liquid/lib/liquid/expression.rb

# frozen_string_literal: true

module Liquid
  class Expression
    LITERALS = {
      nil => nil, 'nil' => nil, 'null' => nil, '' => nil,
      'true' => true,
      'false' => false,
      'blank' => '',
      'empty' => ''
    }.freeze

    SINGLE_QUOTED_STRING = /\A'(.*)'\z/m
    DOUBLE_QUOTED_STRING = /\A"(.*)"\z/m
    INTEGERS_REGEX       = /\A(-?\d+)\z/
    FLOATS_REGEX         = /\A(-?\d[\d\.]+)\z/
    RANGES_REGEX         = /\A\((\S+)\.\.(\S+)\)\z/

    def self.parse(markup)
      if LITERALS.key?(markup)
        LITERALS[markup]
      else
        case markup
        when SINGLE_QUOTED_STRING, DOUBLE_QUOTED_STRING
          Regexp.last_match(1)
        when INTEGERS_REGEX
          Regexp.last_match(1).to_i
        when RANGES_REGEX
          RangeLookup.parse(Regexp.last_match(1), Regexp.last_match(2))
        when FLOATS_REGEX
          Regexp.last_match(1).to_f
        else
          VariableLookup.parse(markup)
        end
      end
    end
  end
end