![](/img/trans.png)
[英]Can I use BOOST_FUSION_ADAPT_STRUCT with struct consisting of std::vector?
[英]BOOST_FUSION_ADAPT_STRUCT using a recursive struct with a std::vector<self_type> member
我正在尝试为 spirit x3 解析器声明递归 AST。 解析器语法正在运行,并且由于建议避免语义操作,我正在尝试改编Rexpr 官方文档示例。
在主文档中,解析的结构可以用 map 表示,其中键是字符串,值是字符串或另一个 map。
在我的例子中,被解析的结构是一个简单的 n-ary 树,我希望我能用递归结构和forward_ast
解决问题:
#include <boost/spirit/home/x3.hpp>
#include <boost/spirit/home/x3/support/ast/variant.hpp>
#include <boost/fusion/adapted/struct/adapt_struct.hpp>
#include <boost/fusion/include/adapt_struct.hpp>
namespace ast
{
struct node
{
std::string name;
double length;
std::vector<boost::spirit::x3::forward_ast<node>> children;
};
}
BOOST_FUSION_ADAPT_STRUCT(ast::node, name, length, children)
但是我没有成功编译 - boost fusion 告诉我
error: explicit specialization of undeclared template struct 'tag_of'
BOOST_FUSION_ADAPT_STRUCT(ast::node, name, length, children)
所以我想我也不明白:
我不确定我是否解决了这个问题,但这也许有帮助:
#include <boost/spirit/home/x3.hpp>
#include <boost/spirit/home/x3/support/ast/variant.hpp>
#include <boost/fusion/include/adapt_struct.hpp>
#include <boost/fusion/include/io.hpp>
#include <iostream>
namespace ast {
using boost::spirit::x3::forward_ast;
struct node {
std::string name;
double length;
std::vector<forward_ast<node>> children;
};
} // namespace ast
BOOST_FUSION_ADAPT_STRUCT(ast::node, name, length, children)
namespace ast {
using boost::fusion::operator<<;
static inline std::ostream& operator<<(std::ostream& os, std::vector<forward_ast<node>> const& nn) {
os << "[";
auto sep = "";
for (auto& n : nn)
os << std::exchange(sep, ", ") << n.get();
return os << "]";
}
} // namespace ast
int main() {
ast::node n{
"demo",
42,
{
ast::node{"nested1", 43, {}},
ast::node{"nested4",
47,
{
ast::node{"nested2", 45, {}},
ast::node{"nested3", 46, {}},
}},
ast::node{"nested5", 48, {}},
},
};
std::cout << "No problem: " << n << "\n";
}
印刷
No problem: (demo 42 [(nested1 43 []), (nested4 47 [(nested2 45 []), (nested3 46 [])]), (nested5 48 [])])
声明:本站的技术帖子网页,遵循CC BY-SA 4.0协议,如果您需要转载,请注明本站网址或者原文地址。任何问题请咨询:yoyou2525@163.com.