Separate ? and - into special tokens

lib/liquid/lexer.rb

@@ -9,9 +9,11 @@ module Liquid
       '['.freeze => :open_square,
       ']'.freeze => :close_square,
       '('.freeze => :open_round,
-      ')'.freeze => :close_round
+      ')'.freeze => :close_round,
+      '?'.freeze => :question,
+      '-'.freeze => :dash
     }
-    IDENTIFIER = /[\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) if look(:id)
+      end
+      if consume?(:question)
+        str << "?".freeze
+      end
       if look(:open_square)
         str << consume
         str << expression

test/unit/lexer_unit_test.rb

@@ -31,8 +31,8 @@ class LexerUnitTest < Minitest::Test
   end
 
   def test_fancy_identifiers
-    tokens = Lexer.new('hi! five?').tokenize
-    assert_equal [[:id,'hi!'], [:id, 'five?'], [:end_of_string]], tokens
+    tokens = Lexer.new('hi five?').tokenize
+    assert_equal [[:id,'hi'], [:id, 'five'], [:question, '?'], [:end_of_string]], tokens
   end
 
   def test_whitespace

test/unit/parser_unit_test.rb

@@ -44,9 +44,9 @@ class ParserUnitTest < Minitest::Test
   end
 
   def test_expressions
-    p = Parser.new("hi.there hi[5].! hi.there.bob")
+    p = Parser.new("hi.there hi?[5].there? hi.there.bob")
     assert_equal 'hi.there', p.expression
-    assert_equal 'hi[5].!', p.expression
+    assert_equal 'hi?[5].there?', p.expression
     assert_equal 'hi.there.bob', p.expression
 
     p = Parser.new("567 6.0 'lol' \"wut\"")