Merge pull request #593 from sass/merge-use

Merge branch 'feature.use' into master

lib/src/ast/sass.dart

@@ -53,6 +53,7 @@ export 'sass/statement/silent_comment.dart';
 export 'sass/statement/style_rule.dart';
 export 'sass/statement/stylesheet.dart';
 export 'sass/statement/supports_rule.dart';
+export 'sass/statement/use_rule.dart';
 export 'sass/statement/variable_declaration.dart';
 export 'sass/statement/warn_rule.dart';
 export 'sass/statement/while_rule.dart';

lib/src/ast/sass/expression/function.dart

@@ -4,7 +4,6 @@
 
 import 'package:source_span/source_span.dart';
 
-import '../../../utils.dart';
 import '../../../visitor/interface/expression.dart';
 import '../expression.dart';
 import '../argument_invocation.dart';
@@ -15,6 +14,10 @@ import '../interpolation.dart';
 ///
 /// This may be a plain CSS function or a Sass function.
 class FunctionExpression implements Expression, CallableInvocation {
+  /// The namespace of the function being invoked, or `null` if it's invoked
+  /// without a namespace.
+  final String namespace;
+
   /// The name of the function being invoked.
   ///
   /// If this is interpolated, the function will be interpreted as plain CSS,
@@ -24,12 +27,17 @@ class FunctionExpression implements Expression, CallableInvocation {
   /// The arguments to pass to the function.
   final ArgumentInvocation arguments;
 
-  FileSpan get span => spanForList([name, arguments]);
+  final FileSpan span;
 
-  FunctionExpression(this.name, this.arguments);
+  FunctionExpression(this.name, this.arguments, this.span, {this.namespace});
 
   T accept<T>(ExpressionVisitor<T> visitor) =>
       visitor.visitFunctionExpression(this);
 
-  String toString() => "$name$arguments";
+  String toString() {
+    var buffer = StringBuffer();
+    if (namespace != null) buffer.write("$namespace.");
+    buffer.write("$name$arguments");
+    return buffer.toString();
+  }
 }

lib/src/ast/sass/expression/variable.dart

@@ -9,15 +9,24 @@ import '../expression.dart';
 
 /// A Sass variable.
 class VariableExpression implements Expression {
+  /// The namespace of the variable being referenced, or `null` if it's
+  /// referenced without a namespace.
+  final String namespace;
+
   /// The name of this variable.
   final String name;
 
   final FileSpan span;
 
-  VariableExpression(this.name, this.span);
+  VariableExpression(this.name, this.span, {this.namespace});
 
   T accept<T>(ExpressionVisitor<T> visitor) =>
       visitor.visitVariableExpression(this);
 
-  String toString() => "\$$name";
+  String toString() {
+    var buffer = StringBuffer("\$");
+    if (namespace != null) buffer.write("$namespace.");
+    buffer.write(name);
+    return buffer.toString();
+  }
 }

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

@@ -12,6 +12,10 @@ import 'content_block.dart';
 
 /// A mixin invocation.
 class IncludeRule implements Statement, CallableInvocation {
+  /// The namespace of the mixin being invoked, or `null` if it's invoked
+  /// without a namespace.
+  final String namespace;
+
   /// The name of the mixin being invoked.
   final String name;
 
@@ -24,12 +28,15 @@ class IncludeRule implements Statement, CallableInvocation {
 
   final FileSpan span;
 
-  IncludeRule(this.name, this.arguments, this.span, {this.content});
+  IncludeRule(this.name, this.arguments, this.span,
+      {this.namespace, this.content});
 
   T accept<T>(StatementVisitor<T> visitor) => visitor.visitIncludeRule(this);
 
   String toString() {
-    var buffer = StringBuffer("@include $name");
+    var buffer = StringBuffer("@include ");
+    if (namespace != null) buffer.write("$namespace.");
+    buffer.write(name);
     if (!arguments.isEmpty) buffer.write("($arguments)");
     buffer.write(content == null ? ";" : " $content");
     return buffer.toString();

