我想实现输入字符串的颜色突出显示,该输入字符串被馈送到给定的精神语法。是否有一种简单(或任何一种,如果不是很简单的方法)将给定字符从输入映射到匹配的规则/ ast类型?最好以规则/ ast类型的数组/ vector 的形式表示,其中index是输入字符串的字符的索引。也许更好-迭代器对ast类型大肆宣传。
最佳答案
当然有这个站点上的几个答案说明了类似的事情。您必须决定如何对待子规则。
使用 on_success
的随机示例:
Live On Coliru
//#define BOOST_SPIRIT_DEBUG
#include <boost/spirit/include/qi.hpp>
#include <iomanip>
namespace qi = boost::spirit::qi;
using It = std::string::const_iterator;
using R = boost::iterator_range<It>;
using RuleId = void const*;
struct token {
R what;
RuleId r_id;
};
struct assocociate_f {
std::vector<token>& into;
RuleId r_id = nullptr;
template <typename Ctx>
void operator()(qi::unused_type, Ctx& ctx) const {
using boost::fusion::at_c;
into.push_back({at_c<0>(ctx.attributes), r_id});
}
};
int main() {
qi::rule<It, R()> numlit, ident, oper;
qi::rule<It, R(), qi::space_type> simple, expr;
numlit = qi::raw[qi::double_];
ident = qi::raw[qi::lexeme[qi::alpha >> *qi::alnum]];
simple = qi::raw[(numlit | ident | '(' >> expr >> ')')];
oper = qi::raw[qi::char_("-+*/%")];
expr = qi::raw[simple >> *(oper >> expr)];
std::vector<token> collect;
qi::on_success(numlit, assocociate_f{collect, &numlit});
qi::on_success(ident, assocociate_f{collect, &ident});
qi::on_success(oper, assocociate_f{collect, &oper});
//qi::on_success(simple, assocociate_f{collect, &simple});
//qi::on_success(expr, assocociate_f{collect, &expr});
BOOST_SPIRIT_DEBUG_NODES((numlit)(ident)(simple)(expr));
auto idof = [&](token const& tok) -> std::string {
auto match = [&](auto const& x) { return tok.r_id == static_cast<void const*>(&x); };
if (match(numlit)) return "numeric literal";
if (match(ident)) return "identifier";
if (match(simple)) return "simple expression";
if (match(expr)) return "expression";
if (match(oper)) return "operator";
return "other";
};
for (std::string const input : { "3 * pi + (13/47 - 5)" }) {
std::cout << std::setw(20) << "input: " << input << "\n";
It f = input.begin(), l = input.end();
if (qi::phrase_parse(f, l, expr, qi::space)) {
for (auto& tok : collect) {
std::cout
<< std::setw(20) << idof(tok) + ": "
<< std::setw(tok.what.begin() - input.begin() + 1) << tok.what
<< "\n";
}
} else {
std::cout << "Parse failed\n";
}
if (f!=l) {
std::cout << "Remaining: '" << std::string(f,l) << "'\n";
}
}
}
版画
input: 3 * pi + (13/47 - 5)
numeric literal: 3
operator: *
identifier: pi
operator: +
numeric literal: 13
operator: /
numeric literal: 47
operator: -
numeric literal: 5
取消多余的评论
//qi::on_success(simple, assocociate_f{collect, &simple});
//qi::on_success(expr, assocociate_f{collect, &expr});
您将获得: Live On Coliru
input: 3 * pi + (13/47 - 5)
numeric literal: 3
simple expression: 3
operator: *
identifier: pi
simple expression: pi
operator: +
numeric literal: 13
simple expression: 13
operator: /
numeric literal: 47
simple expression: 47
operator: -
numeric literal: 5
simple expression: 5
expression: 5
expression: 47 - 5
expression: 13/47 - 5
simple expression: (13/47 - 5)
expression: (13/47 - 5)
expression: pi + (13/47 - 5)
expression: 3 * pi + (13/47 - 5)
更多
一个更时髦的示例是How to provider user with autocomplete suggestions for given boost::spirit grammar?-使用
string_view
或string_ref
代替iterator_range
。而且,该“折叠”相邻范围会导致更多可用范围。其他相关示例: