");

lib/src/ast/selector/list.dart

@@ -49,14 +49,20 @@ class SelectorList extends Selector {
   /// Parses a selector list from [contents].
   ///
   /// If passed, [url] is the name of the file from which [contents] comes.
-  /// [allowParent] controls whether a [ParentSelector] is allowed in this
-  /// selector.
+  /// [allowParent] and [allowPlaceholder] control whether [ParentSelector]s or
+  /// [PlaceholderSelector]s are allowed in this selector, respectively.
   ///
   /// Throws a [SassFormatException] if parsing fails.
   factory SelectorList.parse(String contents,
-          {url, Logger logger, bool allowParent: true}) =>
+          {url,
+          Logger logger,
+          bool allowParent: true,
+          bool allowPlaceholder: true}) =>
       new SelectorParser(contents,
-              url: url, logger: logger, allowParent: allowParent)
+              url: url,
+              logger: logger,
+              allowParent: allowParent,
+              allowPlaceholder: allowPlaceholder)
           .parse();
 
   T accept<T>(SelectorVisitor<T> visitor) => visitor.visitSelectorList(this);

lib/src/async_import_cache.dart

@@ -152,11 +152,8 @@ class AsyncImportCache {
       var displayUrl = originalUrl == null
           ? canonicalUrl
           : originalUrl.resolve(p.url.basename(canonicalUrl.path));
-      return result.isIndented
-          ? new Stylesheet.parseSass(result.contents,
-              url: displayUrl, logger: _logger)
-          : new Stylesheet.parseScss(result.contents,
-              url: displayUrl, logger: _logger);
+      return new Stylesheet.parse(result.contents, result.syntax,
+          url: displayUrl, logger: _logger);
     });
   }
 

lib/src/compile.dart

@@ -17,14 +17,15 @@ import 'importer/node.dart';
 import 'io.dart';
 import 'logger.dart';
 import 'sync_package_resolver.dart';
+import 'syntax.dart';
 import 'visitor/async_evaluate.dart';
 import 'visitor/evaluate.dart';
 import 'visitor/serialize.dart';
 
 /// Like [compile] in `lib/sass.dart`, but provides more options to support the
 /// node-sass compatible API.
 CompileResult compile(String path,
-        {bool indented,
+        {Syntax syntax,
         Logger logger,
         Iterable<Importer> importers,
         NodeImporter nodeImporter,
@@ -37,7 +38,7 @@ CompileResult compile(String path,
         LineFeed lineFeed,
         bool sourceMap: false}) =>
     compileString(readFile(path),
-        indented: indented ?? p.extension(path) == '.sass',
+        syntax: syntax ?? Syntax.forPath(path),
         logger: logger,
         functions: functions,
         importers: importers,
@@ -55,7 +56,7 @@ CompileResult compile(String path,
 /// Like [compileString] in `lib/sass.dart`, but provides more options to support
 /// the node-sass compatible API.
 CompileResult compileString(String source,
-    {bool indented: false,
+    {Syntax syntax,
     Logger logger,
     Iterable<Importer> importers,
     NodeImporter nodeImporter,
@@ -69,11 +70,10 @@ CompileResult compileString(String source,
     LineFeed lineFeed,
     url,
     bool sourceMap: false}) {
-  var sassTree = indented
-      ? new Stylesheet.parseSass(source, url: url, logger: logger)
-      : new Stylesheet.parseScss(source, url: url, logger: logger);
+  var stylesheet = new Stylesheet.parse(source, syntax ?? Syntax.scss,
+      url: url, logger: logger);
 
