class Sass::Selector::Sequence - sass-3.2.19 Documentation

# class Sass::Selector::Sequence

An operator-separated sequence of {SimpleSequence simple selector sequences}.

### Attributes

members[R]

The array of {SimpleSequence simple selector sequences}, operators, and newlines. The operators are strings such as `“+”` and `“>”` representing the corresponding CSS operators, or interpolated SassScript. Newlines are also newline strings; these aren't semantically relevant, but they do affect formatting.

@return [Array<SimpleSequence, String|Array<Sass::Tree::Node, String>>]

### Public Class Methods

new(seqs_and_ops) click to toggle source

@param seqs_and_ops [Array<SimpleSequence, String|Array<Sass::Tree::Node, String>>] See {#members}

    # File lib/sass/selector/sequence.rb, line 37
    def initialize(seqs_and_ops)
      @members = seqs_and_ops
    end

### Public Instance Methods

add_sources!(sources) click to toggle source

Add to the {SimpleSequence#sources} sets of the child simple sequences. This destructively modifies this sequence's members array, but not the child simple sequences.

@param sources [Set<Sequence>]

    # File lib/sass/selector/sequence.rb, line 125
    def add_sources!(sources)
      members.map! {|m| m.is_a?(SimpleSequence) ? m.with_more_sources(sources) : m}
    end

do_extend(extends, parent_directives, seen = Set.new) click to toggle source

Non-destructively extends this selector with the extensions specified in a hash (which should come from {Sass::Tree::Visitors::Cssize}).

@overload def #do_extend(extends, parent_directives) @param extends [Sass::Util::SubsetMap{Selector::Simple =>

                                        Sass::Tree::Visitors::Cssize::Extend}]
    The extensions to perform on this selector

@param parent_directives [Array<Sass::Tree::DirectiveNode>]

    The directives containing this selector.

@return [Array<Sequence>] A list of selectors generated

    by extending this selector with `extends`.
    These correspond to a {CommaSequence}'s {CommaSequence#members members array}.

@see Sass::Selector::CommaSequence#do_extend

    # File lib/sass/selector/sequence.rb, line 80
    def do_extend(extends, parent_directives, seen = Set.new)
      extended_not_expanded = members.map do |sseq_or_op|
        next [[sseq_or_op]] unless sseq_or_op.is_a?(SimpleSequence)
        extended = sseq_or_op.do_extend(extends, parent_directives, seen)
        choices = extended.map {|seq| seq.members}
        choices.unshift([sseq_or_op]) unless extended.any? {|seq| seq.superselector?(sseq_or_op)}
        choices
      end
      weaves = Sass::Util.paths(extended_not_expanded).map {|path| weave(path)}
      Sass::Util.flatten(trim(weaves), 1).map {|p| Sequence.new(p)}
    end

filename=(filename) click to toggle source

Sets the name of the file in which this selector was declared, or `nil` if it was not declared in a file (e.g. on stdin). This also sets the filename for all child selectors.

@param filename [String, nil] @return [String, nil]

    # File lib/sass/selector/sequence.rb, line 22
    def filename=(filename)
      members.each {|m| m.filename = filename if m.is_a?(SimpleSequence)}
      filename
    end

inspect() click to toggle source

Returns a string representation of the sequence. This is basically the selector string.

@return [String]

    # File lib/sass/selector/sequence.rb, line 116
    def inspect
      members.map {|m| m.inspect}.join(" ")
    end

line=(line) click to toggle source

Sets the line of the Sass template on which this selector was declared. This also sets the line for all child selectors.

@param line [Fixnum] @return [Fixnum]

    # File lib/sass/selector/sequence.rb, line 11
    def line=(line)
      members.each {|m| m.line = line if m.is_a?(SimpleSequence)}
      line
    end

resolve_parent_refs(super_seq) click to toggle source

Resolves the {Parent} selectors within this selector by replacing them with the given parent selector, handling commas appropriately.

@param super_seq [Sequence] The parent selector sequence @return [Sequence] This selector, with parent references resolved @raise [Sass::SyntaxError] If a parent selector is invalid

    # File lib/sass/selector/sequence.rb, line 48
    def resolve_parent_refs(super_seq)
      members = @members.dup
      nl = (members.first == "\n" && members.shift)
      unless members.any? do |seq_or_op|
          seq_or_op.is_a?(SimpleSequence) && seq_or_op.members.first.is_a?(Parent)
        end
        old_members, members = members, []
        members << nl if nl
        members << SimpleSequence.new([Parent.new], false)
        members += old_members
      end

      Sequence.new(
        members.map do |seq_or_op|
          next seq_or_op unless seq_or_op.is_a?(SimpleSequence)
          seq_or_op.resolve_parent_refs(super_seq)
        end.flatten)
    end

superselector?(sseq) click to toggle source

Returns whether or not this selector matches all elements that the given selector matches (as well as possibly more).

@example

    (.foo).superselector?(.foo.bar) #=> true
    (.foo).superselector?(.bar) #=> false
    (.bar .foo).superselector?(.foo) #=> false

@param sseq [SimpleSequence] @return [Boolean]

    # File lib/sass/selector/sequence.rb, line 101
    def superselector?(sseq)
      return false unless members.size == 1
      members.last.superselector?(sseq)
    end

to_a() click to toggle source

@see Sass::Selector::Simple#to_a

    # File lib/sass/selector/sequence.rb, line 107
    def to_a
      ary = @members.map {|seq_or_op| seq_or_op.is_a?(SimpleSequence) ? seq_or_op.to_a : seq_or_op}
      Sass::Util.intersperse(ary, " ").flatten.compact
    end

### Private Instance Methods

_eql?(other) click to toggle source

    # File lib/sass/selector/sequence.rb, line 472
    def _eql?(other)
      other.members.reject {|m| m == "\n"}.eql?(self.members.reject {|m| m == "\n"})
    end

_hash() click to toggle source

    # File lib/sass/selector/sequence.rb, line 468
    def _hash
      members.reject {|m| m == "\n"}.hash
    end

_sources(seq) click to toggle source

    # File lib/sass/selector/sequence.rb, line 489
    def _sources(seq)
      s = Set.new
      seq.map {|sseq_or_op| s.merge sseq_or_op.sources if sseq_or_op.is_a?(SimpleSequence)}
      s
    end

_superselector?(seq1, seq2) click to toggle source

Given two selector sequences, returns whether `seq1` is a superselector of `seq2`; that is, whether `seq1` matches every element `seq2` matches.

@param seq1 [Array<SimpleSequence or String>] @param seq2 [Array<SimpleSequence or String>] @return [Boolean]

    # File lib/sass/selector/sequence.rb, line 382
    def _superselector?(seq1, seq2)
      seq1 = seq1.reject {|e| e == "\n"}
      seq2 = seq2.reject {|e| e == "\n"}
      # Selectors with leading or trailing operators are neither
      # superselectors nor subselectors.
      return if seq1.last.is_a?(String) || seq2.last.is_a?(String) ||
        seq1.first.is_a?(String) || seq2.first.is_a?(String)
      # More complex selectors are never superselectors of less complex ones
      return if seq1.size > seq2.size
      return seq1.first.superselector?(seq2.last) if seq1.size == 1

      _, si = Sass::Util.enum_with_index(seq2).find do |e, i|
        return if i == seq2.size - 1
        next if e.is_a?(String)
        seq1.first.superselector?(e)
      end
      return unless si

      if seq1[1].is_a?(String)
        return unless seq2[si+1].is_a?(String)
        # .foo ~ .bar is a superselector of .foo + .bar
        return unless seq1[1] == "~" ? seq2[si+1] != ">" : seq1[1] == seq2[si+1]
        return _superselector?(seq1[2..-1], seq2[si+2..-1])
      elsif seq2[si+1].is_a?(String)
        return unless seq2[si+1] == ">"
        return _superselector?(seq1[1..-1], seq2[si+2..-1])
      else
        return _superselector?(seq1[1..-1], seq2[si+1..-1])
      end
    end

chunks(seq1, seq2) { |seq1| ... } click to toggle source

Takes initial subsequences of `seq1` and `seq2` and returns all orderings of those subsequences. The initial subsequences are determined by a block.

Destructively removes the initial subsequences of `seq1` and `seq2`.

For example, given `(A B C | D E)` and `(1 2 | 3 4 5)` (with `|` denoting the boundary of the initial subsequence), this would return `[(A B C 1 2), (1 2 A B C)]`. The sequences would then be `(D E)` and `(3 4 5)`.

@param seq1 [Array] @param seq2 [Array] @yield [a] Used to determine when to cut off the initial subsequences.

