编辑:我已经淘汰了词法分析器，因为它不能与Qi完美地集成在一起，而只会使语法模糊(请参阅here)。
我正在尝试在Spirit lex框架的基础上发展一种语法。当我尝试将跳过解析器移入语法时，我开始遇到错误。
因此，将qi::grammar<>和qi::rule<> event签名从<Iterator>更改为<Iterator,void(),ascii::space_type>。在语法结构中。我需要做什么？
另外，我已将token_def设置为忽略optional token 以及其他一些属性。为什么在语义 Action 中仍为我提供有效的_val以便在词法分析器中进行可选？我问的原因是因为我认为问题与qi中事件规则的rhs上的可选标记的字符串属性有关，而不是与规则的void()属性签名统一。
#include <boost/spirit/include/phoenix_core.hpp>
#include <boost/spirit/include/lex_lexertl.hpp>
#include <boost/spirit/include/qi.hpp>
#include <boost/cstdint.hpp>
#include <string>
#include<exception>
namespace lex = boost::spirit::lex;
namespace px = boost::phoenix;
namespace qi = boost::spirit::qi;
namespace ascii = boost::spirit::ascii;
template <typename Lexer>
struct tokens : lex::lexer<Lexer>
{
tokens()
: left_paranthesis("\"{\""),
right_paranthesis("\"}\""),
colon(":"),
namespace_("(?i:namespace)"),
event("(?i:event)"),
optional("(?i:optional)"),
required("(?i:required)"),
ordinal("\\d+"),
identifier("\\w+")
{
using boost::spirit::lex::_val;
this->self
= " "
| left_paranthesis [ std::cout << px::val("lpar") << std::endl]
| right_paranthesis [ std::cout << px::val("rpar") << std::endl]
| colon [ std::cout << px::val("colon") << std::endl]
| namespace_ [ std::cout << px::val("kw namesapce") << std::endl]
| event [ std::cout << px::val("kw event") << std::endl]
| optional [ std::cout << px::val("optional ") << "-->" << _val << "<--" << std::endl]
| required [ std::cout << px::val("required") << std::endl]
| ordinal [ std::cout << px::val("val ordinal (") << _val << ")" << std::endl]
| identifier [std::cout << px::val("val identifier(") << _val << ")" << std::endl];
}
lex::token_def<> left_paranthesis, right_paranthesis, colon;
lex::token_def<lex::omit> namespace_, event, optional, required;
lex::token_def<boost::uint32_t> ordinal;
lex::token_def<> identifier;
};
template <typename Iterator>
struct grammar : qi::grammar<Iterator>
{
template <typename TokenDef>
grammar(TokenDef const& tok)
: grammar::base_type(event)
{
//start = event;
event = tok.optional [ std::cout << px::val("== OPTIONAL") << std::endl];
}
qi::rule<Iterator> start;
qi::rule<Iterator> event;
};
// std::string test = "namespace{ event { OPtiONAL 124:hello_world RequireD} } ";
std::string test = "OPTIONAL";
int main()
{
typedef lex::lexertl::token<std::string::iterator, boost::mpl::vector<boost::uint32_t, std::string> > token_type;
typedef lex::lexertl::actor_lexer<token_type> lexer_type;
typedef tokens<lexer_type>::iterator_type iterator_type;
tokens<lexer_type> token_lexer;
grammar<iterator_type> grammar(token_lexer);
std::string::iterator first = test.begin();
std::string::iterator last = test.end();
bool r;
r = lex::tokenize_and_parse(first, last, token_lexer, grammar);
if(r)
;
else
{
std::cout << "parsing failed" << std::endl;
}
/*
lexer_type::iterator_type iter;
try
{
iter = token_lexer.begin(first,last);
}
catch(std::exception & e)
{
std::cout << e.what() << std::endl;
}
lexer_type::iterator_type end = token_lexer.end();
while (iter != end && token_is_valid(*iter))
++iter;
*/
}
该语法失败:
template <typename Iterator>
struct grammar : qi::grammar<Iterator,void(),ascii::space_type>
{
template <typename TokenDef>
grammar(TokenDef const& tok)
: grammar::base_type(event)
{
//start = event;
event = tok.optional [ std::cout << px::val("== OPTIONAL") << std::endl];
