c++ - How to use a slash in Spirit Lex patterns? -

code below compiles fine with

clang++ -std=c++11 test.cpp -o test

but when running exception thrown

terminate called after throwing instance of 'boost::lexer::runtime_error' what(): lookahead ('/') not supported yet.

the problem the slash (/) in input and/or regex (line 12 , 39) can't find solution how escape right. hints?

#include <string> #include <cstring> #include <boost/spirit/include/lex.hpp> #include <boost/spirit/include/lex_lexertl.hpp> #include <boost/spirit/include/qi.hpp> #include <boost/spirit/include/phoenix.hpp>  namespace lex        = boost::spirit::lex; namespace qi         = boost::spirit::qi; namespace phoenix    = boost::phoenix;  std::string regex("foo/bar");  template <typename type> struct lexer : boost::spirit::lex::lexer<type> {     lexer() : foobar_(regex) {         this->self.add(foobar_);     }     boost::spirit::lex::token_def<std::string> foobar_; };  template <typename iterator, typename def> struct grammar   : qi::grammar <iterator, qi::in_state_skipper<def> > {     template <typename lexer> grammar(const lexer & _lexer);     typedef qi::in_state_skipper<def> skipper;     qi::rule<iterator, skipper> rule_; }; template <typename iterator, typename def> template <typename lexer> grammar<iterator, def>::grammar(const lexer & _lexer)   : grammar::base_type(rule_) {     rule_ = _lexer.foobar_; }  int main() {     // input     char const * first("foo/bar");     char const * last(first + strlen(first));      // lexer     typedef lex::lexertl::token<const char *> token;     typedef lex::lexertl::lexer<token> type;     lexer<type> l;      // grammar     typedef lexer<type>::iterator_type iterator;     typedef lexer<type>::lexer_def def;     grammar<iterator, def> g(l);      // parse     bool ok = lex::tokenize_and_phrase_parse (         first       , last       , l       , g       , qi::in_state("ws")[l.self]     );      // check     if (!ok || first != last) {         std::cout << "failed parsing input file" << std::endl;         return 1;     }     return 0; } 

as sehe points out, / intended used lookahead operator, taking after the syntax of flex. it's unfortunate spirit wouldn't use more normal lookahead syntax (not think other syntax more elegant; gets confusing subtle variations in regex syntax).

if @ re_tokeniser.hpp:

// not escape sequence , not inside string, // check meta characters. switch (ch_) {     ...     case '/':         throw runtime_error("lookahead ('/') not supported yet.");         break;     ... } 

it thinks you're not in escape sequence nor inside string, it's checking meta characters. / considered meta character lookahead (even though feature isn't implemented), , must escaped, despite boost docs not mentioning @ all.

try escaping / (not in input) backslash (i.e. "\\/", or "\/" if using raw string). alternatively, others have suggested using [/].

i'd consider bug in spirit lex documentation lacking point out / must escaped.

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edit: kudos sehe , cv_and_he, helped correct of earlier thinking. if post answer here, sure give them +1.