-  var evaluateResult = evaluate(sassTree,
+  var evaluateResult = evaluate(stylesheet,
       importCache: new ImportCache(importers,
           loadPaths: loadPaths,
           packageResolver: packageResolver,
@@ -97,7 +97,7 @@ CompileResult compileString(String source,
 /// Like [compileAsync] in `lib/sass.dart`, but provides more options to support
 /// the node-sass compatible API.
 Future<CompileResult> compileAsync(String path,
-        {bool indented,
+        {Syntax syntax,
         Logger logger,
         Iterable<AsyncImporter> importers,
         NodeImporter nodeImporter,
@@ -110,7 +110,7 @@ Future<CompileResult> compileAsync(String path,
         LineFeed lineFeed,
         bool sourceMap: false}) =>
     compileStringAsync(readFile(path),
-        indented: indented ?? p.extension(path) == '.sass',
+        syntax: syntax ?? Syntax.forPath(path),
         logger: logger,
         importers: importers,
         nodeImporter: nodeImporter,
@@ -128,7 +128,7 @@ Future<CompileResult> compileAsync(String path,
 /// Like [compileStringAsync] in `lib/sass.dart`, but provides more options to
 /// support the node-sass compatible API.
 Future<CompileResult> compileStringAsync(String source,
-    {bool indented: false,
+    {Syntax syntax,
     Logger logger,
     Iterable<AsyncImporter> importers,
     NodeImporter nodeImporter,
@@ -142,11 +142,10 @@ Future<CompileResult> compileStringAsync(String source,
     LineFeed lineFeed,
     url,
     bool sourceMap: false}) async {
-  var sassTree = indented
-      ? new Stylesheet.parseSass(source, url: url, logger: logger)
-      : new Stylesheet.parseScss(source, url: url, logger: logger);
+  var stylesheet = new Stylesheet.parse(source, syntax ?? Syntax.scss,
+      url: url, logger: logger);
 
-  var evaluateResult = await evaluateAsync(sassTree,
+  var evaluateResult = await evaluateAsync(stylesheet,
       importCache: new AsyncImportCache(importers,
           loadPaths: loadPaths,
           packageResolver: packageResolver,

lib/src/executable/compile_stylesheet.dart

@@ -14,6 +14,7 @@ import '../async_import_cache.dart';
 import '../import_cache.dart';
 import '../io.dart';
 import '../stylesheet_graph.dart';
+import '../syntax.dart';
 import '../visitor/async_evaluate.dart';
 import '../visitor/evaluate.dart';
 import '../visitor/serialize.dart';
@@ -98,9 +99,17 @@ Future<Stylesheet> _parseStylesheet(
 
   var text = source == null ? await readStdin() : readFile(source);
   var url = source == null ? null : p.toUri(source);
-  return options.indented ?? (source != null && p.extension(source) == '.sass')
-      ? new Stylesheet.parseSass(text, url: url, logger: options.logger)
-      : new Stylesheet.parseScss(text, url: url, logger: options.logger);
+
+  Syntax syntax;
+  if (options.indented == true) {
+    syntax = Syntax.sass;
+  } else if (source != null) {
+    syntax = Syntax.forPath(source);
+  } else {
+    syntax = Syntax.scss;
+  }
+
+  return new Stylesheet.parse(text, syntax, url: url, logger: options.logger);
 }
 
 /// Writes the source map given by [mapping] to disk (if necessary) according to

lib/src/import_cache.dart

@@ -5,7 +5,7 @@
 // DO NOT EDIT. This file was generated from async_import_cache.dart.
 // See tool/synchronize.dart for details.
 //
-// Checksum: b76ccc1b4de05a239f04d77fe0034795c68498f7
+// Checksum: 172219d313175ec88ce1ced2c37ca4b60348a4d2
 
 import 'package:path/path.dart' as p;
 import 'package:tuple/tuple.dart';
@@ -154,11 +154,8 @@ class ImportCache {
       var displayUrl = originalUrl == null
           ? canonicalUrl
           : originalUrl.resolve(p.url.basename(canonicalUrl.path));
-      return result.isIndented
-          ? new Stylesheet.parseSass(result.contents,
-              url: displayUrl, logger: _logger)
-          : new Stylesheet.parseScss(result.contents,
-              url: displayUrl, logger: _logger);
+      return new Stylesheet.parse(result.contents, result.syntax,
+          url: displayUrl, logger: _logger);
     });
   }
 

lib/src/importer/filesystem.dart

@@ -6,6 +6,7 @@ import 'package:path/path.dart' as p;
 
 import '../importer.dart';
 import '../io.dart' as io;
+import '../syntax.dart';
 import 'result.dart';
 import 'utils.dart';
 
@@ -26,7 +27,7 @@ class FilesystemImporter extends Importer {
   ImporterResult load(Uri url) {
     var path = p.fromUri(url);
     return new ImporterResult(io.readFile(path),
-        sourceMapUrl: url, indented: p.extension(path) == '.sass');
+        sourceMapUrl: url, syntax: Syntax.forPath(path));
   }
 
   DateTime modificationTime(Uri url) => io.modificationTime(p.fromUri(url));