2

我试图简单地在这个答案中找到精神解析器：

删除xor运算符和逻辑。我看不到该怎么做，我尝试使用

expr_  = or_.alias();

or_  = (and__ >> "or"  >> or_ )[ _val = phx::construct<binop<op_or >>(_1, _2) ]     | and_   [ _val = _1 ];
and_ = (not_ >> "and" >> and_) [ _val = phx::construct<binop<op_and>>(_1, _2) ] | not_   [ _val = _1 ];
not_ = ("not" > simple       ) [ _val = phx::construct<unop <op_not>>(_1)     ] | simple [ _val = _1 ];

对于规则定义，但我收到一条我不明白的神秘编译器消息：

test\test.cpp `boost::spirit::_2' cannot appear in a constant-expression

如果有人能提供一些启示，我将不胜感激。

这是日志：

compiler: Default compiler  Building Makefile:
   "D:\Dev-Cpp\test\Makefile.win" Executing  make... make.exe -f
   "D:\Dev-Cpp\test\Makefile.win" all g++.exe -c test.cpp -o test.o
   -I"D:/Dev-Cpp/lib/gcc/mingw32/3.4.2/include"  -I"D:/Dev-Cpp/include/c++/3.4.2/backward"  -I"D:/Dev-Cpp/include/c++/3.4.2/mingw32"  -I"D:/Dev-Cpp/include/c++/3.4.2"  -I"D:/Dev-Cpp/include"   

   test.cpp: In constructor `parser<It, Skipper>::parser()':
   test.cpp:76: error: `boost::spirit::_1' cannot appear in a
   constant-expression test.cpp:76: error: a comma operator cannot
   appear in a constant-expression test.cpp:76: error:
   `boost::spirit::_2' cannot appear in a constant-expression
   test.cpp:76: error: `>>' should be `> >' within a nested template
   argument list

   test.cpp:77: error: `boost::spirit::_1' cannot appear in a
   constant-expression

   test.cpp:77: error: a comma operator cannot appear in a
   constant-expression test.cpp:77: error: `boost::spirit::_2' cannot
   appear in a constant-expression test.cpp:77: error: `>>' should be `>
   >' within a nested template argument list

   test.cpp:78: error: `boost::spirit::_1' cannot appear in a
   constant-expression

   test.cpp:78: error: `>>' should be `> >' within a nested template
   argument list

   test.cpp: In function `int main()': test.cpp:98: error: expected
   primary-expression before "auto" test.cpp:98: error: expected `;'
   before "auto"

   test.cpp:111: error: expected primary-expression before ')' token
   test.cpp:111: error: expected `;' before ')' token test.cpp:113:
   error: ISO C++ forbids declaration of `f' with no type test.cpp:113:
   error: `begin' is not a member of `std' test.cpp:113: error: `input'
   undeclared (first use this function) test.cpp:113: error: (Each
   undeclared identifier is reported only once for each function it
   appears in.) test.cpp:113: error: ISO C++ forbids declaration of `l'
   with no type test.cpp:113: error: `end' is not a member of `std'
   test.cpp:114: error: `f' cannot appear in a constant-expression
   test.cpp:114: error: a function call cannot appear in a
   constant-expression test.cpp:114: error: template argument 1 is
   invalid test.cpp:114: error: invalid type in declaration before ';'
   token

   test.cpp:126: error: `f' cannot appear in a constant-expression
   test.cpp:126: error: a function call cannot appear in a
   constant-expression test.cpp:126: error: template argument 1 is
   invalid test.cpp:126: error: ISO C++ forbids declaration of `e' with
   no type

   test.cpp:128: error: expected primary-expression before '(' token
   test.cpp:128: error: `first' has not been declared test.cpp:128:
   error: request for member of non-aggregate type before ',' token
   test.cpp:128: error: `last' has not been declared test.cpp:128:
   error: request for member of non-aggregate type before ')' token