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

@@ -0,0 +1,30 @@
+// Copyright 2016 Google Inc. Use of this source code is governed by an
+// MIT-style license that can be found in the LICENSE file or at
+// https://opensource.org/licenses/MIT.
+
+import 'package:source_span/source_span.dart';
+
+import '../../../visitor/interface/statement.dart';
+import '../expression/string.dart';
+import '../statement.dart';
+
+/// A `@use` rule.
+class UseRule implements Statement {
+  /// The URI of the module to use.
+  ///
+  /// If this is relative, it's relative to the containing file.
+  final Uri url;
+
+  /// The namespace for members of the used module, or `null` if the members
+  /// can be accessed without a namespace.
+  final String namespace;
+
+  final FileSpan span;
+
+  UseRule(this.url, this.namespace, this.span);
+
+  T accept<T>(StatementVisitor<T> visitor) => visitor.visitUseRule(this);
+
+  String toString() => "@use ${StringExpression.quoteText(url.toString())} as "
+      "${namespace ?? "*"};";
+}

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

@@ -15,6 +15,10 @@ import 'silent_comment.dart';
 ///
 /// This defines or sets a variable.
 class VariableDeclaration implements Statement {
+  /// The namespace of the variable being set, or `null` if it's defined or set
+  /// without a namespace.
+  final String namespace;
+
   /// The name of the variable.
   final String name;
 
@@ -37,10 +41,18 @@ class VariableDeclaration implements Statement {
   final FileSpan span;
 
   VariableDeclaration(this.name, this.expression, this.span,
-      {bool guarded = false, bool global = false, SilentComment comment})
+      {this.namespace,
+      bool guarded = false,
+      bool global = false,
+      SilentComment comment})
       : isGuarded = guarded,
         isGlobal = global,
-        comment = comment;
+        comment = comment {
+    if (namespace != null && global) {
+      throw ArgumentError(
+          "Other modules' members can't be defined with !global.");
+    }
+  }
 
   /// Parses a variable declaration from [contents].
   ///
@@ -53,5 +65,10 @@ class VariableDeclaration implements Statement {
   T accept<T>(StatementVisitor<T> visitor) =>
       visitor.visitVariableDeclaration(this);
 
-  String toString() => "\$$name: $expression;";
+  String toString() {
+    var buffer = StringBuffer("\$");
+    if (namespace != null) buffer.write("$namespace.");
+    buffer.write("$name: $expression;");
+    return buffer.toString();
+  }
 }

lib/src/parse/css.dart

@@ -139,6 +139,7 @@ class CssParser extends ScssParser {
         // as plain CSS, rather than calling a user-defined function.
         Interpolation([StringExpression(identifier)], identifier.span),
         ArgumentInvocation(
-            arguments, const {}, scanner.spanFrom(beforeArguments)));
+            arguments, const {}, scanner.spanFrom(beforeArguments)),
+        scanner.spanFrom(start));
   }
 }

lib/src/parse/parser.dart

@@ -17,7 +17,7 @@ import '../utils.dart';
 /// This provides utility methods and common token parsing. Unless specified
 /// otherwise, a parse method throws a [SassFormatException] if it fails to
 /// parse.
-abstract class Parser {
+class Parser {
   /// The scanner that scans through the text being parsed.
   final SpanScanner scanner;
 
@@ -25,10 +25,25 @@ abstract class Parser {
   @protected
   final Logger logger;
 
+  /// Parses [text] as a CSS identifier and returns the result.
+  ///
+  /// Throws a [SassFormatException] if parsing fails.
+  static String parseIdentifier(String text, {Logger logger}) =>
+      Parser(text, logger: logger)._parseIdentifier();
+
+  @protected
   Parser(String contents, {url, Logger logger})
       : scanner = SpanScanner(contents, sourceUrl: url),
         logger = logger ?? const Logger.stderr();
 
+  String _parseIdentifier() {
+    return wrapSpanFormatException(() {
+      var result = identifier();
+      scanner.expectDone();
+      return result;
+    });
+  }
+
   // ## Tokens
 
   /// Consumes whitespace, including any comments.
@@ -114,8 +129,8 @@ abstract class Parser {
   @protected
   String identifier({bool unit = false}) {
     // NOTE: this logic is largely duplicated in
-    // StylesheetParser._interpolatedIdentifier. Most changes here should be
-    // mirrored there.
+    // StylesheetParser._interpolatedIdentifier and isIdentifier in utils.dart.
+    // Most changes here should be mirrored there.
 
     var text = StringBuffer();
     while (scanner.scanChar($dash)) {

lib/src/parse/stylesheet.dart

@@ -13,6 +13,7 @@ import 'package:tuple/tuple.dart';
 
 import '../ast/sass.dart';
 import '../color_names.dart';
+import '../exception.dart';
 import '../interpolation_buffer.dart';
 import '../logger.dart';
 import '../util/character.dart';
@@ -21,6 +22,14 @@ import '../value.dart';
 import '../value/color.dart';
 import 'parser.dart';
 