    Called repeatedly for each sequence until it returns true.

@yieldparam a [Array] A final subsequence of one input sequence after

    cutting off some initial subsequence.

@yieldreturn [Boolean] Whether or not to cut off the initial subsequence

    here.

@return [Array<Array>] All possible orderings of the initial subsequences.

    # File lib/sass/selector/sequence.rb, line 342
    def chunks(seq1, seq2)
      chunk1 = []
      chunk1 << seq1.shift until yield seq1
      chunk2 = []
      chunk2 << seq2.shift until yield seq2
      return [] if chunk1.empty? && chunk2.empty?
      return [chunk2] if chunk1.empty?
      return [chunk1] if chunk2.empty?
      [chunk1 + chunk2, chunk2 + chunk1]
    end

extended_not_expanded_to_s(extended_not_expanded) click to toggle source

    # File lib/sass/selector/sequence.rb, line 495
    def extended_not_expanded_to_s(extended_not_expanded)
      extended_not_expanded.map do |choices|
        choices = choices.map do |sel|
          next sel.first.to_s if sel.size == 1
          "#{sel.join ' '}"
        end
        next choices.first if choices.size == 1 && !choices.include?(' ')
        "(#{choices.join ', '})"
      end.join ' '
    end

group_selectors(seq) click to toggle source

Groups a sequence into subsequences. The subsequences are determined by strings; adjacent non-string elements will be put into separate groups, but any element adjacent to a string will be grouped with that string.

For example, `(A B “C” D E “F” G “H” “I” J)` will become `[(A) (B “C” D) (E “F” G “H” “I” J)]`.

@param seq [Array] @return [Array<Array>]

    # File lib/sass/selector/sequence.rb, line 362
    def group_selectors(seq)
      newseq = []
      tail = seq.dup
      until tail.empty?
        head = []
        begin
          head << tail.shift
        end while !tail.empty? && head.last.is_a?(String) || tail.first.is_a?(String)
        newseq << head
      end
      return newseq
    end

merge_final_ops(seq1, seq2, res = []) click to toggle source

Extracts final selector combinators (`“+”`, `“>”`, `“~”`) and the selectors to which they apply from two sequences and merges them together into a single array.

@param seq1 [Array<SimpleSequence or String>] @param seq2 [Array<SimpleSequence or String>] @return [Array<SimpleSequence or String or

      Array<Array<SimpleSequence or String>>]
    If there are no trailing combinators to be merged, this will be the
    empty array. If the trailing combinators cannot be merged, this will
    be nil. Otherwise, this will contained the merged selector. Array
    elements are [Sass::Util#paths]-style options; conceptually, an "or"
    of multiple selectors.

    # File lib/sass/selector/sequence.rb, line 241
    def merge_final_ops(seq1, seq2, res = [])
      ops1, ops2 = [], []
      ops1 << seq1.pop while seq1.last.is_a?(String)
      ops2 << seq2.pop while seq2.last.is_a?(String)

      # Not worth the headache of trying to preserve newlines here. The most
      # important use of newlines is at the beginning of the selector to wrap
      # across lines anyway.
      ops1.reject! {|o| o == "\n"}
      ops2.reject! {|o| o == "\n"}

      return res if ops1.empty? && ops2.empty?
      if ops1.size > 1 || ops2.size > 1
        # If there are multiple operators, something hacky's going on. If one
        # is a supersequence of the other, use that, otherwise give up.
        lcs = Sass::Util.lcs(ops1, ops2)
        return unless lcs == ops1 || lcs == ops2
        res.unshift(*(ops1.size > ops2.size ? ops1 : ops2).reverse)
        return res
      end

      # This code looks complicated, but it's actually just a bunch of special
      # cases for interactions between different combinators.
      op1, op2 = ops1.first, ops2.first
      if op1 && op2
        sel1 = seq1.pop
        sel2 = seq2.pop
        if op1 == '~' && op2 == '~'
          if sel1.superselector?(sel2)
            res.unshift sel2, '~'
          elsif sel2.superselector?(sel1)
            res.unshift sel1, '~'
          else
            merged = sel1.unify(sel2.members, sel2.subject?)
            res.unshift [
              [sel1, '~', sel2, '~'],
              [sel2, '~', sel1, '~'],
              ([merged, '~'] if merged)
            ].compact
          end
        elsif (op1 == '~' && op2 == '+') || (op1 == '+' && op2 == '~')
          if op1 == '~'
            tilde_sel, plus_sel = sel1, sel2
          else
            tilde_sel, plus_sel = sel2, sel1
          end

