class Sass::Script::Parser

The parser for SassScript. It parses a string of code into a tree of {Script::Node}s.

Constants

ASSOCIATIVE
EXPR_NAMES

It would be possible to have unified assert and try methods, but detecting the method/token difference turns out to be quite expensive.

PRECEDENCE

Public Class Methods

associative?(op) click to toggle source

Returns whether or not the given operation is associative.

@private

# File lib/sass/script/parser.rb, line 195
def associative?(op)
  ASSOCIATIVE.include?(op)
end
new(str, line, offset, options = {}) click to toggle source

@param str [String, StringScanner] The source text to parse @param line [Fixnum] The line on which the SassScript appears.

Used for error reporting

@param offset [Fixnum] The number of characters in on which the SassScript appears.

Used for error reporting

@param options [{Symbol => Object}] An options hash;

see {file:SASS_REFERENCE.md#sass_options the Sass options documentation}
# File lib/sass/script/parser.rb, line 22
def initialize(str, line, offset, options = {})
  @options = options
  @lexer = lexer_class.new(str, line, offset, options)
end
parse(*args) click to toggle source

Parses a SassScript expression.

@overload parse(str, line, offset, filename = nil) @return [Script::Node] The root node of the parse tree @see Parser#initialize @see #parse

# File lib/sass/script/parser.rb, line 165
def self.parse(*args)
  new(*args).parse
end
precedence_of(op) click to toggle source

Returns an integer representing the precedence of the given operator. A lower integer indicates a looser binding.

@private

# File lib/sass/script/parser.rb, line 185
def precedence_of(op)
  PRECEDENCE.each_with_index do |e, i|
    return i if Array(e).include?(op)
  end
  raise "[BUG] Unknown operator #{op}"
end

Private Class Methods

production(name, sub, *ops) click to toggle source

Defines a simple left-associative production. name is the name of the production, sub is the name of the production beneath it, and ops is a list of operators for this precedence level

# File lib/sass/script/parser.rb, line 205
        def production(name, sub, *ops)
          class_eval "            def #{name}
              interp = try_ops_after_interp(#{ops.inspect}, #{name.inspect}) and return interp
              return unless e = #{sub}
              while tok = try_tok(#{ops.map {|o| o.inspect}.join(', ')})
                if interp = try_op_before_interp(tok, e)
                  return interp unless other_interp = try_ops_after_interp(#{ops.inspect}, #{name.inspect}, interp)
                  return other_interp
                end

                line = @lexer.line
                e = Operation.new(e, assert_expr(#{sub.inspect}), tok.type)
                e.line = line
              end
              e
            end
", __FILE__, __LINE__ + 1
        end
unary(op, sub) click to toggle source
# File lib/sass/script/parser.rb, line 225
        def unary(op, sub)
          class_eval "            def unary_#{op}
              return #{sub} unless tok = try_tok(:#{op})
              interp = try_op_before_interp(tok) and return interp
              line = @lexer.line 
              op = UnaryOperation.new(assert_expr(:unary_#{op}), :#{op})
              op.line = line
              op
            end
", __FILE__, __LINE__ + 1
        end

Public Instance Methods

line() click to toggle source

The line number of the parser's current position.

@return [Fixnum]

# File lib/sass/script/parser.rb, line 11
def line
  @lexer.line
end
parse() click to toggle source

Parses a SassScript expression.

@return [Script::Node] The root node of the parse tree @raise [Sass::SyntaxError] if the expression isn't valid SassScript

# File lib/sass/script/parser.rb, line 48
def parse
  expr = assert_expr :expr
  assert_done
  expr.options = @options
  expr
rescue Sass::SyntaxError => e
  e.modify_backtrace :line => @lexer.line, :filename => @options[:filename]
  raise e
end
parse_function_definition_arglist() click to toggle source

Parses the argument list for a function definition.

@return [(Array<Script::Node>, Script::Node)]

The root nodes of the arguments, and the splat argument.

