Change variable syntax to namespace.$name (#803)

See sass/sass#2731

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;
 

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: 587acdaa22fa4fdecfe796af866ba4dd4aa4d006
+// Checksum: 1a6678b9aa71d8d8ea5aab9216a48e401a892453
 //
 // 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;
 

lib/src/module/forwarded_view.dart

@@ -11,7 +11,6 @@ import '../extend/extender.dart';
 import '../module.dart';
 import '../util/limited_map_view.dart';
 import '../util/prefixed_map_view.dart';
-import '../utils.dart';
 import '../value.dart';
 
 /// A [Module] that exposes members according to a [ForwardRule].
@@ -82,7 +81,7 @@ class ForwardedModuleView<T extends AsyncCallable> implements Module<T> {
     }
 
     if (_rule.prefix != null) {
-      if (!startsWithIgnoreSeparator(name, _rule.prefix)) {
+      if (!name.startsWith(_rule.prefix)) {
         throw SassScriptException("Undefined variable.");
       }
 

lib/src/parse/sass.dart

@@ -159,7 +159,7 @@ class SassParser extends StylesheetParser {
         return null;
 
       case $dollar:
-        return variableDeclaration();
+        return variableDeclarationWithoutNamespace();
         break;
 
       case $slash:

lib/src/parse/scss.dart

@@ -66,7 +66,7 @@ class ScssParser extends StylesheetParser {
     while (true) {
       switch (scanner.peekChar()) {
         case $dollar:
-          children.add(variableDeclaration());
+          children.add(variableDeclarationWithoutNamespace());
           break;
 
         case $slash:
@@ -107,7 +107,7 @@ class ScssParser extends StylesheetParser {
     while (!scanner.isDone) {
       switch (scanner.peekChar()) {
         case $dollar:
-          statements.add(variableDeclaration());
+          statements.add(variableDeclarationWithoutNamespace());
           break;
 
         case $slash: