ExpandNestedSelectors class

Traverse all rulesets looking for nested ones. If a ruleset is in a declaration group (implies nested selector) then generate new ruleset(s) at level 0 of CSS using selector inheritance syntax (flattens the nesting).

How the AST works for a rule RuleSet and nested rules. First of all a CSS rule RuleSet consist of a selector and a declaration e.g.,

selector {
  declaration
}

AST structure of a RuleSet is:

RuleSet
   SelectorGroup
     List<Selector>
        List<SimpleSelectorSequence>
          Combinator      // +, >, ~, DESCENDENT, or NONE
          SimpleSelector  // class, id, element, namespace, attribute
    DeclarationGroup
      List                // Declaration or RuleSet

For the simple rule:

div + span { color: red; }

the AST RuleSet is:

RuleSet
   SelectorGroup
     List<Selector>
      [0]
        List<SimpleSelectorSequence>
          [0] Combinator = COMBINATOR_NONE
              ElementSelector (name = div)
          [1] Combinator = COMBINATOR_PLUS
              ElementSelector (name = span)
    DeclarationGroup
      List                // Declarations or RuleSets
        [0]
          Declaration (property = color, expression = red)

Usually a SelectorGroup contains 1 Selector. Consider the selectors:

div { color: red; }
a { color: red; }

are equivalent to

div, a { color : red; }

In the above the RuleSet would have a SelectorGroup with 2 selectors e.g.,

RuleSet
   SelectorGroup
     List<Selector>
      [0]
        List<SimpleSelectorSequence>
          [0] Combinator = COMBINATOR_NONE
              ElementSelector (name = div)
      [1]
        List<SimpleSelectorSequence>
          [0] Combinator = COMBINATOR_NONE
              ElementSelector (name = a)
    DeclarationGroup
      List                // Declarations or RuleSets
        [0]
          Declaration (property = color, expression = red)

For a nested rule e.g.,

div {
  color : blue;
  a { color : red; }
}

Would map to the follow CSS rules:

div { color: blue; }
div a { color: red; }

The AST for the former nested rule is:

RuleSet
   SelectorGroup
     List<Selector>
      [0]
        List<SimpleSelectorSequence>
          [0] Combinator = COMBINATOR_NONE
              ElementSelector (name = div)
    DeclarationGroup
      List                // Declarations or RuleSets
        [0]
          Declaration (property = color, expression = blue)
        [1]
          RuleSet
            SelectorGroup
              List<Selector>
                [0]
                  List<SimpleSelectorSequence>
                    [0] Combinator = COMBINATOR_NONE
                        ElementSelector (name = a)
            DeclarationGroup
              List                // Declarations or RuleSets
                [0]
                  Declaration (property = color, expression = red)

Nested rules is a terse mechanism to describe CSS inheritance. The analyzer will flatten and expand the nested rules to it's flatten strucure. Using the all parent RuleSets (selector expressions) and applying each nested RuleSet to the list of Selectors in a SelectorGroup.

Then result is a style sheet where all nested rules have been flatten and expanded.

Inheritance

Object
Visitor
ExpandNestedSelectors

Constructors

ExpandNestedSelectors()

Properties

hashCode → int: The hash code for this object.
no setterinherited
runtimeType → Type: A representation of the runtime type of the object.
no setterinherited

