Merge and enable feature.use 🎉

CHANGELOG.md

@@ -1,3 +1,44 @@
+## 1.23.0
+
+* **Launch the new Sass module system!** This adds:
+
+  * The [`@use` rule][], which loads Sass files as *modules* and makes their
+    members available only in the current file, with automatic namespacing.
+
+    [`@use` rule]: https://sass-lang.com/documentation/at-rules/use
+
+  * The [`@forward` rule][], which makes members of another Sass file available
+    to stylesheets that `@use` the current file.
+
+    [`@forward` rule]: https://sass-lang.com/documentation/at-rules/forward
+
+  * Built-in modules named `sass:color`, `sass:list`, `sass:map`, `sass:math`,
+    `sass:meta`, `sass:selector`, and `sass:string` that provide access to all
+    the built-in Sass functions you know and love, with automatic module
+    namespaces.
+
+  * The [`meta.load-css()` mixin][], which includes the CSS contents of a module
+    loaded from a (potentially dynamic) URL.
+
+    [`meta.load-css()` function]: https://sass-lang.com/documentation/modules/meta#load-css
+
+  * The [`meta.module-variables()` function][], which provides access to the
+    variables defined in a given module.
+
+    [`meta.module-variables()` function]: https://sass-lang.com/documentation/modules/meta#module-variables
+
+  * The [`meta.module-functions()` function][], which provides access to the
+    functions defined in a given module.
+
+    [`meta.module-functions()` function]: https://sass-lang.com/documentation/modules/meta#module-functions
+
+  Check out [the Sass blog][migrator blog] for more information on the new
+  module system. You can also use the new [Sass migrator][] to automatically
+  migrate your stylesheets to the new module system!
+
+  [migrator blog]: https://sass-lang.com/blog/7858341-the-module-system-is-launched
+  [Sass migrator]: https://sass-lang.com/documentation/cli/migrator
+
 ## 1.22.12
 
 * **Potentially breaking bug fix:** character sequences consisting of two or

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

@@ -3,8 +3,12 @@
 // https://opensource.org/licenses/MIT.
 
 import 'package:source_span/source_span.dart';
+import 'package:tuple/tuple.dart';
 
+import '../../../logger.dart';
+import '../../../parse/scss.dart';
 import '../../../visitor/interface/statement.dart';
+import '../expression.dart';
 import '../expression/string.dart';
 import '../statement.dart';
 
@@ -19,12 +23,45 @@ class UseRule implements Statement {
   /// can be accessed without a namespace.
   final String namespace;
 
+  /// A map from variable names to their values and the spans for those
+  /// variables, used to configure the loaded modules.
+  final Map<String, Tuple2<Expression, FileSpan>> configuration;
+
   final FileSpan span;
 
-  UseRule(this.url, this.namespace, this.span);
+  UseRule(this.url, this.namespace, this.span,
+      {Map<String, Tuple2<Expression, FileSpan>> configuration})
+      : configuration = Map.unmodifiable(configuration ?? const {});
+
+  /// Parses a `@use` rule from [contents].
+  ///
+  /// If passed, [url] is the name of the file from which [contents] comes.
+  ///
+  /// Throws a [SassFormatException] if parsing fails.
+  factory UseRule.parse(String contents, {url, Logger logger}) =>
+      ScssParser(contents, url: url, logger: logger).parseUseRule();
 
   T accept<T>(StatementVisitor<T> visitor) => visitor.visitUseRule(this);
 
-  String toString() => "@use ${StringExpression.quoteText(url.toString())} as "
-      "${namespace ?? "*"};";
+  String toString() {
+    var buffer =
+        StringBuffer("@use ${StringExpression.quoteText(url.toString())}");
+
+    var basename = url.pathSegments.isEmpty ? "" : url.pathSegments.last;
+    var dot = basename.indexOf(".");
+    if (namespace != basename.substring(0, dot == -1 ? basename.length : dot)) {
+      buffer.write(" as ${namespace ?? "*"}");
+    }
+
+    if (configuration.isNotEmpty) {
+      buffer.write(" with (");
+      buffer.write(configuration.entries
+          .map((entry) => "\$${entry.key}: ${entry.value.item1}")
+          .join(", "));
+      buffer.write(")");
+    }
+
+    buffer.write(";");
+    return buffer.toString();
+  }
 }

lib/src/ast/selector/placeholder.dart

@@ -2,8 +2,7 @@
 // MIT-style license that can be found in the LICENSE file or at
 // https://opensource.org/licenses/MIT.
 