   D:/Dev-Cpp/include/c++/3.4.2/bits/stl_iterator_base_types.h: At
   global scope:
   D:/Dev-Cpp/include/c++/3.4.2/bits/stl_iterator_base_types.h: In
   instantiation of `std::iterator_traits<int>':
   D:/Dev-Cpp/include/boost/detail/iterator.hpp:83:   instantiated from
   `boost::detail::iterator_traits<int>'
   D:/Dev-Cpp/include/boost/concept_check.hpp:509:   instantiated from
   `boost::InputIterator<int>'
   D:/Dev-Cpp/include/boost/concept_check.hpp:545:   instantiated from
   `boost::ForwardIterator<int>'
   D:/Dev-Cpp/include/boost/concept/detail/has_constraints.hpp:42:  
   instantiated from
   `boost::concepts::not_satisfied<boost::ForwardIterator<int> >'
   D:/Dev-Cpp/include/boost/mpl/if.hpp:67:   instantiated from
   `boost::mpl::if_<boost::concepts::not_satisfied<boost::ForwardIterator<int>
   >, boost::concepts::constraint<boost::ForwardIterator<int> >, boost::concepts::requirement<boost::concepts::failed************boost::ForwardIterator<int>::************>
   >' D:/Dev-Cpp/include/boost/concept/detail/general.hpp:56:   instantiated from `boost::concepts::requirement_<void
   (*)(boost::ForwardIterator<int>)>'
   D:/Dev-Cpp/include/boost/spirit/home/qi/parse.hpp:149:   instantiated
   from `bool boost::spirit::qi::phrase_parse(Iterator&, Iterator, const
   Expr&, const Skipper&, boost::spirit::qi::skip_flag::enum_type,
   Attr&) [with Iterator = int, Expr = bool, Skipper =
   boost::proto::exprns_::expr<boost::proto::tagns_::tag::terminal,
   boost::proto::argsns_::term<boost::spirit::tag::char_code<boost::spirit::tag::space,
   boost::spirit::char_encoding::standard> >, 0l>, Attr =
   boost::variant<var, boost::recursive_wrapper<unop<op_not> >,
   boost::recursive_wrapper<binop<op_and> >,
   boost::recursive_wrapper<binop<op_or> >,
   boost::detail::variant::void_, boost::detail::variant::void_,
   boost::detail::variant::void_, boost::detail::variant::void_,
   boost::detail::variant::void_, boost::detail::variant::void_,
   boost::detail::variant::void_, boost::detail::variant::void_,
   boost::detail::variant::void_, boost::detail::variant::void_,
   boost::detail::variant::void_, boost::detail::variant::void_,
   boost::detail::variant::void_, boost::detail::variant::void_,
   boost::detail::variant::void_, boost::detail::variant::void_>]'
   D:/Dev-Cpp/include/boost/spirit/home/qi/parse.hpp:197:   instantiated
   from `bool boost::spirit::qi::phrase_parse(Iterator&, Iterator, const
   Expr&, const Skipper&, Attr&) [with Iterator = int, Expr = bool,
   Skipper = boost::spirit::standard::space_type, Attr = expr]'
   test.cpp:119:   instantiated from here
   D:/Dev-Cpp/include/c++/3.4.2/bits/stl_iterator_base_types.h:129:
   error: `int' is not a class, struct, or union type
   D:/Dev-Cpp/include/c++/3.4.2/bits/stl_iterator_base_types.h:130:
   error: `int' is not a class, struct, or union type
   D:/Dev-Cpp/include/c++/3.4.2/bits/stl_iterator_base_types.h:131:
   error: `int' is not a class, struct, or union type
   D:/Dev-Cpp/include/c++/3.4.2/bits/stl_iterator_base_types.h:132:
   error: `int' is not a class, struct, or union type
   D:/Dev-Cpp/include/c++/3.4.2/bits/stl_iterator_base_types.h:133:
   error: `int' is not a class, struct, or union type
   D:/Dev-Cpp/include/boost/concept_check.hpp: In instantiation of
   `boost::InputIterator<int>':
   D:/Dev-Cpp/include/boost/concept_check.hpp:545:   instantiated from
   `boost::ForwardIterator<int>'
   D:/Dev-Cpp/include/boost/concept/detail/has_constraints.hpp:42:  
   instantiated from
   `boost::concepts::not_satisfied<boost::ForwardIterator<int> >'
   D:/Dev-Cpp/include/boost/mpl/if.hpp:67:   instantiated from
   `boost::mpl::if_<boost::concepts::not_satisfied<boost::ForwardIterator<int>
   >, boost::concepts::constraint<boost::ForwardIterator<int> >, boost::concepts::requirement<boost::concepts::failed************boost::ForwardIterator<int>::************>
   >' D:/Dev-Cpp/include/boost/concept/detail/general.hpp:56:   instantiated from `boost::concepts::requirement_<void
   (*)(boost::ForwardIterator<int>)>'
   D:/Dev-Cpp/include/boost/spirit/home/qi/parse.hpp:149:   instantiated
   from `bool boost::spirit::qi::phrase_parse(Iterator&, Iterator, const
   Expr&, const Skipper&, boost::spirit::qi::skip_flag::enum_type,
   Attr&) [with Iterator = int, Expr = bool, Skipper =
   boost::proto::exprns_::expr<boost::proto::tagns_::tag::terminal,
   boost::proto::argsns_::term<boost::spirit::tag::char_code<boost::spirit::tag::space,
   boost::spirit::char_encoding::standard> >, 0l>, Attr =
   boost::variant<var, boost::recursive_wrapper<unop<op_not> >,
   boost::recursive_wrapper<binop<op_and> >,
   boost::recursive_wrapper<binop<op_or> >,
   boost::detail::variant::void_, boost::detail::variant::void_,
   boost::detail::variant::void_, boost::detail::variant::void_,
   boost::detail::variant::void_, boost::detail::variant::void_,
   boost::detail::variant::void_, boost::detail::variant::void_,
   boost::detail::variant::void_, boost::detail::variant::void_,
   boost::detail::variant::void_, boost::detail::variant::void_,
   boost::detail::variant::void_, boost::detail::variant::void_,
   boost::detail::variant::void_, boost::detail::variant::void_>]'
   D:/Dev-Cpp/include/boost/spirit/home/qi/parse.hpp:197:   instantiated
   from `bool boost::spirit::qi::phrase_parse(Iterator&, Iterator, const
   Expr&, const Skipper&, Attr&) [with Iterator = int, Expr = bool,
   Skipper = boost::spirit::standard::space_type, Attr = expr]'

