Re: [Boost-users] Boost.Spirit Karma: debug() alters result

Subject: Re: [Boost-users] Boost.Spirit Karma: debug() alters result
From: Matwey V. Kornilov (matwey.kornilov_at_[hidden])
Date: 2016-03-05 03:53:34

It feels like debug() implicitly does buffer[] on the specific term.

04.03.2016 18:48, Hartmut Kaiser пишет:
> That looks like a bug, however I don't have an immediate solution for that.
> I'll try to look into this as soon as I find some free time.
> 
> Regards Hartmut
> ---------------
> http://boost-spirit.com
> http://stellar.cct.lsu.edu
> 
> 
>> -----Original Message-----
>> From: Boost-users [mailto:boost-users-bounces_at_[hidden]] On Behalf
>> Of Matwey V. Kornilov
>> Sent: Friday, March 4, 2016 9:02 AM
>> To: boost-users_at_[hidden]
>> Subject: [Boost-users] Boost.Spirit Karma: debug() alters result
>>
>> Hello,
>>
>> I am using boost 1.58 and I see the following.
>>
>> template <class Iterator>
>> struct test_generator:
>>         karma::grammar<Iterator, std::string()> {
>>
>>         test_generator(): test_generator::base_type(start) {
>>                 using karma::ascii::string;
>>                 using boost::spirit::ascii::char_;
>>                 using karma::lit;
>>                 using karma::buffer;
>>                 using karma::debug;
>>
>>                 value2 = +(~char_(' '));
>>                 value1 = value2;
>>                 value = lit('=') << value1;
>>                 start = buffer[-value];
>>         }
>>
>>         karma::rule<Iterator, std::string()> start;
>>         karma::rule<Iterator, std::string()> value;
>>         karma::rule<Iterator, std::string()> value1;
>>         karma::rule<Iterator, std::string()> value2;
>> };
>> template <class Iterator>
>> struct test_generator2:
>>         karma::grammar<Iterator, std::string()> {
>>
>>         test_generator2(): test_generator2::base_type(start) {
>>                 using karma::ascii::string;
>>                 using boost::spirit::ascii::char_;
>>                 using karma::lit;
>>                 using karma::buffer;
>>                 using karma::debug;
>>
>>                 value2 = +(~char_(' '));
>>                 value1 = value2;
>>                 value = lit('=') << value1;
>>                 debug(value);
>>                 start = buffer[-value];
>>         }
>>
>>         karma::rule<Iterator, std::string()> start;
>>         karma::rule<Iterator, std::string()> value;
>>         karma::rule<Iterator, std::string()> value1;
>>         karma::rule<Iterator, std::string()> value2;
>> };
>>
>> template<class It>
>> bool do_generate(It it, const std::string& x) {
>>         test_generator<It> g;
>>         return karma::generate(it, g, x);
>> }
>> template<class It>
>> bool do_generate2(It it, const std::string& x) {
>>         test_generator2<It> g;
>>         return karma::generate(it, g, x);
>> }
>>
>> //...
>>
>>         std::string x2,x3;
>>         do_generate(std::back_inserter(x2), std::string(""));
>>         do_generate2(std::back_inserter(x3), std::string(""));
>>         std::cerr << "|" << x2 << "|" << std::endl;
>>         std::cerr << "|" << x3 << "|" << std::endl;
>>
>> //...
>>
>> The code prints:
>>
>> <unnamed-rule>
>>   <try>
>>     <attributes>[[]]</attributes>
>>   </try>
>>   <fail/>
>> </unnamed-rule>
>> |=|
>> ||
>>
>> I.e. introduction of debug() alters result of the generator. Could you
>> please explain me where I am wrong? I am stuck now.
>>
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