使用boost :: spirit制作的计算器有一个奇怪的问题。该计算器应该将一个字符串作为参数，表示用逗号分隔的一系列算术表达式，如“a + 4 * 5,77，（b-c）* 4”。它还允许字符串“？”并返回包含-1的数组。计算器用SymTable初始化，SymTable是一个模板类参数，用于描述提供[string] - ＆gt;的任何类。 int运算符（例如：map），用于解析变量的值。
以下代码适用于我的Ubuntu 10.4，包括gcc 4.6.2和gcc 4.4，并且都提升1.47和1.48。它在过去的Cray Linux机器上也运行了gcc 4.5.3和boost 1.47。
#include <boost/bind.hpp>
#include <boost/spirit/include/qi.hpp>
#include <boost/spirit/include/phoenix_core.hpp>
#include <boost/spirit/include/phoenix_operator.hpp>
namespace sp = boost::spirit;
namespace qi = boost::spirit::qi;
namespace ascii = boost::spirit::ascii;
namespace Damaris {
template <typename Iterator, typename SymTable>
struct Calc : qi::grammar<Iterator, std::vector<int>(), ascii::space_type>
{
qi::rule<Iterator, std::vector<int>(), ascii::space_type> start;
qi::rule<Iterator, int(), ascii::space_type> expr;
qi::rule<Iterator, int(), ascii::space_type> qmark;
qi::rule<Iterator, int(), ascii::space_type> factor;
qi::rule<Iterator, int(), ascii::space_type> simple;
qi::rule<Iterator, std::string(), ascii::space_type> identifier;
qi::rule<Iterator, int(SymTable), ascii::space_type> value;
/**
* \brief Constructor.
* \param[in] sym : table of symboles.
*/
Calc(SymTable &sym) : Calc::base_type(start)
{
identifier = qi::lexeme[( qi::alpha | '_') >> *( qi::alnum | '_')];
value = identifier[qi::_val = qi::labels::_r1[qi::_1]];
simple = ('(' >> expr >> ')')
| qi::int_
| value(boost::phoenix::ref(sym));
factor %= (simple >> '*' >> factor)[qi::_val = qi::_1 * qi::_2]
| (simple >> '/' >> factor)[qi::_val = qi::_1 / qi::_2]
| (simple >> '%' >> factor)[qi::_val = qi::_1 % qi::_2]
| simple;
expr %= (factor >> '+' >> expr)[qi::_val = qi::_1 + qi::_2]
| (factor >> '-' >> expr)[qi::_val = qi::_1 - qi::_2]
| factor;
qmark = qi::char_('?')[qi::_val = -1];
start = qmark
| (expr % ',');
}
};
}
今天我再次尝试在Cray机器上编译相同的代码（从那时起我已经升级了，我认为），我尝试使用gcc 4.6.2和gcc 4.5.2，并使用boost 1.48和1.49，以及我总是得到我不理解的相同编译错误：
/nics/b/home/mdorier/damaris-0.4/common/Calc.hpp:74:3: instantiated from 'Damaris::Calc<Iterator, SymTable>::Calc(SymTable&) [with Iterator = __gnu_cxx::__normal_iterator<const char*, std::basic_string<char> >, SymTable = Damaris::ParameterSet]'
/nics/b/home/mdorier/damaris-0.4/common/MetadataManager.cpp:45:79: instantiated from here
/nics/b/home/mdorier/deploy/include/boost/spirit/home/qi/detail/assign_to.hpp:123:13: error: invalid static_cast from type 'const boost::fusion::vector2<int, int>' to type 'int'
Calc.hpp中的第74行对应于“factor = ...”行。 指示的实例化行（MetadataManager.cpp：45）如下：
layoutInterp = new Calc<std::string::const_iterator,ParameterSet>(*parameters);
layoutInterp的类型为Calc *，参数的类型为ParameterSet *。
知道这个错误来自哪里？感谢
答案 0 :(得分：4)
我很确定你可能会在你的规则中重新安排内容。事实上，%=自动规则表达式分配将无效，因为解析器表达式的合成类型与int不相似。
基本上，你要改变
factor %= (simple >> '*' >> factor)[ _val = _1 * _2 ]
| (simple >> '/' >> factor)[ _val = _1 / _2 ]