Methods

flatten(StyleSheet styleSheet) → void: Replace the rule set that contains nested rules with the flatten rule sets.
noSuchMethod(Invocation invocation) → dynamic: Invoked when a nonexistent method or property is accessed.
inherited
toString() → String: A string representation of this object.
inherited
visitAngleTerm(AngleTerm node) → dynamic: inherited
visitAttributeSelector(AttributeSelector node) → dynamic: inherited
visitBinaryExpression(BinaryExpression node) → dynamic: inherited
visitBorderExpression(BorderExpression node) → dynamic: inherited
visitBoxExpression(BoxExpression node) → dynamic: inherited
visitCalcTerm(CalcTerm node) → dynamic: inherited
visitCharsetDirective(CharsetDirective node) → dynamic: inherited
visitChTerm(ChTerm node) → dynamic: inherited
visitClassSelector(ClassSelector node) → dynamic: inherited
visitCommentDefinition(CommentDefinition node) → dynamic: inherited
visitContentDirective(ContentDirective node) → dynamic: inherited
visitCssComment(CssComment node) → dynamic: inherited
visitDartStyleExpression(DartStyleExpression node) → dynamic: inherited
visitDeclaration(Declaration node) → void: override
visitDeclarationGroup(DeclarationGroup node) → void: override
visitDirective(Directive node) → dynamic: inherited
visitDocumentDirective(DocumentDirective node) → dynamic: inherited
visitElementSelector(ElementSelector node) → dynamic: inherited
visitEmTerm(EmTerm node) → dynamic: inherited
visitExpressions(Expressions node) → dynamic: inherited
visitExtendDeclaration(ExtendDeclaration node) → void: override
visitExTerm(ExTerm node) → dynamic: inherited
visitFontExpression(FontExpression node) → dynamic: inherited
visitFontFaceDirective(FontFaceDirective node) → dynamic: inherited
visitFractionTerm(FractionTerm node) → dynamic: inherited
visitFreqTerm(FreqTerm node) → dynamic: inherited
visitFunctionTerm(FunctionTerm node) → dynamic: inherited
visitGroupTerm(GroupTerm node) → dynamic: inherited
visitHeightExpression(HeightExpression node) → dynamic: inherited
visitHexColorTerm(HexColorTerm node) → dynamic: inherited
visitHostDirective(HostDirective node) → dynamic: inherited
visitIdentifier(Identifier node) → dynamic: inherited
visitIdSelector(IdSelector node) → dynamic: inherited
visitIE8Term(IE8Term node) → dynamic: inherited
visitImportDirective(ImportDirective node) → dynamic: inherited
visitIncludeDirective(IncludeDirective node) → dynamic: inherited
visitIncludeMixinAtDeclaration(IncludeMixinAtDeclaration node) → dynamic: inherited
visitItemTerm(ItemTerm node) → dynamic: inherited
visitKeyFrameBlock(KeyFrameBlock node) → dynamic: inherited
visitKeyFrameDirective(KeyFrameDirective node) → dynamic: inherited
visitLengthTerm(LengthTerm node) → dynamic: inherited
visitLiteralTerm(LiteralTerm node) → dynamic: inherited
visitMarginExpression(MarginExpression node) → dynamic: inherited
visitMarginGroup(MarginGroup node) → void: override
visitMediaDirective(MediaDirective node) → dynamic: inherited
visitMediaExpression(MediaExpression node) → dynamic: inherited
visitMediaQuery(MediaQuery node) → dynamic: inherited
visitMixinDeclarationDirective(MixinDeclarationDirective node) → dynamic: inherited
visitMixinDefinition(MixinDefinition node) → dynamic: inherited
visitMixinRulesetDirective(MixinRulesetDirective node) → dynamic: inherited
visitNamespaceDirective(NamespaceDirective node) → dynamic: inherited
visitNamespaceSelector(NamespaceSelector node) → dynamic: inherited
visitNegation(Negation node) → dynamic: inherited
visitNegationSelector(NegationSelector node) → dynamic: inherited
visitNoOp(NoOp node) → dynamic: inherited
visitNumberTerm(NumberTerm node) → dynamic: inherited
visitOperatorComma(OperatorComma node) → dynamic: inherited
visitOperatorMinus(OperatorMinus node) → dynamic: inherited
visitOperatorPlus(OperatorPlus node) → dynamic: inherited
visitOperatorSlash(OperatorSlash node) → dynamic: inherited
visitPaddingExpression(PaddingExpression node) → dynamic: inherited
visitPageDirective(PageDirective node) → dynamic: inherited
visitPercentageTerm(PercentageTerm node) → dynamic: inherited
visitPseudoClassFunctionSelector(PseudoClassFunctionSelector node) → dynamic: inherited
visitPseudoClassSelector(PseudoClassSelector node) → dynamic: inherited
visitPseudoElementFunctionSelector(PseudoElementFunctionSelector node) → dynamic: inherited
visitPseudoElementSelector(PseudoElementSelector node) → dynamic: inherited
visitRemTerm(RemTerm node) → dynamic: inherited
visitResolutionTerm(ResolutionTerm node) → dynamic: inherited
visitRuleSet(RuleSet node) → void: override
visitSelector(Selector node) → dynamic: inherited
visitSelectorExpression(SelectorExpression node) → dynamic: inherited
visitSelectorGroup(SelectorGroup node) → dynamic: inherited
visitSimpleSelector(SimpleSelector node) → dynamic: inherited
visitSimpleSelectorSequence(SimpleSelectorSequence node) → dynamic: inherited
visitStyleSheet(StyleSheet ss) → dynamic: inherited
visitStyletDirective(StyletDirective node) → dynamic: inherited
visitSupportsConditionInParens(SupportsConditionInParens node) → dynamic: inherited
visitSupportsConjunction(SupportsConjunction node) → dynamic: inherited
visitSupportsDirective(SupportsDirective node) → dynamic: inherited
visitSupportsDisjunction(SupportsDisjunction node) → dynamic: inherited
visitSupportsNegation(SupportsNegation node) → dynamic: inherited
visitThisOperator(ThisOperator node) → dynamic: inherited
visitTimeTerm(TimeTerm node) → dynamic: inherited
visitTopLevelProduction(TopLevelProduction node) → dynamic: inherited
visitTree(StyleSheet tree) → dynamic: inherited
visitUnaryExpression(UnaryExpression node) → dynamic: inherited
visitUnicodeRangeTerm(UnicodeRangeTerm node) → dynamic: inherited
visitUnitTerm(UnitTerm node) → dynamic: inherited
visitUriTerm(UriTerm node) → dynamic: inherited
visitVarDefinition(VarDefinition node) → void: override
visitVarDefinitionDirective(VarDefinitionDirective node) → dynamic: inherited
visitVarUsage(VarUsage node) → dynamic: inherited
visitViewportDirective(ViewportDirective node) → dynamic: inherited
visitViewportTerm(ViewportTerm node) → dynamic: inherited
visitWidthExpression(WidthExpression node) → dynamic: inherited
visitWildcard(Wildcard node) → dynamic: inherited

Operators

operator ==(Object other) → bool: The equality operator.
inherited

ExpandNestedSelectors class

Constructors

Properties

Methods

Operators

parser library