@raise [Sass::SyntaxError] if the argument list isn't valid SassScript

# File lib/sass/script/parser.rb, line 123
def parse_function_definition_arglist
  args, splat = defn_arglist!(true)
  assert_done

  args.each do |k, v|
    k.options = @options
    v.options = @options if v
  end
  splat.options = @options if splat
  return args, splat
rescue Sass::SyntaxError => e
  e.modify_backtrace :line => @lexer.line, :filename => @options[:filename]
  raise e
end
parse_interpolated() click to toggle source

Parses a SassScript expression within an interpolated segment (`#{}`). This means that it stops when it comes across an unmatched `}`, which signals the end of an interpolated segment, it returns rather than throwing an error.

@return [Script::Node] The root node of the parse tree @raise [Sass::SyntaxError] if the expression isn't valid SassScript

# File lib/sass/script/parser.rb, line 34
def parse_interpolated
  expr = assert_expr :expr
  assert_tok :end_interpolation
  expr.options = @options
  expr
rescue Sass::SyntaxError => e
  e.modify_backtrace :line => @lexer.line, :filename => @options[:filename]
  raise e
end
parse_mixin_definition_arglist() click to toggle source

Parses the argument list for a mixin definition.

@return [(Array<Script::Node>, Script::Node)]

The root nodes of the arguments, and the splat argument.

@raise [Sass::SyntaxError] if the argument list isn't valid SassScript

# File lib/sass/script/parser.rb, line 103
def parse_mixin_definition_arglist
  args, splat = defn_arglist!(false)
  assert_done

  args.each do |k, v|
    k.options = @options
    v.options = @options if v
  end
  splat.options = @options if splat
  return args, splat
rescue Sass::SyntaxError => e
  e.modify_backtrace :line => @lexer.line, :filename => @options[:filename]
  raise e
end
parse_mixin_include_arglist() click to toggle source

Parses the argument list for a mixin include.

@return [(Array<Script::Node>, {String => Script::Node}, Script::Node)]

The root nodes of the positional arguments, keyword arguments, and
splat argument. Keyword arguments are in a hash from names to values.

@raise [Sass::SyntaxError] if the argument list isn't valid SassScript

# File lib/sass/script/parser.rb, line 81
def parse_mixin_include_arglist
  args, keywords = [], {}
  if try_tok(:lparen)
    args, keywords, splat = mixin_arglist || [[], {}]
    assert_tok(:rparen)
  end
  assert_done

  args.each {|a| a.options = @options}
  keywords.each {|k, v| v.options = @options}
  splat.options = @options if splat
  return args, keywords, splat
rescue Sass::SyntaxError => e
  e.modify_backtrace :line => @lexer.line, :filename => @options[:filename]
  raise e
end
parse_string() click to toggle source

Parse a single string value, possibly containing interpolation. Doesn't assert that the scanner is finished after parsing.

@return [Script::Node] The root node of the parse tree. @raise [Sass::SyntaxError] if the string isn't valid SassScript

# File lib/sass/script/parser.rb, line 143
def parse_string
  unless (peek = @lexer.peek) &&
      (peek.type == :string ||
      (peek.type == :funcall && peek.value.downcase == 'url'))
    lexer.expected!("string")
  end

  expr = assert_expr :funcall
  expr.options = @options
  @lexer.unpeek!
  expr
rescue Sass::SyntaxError => e
  e.modify_backtrace :line => @lexer.line, :filename => @options[:filename]
  raise e
end
parse_until(tokens) click to toggle source

Parses a SassScript expression, ending it when it encounters one of the given identifier tokens.

@param [#include?(String)] A set of strings that delimit the expression. @return [Script::Node] The root node of the parse tree @raise [Sass::SyntaxError] if the expression isn't valid SassScript

# File lib/sass/script/parser.rb, line 64
def parse_until(tokens)
  @stop_at = tokens
  expr = assert_expr :expr
  assert_done
  expr.options = @options
  expr
rescue Sass::SyntaxError => e
  e.modify_backtrace :line => @lexer.line, :filename => @options[:filename]
  raise e
end