   test.cpp:119:   instantiated from here
   D:/Dev-Cpp/include/boost/concept_check.hpp:509: error: no type named
   `value_type' in `struct boost::detail::iterator_traits<int>'
   D:/Dev-Cpp/include/boost/concept_check.hpp:510: error: no type named
   `difference_type' in `struct boost::detail::iterator_traits<int>'
   D:/Dev-Cpp/include/boost/concept_check.hpp:511: error: no type named
   `reference' in `struct boost::detail::iterator_traits<int>'
   D:/Dev-Cpp/include/boost/concept_check.hpp:512: error: no type named
   `pointer' in `struct boost::detail::iterator_traits<int>'
   D:/Dev-Cpp/include/boost/concept_check.hpp:513: error: no type named
   `iterator_category' in `struct boost::detail::iterator_traits<int>'

   D:/Dev-Cpp/include/boost/spirit/home/qi/parse.hpp: In function `bool
   boost::spirit::qi::phrase_parse(Iterator&, Iterator, const Expr&,
   const Skipper&, boost::spirit::qi::skip_flag::enum_type, Attr&) [with
   Iterator = int, Expr = bool, Skipper =
   boost::proto::exprns_::expr<boost::proto::tagns_::tag::terminal,
   boost::proto::argsns_::term<boost::spirit::tag::char_code<boost::spirit::tag::space,
   boost::spirit::char_encoding::standard> >, 0l>, Attr =
   boost::variant<var, boost::recursive_wrapper<unop<op_not> >,
   boost::recursive_wrapper<binop<op_and> >,
   boost::recursive_wrapper<binop<op_or> >,
   boost::detail::variant::void_, boost::detail::variant::void_,
   boost::detail::variant::void_, boost::detail::variant::void_,
   boost::detail::variant::void_, boost::detail::variant::void_,
   boost::detail::variant::void_, boost::detail::variant::void_,
   boost::detail::variant::void_, boost::detail::variant::void_,
   boost::detail::variant::void_, boost::detail::variant::void_,
   boost::detail::variant::void_, boost::detail::variant::void_,
   boost::detail::variant::void_, boost::detail::variant::void_>]':
   D:/Dev-Cpp/include/boost/spirit/home/qi/parse.hpp:197:   instantiated
   from `bool boost::spirit::qi::phrase_parse(Iterator&, Iterator, const
   Expr&, const Skipper&, Attr&) [with Iterator = int, Expr = bool,
   Skipper = boost::spirit::standard::space_type, Attr = expr]'