-import 'package:charcode/charcode.dart';
-
+import '../../util/character.dart' as character;
 import '../../visitor/interface/selector.dart';
 import '../selector.dart';
 
@@ -20,10 +19,7 @@ class PlaceholderSelector extends SimpleSelector {
 
   /// Returns whether this is a private selector (that is, whether it begins
   /// with `-` or `_`).
-  bool get isPrivate {
-    var start = name.codeUnitAt(0);
-    return start == $dash || start == $underscore;
-  }
+  bool get isPrivate => character.isPrivate(name);
 
   PlaceholderSelector(this.name);
 

lib/src/async_environment.dart

@@ -48,9 +48,7 @@ class AsyncEnvironment {
 
   /// A list of variables defined at each lexical scope level.
   ///
-  /// Each scope maps the names of declared variables to their values. These
-  /// maps are *normalized*, meaning that they treat hyphens and underscores in
-  /// its keys interchangeably.
+  /// Each scope maps the names of declared variables to their values.
   ///
   /// The first element is the global scope, and each successive element is
   /// deeper in the tree.
@@ -67,45 +65,32 @@ class AsyncEnvironment {
 
   /// A map of variable names to their indices in [_variables].
   ///
-  /// This map is *normalized*, meaning that it treats hyphens and underscores
-  /// in its keys interchangeably.
-  ///
   /// This map is filled in as-needed, and may not be complete.
   final Map<String, int> _variableIndices;
 
   /// A list of functions defined at each lexical scope level.
   ///
-  /// Each scope maps the names of declared functions to their values. These
-  /// maps are *normalized*, meaning that they treat hyphens and underscores in
-  /// its keys interchangeably.
+  /// Each scope maps the names of declared functions to their values.
   ///
   /// The first element is the global scope, and each successive element is
   /// deeper in the tree.
   final List<Map<String, AsyncCallable>> _functions;
 
   /// A map of function names to their indices in [_functions].
   ///
-  /// This map is *normalized*, meaning that it treats hyphens and underscores
-  /// in its keys interchangeably.
-  ///
   /// This map is filled in as-needed, and may not be complete.
   final Map<String, int> _functionIndices;
 
   /// A list of mixins defined at each lexical scope level.
   ///
-  /// Each scope maps the names of declared mixins to their values. These
-  /// maps are *normalized*, meaning that they treat hyphens and underscores in
-  /// its keys interchangeably.
+  /// Each scope maps the names of declared mixins to their values.
   ///
   /// The first element is the global scope, and each successive element is
   /// deeper in the tree.
   final List<Map<String, AsyncCallable>> _mixins;
 
   /// A map of mixin names to their indices in [_mixins].
   ///
-  /// This map is *normalized*, meaning that it treats hyphens and underscores
-  /// in its keys interchangeably.
-  ///
   /// This map is filled in as-needed, and may not be complete.
   final Map<String, int> _mixinIndices;
 
@@ -211,7 +196,7 @@ class AsyncEnvironment {
   /// with the same name as a variable defined in this environment.
   void addModule(Module module, {String namespace}) {
     if (namespace == null) {
-      _globalModules ??= Set();
+      _globalModules ??= {};
       _globalModules.add(module);
       _allModules.add(module);
 
@@ -715,10 +700,14 @@ class AsyncEnvironment {
     T value;
     for (var module in _globalModules) {
       var valueInModule = callback(module);
-      if (valueInModule != null && value != null) {
-        // TODO(nweiz): List the module URLs.
+      if (valueInModule == null) continue;
+
+      if (value != null) {
         throw SassScriptException(
-            'This $type is available from multiple global modules.');
+            'This $type is available from multiple global modules:\n' +
+                bulletedList(_globalModules
+                    .where((module) => callback(module) != null)
+                    .map((module) => p.prettyUri(module.url))));
       }
 
       value = valueInModule;

lib/src/environment.dart

@@ -5,7 +5,7 @@
 // DO NOT EDIT. This file was generated from async_environment.dart.
 // See tool/grind/synchronize.dart for details.
 //
-// Checksum: 0e6357eae4a02ebe64d8cdbf48a14797f98a418c
+// Checksum: 2522d5fbfb9d301b361a9bacac97228de2c6fd68
 //
 // ignore_for_file: unused_import
 
@@ -54,9 +54,7 @@ class Environment {
 
   /// A list of variables defined at each lexical scope level.
   ///
-  /// Each scope maps the names of declared variables to their values. These
-  /// maps are *normalized*, meaning that they treat hyphens and underscores in
-  /// its keys interchangeably.
+  /// Each scope maps the names of declared variables to their values.
   ///
   /// The first element is the global scope, and each successive element is
   /// deeper in the tree.
@@ -73,45 +71,32 @@ class Environment {
 
   /// A map of variable names to their indices in [_variables].
   ///
-  /// This map is *normalized*, meaning that it treats hyphens and underscores
-  /// in its keys interchangeably.
-  ///
   /// This map is filled in as-needed, and may not be complete.
   final Map<String, int> _variableIndices;
 
   /// A list of functions defined at each lexical scope level.
   ///
-  /// Each scope maps the names of declared functions to their values. These
-  /// maps are *normalized*, meaning that they treat hyphens and underscores in
-  /// its keys interchangeably.
+  /// Each scope maps the names of declared functions to their values.
   ///
   /// The first element is the global scope, and each successive element is
   /// deeper in the tree.
   final List<Map<String, Callable>> _functions;
 
   /// A map of function names to their indices in [_functions].
   ///
-  /// This map is *normalized*, meaning that it treats hyphens and underscores
-  /// in its keys interchangeably.
-  ///
   /// This map is filled in as-needed, and may not be complete.
   final Map<String, int> _functionIndices;
 