+/// Whether to parse `@use` rules.
+///
+/// This is set to `false` on Dart Sass's master branch and `true` on the
+/// `feature.use` branch. It allows us to avoid having separate development
+/// tracks as much as possible without shipping `@use` support until we're
+/// ready.
+const _parseUse = false;
+
 /// The base class for both the SCSS and indented syntax parsers.
 ///
 /// Having a base class that's separate from both parsers allows us to make
@@ -33,6 +42,10 @@ import 'parser.dart';
 /// private, except where they have to be public for subclasses to refer to
 /// them.
 abstract class StylesheetParser extends Parser {
+  /// Whether we've consumed a rule other than `@charset`, `@forward`, or
+  /// `@use`.
+  var _isUseAllowed = true;
+
   /// Whether the parser is currently parsing the contents of a mixin
   /// declaration.
   var _inMixin = false;
@@ -131,18 +144,21 @@ abstract class StylesheetParser extends Parser {
 
       case $plus:
         if (!indented || !lookingAtIdentifier(1)) return _styleRule();
+        _isUseAllowed = false;
         var start = scanner.state;
         scanner.readChar();
         return _includeRule(start);
 
       case $equal:
         if (!indented) return _styleRule();
+        _isUseAllowed = false;
         var start = scanner.state;
         scanner.readChar();
         whitespace();
         return _mixinRule(start);
 
       default:
+        _isUseAllowed = false;
         return _inStyleRule || _inUnknownAtRule || _inMixin || _inContentBlock
             ? _declarationOrStyleRule()
             : _styleRule();
@@ -155,7 +171,13 @@ abstract class StylesheetParser extends Parser {
     var precedingComment = lastSilentComment;
     lastSilentComment = null;
     var start = scanner.state;
+
+    String namespace;
     var name = variableName();
+    if (scanner.scanChar($dot)) {
+      namespace = name;
+      name = _publicIdentifier();
+    }
 
     if (plainCss) {
       error("Sass variables aren't allowed in plain CSS.",
@@ -170,23 +192,32 @@ abstract class StylesheetParser extends Parser {
 
     var guarded = false;
     var global = false;
+    var flagStart = scanner.state;
     while (scanner.scanChar($exclamation)) {
-      var flagStart = scanner.state;
       var flag = identifier();
       if (flag == 'default') {
         guarded = true;
       } else if (flag == 'global') {
+        if (namespace != null) {
+          error("!global isn't allowed for variables in other modules.",
+              scanner.spanFrom(flagStart));
+        }
+
         global = true;
       } else {
         error("Invalid flag name.", scanner.spanFrom(flagStart));
       }
 
       whitespace();
+      flagStart = scanner.state;
     }
 
     expectStatementSeparator("variable declaration");
     return VariableDeclaration(name, value, scanner.spanFrom(start),
-        guarded: guarded, global: global, comment: precedingComment);
+        namespace: namespace,
+        guarded: guarded,
+        global: global,
+        comment: precedingComment);
   }
 
   /// Consumes a style rule.
@@ -455,10 +486,18 @@ abstract class StylesheetParser extends Parser {
     var name = interpolatedIdentifier();
     whitespace();
 
+    // We want to set [_isUseAllowed] to `false` *unless* we're parsing
+    // `@charset`, `@forward`, or `@use`. To avoid double-comparing the rule
+    // name, we always set it to `false` and then set it back to its previous
+    // value if we're parsing an allowed rule.
+    var wasUseAllowed = _isUseAllowed;
+    _isUseAllowed = false;
+
     switch (name.asPlain) {
       case "at-root":
         return _atRootRule(start);
       case "charset":
+        _isUseAllowed = wasUseAllowed;
         if (!root) _disallowedAtRule(start);
         string();
         return null;
@@ -494,6 +533,10 @@ abstract class StylesheetParser extends Parser {
         return _disallowedAtRule(start);
       case "supports":
         return supportsRule(start);
+      case "use":
+        _isUseAllowed = wasUseAllowed;
+        if (!root) _disallowedAtRule(start);
+        return _useRule(start);
       case "warn":
         return _warnRule(start);
       case "while":
@@ -933,7 +976,13 @@ abstract class StylesheetParser extends Parser {
   ///
   /// [start] should point before the `@`.
   IncludeRule _includeRule(LineScannerState start) {
+    String namespace;
     var name = identifier();
+    if (scanner.scanChar($dot)) {
+      namespace = name;
+      name = _publicIdentifier();
+    }
+
     whitespace();
     var arguments = scanner.peekChar() == $lparen
         ? _argumentInvocation(mixin: true)
@@ -965,7 +1014,8 @@ abstract class StylesheetParser extends Parser {
 
     var span =
         scanner.spanFrom(start, start).expand((content ?? arguments).span);
-    return IncludeRule(name, arguments, span, content: content);
+    return IncludeRule(name, arguments, span,
+        namespace: namespace, content: content);
   }
 