   test.cpp:119:   instantiated from here
   D:/Dev-Cpp/include/boost/spirit/home/qi/parse.hpp:155: error:
   conversion from
   `mpl_::failed************(boost::spirit::qi::phrase_parse(Iterator&,
   Iterator, const Expr&, const Skipper&,
   boost::spirit::qi::skip_flag::enum_type, Attr&) [with Iterator = int,
   Expr = bool, Skipper =
   boost::proto::exprns_::expr<boost::proto::tagns_::tag::terminal,
   boost::proto::argsns_::term<boost::spirit::tag::char_code<boost::spirit::tag::space,
   boost::spirit::char_encoding::standard> >, 0l>, Attr =
   boost::variant<var, boost::recursive_wrapper<unop<op_not> >,
   boost::recursive_wrapper<binop<op_and> >,
   boost::recursive_wrapper<binop<op_or> >,
   boost::detail::variant::void_, boost::detail::variant::void_,
   boost::detail::variant::void_, boost::detail::variant::void_,
   boost::detail::variant::void_, boost::detail::variant::void_,
   boost::detail::variant::void_, boost::detail::variant::void_,
   boost::detail::variant::void_, boost::detail::variant::void_,
   boost::detail::variant::void_, boost::detail::variant::void_,
   boost::detail::variant::void_, boost::detail::variant::void_,
   boost::detail::variant::void_,
   boost::detail::variant::void_>]::error_invalid_expression::************)(bool)'
   to non-scalar type `mpl_::assert< false>' requested
   D:/Dev-Cpp/include/boost/spirit/home/qi/parse.hpp:155: error:
   enumerator value for `mpl_assertion_in_line_155' not integer constant

   D:/Dev-Cpp/include/boost/spirit/home/qi/parse.hpp:197:   instantiated
   from `bool boost::spirit::qi::phrase_parse(Iterator&, Iterator, const
   Expr&, const Skipper&, Attr&) [with Iterator = int, Expr = bool,
   Skipper = boost::spirit::standard::space_type, Attr = expr]'
   test.cpp:119:   instantiated from here
   D:/Dev-Cpp/include/boost/spirit/home/qi/parse.hpp:164: error: request
   for member `parse' in `boost::spirit::compile [with Domain =
   boost::spirit::qi::domain, Expr = bool](((const bool&)(+expr)))',
   which is of non-class type `bool'

