Add support for attribute selector modifiers (#658)

Closes #656

CHANGELOG.md

@@ -1,3 +1,7 @@
+## 1.20.0
+
+* Support attribute selector modifiers, such as the `i` in `[title="test" i]`.
+
 ## 1.19.0
 
 * Allow `!` in `url()`s without quotes.

lib/src/ast/selector/attribute.dart

@@ -27,15 +27,27 @@ class AttributeSelector extends SimpleSelector {
   /// regardless of this value. It's `null` if and only if [op] is `null`.
   final String value;
 
+  /// The modifier which indicates how the attribute selector should be
+  /// processed.
+  ///
+  /// See for example [case-sensitivity][] modifiers.
+  ///
+  /// [case-sensitivity]: https://www.w3.org/TR/selectors-4/#attribute-case
+  ///
+  /// If [op] is `null`, this is always `null` as well.
+  final String modifier;
+
   /// Creates an attribute selector that matches any element with a property of
   /// the given name.
   AttributeSelector(this.name)
       : op = null,
-        value = null;
+        value = null,
+        modifier = null;
 
   /// Creates an attribute selector that matches an element with a property
   /// named [name], whose value matches [value] based on the semantics of [op].
-  AttributeSelector.withOperator(this.name, this.op, this.value);
+  AttributeSelector.withOperator(this.name, this.op, this.value,
+      {this.modifier});
 
   T accept<T>(SelectorVisitor<T> visitor) =>
       visitor.visitAttributeSelector(this);
@@ -44,9 +56,11 @@ class AttributeSelector extends SimpleSelector {
       other is AttributeSelector &&
       other.name == name &&
       other.op == op &&
-      other.value == value;
+      other.value == value &&
+      other.modifier == modifier;
 
-  int get hashCode => name.hashCode ^ op.hashCode ^ value.hashCode;
+  int get hashCode =>
+      name.hashCode ^ op.hashCode ^ value.hashCode ^ modifier.hashCode;
 }
 
 /// An operator that defines the semantics of an [AttributeSelector].

lib/src/parse/selector.dart

@@ -201,8 +201,13 @@ class SelectorParser extends Parser {
         : identifier();
     whitespace();
 
+    var modifier = isAlphabetic(scanner.peekChar())
+        ? String.fromCharCode(scanner.readChar())
+        : null;
+
     scanner.expectChar($rbracket);
-    return AttributeSelector.withOperator(name, operator, value);
+    return AttributeSelector.withOperator(name, operator, value,
+        modifier: modifier);
   }
 
   /// Consumes a qualified name as part of an attribute selector.

lib/src/visitor/serialize.dart

@@ -914,9 +914,13 @@ class _SerializeVisitor implements CssVisitor, ValueVisitor, SelectorVisitor {
           // doesn't consider them to be valid identifiers.
           !attribute.value.startsWith('--')) {
         _buffer.write(attribute.value);
+
+        if (attribute.modifier != null) _buffer.writeCharCode($space);
       } else {
         _visitQuotedString(attribute.value);
+        if (attribute.modifier != null) _writeOptionalSpace();
       }
+      if (attribute.modifier != null) _buffer.write(attribute.modifier);
     }
     _buffer.writeCharCode($rbracket);
   }

pubspec.yaml

@@ -1,5 +1,5 @@
 name: sass
-version: 1.19.0
+version: 1.20.0-dev
 description: A Sass implementation in Dart.
 author: Dart Team <misc@dartlang.org>
 homepage: https://github.com/sass/dart-sass

test/compressed_test.dart

@@ -42,6 +42,16 @@ void main() {
               equals("a:nth-child(2n of b,c){x:y}"));
         });
       });
+
+      group("in attribute selectors with modifiers", () {
+        test("removes whitespace when quotes are required", () {
+          expect(_compile('[a=" " b] {x: y}'), equals('[a=" "b]{x:y}'));
+        });
+
+        test("doesn't remove whitespace when quotes aren't required", () {
+          expect(_compile('[a="b"c] {x: y}'), equals('[a=b c]{x:y}'));
+        });
+      });
     });
 
     group("for declarations", () {