Error with Phoenix placeholder _val in Boost.Spirit.Lex :(
- by GooRoo
Hello, everybody.
I'm newbie in Boost.Spirit.Lex.
Some strange error appears every time I try to use lex::_val in semantics actions in my simple lexer:
#ifndef _TOKENS_H_
#define _TOKENS_H_
#include <iostream>
#include <string>
#include <boost/spirit/include/lex_lexertl.hpp>
#include <boost/spirit/include/phoenix_operator.hpp>
#include <boost/spirit/include/phoenix_statement.hpp>
#include <boost/spirit/include/phoenix_container.hpp>
namespace lex = boost::spirit::lex;
namespace phx = boost::phoenix;
enum tokenids
{
ID_IDENTIFICATOR = 1,
ID_CONSTANT,
ID_OPERATION,
ID_BRACKET,
ID_WHITESPACES
};
template <typename Lexer>
struct mega_tokens
: lex::lexer<Lexer>
{
mega_tokens()
: identifier(L"[a-zA-Z_][a-zA-Z0-9_]*", ID_IDENTIFICATOR)
, constant (L"[0-9]+(\\.[0-9]+)?", ID_CONSTANT )
, operation (L"[\\+\\-\\*/]", ID_OPERATION )
, bracket (L"[\\(\\)\\[\\]]", ID_BRACKET )
{
using lex::_tokenid;
using lex::_val;
using phx::val;
this->self
= operation [ std::wcout
<< val(L'<') << _tokenid
// << val(L':') << lex::_val
<< val(L'>')
]
| identifier [ std::wcout
<< val(L'<') << _tokenid
<< val(L':') << _val
<< val(L'>')
]
| constant [ std::wcout
<< val(L'<') << _tokenid
// << val(L':') << _val
<< val(L'>')
]
| bracket [ std::wcout << phx::val(lex::_val)
<< val(L'<') << _tokenid
// << val(L':') << lex::_val
<< val(L'>')
]
;
}
lex::token_def<wchar_t, wchar_t> operation;
lex::token_def<std::wstring, wchar_t> identifier;
lex::token_def<double, wchar_t> constant;
lex::token_def<wchar_t, wchar_t> bracket;
};
#endif // _TOKENS_H_
and
#include <cstdlib>
#include <iostream>
#include <locale>
#include <boost/spirit/include/lex_lexertl.hpp>
#include "tokens.h"
int main()
{
setlocale(LC_ALL, "Russian");
namespace lex = boost::spirit::lex;
typedef std::wstring::iterator base_iterator;
typedef lex::lexertl::token <
base_iterator,
boost::mpl::vector<wchar_t, std::wstring, double, wchar_t>,
boost::mpl::true_
> token_type;
typedef lex::lexertl::actor_lexer<token_type> lexer_type;
typedef mega_tokens<lexer_type>::iterator_type iterator_type;
mega_tokens<lexer_type> mega_lexer;
std::wstring str = L"alfa+x1*(2.836-x2[i])";
base_iterator first = str.begin();
bool r = lex::tokenize(first, str.end(), mega_lexer);
if (r) {
std::wcout << L"Success" << std::endl;
}
else {
std::wstring rest(first, str.end());
std::wcerr << L"Lexical analysis failed\n" << L"stopped at: \""
<< rest << L"\"\n";
}
return EXIT_SUCCESS;
}
This code causes an error in Boost header 'boost/spirit/home/lex/argument.hpp' on line 167 while compiling:
return: can't convert 'const
boost::variant' to
'boost::variant &'
When I don't use lex::_val program compiles with no errors.
Obviously, I use _val in wrong way, but I do not know how to do this correctly. Help, please! :)
P.S. And sorry for my terrible English…