   /// Consumes a `@media` rule.
@@ -1115,6 +1165,49 @@ relase. For details, see http://bit.ly/moz-document.
         (children, span) => SupportsRule(condition, children, span));
   }
 
+  /// Consumes a `@use` rule.
+  ///
+  /// [start] should point before the `@`.
+  UseRule _useRule(LineScannerState start) {
+    var urlString = string();
+    Uri url;
+    try {
+      url = Uri.parse(urlString);
+    } on FormatException catch (innerError) {
+      error("Invalid URL: ${innerError.message}", scanner.spanFrom(start));
+    }
+    whitespace();
+
+    String namespace;
+    if (scanIdentifier("as")) {
+      whitespace();
+      namespace = scanner.scanChar($asterisk) ? null : identifier();
+    } else {
+      var basename = url.pathSegments.isEmpty ? "" : url.pathSegments.last;
+      var dot = basename.indexOf(".");
+      namespace = basename.substring(0, dot == -1 ? basename.length : dot);
+
+      try {
+        namespace = Parser.parseIdentifier(namespace, logger: logger);
+      } on SassFormatException {
+        error('Invalid Sass identifier "$namespace"', scanner.spanFrom(start));
+      }
+    }
+    expectStatementSeparator("@use rule");
+
+    var span = scanner.spanFrom(start);
+    if (!_parseUse) {
+      error(
+          "@use is coming soon, but it's not supported in this version of "
+          "Dart Sass.",
+          span);
+    } else if (!_isUseAllowed) {
+      error("@use rules must be written before any other rules.", span);
+    }
+
+    return UseRule(url, namespace, span);
+  }
+
   /// Consumes a `@warn` rule.
   ///
   /// [start] should point before the `@`.
@@ -2143,11 +2236,22 @@ relase. For details, see http://bit.ly/moz-document.
   /// Consumes a variable expression.
   VariableExpression _variable() {
     var start = scanner.state;
-    var name = variableName();
-    if (!plainCss) return VariableExpression(name, scanner.spanFrom(start));
 
-    error(
-        "Sass variables aren't allowed in plain CSS.", scanner.spanFrom(start));
+    String namespace;
+    var name = variableName();
+    if (scanner.peekChar() == $dot && scanner.peekChar(1) != $dot) {
+      scanner.readChar();
+      namespace = name;
+      name = _publicIdentifier();
+    }
+
+    if (plainCss) {
+      error("Sass variables aren't allowed in plain CSS.",
+          scanner.spanFrom(start));
+    }
+
+    return VariableExpression(name, scanner.spanFrom(start),
+        namespace: namespace);
   }
 
   /// Consumes a selector expression.
@@ -2254,9 +2358,31 @@ relase. For details, see http://bit.ly/moz-document.
       if (specialFunction != null) return specialFunction;
     }
 
-    return scanner.peekChar() == $lparen
-        ? FunctionExpression(identifier, _argumentInvocation())
-        : StringExpression(identifier);
+    switch (scanner.peekChar()) {
+      case $dot:
+        if (scanner.peekChar(1) == $dot) return StringExpression(identifier);
+
+        var namespace = identifier.asPlain;
+        scanner.readChar();
+        var beforeName = scanner.state;
+        var name = Interpolation(
+            [this._publicIdentifier()], scanner.spanFrom(beforeName));
+
+        if (namespace == null) {
+          error("Interpolation isn't allowed in namespaces.", identifier.span);
+        }
+
+        return FunctionExpression(
+            name, _argumentInvocation(), scanner.spanFrom(start),
+            namespace: namespace);
+
+      case $lparen:
+        return FunctionExpression(
+            identifier, _argumentInvocation(), scanner.spanFrom(start));
+
+      default:
+        return StringExpression(identifier);
+    }
   }
 
   /// If [name] is the name of a function with special syntax, consumes it.
@@ -2510,8 +2636,8 @@ relase. For details, see http://bit.ly/moz-document.
     var contents = _tryUrlContents(start);
     if (contents != null) return StringExpression(contents);
 