   D:/Dev-Cpp/include/boost/concept_check.hpp: In destructor
   `boost::ForwardIterator<TT>::~ForwardIterator() [with TT = int]':
   D:/Dev-Cpp/include/boost/concept/detail/general.hpp:38:  
   instantiated from `static void
   boost::concepts::requirement<boost::concepts::failed************Model::************>::failed()
   [with Model = boost::ForwardIterator<int>]'
   D:/Dev-Cpp/include/boost/spirit/home/qi/parse.hpp:149:   instantiated
   from `bool boost::spirit::qi::phrase_parse(Iterator&, Iterator, const
   Expr&, const Skipper&, boost::spirit::qi::skip_flag::enum_type,
   Attr&) [with Iterator = int, Expr = bool, Skipper =
   boost::proto::exprns_::expr<boost::proto::tagns_::tag::terminal,
   boost::proto::argsns_::term<boost::spirit::tag::char_code<boost::spirit::tag::space,
   boost::spirit::char_encoding::standard> >, 0l>, Attr =
   boost::variant<var, boost::recursive_wrapper<unop<op_not> >,
   boost::recursive_wrapper<binop<op_and> >,
   boost::recursive_wrapper<binop<op_or> >,
   boost::detail::variant::void_, boost::detail::variant::void_,
   boost::detail::variant::void_, boost::detail::variant::void_,
   boost::detail::variant::void_, boost::detail::variant::void_,
   boost::detail::variant::void_, boost::detail::variant::void_,
   boost::detail::variant::void_, boost::detail::variant::void_,
   boost::detail::variant::void_, boost::detail::variant::void_,
   boost::detail::variant::void_, boost::detail::variant::void_,
   boost::detail::variant::void_, boost::detail::variant::void_>]'
   D:/Dev-Cpp/include/boost/spirit/home/qi/parse.hpp:197:   instantiated
   from `bool boost::spirit::qi::phrase_parse(Iterator&, Iterator, const
   Expr&, const Skipper&, Attr&) [with Iterator = int, Expr = bool,
   Skipper = boost::spirit::standard::space_type, Attr = expr]'
   test.cpp:119:   instantiated from here
   D:/Dev-Cpp/include/boost/concept_check.hpp:548: error: no type named
   `iterator_category' in `struct boost::ForwardIterator<int>'
   D:/Dev-Cpp/include/boost/concept_check.hpp:548: error: `failed' is
   not a member of `<declaration error>'
   D:/Dev-Cpp/include/boost/concept_check.hpp:553: error: no type named
   `reference' in `struct boost::InputIterator<int>'
   D:/Dev-Cpp/include/boost/concept_check.hpp:554: error: no type named
   `reference' in `struct boost::InputIterator<int>'

   D:/Dev-Cpp/include/boost/spirit/home/qi/char/char_parser.hpp: In
   member function `bool boost::spirit::qi::char_parser<Derived, Char,
   Attr>::parse(Iterator&, const Iterator&, Context&, const Skipper&,
   Attribute&) const [with Iterator = int, Context = const
   boost::spirit::unused_type, Skipper = boost::spirit::unused_type,
   Attribute = const boost::spirit::unused_type, Derived =
   boost::spirit::qi::char_class<boost::spirit::tag::char_code<boost::spirit::tag::space,
   boost::spirit::char_encoding::standard> >, Char = char, Attr =
   char]': D:/Dev-Cpp/include/boost/spirit/home/qi/skip_over.hpp:27:  
   instantiated from `void boost::spirit::qi::skip_over(Iterator&, const
   Iterator&, const T&) [with Iterator = int, T =
   boost::spirit::qi::char_class<boost::spirit::tag::char_code<boost::spirit::tag::space,
   boost::spirit::char_encoding::standard> >]'
   D:/Dev-Cpp/include/boost/spirit/home/qi/parse.hpp:169:   instantiated
   from `bool boost::spirit::qi::phrase_parse(Iterator&, Iterator, const
   Expr&, const Skipper&, boost::spirit::qi::skip_flag::enum_type,
   Attr&) [with Iterator = int, Expr = bool, Skipper =
   boost::proto::exprns_::expr<boost::proto::tagns_::tag::terminal,
   boost::proto::argsns_::term<boost::spirit::tag::char_code<boost::spirit::tag::space,
   boost::spirit::char_encoding::standard> >, 0l>, Attr =
   boost::variant<var, boost::recursive_wrapper<unop<op_not> >,
   boost::recursive_wrapper<binop<op_and> >,
   boost::recursive_wrapper<binop<op_or> >,
   boost::detail::variant::void_, boost::detail::variant::void_,
   boost::detail::variant::void_, boost::detail::variant::void_,
   boost::detail::variant::void_, boost::detail::variant::void_,
   boost::detail::variant::void_, boost::detail::variant::void_,
   boost::detail::variant::void_, boost::detail::variant::void_,
   boost::detail::variant::void_, boost::detail::variant::void_,
   boost::detail::variant::void_, boost::detail::variant::void_,
   boost::detail::variant::void_, boost::detail::variant::void_>]'
   D:/Dev-Cpp/include/boost/spirit/home/qi/parse.hpp:197:   instantiated
   from `bool boost::spirit::qi::phrase_parse(Iterator&, Iterator, const
   Expr&, const Skipper&, Attr&) [with Iterator = int, Expr = bool,
   Skipper = boost::spirit::standard::space_type, Attr = expr]'
   test.cpp:119:   instantiated from here
   D:/Dev-Cpp/include/boost/spirit/home/qi/char/char_parser.hpp:68:
   error: invalid type argument of `unary *'
   D:/Dev-Cpp/include/boost/spirit/home/qi/char/char_parser.hpp:70:
   error: invalid type argument of `unary *'