| (simple >> '%' >> factor)[ _val = _1 % _2 ]
| simple;
expr %= (factor >> '+' >> expr)[ _val = _1 + _2 ]
| (factor >> '-' >> expr)[ _val = _1 - _2 ]
| factor;
到
factor = (simple >> '*' >> factor)[ _val = _1 * _2 ]
| (simple >> '/' >> factor)[ _val = _1 / _2 ]
| (simple >> '%' >> factor)[ _val = _1 % _2 ]
| (simple) [_val = _1 ];
expr = (factor >> '+' >> expr)[ _val = _1 + _2 ]
| (factor >> '-' >> expr)[ _val = _1 - _2 ]
| (factor) [_val = _1 ];
我已经解决了一些小问题并创建了你的帖子的SSCCE，据我所知， 1 ：
#include <boost/spirit/include/qi.hpp>
#include <boost/spirit/include/karma.hpp>
#include <boost/spirit/include/phoenix.hpp>
namespace sp = boost::spirit;
namespace qi = boost::spirit::qi;
namespace ascii = boost::spirit::ascii;
namespace karma = boost::spirit::karma;
namespace phx = boost::phoenix;
namespace Damaris {
template <typename Iterator, typename SymTable>
struct Calc : qi::grammar<Iterator, std::vector<int>(), ascii::space_type>
{
qi::rule<Iterator, std::vector<int>(), ascii::space_type> start;
qi::rule<Iterator, int(), ascii::space_type> expr;
qi::rule<Iterator, int(), ascii::space_type> qmark;
qi::rule<Iterator, int(), ascii::space_type> factor;
qi::rule<Iterator, int(), ascii::space_type> simple;
qi::rule<Iterator, std::string(), ascii::space_type> identifier;
qi::rule<Iterator, int(SymTable), ascii::space_type> value;
Calc(SymTable &sym) : Calc::base_type(start)
{
using namespace qi;
identifier = lexeme[( alpha | '_') >> *( alnum | '_')];
value = identifier[ _val = _r1[_1] ];
simple = ('(' >> expr >> ')')
| int_
| value(boost::phoenix::ref(sym));
factor = (simple >> '*' >> factor)[ _val = _1 * _2 ]
| (simple >> '/' >> factor)[ _val = _1 / _2 ]
| (simple >> '%' >> factor)[ _val = _1 % _2 ]
| (simple) [_val = _1 ];
expr = (factor >> '+' >> expr)[ _val = _1 + _2 ]
| (factor >> '-' >> expr)[ _val = _1 - _2 ]
| (factor) [_val = _1 ];
qmark = char_('?')[ _val = -1 ];
start = qmark
| (expr % ',');
BOOST_SPIRIT_DEBUG_NODE(start);
BOOST_SPIRIT_DEBUG_NODE(qmark);
BOOST_SPIRIT_DEBUG_NODE(expr);
BOOST_SPIRIT_DEBUG_NODE(factor);
BOOST_SPIRIT_DEBUG_NODE(simple);
BOOST_SPIRIT_DEBUG_NODE(value);
BOOST_SPIRIT_DEBUG_NODE(identifier);
}
};
}
int main(int argc, const char *argv[])
{
typedef std::map<std::string, int> SymTable;
SymTable symbols;
Damaris::Calc<std::string::const_iterator, SymTable> calc(symbols);
symbols["TheAnswerToLifeUniverse"] = 100;
symbols["Everything"] = -58;
std::string input = "3*4+5/4, TheAnswerToLifeUniverse + Everything";
std::string::const_iterator f(input.begin()), l(input.end());
std::vector<int> data;
if (qi::phrase_parse(f,l,calc,ascii::space,data))
std::cout << "output: " << karma::format(karma::int_ % ", " << karma::eol, data);
else
std::cout << "problem: '" << std::string(f,l) << "'\n";
return 0;
}
输出：
output: 13, 42
1 gcc 4.6.1，boost 1_48