[Boost-users] [spirit] closures and actions

...

]' ../../../../opensource/opt/include/boost/spirit/core/scanner/ scanner.hpp:161: instantiated from 'void boost::spirit::action_policy::do_action(const ActorT&, AttrT&, const IteratorT&, const IteratorT&) const [with ActorT = boost::spirit::ref_value_actor

...

]' ../../../../opensource/opt/include/boost/spirit/core/composite/ actions.hpp:109: instantiated from 'typename boost::spirit::parser_result, ScannerT>::type boost::spirit::action::parse(const ScannerT&) const [with ScannerT = boost::spirit::scanner<__gnu_cxx::__normal_iterator >, ParserT = boost::spirit::rule >, boost::spirit::scanner_policies >, boost::spirit::nil_t, boost::spirit::nil_t>, ActionT = boost::spirit::ref_value_actor

I'm trying to build a parser that does a fairly simple transformation of an input string - kind of like an L-System. I can get rules to properly match the input string, but I'm having real trouble with DOING anything. For testing, I've created some simple actions and a grammar (and rules) with a closure. When I don't use the closure for "temporary" variables, I seem to be able to proceed, but when I do anything except assign a value to my closure result, I'm getting failures to compile. This is using gcc4.01 on MacOSX and spirit 1.8.3 (from boost 1.34). The specific compiler error is: ../../src/lsystem/catalog_lsystem.cpp: In member function 'void do_appender::act(T&, const IteratorT&, const IteratorT&) const [with T = phoenix::actor > >, IteratorT = __gnu_cxx::__normal_iterator >]': <snip> ../../src/lsystem/catalog_lsystem.cpp:211: error: no matching function for call to 'std::basic_string::basic_string (phoenix::actor > >&)' From the error, it appears that I need some transformation from phoenix::actor back into my closure member, which is a String (typedef for std::basic_string<char>). Any suggestions? do_appender (a simple example actor) looks like: struct do_appender { template void act(T& ref, ValueT const &val) const { ref += val; } template void act(T& ref, IteratorT const &first, IteratorT const & last) const { String s(first, last); ref += s; } }; template <typename T> inline ref_value_actor do_append(T& lhs) { return ref_value_actor(lhs); } template inline ref_const_ref_actor do_append(T& lhs, ValueT const& val) { return ref_const_ref_actor(lhs,val); } and the closure and grammar (stripped slightly) look like: struct ProductionClosure : boost::spirit::closure { member1 m_result; member2 m_count; member3 m_temporary; }; struct ParameterLSystem::ProductionGrammar : public grammar { String * m_append; ProductionGrammar(String * ap) : m_append(ap) {} template <typename ScannerT> struct definition { typedef rule rule_t; typedef rule<ScannerT> srule_t; srule_t r_segment; rule_t r_segments; srule_t r_leaf; rule_t r_leaves; srule_t r_push; srule_t r_pop; rule_t r_start; rule_t r_terminalLeaves; rule_t r_branch; rule_t r_top; definition(ProductionGrammar const& self) { // basics r_leaf = ch_p('L'); r_leaves = (+r_leaf)[r_leaves.m_result = construct_<String>(arg1, arg2)]; r_segment = ch_p('S'); r_segments = (+r_segment)[r_segments.m_result = construct_<String>(arg1, arg2)]; r_push = ch_p('['); r_pop = ch_p(']'); r_terminalLeaves = r_push[do_append (r_terminalLeaves.m_result)]; r_top = r_branch[self.m_result = arg1]; } rule_t const& start() const { return r_top; } }; }; }; String is a typedef for std::basic_string<char> in my namespace. When I use m_append for a "temporary", I can get things to "work", i.e., it compiles and generates the correct output but the grammar will get more complex and I don't believe I can get away without using a closure variable. The full error stack from the compiler is: ../../src/lsystem/catalog_lsystem.cpp: In member function 'void do_appender::act(T&, const IteratorT&, const IteratorT&) const [with T = phoenix::actor > >, IteratorT = __gnu_cxx::__normal_iterator >]': ../../../../opensource/opt/include/boost/spirit/actor/ ref_value_actor.hpp:59: instantiated from 'void boost::spirit::ref_value_actor::operator()(const IteratorT&, const IteratorT&) const [with IteratorT = __gnu_cxx::__normal_iterator >, T = phoenix::actor > >, ActionT = do_appender]' ../../../../opensource/opt/include/boost/spirit/core/scanner/ scanner.hpp:146: instantiated from 'static void boost::spirit::attributed_action_policyboost::spirit::nil_t::call (const ActorT&, boost::spirit::nil_t, const IteratorT&, const IteratorT&) [with ActorT = boost::spirit::ref_value_actor > >, do_appender>, IteratorT = __gnu_cxx::__normal_iterator > >, do_appender>, AttrT = boost::spirit::nil_t, IteratorT = __gnu_cxx::__normal_iterator > >, do_appender>]' ../../../../opensource/opt/include/boost/spirit/core/non_terminal/ impl/rule.ipp:233: instantiated from 'typename boost::spirit::match_result::type boost::spirit::impl::concrete_parser::do_parse_virtual(const ScannerT&) const [with ParserT = boost::spirit::action >, boost::spirit::scanner_policies >, boost::spirit::nil_t, boost::spirit::nil_t>, boost::spirit::ref_value_actor > >, do_appender> >, ScannerT = boost::spirit::scanner<__gnu_cxx::__normal_iterator

...

, boost::spirit::scanner_policies >, AttrT = String]' ../../src/lsystem/catalog_lsystem.cpp:547: instantiated from here ../../src/lsystem/catalog_lsystem.cpp:211: error: no matching function for call to 'std::basic_string::basic_string (phoenix::actor > >&)'