   D:/Dev-Cpp/include/boost/concept_check.hpp: In destructor
   `boost::InputIterator<TT>::~InputIterator() [with TT = int]':
   D:/Dev-Cpp/include/boost/concept_check.hpp:547:   instantiated from
   `boost::ForwardIterator<TT>::~ForwardIterator() [with TT = int]'
   D:/Dev-Cpp/include/boost/concept/detail/general.hpp:38:  
   instantiated from `static void
   boost::concepts::requirement<boost::concepts::failed************Model::************>::failed()
   [with Model = boost::ForwardIterator<int>]'
   D:/Dev-Cpp/include/boost/spirit/home/qi/parse.hpp:149:   instantiated
   from `bool boost::spirit::qi::phrase_parse(Iterator&, Iterator, const
   Expr&, const Skipper&, boost::spirit::qi::skip_flag::enum_type,
   Attr&) [with Iterator = int, Expr = bool, Skipper =
   boost::proto::exprns_::expr<boost::proto::tagns_::tag::terminal,
   boost::proto::argsns_::term<boost::spirit::tag::char_code<boost::spirit::tag::space,
   boost::spirit::char_encoding::standard> >, 0l>, Attr =
   boost::variant<var, boost::recursive_wrapper<unop<op_not> >,
   boost::recursive_wrapper<binop<op_and> >,
   boost::recursive_wrapper<binop<op_or> >,
   boost::detail::variant::void_, boost::detail::variant::void_,
   boost::detail::variant::void_, boost::detail::variant::void_,
   boost::detail::variant::void_, boost::detail::variant::void_,
   boost::detail::variant::void_, boost::detail::variant::void_,
   boost::detail::variant::void_, boost::detail::variant::void_,
   boost::detail::variant::void_, boost::detail::variant::void_,
   boost::detail::variant::void_, boost::detail::variant::void_,
   boost::detail::variant::void_, boost::detail::variant::void_>]'
   D:/Dev-Cpp/include/boost/spirit/home/qi/parse.hpp:197:   instantiated
   from `bool boost::spirit::qi::phrase_parse(Iterator&, Iterator, const
   Expr&, const Skipper&, Attr&) [with Iterator = int, Expr = bool,
   Skipper = boost::spirit::standard::space_type, Attr = expr]'
   test.cpp:119:   instantiated from here
   D:/Dev-Cpp/include/boost/concept_check.hpp:517: error: no type named
   `difference_type' in `struct boost::detail::iterator_traits<int>'
   D:/Dev-Cpp/include/boost/concept_check.hpp:517: error: `failed' is
   not a member of `<declaration error>'
   D:/Dev-Cpp/include/boost/concept_check.hpp:518: error: no type named
   `iterator_category' in `struct boost::detail::iterator_traits<int>'
   D:/Dev-Cpp/include/boost/concept_check.hpp:518: error: `failed' is
   not a member of `<declaration error>'
   D:/Dev-Cpp/include/boost/concept_check.hpp:521: error: invalid type
   argument of `unary *'

   make.exe: *** [test.o] Error 1

   Execution terminated
4

1 回答 1

5

你不小心打错and_了and__。

更改and__为and_将使其编译。

这是一个更干净的版本，删除了现在不需要的与 相关的声明xor：

编辑对于不了解 auto、decltype、正确模板解析（>>vs. > >）等的旧编译器也“向后移植”）：

#include <boost/spirit/include/qi.hpp>
#include <boost/spirit/include/phoenix.hpp>
#include <boost/spirit/include/phoenix_operator.hpp>
#include <boost/variant/recursive_wrapper.hpp>

namespace qi    = boost::spirit::qi;
namespace phx   = boost::phoenix;

struct op_or  {};
struct op_and {};
struct op_not {};

typedef std::string var; 
template <typename tag> struct binop;
template <typename tag> struct unop;

typedef boost::variant<var, 
        boost::recursive_wrapper<unop <op_not> >, 
        boost::recursive_wrapper<binop<op_and> >,
        boost::recursive_wrapper<binop<op_or> >
        > expr;

template <typename tag> struct binop
{
    explicit binop(const expr& l, const expr& r) : oper1(l), oper2(r) { }
    expr oper1, oper2;
};

template <typename tag> struct unop
{
    explicit unop(const expr& o) : oper1(o) { }
    expr oper1;
};

struct printer : boost::static_visitor<void> 
{
    printer(std::ostream& os) : _os(os) {}
    std::ostream& _os;

