refactored parser

[mint/mint-lib.git] / lib / mint / builder.rb

diff --git a/lib/mint/builder.rb b/lib/mint/builder.rb
index 7e39cab..b78421e 100644 (file)
--- a/lib/mint/builder.rb
+++ b/lib/mint/builder.rb
@@ -11,9 +11,13 @@ module Mint
 
     class << self
       def build(expression)
+        if expression.nil? || expression.empty?
+          return NullExpression.new
+        end
+        parser.instance_variable_set(:@yydebug, true)
         parser.parse(expression)
       rescue
-        raise InvalidExpressionError
+        raise InvalidExpressionError, expression
       end
 
       def parser