          if tilde_sel.superselector?(plus_sel)
            res.unshift plus_sel, '+'
          else
            merged = plus_sel.unify(tilde_sel.members, tilde_sel.subject?)
            res.unshift [
              [tilde_sel, '~', plus_sel, '+'],
              ([merged, '+'] if merged)
            ].compact
          end
        elsif op1 == '>' && %w[~ +].include?(op2)
          res.unshift sel2, op2
          seq1.push sel1, op1
        elsif op2 == '>' && %w[~ +].include?(op1)
          res.unshift sel1, op1
          seq2.push sel2, op2
        elsif op1 == op2
          return unless merged = sel1.unify(sel2.members, sel2.subject?)
          res.unshift merged, op1
        else
          # Unknown selector combinators can't be unified
          return
        end
        return merge_final_ops(seq1, seq2, res)
      elsif op1
        seq2.pop if op1 == '>' && seq2.last && seq2.last.superselector?(seq1.last)
        res.unshift seq1.pop, op1
        return merge_final_ops(seq1, seq2, res)
      else # op2
        seq1.pop if op2 == '>' && seq1.last && seq1.last.superselector?(seq2.last)
        res.unshift seq2.pop, op2
        return merge_final_ops(seq1, seq2, res)
      end
    end

merge_initial_ops(seq1, seq2) click to toggle source

Extracts initial selector combinators (`“+”`, `“>”`, `“~”`, and `“n”`) from two sequences and merges them together into a single array of selector combinators.

@param seq1 [Array<SimpleSequence or String>] @param seq2 [Array<SimpleSequence or String>] @return [Array<String>, nil] If there are no operators in the merged

    sequence, this will be the empty array. If the operators cannot be
    merged, this will be nil.

    # File lib/sass/selector/sequence.rb, line 212
    def merge_initial_ops(seq1, seq2)
      ops1, ops2 = [], []
      ops1 << seq1.shift while seq1.first.is_a?(String)
      ops2 << seq2.shift while seq2.first.is_a?(String)

      newline = false
      newline ||= !!ops1.shift if ops1.first == "\n"
      newline ||= !!ops2.shift if ops2.first == "\n"

      # If neither sequence is a subsequence of the other, they cannot be
      # merged successfully
      lcs = Sass::Util.lcs(ops1, ops2)
      return unless lcs == ops1 || lcs == ops2
      return (newline ? ["\n"] : []) + (ops1.size > ops2.size ? ops1 : ops2)
    end

parent_superselector?(seq1, seq2) click to toggle source

Like {#_superselector?}, but compares the selectors in the context of parent selectors, as though they shared an implicit base simple selector. For example, `B` is not normally a superselector of `B A`, since it doesn't match `A` elements. However, it is a parent superselector, since `B X` is a superselector of `B A X`.

@param seq1 [Array<SimpleSequence or String>] @param seq2 [Array<SimpleSequence or String>] @return [Boolean]

    # File lib/sass/selector/sequence.rb, line 423
    def parent_superselector?(seq1, seq2)
      base = Sass::Selector::SimpleSequence.new([Sass::Selector::Placeholder.new('<temp>')], false)
      _superselector?(seq1 + [base], seq2 + [base])
    end

path_has_two_subjects?(path) click to toggle source

    # File lib/sass/selector/sequence.rb, line 478
    def path_has_two_subjects?(path)
      subject = false
      path.each do |sseq_or_op|
        next unless sseq_or_op.is_a?(SimpleSequence)
        next unless sseq_or_op.subject?
        return true if subject
        subject = true
      end
      false
    end

subweave(seq1, seq2) click to toggle source

This interweaves two lists of selectors, returning all possible orderings of them (including using unification) that maintain the relative ordering of the input arrays.

For example, given `.foo .bar` and `.baz .bang`, this would return `.foo .bar .baz .bang`, `.foo .bar.baz .bang`, `.foo .baz .bar .bang`, `.foo .baz .bar.bang`, `.foo .baz .bang .bar`, and so on until `.baz .bang .foo .bar`.

