我正在继续学习Boost Spirit库,我有一些问题,我无法编译。您可以在此处找到示例来源:source place。您也可以查看此代码并在Coliru上编译结果。
#include <boost/config/warning_disable.hpp>
#include <boost/spirit/include/qi.hpp>
#include <boost/spirit/include/lex_lexertl.hpp>
#include <boost/spirit/include/phoenix_operator.hpp>
#include <iostream>
#include <fstream>
#include <string>
using namespace boost::spirit;
using boost::phoenix::val;
///////////////////////////////////////////////////////////////////////////////
// Token definition
///////////////////////////////////////////////////////////////////////////////
template <typename Lexer>
struct example4_tokens : lex::lexer<Lexer>
{
example4_tokens()
{
identifier = "[a-zA-Z_][a-zA-Z0-9_]*";
constant = "[0-9]+";
if_ = "if";
else_ = "else";
while_ = "while";
this->self = lex::token_def<>('(') | ')' | '{' | '}' | '=' | ';' | constant;
this->self += if_ | else_ | while_ | identifier;
this->self("WS")
= lex::token_def<>("[ \\t\\n]+")
| "\\/\\*[^*]*\\*+([^/*][^*]*\\*+)*\\/"
;
}
lex::token_def<> if_, else_, while_;
lex::token_def<std::string> identifier;
lex::token_def<unsigned int> constant;
//]
};
template <typename Iterator, typename Lexer>
struct example4_grammar
: qi::grammar<Iterator, qi::in_state_skipper<Lexer> >
{
template <typename TokenDef>
example4_grammar(TokenDef const& tok)
: example4_grammar::base_type(program)
{
using boost::spirit::_val;
program
= +block
;
block
= '{' >> *statement >> '}'
;
statement
= assignment
| if_stmt
| while_stmt
;
assignment
= (tok.identifier >> '=' >> expression >> ';')
[
std::cout << val("assignment statement to: ") << _1 << "\n"
]
;
if_stmt
= ( tok.if_ >> '(' >> expression >> ')' >> block
>> -(tok.else_ >> block)
)
[
std::cout << val("if expression: ") << _2 << "\n"
]
;
while_stmt
= (tok.while_ >> '(' >> expression >> ')' >> block)
[
std::cout << val("while expression: ") << _2 << "\n"
]
;
expression
= tok.identifier [ _val = _1 ]
| tok.constant [ _val = _1 ]
;
}
typedef boost::variant<unsigned int, std::string> expression_type;
qi::rule<Iterator, qi::in_state_skipper<Lexer> > program, block, statement;
qi::rule<Iterator, qi::in_state_skipper<Lexer> > assignment, if_stmt;
qi::rule<Iterator, qi::in_state_skipper<Lexer> > while_stmt;
qi::rule<Iterator, expression_type(), qi::in_state_skipper<Lexer> > expression;
};
///////////////////////////////////////////////////////////////////////////////
int main()
{
typedef std::string::iterator base_iterator_type;
typedef lex::lexertl::token<base_iterator_type, boost::mpl::vector<unsigned int, std::string> > token_type;
typedef lex::lexertl::lexer<token_type> lexer_type;
typedef example4_tokens<lexer_type> example4_tokens;
typedef example4_tokens::iterator_type iterator_type;
typedef example4_grammar<iterator_type, example4_tokens::lexer_def> example4_grammar;
example4_tokens tokens; // Our lexer
example4_grammar calc(tokens); // Our parser
std::string str;
std::string::iterator it = str.begin();
iterator_type iter = tokens.begin(it, str.end());
iterator_type end = tokens.end();
bool r = qi::phrase_parse(iter, end, calc, qi::in_state("WS")[tokens.self]);
if (r && iter == end)
{
std::cout << "-------------------------\n";
std::cout << "Parsing succeeded\n";
std::cout << "-------------------------\n";
}
else
{
std::cout << "-------------------------\n";
std::cout << "Parsing failed\n";
std::cout << "-------------------------\n";
}
std::cout << "Bye... :-) \n\n";
return 0;
}
当我尝试编译它时,我收到很多错误,请参阅Coliru上的完整列表。
这个例子有什么问题?什么和为什么需要改变来编译它?如何确定编译过程究竟失败了什么?
答案 0 :(得分:4)
正如 Fsmv 所说,应添加以下define
:
#define BOOST_VARIANT_USE_RELAXED_GET_BY_DEFAULT
之后,可以编译该示例。