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/*=============================================================================
/*=============================================================================
Copyright (c) 2001-2014 Joel de Guzman
Copyright (c) 2001-2014 Joel de Guzman
Distributed under the Boost Software License, Version 1.0. (See accompanying
Distributed under the Boost Software License, Version 1.0. (See accompanying
file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
=============================================================================*/
=============================================================================*/
///////////////////////////////////////////////////////////////////////////////
///////////////////////////////////////////////////////////////////////////////
//
//
// Same as Calc4, this time, we'll incorporate debugging support,
// Same as Calc4, this time, we'll incorporate debugging support,
// plus error handling and reporting.
// plus error handling and reporting.
//
//
// [ JDG April 28, 2008 ] For BoostCon 2008
// [ JDG April 28, 2008 ] For BoostCon 2008
// [ JDG February 18, 2011 ] Pure attributes. No semantic actions.
// [ JDG February 18, 2011 ] Pure attributes. No semantic actions.
// [ JDG April 9, 2014 ] Spirit X3
// [ JDG April 9, 2014 ] Spirit X3
//
//
///////////////////////////////////////////////////////////////////////////////
///////////////////////////////////////////////////////////////////////////////
///////////////////////////////////////////////////////////////////////////////
///////////////////////////////////////////////////////////////////////////////
// Uncomment this if you want to enable debugging
// Uncomment this if you want to enable debugging
//#define BOOST_SPIRIT_X3_DEBUG
//#define BOOST_SPIRIT_X3_DEBUG
#include <boost/config/warning_disable.hpp>
#include <boost/config/warning_disable.hpp>
#include <boost/spirit/home/x3.hpp>
#include <boost/spirit/home/x3.hpp>
#include <boost/spirit/home/x3/support/ast/variant.hpp>
#include <boost/spirit/home/x3/support/ast/variant.hpp>
#include <boost/fusion/include/adapt_struct.hpp>
#include <boost/fusion/include/adapt_struct.hpp>
#include <iostream>
#include <iostream>
#include <string>
#include <string>
#include <list>
#include <list>
#include <numeric>
#include <numeric>
namespace x3 = boost::spirit::x3;
namespace x3 = boost::spirit::x3;
namespace client { namespace ast
namespace client { namespace ast
{
{
///////////////////////////////////////////////////////////////////////////
///////////////////////////////////////////////////////////////////////////
// The AST
// The AST
///////////////////////////////////////////////////////////////////////////
///////////////////////////////////////////////////////////////////////////
struct nil {};
struct nil {};
struct signed_;
struct signed_;
struct program;
struct program;
struct operand : x3::variant<
struct operand : x3::variant<
nil
nil
, unsigned int
, unsigned int
, x3::forward_ast<signed_>
, x3::forward_ast<signed_>
, x3::forward_ast<program>
, x3::forward_ast<program>
>
>
{
{
using base_type::base_type;
using base_type::base_type;
using base_type::operator=;
using base_type::operator=;
};
};
struct signed_
struct signed_
{
{
char sign;
char sign;
operand operand_;
operand operand_;
};
};
struct operation
struct operation
{
{
char operator_;
char operator_;
operand operand_;
operand operand_;
};
};
struct program
struct program
{
{
operand first;
operand first;
std::list<operation> rest;
std::list<operation> rest;
};
};
// print function for debugging
// print function for debugging
inline std::ostream& operator<<(std::ostream& out, nil) { out << "nil"; return out; }
inline std::ostream& operator<<(std::ostream& out, nil) { out << "nil"; return out; }
}}
}}
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BOOST_FUSION_ADAPT_STRUCT(
BOOST_FUSION_ADAPT_STRUCT(
client::ast::signed_,
client::ast::signed_,
sign
, operand_
(char,
sign
)
(client::ast::operand
, operand_
)
)
)
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BOOST_FUSION_ADAPT_STRUCT(
BOOST_FUSION_ADAPT_STRUCT(
client::ast::operation,
client::ast::operation,
operator_
, operand_
(char,
operator_
)
(client::ast::operand
, operand_
)
)
)
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BOOST_FUSION_ADAPT_STRUCT(
BOOST_FUSION_ADAPT_STRUCT(
client::ast::program,
client::ast::program,
first
, rest
(client::ast::operand,
first
)
(std::list<client::ast::operation>
, rest
)
)
)
namespace client { namespace ast
namespace client { namespace ast