Private Instance Methods

arglist(subexpr, description) click to toggle source
# File lib/sass/script/parser.rb, line 381
def arglist(subexpr, description)
  return unless e = send(subexpr)

  args = []
  keywords = {}
  loop do
    if @lexer.peek && @lexer.peek.type == :colon
      name = e
      @lexer.expected!("comma") unless name.is_a?(Variable)
      assert_tok(:colon)
      value = assert_expr(subexpr, description)

      if keywords[name.underscored_name]
        raise SyntaxError.new("Keyword argument \"#{name.to_sass}\" passed more than once")
      end

      keywords[name.underscored_name] = value
    else
      if !keywords.empty?
        raise SyntaxError.new("Positional arguments must come before keyword arguments.")
      end

      return args, keywords, e if try_tok(:splat)
      args << e
    end

    return args, keywords unless try_tok(:comma)
    e = assert_expr(subexpr, description)
  end
end
assert_done() click to toggle source
# File lib/sass/script/parser.rb, line 491
def assert_done
  return if @lexer.done?
  @lexer.expected!(EXPR_NAMES[:default])
end
assert_expr(name, expected = nil) click to toggle source
# File lib/sass/script/parser.rb, line 476
def assert_expr(name, expected = nil)
  (e = send(name)) && (return e)
  @lexer.expected!(expected || EXPR_NAMES[name] || EXPR_NAMES[:default])
end
assert_tok(*names) click to toggle source
# File lib/sass/script/parser.rb, line 481
def assert_tok(*names)
  (t = try_tok(*names)) && (return t)
  @lexer.expected!(names.map {|tok| Lexer::TOKEN_NAMES[tok] || tok}.join(" or "))
end
defn_arglist!(must_have_parens) click to toggle source
# File lib/sass/script/parser.rb, line 343
def defn_arglist!(must_have_parens)
  if must_have_parens
    assert_tok(:lparen)
  else
    return [], nil unless try_tok(:lparen)
  end
  return [], nil if try_tok(:rparen)

  res = []
  splat = nil
  must_have_default = false
  loop do
    c = assert_tok(:const)
    var = Script::Variable.new(c.value)
    if try_tok(:colon)
      val = assert_expr(:space)
      must_have_default = true
    elsif must_have_default
      raise SyntaxError.new("Required argument #{var.inspect} must come before any optional arguments.")
    elsif try_tok(:splat)
      splat = var
      break
    end
    res << [var, val]
    break unless try_tok(:comma)
  end
  assert_tok(:rparen)
  return res, splat
end
expr() click to toggle source
# File lib/sass/script/parser.rb, line 244
def expr
  line = @lexer.line
  return unless e = interpolation
  list = node(List.new([e], :comma), line)
  while tok = try_tok(:comma)
    if interp = try_op_before_interp(tok, list)
      return interp unless other_interp = try_ops_after_interp([:comma], :expr, interp)
      return other_interp
    end
    list.value << assert_expr(:interpolation)
  end
  list.value.size == 1 ? list.value.first : list
end
fn_arglist() click to toggle source
# File lib/sass/script/parser.rb, line 373
def fn_arglist
  arglist(:equals, "function argument")
end
funcall() click to toggle source
# File lib/sass/script/parser.rb, line 336
def funcall
  return raw unless tok = try_tok(:funcall)
  args, keywords, splat = fn_arglist || [[], {}]
  assert_tok(:rparen)
  node(Script::Funcall.new(tok.value, args, keywords, splat))
end
ident() click to toggle source
# File lib/sass/script/parser.rb, line 318
def ident
  return funcall unless @lexer.peek && @lexer.peek.type == :ident
  return if @stop_at && @stop_at.include?(@lexer.peek.value)

  name = @lexer.next
  if color = Color::COLOR_NAMES[name.value.downcase]
    node(Color.new(color))
  elsif name.value == "true"
    node(Script::Bool.new(true))
  elsif name.value == "false"
    node(Script::Bool.new(false))
  elsif name.value == "null"
    node(Script::Null.new)
  else
    node(Script::String.new(name.value, :identifier))
  end
end
interpolation(first = space) click to toggle source
# File lib/sass/script/parser.rb, line 283
def interpolation(first = space)
  e = first
  while interp = try_tok(:begin_interpolation)
    wb = @lexer.whitespace?(interp)
    line = @lexer.line
    mid = parse_interpolated
    wa = @lexer.whitespace?
    e = Script::Interpolation.new(e, mid, space, wb, wa)
    e.line = line
  end
  e
end
lexer_class() click to toggle source