   /// A list of mixins defined at each lexical scope level.
   ///
-  /// Each scope maps the names of declared mixins to their values. These
-  /// maps are *normalized*, meaning that they treat hyphens and underscores in
-  /// its keys interchangeably.
+  /// Each scope maps the names of declared mixins to their values.
   ///
   /// The first element is the global scope, and each successive element is
   /// deeper in the tree.
   final List<Map<String, Callable>> _mixins;
 
   /// A map of mixin names to their indices in [_mixins].
   ///
-  /// This map is *normalized*, meaning that it treats hyphens and underscores
-  /// in its keys interchangeably.
-  ///
   /// This map is filled in as-needed, and may not be complete.
   final Map<String, int> _mixinIndices;
 
@@ -217,7 +202,7 @@ class Environment {
   /// with the same name as a variable defined in this environment.
   void addModule(Module<Callable> module, {String namespace}) {
     if (namespace == null) {
-      _globalModules ??= Set();
+      _globalModules ??= {};
       _globalModules.add(module);
       _allModules.add(module);
 
@@ -719,10 +704,14 @@ class Environment {
     T value;
     for (var module in _globalModules) {
       var valueInModule = callback(module);
-      if (valueInModule != null && value != null) {
-        // TODO(nweiz): List the module URLs.
+      if (valueInModule == null) continue;
+
+      if (value != null) {
         throw SassScriptException(
-            'This $type is available from multiple global modules.');
+            'This $type is available from multiple global modules:\n' +
+                bulletedList(_globalModules
+                    .where((module) => callback(module) != null)
+                    .map((module) => p.prettyUri(module.url))));
       }
 
       value = valueInModule;

lib/src/executable/options.dart

@@ -138,8 +138,8 @@ class ExecutableOptions {
     if (!_interactive) return false;
 
     var invalidOptions = [
-      'stdin', 'indented', 'load-path', 'style', 'source-map', //
-      'source-map-urls', 'embed-sources', 'embed-source-map', 'update', 'watch'
+      'stdin', 'indented', 'style', 'source-map', 'source-map-urls', //
+      'embed-sources', 'embed-source-map', 'update', 'watch'
     ];
     for (var option in invalidOptions) {
       if (_options.wasParsed(option)) {

lib/src/executable/repl.dart

@@ -11,32 +11,38 @@ import 'package:stack_trace/stack_trace.dart';
 import '../ast/sass.dart';
 import '../exception.dart';
 import '../executable/options.dart';
+import '../import_cache.dart';
+import '../importer/filesystem.dart';
 import '../logger/tracking.dart';
 import '../parse/parser.dart';
-import '../value.dart' as internal;
 import '../visitor/evaluate.dart';
 
 /// Runs an interactive SassScript shell according to [options].
 Future<void> repl(ExecutableOptions options) async {
   var repl = Repl(prompt: '>> ');
-  var variables = <String, internal.Value>{};
+  var logger = TrackingLogger(options.logger);
+  var evaluator = Evaluator(
+      importer: FilesystemImporter('.'),
+      importCache:
+          ImportCache(const [], loadPaths: options.loadPaths, logger: logger),
+      logger: logger);
   await for (String line in repl.runAsync()) {
     if (line.trim().isEmpty) continue;
-    var logger = TrackingLogger(options.logger);
     try {
-      VariableDeclaration declaration;
-      Expression expression;
+      if (line.startsWith("@")) {
+        evaluator.use(UseRule.parse(line, logger: logger));
+        continue;
+      }
+
       if (Parser.isVariableDeclarationLike(line)) {
-        declaration = VariableDeclaration.parse(line, logger: logger);
-        expression = declaration.expression;
+        var declaration = VariableDeclaration.parse(line, logger: logger);
+        evaluator.setVariable(declaration);
+        print(evaluator.evaluate(VariableExpression(
+            declaration.name, declaration.span,
+            namespace: declaration.namespace)));
       } else {
-        expression = Expression.parse(line, logger: logger);
+        print(evaluator.evaluate(Expression.parse(line, logger: logger)));
       }
-
-      var result =
-          evaluateExpression(expression, variables: variables, logger: logger);
-      if (declaration != null) variables[declaration.name] = result;
-      print(result);
     } on SassException catch (error, stackTrace) {
       _logError(error, stackTrace, line, repl, options, logger);
     }
@@ -46,10 +52,11 @@ Future<void> repl(ExecutableOptions options) async {
 /// Logs an error from the interactive shell.
 void _logError(SassException error, StackTrace stackTrace, String line,
     Repl repl, ExecutableOptions options, TrackingLogger logger) {
-  // If something was logged after the input, just print the error.
-  if (!options.quiet && (logger.emittedDebug || logger.emittedWarning)) {
-    print("Error: ${error.message}");
-    print(error.span.highlight(color: options.color));
+  // If the error doesn't come from the repl line, or if something was logged
+  // after the user's input, just print the error normally.
+  if (error.span.sourceUrl != null ||
+      (!options.quiet && (logger.emittedDebug || logger.emittedWarning))) {
+    print(error.toString(color: options.color));
     return;
   }