New variable parser!

lib/liquid/parser.rb

@@ -8,6 +8,10 @@ module Liquid
       @p = 0 # pointer to current location
     end
 
+    def jump(point)
+      @p = point
+    end
+
     def consume(type = nil)
       token = @tokens[@p]
       if type && token.type != type
@@ -17,14 +21,24 @@ module Liquid
       token.contents
     end
 
+    # Only consumes the token if it matches the type
+    # Returns the token's contents if it was consumed
+    # or false otherwise.
+    def consume?(type)
+      token = @tokens[@p]
+      return false unless token && token.type == type
+      @p += 1
+      token.contents
+    end
+
     def cur_token()
       tok = @tokens[@p]
       raise SyntaxError, 'Expected more input.' unless tok
       tok
     end
 
-    def look(type)
-      tok = @tokens[@p]
+    def look(type, ahead = 0)
+      tok = @tokens[@p + ahead]
       return false unless tok
       tok.type == type
     end
@@ -36,22 +50,34 @@ module Liquid
       if token.type == :id
         variable_signature
       elsif [:string, :integer, :float].include? token.type
+        consume
         token.contents
       else
         raise SyntaxError, "#{token} is not a valid expression."
       end
     end
 
+    def argument
+      str = ""
+      # might be a keyword argument (identifier: expression)
+      if look(:id) && look(:colon, 1)
+        str << consume << consume << ' '
+      end
+
+      str << expression
+    end
+
     def variable_signature
       str = consume(:id)
-      if look(:dot)
-        str << consume
-        str << variable_signature
-      elsif look(:open_square)
+      if look(:open_square)
         str << consume
         str << expression
         str << consume(:close_square)
       end
+      if look(:dot)
+        str << consume
+        str << variable_signature
+      end
       str
     end
   end