    //
    void operator()(const var& v) const { _os << v; }

    void operator()(const binop<op_and>& b) const { print(" & ", b.oper1, b.oper2); }
    void operator()(const binop<op_or >& b) const { print(" | ", b.oper1, b.oper2); }

    void print(const std::string& op, const expr& l, const expr& r) const
    {
        _os << "(";
        boost::apply_visitor(*this, l);
        _os << op;
        boost::apply_visitor(*this, r);
        _os << ")";
    }

    void operator()(const unop<op_not>& u) const
    {
        _os << "(";
        _os << "!";
        boost::apply_visitor(*this, u.oper1);
        _os << ")";
    } 
};

std::ostream& operator<<(std::ostream& os, const expr& e) 
{ boost::apply_visitor(printer(os), e); return os; }

    template <typename It, typename Skipper = qi::space_type>
    struct parser : qi::grammar<It, expr(), Skipper>
{
        parser() : parser::base_type(expr_)
        {
            using namespace qi;

            expr_  = or_.alias();

            or_  = (and_ >> "or"  >> or_ ) [ _val = phx::construct<binop<op_or > >(_1, _2) ] | and_   [ _val = _1 ];
            and_ = (not_ >> "and" >> and_) [ _val = phx::construct<binop<op_and> >(_1, _2) ] | not_   [ _val = _1 ];
            not_ = ("not" > simple       ) [ _val = phx::construct<unop <op_not> >(_1)     ] | simple [ _val = _1 ];

            simple = (('(' > expr_ > ')') | var_);
            var_ = qi::lexeme[ +alpha ];

            BOOST_SPIRIT_DEBUG_NODE(expr_);
            BOOST_SPIRIT_DEBUG_NODE(or_);
            BOOST_SPIRIT_DEBUG_NODE(and_);
            BOOST_SPIRIT_DEBUG_NODE(not_);
            BOOST_SPIRIT_DEBUG_NODE(simple);
            BOOST_SPIRIT_DEBUG_NODE(var_);
        }

        private:
        qi::rule<It, var() , Skipper> var_;
        qi::rule<It, expr(), Skipper> not_, and_, or_, simple, expr_; 
};

int main() 
{
    const std::string inputs[] = { 
        // From the OP:
        std::string("(a and b) or ((c and d) or (a and b));"),
        std::string("a and b or (c and d or a and b);"),

        /// Simpler tests:
        std::string("a and b;"),
        std::string("a or b;"),
        std::string("a or b;"),
        std::string("not a;"),
        std::string("not a and b;"),
        std::string("not (a and b);"),
        std::string("a or b or c;"),
        std::string("") // marker
    };

    for (const std::string *i = inputs; !i->empty(); ++i)
    {
        typedef std::string::const_iterator It;
        It f(i->begin()), l(i->end());
        parser<It> p;

        try
        {
            expr result;
            bool ok = qi::phrase_parse(f,l,p > ';',qi::space,result);

            if (!ok)
                std::cerr << "invalid input\n";
            else
                std::cout << "result: " << result << "\n";

        } catch (const qi::expectation_failure<It>& e)
        {
            std::cerr << "expectation_failure at '" << std::string(e.first, e.last) << "'\n";
        }

        if (f!=l) std::cerr << "unparsed: '" << std::string(f,l) << "'\n";
    }

    return 0; 
}

运行此示例的输出是

result: ((a & b) | ((c & d) | (a & b)))
result: ((a & b) | ((c & d) | (a & b)))
result: (a & b)
result: (a | b)
result: (a | b)
result: (!a)
result: ((!a) & b)
result: (!(a & b))
result: (a | (b | c))
于 2012-09-26T00:01:52.793 回答