}
qi::rule<Iterator> start;
qi::rule<Iterator,void(),ascii::space_type> event;
};
最佳答案
和大多数精神一样。如果您想做些现实主义的事情，就得花几个小时寻找一个没有记载但埋在示例和邮件列表中的解决方案。认真考虑迁移到ragel或flex / bison。问题不是机器不可用，而是没有文件记录。
在这种情况下，当查看lex文档时，通过查看具有tokenize_and_phrase_parse函数的lex解析器api调用，一个人大为误导。当您尝试像qi::phrase_parse一样使用它时，这实际上是行不通的，文档也没有解释如何使用此功能连接船长。
通过更改词法分析器，然后使用一些未记录的qi-skipper构造初始化语法和规则，可以完成将空间跳线放入解析器的操作。您可以在lex示例目录(示例5)中看到这一点。可以编译和运行的代码:
#include <boost/spirit/include/phoenix_core.hpp>
#include <boost/spirit/include/lex_lexertl.hpp>
#include <boost/spirit/include/qi.hpp>
#include <boost/cstdint.hpp>
#include <string>
#include<exception>
namespace lex = boost::spirit::lex;
namespace px = boost::phoenix;
namespace qi = boost::spirit::qi;
namespace ascii = boost::spirit::ascii;
template <typename Lexer>
struct tokens : lex::lexer<Lexer>
{
tokens()
: left_paranthesis("\"{\""),
right_paranthesis("\"}\""),
colon(":"),
namespace_("(?i:namespace)"),
event("(?i:event)"),
optional("(?i:optional)"),
required("(?i:required)"),
ordinal("\\d+"),
identifier("\\w+")
{
using boost::spirit::lex::_val;
this->self
=
left_paranthesis [ std::cout << px::val("lpar") << std::endl]
| right_paranthesis [ std::cout << px::val("rpar") << std::endl]
| colon [ std::cout << px::val("colon") << std::endl]
| namespace_ [ std::cout << px::val("kw namesapce") << std::endl]
| event [ std::cout << px::val("kw event") << std::endl]
| optional [ std::cout << px::val("optional ") << "-->" << _val << "<--" << std::endl]
| required [ std::cout << px::val("required") << std::endl]
| ordinal [ std::cout << px::val("val ordinal (") << _val << ")" << std::endl]
| identifier [std::cout << px::val("val identifier(") << _val << ")" << std::endl];
this->self("WS") = lex::token_def<>("[ \\t\\n]+");
}
lex::token_def<> left_paranthesis, right_paranthesis, colon;
lex::token_def<lex::omit> namespace_, event, optional, required;
lex::token_def<boost::uint32_t> ordinal;
lex::token_def<> identifier;
};
template <typename Iterator, typename Lexer>
struct grammar : qi::grammar<Iterator,qi::in_state_skipper<Lexer> >
{
template <typename TokenDef>
grammar(TokenDef const& tok)
: grammar::base_type(event)
{
//start = event;
event = tok.optional [ std::cout << px::val("== OPTIONAL") << std::endl];
}
qi::rule<Iterator> start;
qi::rule<Iterator, qi::in_state_skipper<Lexer> > event;
};
// std::string test = "namespace{ event { OPtiONAL 124:hello_world RequireD} } ";
std::string test = " OPTIONAL ";
int main()
{
typedef lex::lexertl::token<std::string::iterator, boost::mpl::vector<boost::uint32_t, std::string> > token_type;
typedef lex::lexertl::actor_lexer<token_type> lexer_type;
typedef tokens<lexer_type>::iterator_type iterator_type;
tokens<lexer_type> token_lexer;
grammar<iterator_type,tokens<lexer_type>::lexer_def> grammar(token_lexer);
std::string::iterator it = test.begin();
iterator_type first = token_lexer.begin(it, test.end());
iterator_type last = token_lexer.end();
bool r;
r = qi::phrase_parse(first, last, grammar, qi::in_state("WS")[token_lexer.self]);
if(r)
;
else
{
std::cout << "parsing failed" << std::endl;
}
/*
lexer_type::iterator_type iter;
try
{
iter = token_lexer.begin(first,last);
}
catch(std::exception & e)
{
std::cout << e.what() << std::endl;
}
lexer_type::iterator_type end = token_lexer.end();
while (iter != end && token_is_valid(*iter))
++iter;
*/
}