Semantically, for selectors A and B, this returns all selectors `AB_i` such that the union over all i of elements matched by `AB_i X` is identical to the intersection of all elements matched by `A X` and all elements matched by `B X`. Some `AB_i` are elided to reduce the size of the output.

@param seq1 [Array<SimpleSequence or String>] @param seq2 [Array<SimpleSequence or String>] @return [Array<Array<SimpleSequence or String>>]

    # File lib/sass/selector/sequence.rb, line 174
    def subweave(seq1, seq2)
      return [seq2] if seq1.empty?
      return [seq1] if seq2.empty?

      seq1, seq2 = seq1.dup, seq2.dup
      return unless init = merge_initial_ops(seq1, seq2)
      return unless fin = merge_final_ops(seq1, seq2)
      seq1 = group_selectors(seq1)
      seq2 = group_selectors(seq2)
      lcs = Sass::Util.lcs(seq2, seq1) do |s1, s2|
        next s1 if s1 == s2
        next unless s1.first.is_a?(SimpleSequence) && s2.first.is_a?(SimpleSequence)
        next s2 if parent_superselector?(s1, s2)
        next s1 if parent_superselector?(s2, s1)
      end

      diff = [[init]]
      until lcs.empty?
        diff << chunks(seq1, seq2) {|s| parent_superselector?(s.first, lcs.first)} << [lcs.shift]
        seq1.shift
        seq2.shift
      end
      diff << chunks(seq1, seq2) {|s| s.empty?}
      diff += fin.map {|sel| sel.is_a?(Array) ? sel : [sel]}
      diff.reject! {|c| c.empty?}

      Sass::Util.paths(diff).map {|p| p.flatten}.reject {|p| path_has_two_subjects?(p)}
    end

trim(seqses) click to toggle source

Removes redundant selectors from between multiple lists of selectors. This takes a list of lists of selector sequences; each individual list is assumed to have no redundancy within itself. A selector is only removed if it's redundant with a selector in another list.

“Redundant” here means that one selector is a superselector of the other. The more specific selector is removed.

@param seqses [Array<Array<Array<SimpleSequence or String>>>] @return [Array<Array<Array<SimpleSequence or String>>>]

    # File lib/sass/selector/sequence.rb, line 439
    def trim(seqses)
      # Avoid truly horrific quadratic behavior. TODO: I think there
      # may be a way to get perfect trimming without going quadratic.
      return seqses if seqses.size > 100

      # Keep the results in a separate array so we can be sure we aren't
      # comparing against an already-trimmed selector. This ensures that two
      # identical selectors don't mutually trim one another.
      result = seqses.dup

      # This is n^2 on the sequences, but only comparing between
      # separate sequences should limit the quadratic behavior.
      seqses.each_with_index do |seqs1, i|
        result[i] = seqs1.reject do |seq1|
          max_spec = _sources(seq1).map {|seq| seq.specificity}.max || 0
          result.any? do |seqs2|
            next if seqs1.equal?(seqs2)
            # Second Law of Extend: the specificity of a generated selector
            # should never be less than the specificity of the extending
            # selector.
            #
            # See https://github.com/nex3/sass/issues/324.
            seqs2.any? {|seq2| _specificity(seq2) >= max_spec && _superselector?(seq2, seq1)}
          end
        end
      end
      result
    end

weave(path) click to toggle source

Conceptually, this expands “parenthesized selectors”. That is, if we have `.A .B {@extend .C}` and `.D .C {…}`, this conceptually expands into `.D .C, .D (.A .B)`, and this function translates `.D (.A .B)` into `.D .A .B, .A.D .B, .D .A .B`.

@param path [Array<Array<SimpleSequence or String>>] A list of parenthesized selector groups. @return [Array<Array<SimpleSequence or String>>] A list of fully-expanded selectors.

    # File lib/sass/selector/sequence.rb, line 138
    def weave(path)
      # This function works by moving through the selector path left-to-right,
      # building all possible prefixes simultaneously. These prefixes are
      # `befores`, while the remaining parenthesized suffixes is `afters`.
      befores = [[]]
      afters = path.dup

      until afters.empty?
        current = afters.shift.dup
        last_current = [current.pop]
        befores = Sass::Util.flatten(befores.map do |before|
            next [] unless sub = subweave(before, current)
            sub.map {|seqs| seqs + last_current}
          end, 1)
      end
      return befores
    end