-    return FunctionExpression(
-        Interpolation(["url"], scanner.spanFrom(start)), _argumentInvocation());
+    return FunctionExpression(Interpolation(["url"], scanner.spanFrom(start)),
+        _argumentInvocation(), scanner.spanFrom(start));
   }
 
   /// Consumes tokens up to "{", "}", ";", or "!".
@@ -2620,8 +2746,8 @@ relase. For details, see http://bit.ly/moz-document.
   ///
   /// Unlike [declarationValue], this allows interpolation.
   StringExpression _interpolatedDeclarationValue({bool allowEmpty = false}) {
-    // NOTE: this logic is largely duplicated in Parser.declarationValue. Most
-    // changes here should be mirrored there.
+    // NOTE: this logic is largely duplicated in Parser.declarationValue and
+    // isIdentifier in utils.dart. Most changes here should be mirrored there.
 
     var start = scanner.state;
     var buffer = InterpolationBuffer();
@@ -3088,6 +3214,20 @@ relase. For details, see http://bit.ly/moz-document.
     return result;
   }
 
+  /// Like [identifier], but rejects identifiers that begin with `_` or `-`.
+  String _publicIdentifier() {
+    var start = scanner.state;
+    var result = identifier();
+
+    var first = result.codeUnitAt(0);
+    if (first == $dash || first == $underscore) {
+      error("Private members can't be accessed from outside their modules.",
+          scanner.spanFrom(start));
+    }
+
+    return result;
+  }
+
   // ## Abstract Methods
 
   /// Whether this is parsing the indented syntax.

lib/src/visitor/async_evaluate.dart

@@ -290,7 +290,9 @@ class _EvaluateVisitor
             deprecation: true);
 
         var expression = FunctionExpression(
-            Interpolation([function.text], _callableNode.span), invocation);
+            Interpolation([function.text], _callableNode.span),
+            invocation,
+            _callableNode.span);
         return await expression.accept(this);
       }
 
@@ -1130,6 +1132,10 @@ class _EvaluateVisitor
     return null;
   }
 
+  Future<Value> visitUseRule(UseRule node) async {
+    return null;
+  }
+
   Future<Value> visitWarnRule(WarnRule node) async {
     var value =
         await _addExceptionSpanAsync(node, () => node.expression.accept(this));

lib/src/visitor/evaluate.dart

@@ -5,7 +5,7 @@
 // DO NOT EDIT. This file was generated from async_evaluate.dart.
 // See tool/synchronize.dart for details.
 //
-// Checksum: 262c642b0cda0a5ed4984e763e9970422405efaa
+// Checksum: 08c3aaa09f3be71dd315bf36665e249983ce3d53
 //
 // ignore_for_file: unused_import
 
@@ -297,7 +297,9 @@ class _EvaluateVisitor
             deprecation: true);
 
         var expression = FunctionExpression(
-            Interpolation([function.text], _callableNode.span), invocation);
+            Interpolation([function.text], _callableNode.span),
+            invocation,
+            _callableNode.span);
         return expression.accept(this);
       }
 
@@ -1125,6 +1127,10 @@ class _EvaluateVisitor
     return null;
   }
 
+  Value visitUseRule(UseRule node) {
+    return null;
+  }
+
   Value visitWarnRule(WarnRule node) {
     var value = _addExceptionSpan(node, () => node.expression.accept(this));
     _logger.warn(

lib/src/visitor/find_imports.dart

@@ -28,6 +28,10 @@ class _FindImportsVisitor extends RecursiveStatementVisitor {
   void visitInterpolation(Interpolation interpolation) {}
   void visitSupportsCondition(SupportsCondition condition) {}
 
+  void visitUseRule(UseRule node) {
+    _imports.add(DynamicImport(node.url.toString(), node.span));
+  }
+
   void visitImportRule(ImportRule node) {
     for (var import in node.imports) {
       if (import is DynamicImport) _imports.add(import);

lib/src/visitor/interface/statement.dart

@@ -30,6 +30,7 @@ abstract class StatementVisitor<T> {
   T visitStyleRule(StyleRule node);
   T visitStylesheet(Stylesheet node);
   T visitSupportsRule(SupportsRule node);
+  T visitUseRule(UseRule node);
   T visitVariableDeclaration(VariableDeclaration node);
   T visitWarnRule(WarnRule node);
   T visitWhileRule(WhileRule node);