Revert "Merge pull request #478 from Shopify/numbers-in-identifiers"

This reverts commit 263e90e772, reversing
changes made to 4dc682313f.

lib/liquid/lexer.rb

@@ -13,7 +13,7 @@ module Liquid
       '?'.freeze => :question,
       '-'.freeze => :dash
     }
-    IDENTIFIER = /[a-zA-Z_][\w-]*\??/
+    IDENTIFIER = /\w+/
     SINGLE_STRING_LITERAL = /'[^\']*'/
     DOUBLE_STRING_LITERAL = /"[^\"]*"/
     NUMBER_LITERAL = /-?\d+(\.\d+)?/

lib/liquid/parser.rb

@@ -75,6 +75,13 @@ module Liquid
 
     def variable_signature
       str = consume(:id)
+      while consume?(:dash)
+        str << "-".freeze
+        str << consume(:id)
+      end
+      if consume?(:question)
+        str << "?".freeze
+      end
       if look(:open_square)
         str << consume
         str << expression

lib/liquid/variable.rb

@@ -12,6 +12,7 @@ module Liquid
   #
   class Variable
     FilterParser = /(?:\s+|#{QuotedFragment}|#{ArgumentSeparator})+/o
+    EasyParse = /\A *(\w+(?:\.\w+)*) *\z/
     attr_accessor :filters, :name, :warnings
     attr_accessor :line_number
     include ParserSwitching
@@ -52,6 +53,13 @@ module Liquid
     end
 
     def strict_parse(markup)
+      # Very simple valid cases
+      if markup =~ EasyParse
+        @name = Expression.parse($1)
+        @filters = []
+        return
+      end
+
       @filters = []
       p = Parser.new(markup)