{"id":540,"date":"2009-11-19T21:31:17","date_gmt":"2009-11-20T05:31:17","guid":{"rendered":"http:\/\/boost-spirit.com\/home\/?page_id=540"},"modified":"2010-01-16T11:03:25","modified_gmt":"2010-01-16T19:03:25","slug":"debugging","status":"publish","type":"page","link":"http:\/\/boost-spirit.com\/home\/articles\/doc-addendum\/debugging\/","title":{"rendered":"Debugging"},"content":{"rendered":"

Preliminary documentation for Spirit2 debugging support.<\/p>\n

<\/p>\n

Requirements:<\/h4>\n
    \n
  1. It should provide info on rule attributes and locals.<\/li>\n
  2. It should be easy to set a breakpoint for conditional debugging in the IDE.<\/li>\n
  3. The user should be able to easily supply her own debug handler.<\/li>\n
  4. The output should be valid xml (snippet) that can be read by any xml editor.<\/li>\n<\/ol>\n

    One thing that’s nice about having an xml format for debugging is that you can use an xml editor or viewer to inspect the results. A good debugging strategy is to collect the debug result into a text editor and inspect it with an XML editor. Some (most?) editors have display filter capabilities to make it easy to spot the piece of XML you are looking for.<\/p><\/blockquote>\n

    Here’s how to add debugging to a rule in Spirit 2.1:<\/p>\n

    \r\ndebug(my_rule)\r\n<\/pre>\n
    Yep, that was easy. That one uses Spirit 2.1’s simple_trace class which provides simple tracing capabilities (similar to Classic’s). Be aware that:<\/p>\n
      \n
    1. Your attributes and local variables need to have a streaming operator defined, otherwise you’ll be getting a compiler error.<\/li>\n
    2. That your rule is named. Check the docs on how to do this. Otherwise, you will get a printout with ‘unamed-rule’. If you want to have the rule named and enable debugging at the same time, you can use the convenience macro: BOOST_SPIRIT_DEBUG_NODE(my_rule).<\/li>\n<\/ol>\n
      The example calc4_debug.cpp<\/a> highlights the debugger. Here’s a sample session:<\/p>\n
      \r\n1+1\r\n<expression>\r\n   <try>1+1<\/try>\r\n   <term>\r\n     <try>1+1<\/try>\r\n     <factor>\r\n       <try>1+1<\/try>\r\n       <success>+1<\/success>\r\n       <attributes>(1)<\/attributes>\r\n     <\/factor>\r\n     <success>+1<\/success>\r\n     <attributes>(1)<\/attributes>\r\n   <\/term>\r\n   <term>\r\n     <try>1<\/try>\r\n     <factor>\r\n       <try>1<\/try>\r\n       <success><\/success>\r\n       <attributes>(1)<\/attributes>\r\n     <\/factor>\r\n     <success><\/success>\r\n     <attributes>(1)<\/attributes>\r\n   <\/term>\r\n   <success><\/success>\r\n   <attributes>(2)<\/attributes>\r\n<\/expression>\r\n-------------------------\r\nParsing succeeded\r\nresult = 2\r\n-------------------------\r\n<\/pre>\n
      Things to note:<\/p>\n