remove Expression2 strscan workaround

lib/liquid/expression.rb

@@ -3,52 +3,7 @@
 require "lru_redux"
 
 module Liquid
-  class Expression1
-    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, _ss = nil, _cache = nil)
-      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), nil)
-      when FLOATS_REGEX
-        Regexp.last_match(1).to_f
-      else
-        if LITERALS.key?(markup)
-          LITERALS[markup]
-        else
-          VariableLookup.parse(markup, nil)
-        end
-      end
-    end
-  end
-
-  class Expression2
+  class Expression
     LITERALS = {
       nil => nil,
       'nil' => nil,
@@ -161,7 +116,4 @@ module Liquid
       end
     end
   end
-
-  # Remove this once we can depend on strscan >= 3.1.1
-  Expression = HAS_STRING_SCANNER_SCAN_BYTE ? Expression2 : Expression1
 end