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# frozen_string_literal: true
module Liquid
class Expression
LITERALS = {
nil => nil, 'nil' => nil, 'null' => nil, '' => nil,
'true' => true,
'false' => false,
'blank' => '',
'empty' => ''
}.freeze
INTEGERS_REGEX = /\A(-?\d+)\z/
FLOATS_REGEX = /\A(-?\d[\d\.]+)\z/
# Use an atomic group (?>...) to avoid pathological backtracing from
# malicious input as described in https://github.com/Shopify/liquid/issues/1357
RANGES_REGEX = /\A\(\s*(?>(\S+)\s*\.\.)\s*(\S+)\s*\)\z/
def self.parse(markup)
return nil unless markup
markup = markup.strip
if (markup.start_with?('"') && markup.end_with?('"')) ||
(markup.start_with?("'") && markup.end_with?("'"))
return markup[1..-2]
end
case markup
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
if LITERALS.key?(markup)
LITERALS[markup]
else
VariableLookup.parse(markup)
end
end
end
end
end
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