@private

# File lib/sass/script/parser.rb, line 242
def lexer_class; Lexer; end
literal() click to toggle source
# File lib/sass/script/parser.rb, line 462
def literal
  (t = try_tok(:color)) && (return t.value)
end
mixin_arglist() click to toggle source
# File lib/sass/script/parser.rb, line 377
def mixin_arglist
  arglist(:interpolation, "mixin argument")
end
node(node, line = @lexer.line) click to toggle source
# File lib/sass/script/parser.rb, line 496
def node(node, line = @lexer.line)
  node.line = line
  node
end
number() click to toggle source
# File lib/sass/script/parser.rb, line 455
def number
  return literal unless tok = try_tok(:number)
  num = tok.value
  num.original = num.to_s unless @in_parens
  num
end
paren() click to toggle source
# File lib/sass/script/parser.rb, line 427
def paren
  return variable unless try_tok(:lparen)
  was_in_parens = @in_parens
  @in_parens = true
  line = @lexer.line
  e = expr
  assert_tok(:rparen)
  return e || node(List.new([], :space), line)
ensure
  @in_parens = was_in_parens
end
raw() click to toggle source
# File lib/sass/script/parser.rb, line 412
def raw
  return special_fun unless tok = try_tok(:raw)
  node(Script::String.new(tok.value))
end
space() click to toggle source
# File lib/sass/script/parser.rb, line 296
def space
  line = @lexer.line
  return unless e = or_expr
  arr = [e]
  while e = or_expr
    arr << e
  end
  arr.size == 1 ? arr.first : node(List.new(arr, :space), line)
end
special_fun() click to toggle source
# File lib/sass/script/parser.rb, line 417
def special_fun
  return paren unless tok = try_tok(:special_fun)
  first = node(Script::String.new(tok.value.first))
  Sass::Util.enum_slice(tok.value[1..-1], 2).inject(first) do |l, (i, r)|
    Script::Interpolation.new(
      l, i, r && node(Script::String.new(r)),
      false, false)
  end
end
string() click to toggle source
# File lib/sass/script/parser.rb, line 444
def string
  return number unless first = try_tok(:string)
  return first.value unless try_tok(:begin_interpolation)
  line = @lexer.line
  mid = parse_interpolated
  last = assert_expr(:string)
  interp = StringInterpolation.new(first.value, mid, last)
  interp.line = line
  interp
end
try_op_before_interp(op, prev = nil) click to toggle source
# File lib/sass/script/parser.rb, line 260
def try_op_before_interp(op, prev = nil)
  return unless @lexer.peek && @lexer.peek.type == :begin_interpolation
  wb = @lexer.whitespace?(op)
  str = Script::String.new(Lexer::OPERATORS_REVERSE[op.type])
  str.line = @lexer.line
  interp = Script::Interpolation.new(prev, str, nil, wb, !:wa, :originally_text)
  interp.line = @lexer.line
  interpolation(interp)
end
try_ops_after_interp(ops, name, prev = nil) click to toggle source
# File lib/sass/script/parser.rb, line 270
def try_ops_after_interp(ops, name, prev = nil)
  return unless @lexer.after_interpolation?
  return unless op = try_tok(*ops)
  interp = try_op_before_interp(op, prev) and return interp

  wa = @lexer.whitespace?
  str = Script::String.new(Lexer::OPERATORS_REVERSE[op.type])
  str.line = @lexer.line
  interp = Script::Interpolation.new(prev, str, assert_expr(name), !:wb, wa, :originally_text)
  interp.line = @lexer.line
  return interp
end
try_tok(*names) click to toggle source
# File lib/sass/script/parser.rb, line 486
def try_tok(*names)
  peeked =  @lexer.peek
  peeked && names.include?(peeked.type) && @lexer.next
end
variable() click to toggle source
# File lib/sass/script/parser.rb, line 439
def variable
  return string unless c = try_tok(:const)
  node(Variable.new(*c.value))
end