{
{
///////////////////////////////////////////////////////////////////////////
///////////////////////////////////////////////////////////////////////////
// The AST Printer
// The AST Printer
///////////////////////////////////////////////////////////////////////////
///////////////////////////////////////////////////////////////////////////
struct printer
struct printer
{
{
typedef void result_type;
typedef void result_type;
void operator()(nil) const {}
void operator()(nil) const {}
void operator()(unsigned int n) const { std::cout << n; }
void operator()(unsigned int n) const { std::cout << n; }
void operator()(operation const& x) const
void operator()(operation const& x) const
{
{
boost::apply_visitor(*this, x.operand_);
boost::apply_visitor(*this, x.operand_);
switch (x.operator_)
switch (x.operator_)
{
{
case '+': std::cout << " add"; break;
case '+': std::cout << " add"; break;
case '-': std::cout << " subt"; break;
case '-': std::cout << " subt"; break;
case '*': std::cout << " mult"; break;
case '*': std::cout << " mult"; break;
case '/': std::cout << " div"; break;
case '/': std::cout << " div"; break;
}
}
}
}
void operator()(signed_ const& x) const
void operator()(signed_ const& x) const
{
{
boost::apply_visitor(*this, x.operand_);
boost::apply_visitor(*this, x.operand_);
switch (x.sign)
switch (x.sign)
{
{
case '-': std::cout << " neg"; break;
case '-': std::cout << " neg"; break;
case '+': std::cout << " pos"; break;
case '+': std::cout << " pos"; break;
}
}
}
}
void operator()(program const& x) const
void operator()(program const& x) const
{
{
boost::apply_visitor(*this, x.first);
boost::apply_visitor(*this, x.first);
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BOOST_FOREACH
(operation const& oper
,
x.rest)
for
(operation const& oper
:
x.rest)
{
{
std::cout << ' ';
std::cout << ' ';
(*this)(oper);
(*this)(oper);
}
}
}
}
};
};
///////////////////////////////////////////////////////////////////////////
///////////////////////////////////////////////////////////////////////////
// The AST evaluator
// The AST evaluator
///////////////////////////////////////////////////////////////////////////
///////////////////////////////////////////////////////////////////////////
struct eval
struct eval
{
{
typedef int result_type;
typedef int result_type;
int operator()(nil) const { BOOST_ASSERT(0); return 0; }
int operator()(nil) const { BOOST_ASSERT(0); return 0; }
int operator()(unsigned int n) const { return n; }
int operator()(unsigned int n) const { return n; }
int operator()(operation const& x, int lhs) const
int operator()(operation const& x, int lhs) const
{
{
int rhs = boost::apply_visitor(*this, x.operand_);
int rhs = boost::apply_visitor(*this, x.operand_);
switch (x.operator_)
switch (x.operator_)
{
{
case '+': return lhs + rhs;
case '+': return lhs + rhs;
case '-': return lhs - rhs;
case '-': return lhs - rhs;
case '*': return lhs * rhs;
case '*': return lhs * rhs;
case '/': return lhs / rhs;
case '/': return lhs / rhs;
}
}
BOOST_ASSERT(0);
BOOST_ASSERT(0);
return 0;
return 0;
}
}
int operator()(signed_ const& x) const
int operator()(signed_ const& x) const
{
{
int rhs = boost::apply_visitor(*this, x.operand_);
int rhs = boost::apply_visitor(*this, x.operand_);
switch (x.sign)
switch (x.sign)
{
{
case '-': return -rhs;
case '-': return -rhs;
case '+': return +rhs;
case '+': return +rhs;
}
}
BOOST_ASSERT(0);
BOOST_ASSERT(0);
return 0;
return 0;
}
}
int operator()(program const& x) const
int operator()(program const& x) const
{
{
int state = boost::apply_visitor(*this, x.first);
int state = boost::apply_visitor(*this, x.first);
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BOOST_FOREACH
(operation const& oper
,
x.rest)
for
(operation const& oper
:
x.rest)
{
{
state = (*this)(oper, state);
state = (*this)(oper, state);
}
}
return state;
return state;
}
}
};
};
}}
}}
namespace client
namespace client
{
{
///////////////////////////////////////////////////////////////////////////////
///////////////////////////////////////////////////////////////////////////////
// The calculator grammar
// The calculator grammar
///////////////////////////////////////////////////////////////////////////////
///////////////////////////////////////////////////////////////////////////////
namespace calculator_grammar
namespace calculator_grammar
{
{
using x3::uint_;
using x3::uint_;
using x3::char_;
using x3::char_;
struct expression_class;
struct expression_class;
struct term_class;
struct term_class;
struct factor_class;
struct factor_class;
x3::rule<expression_class, ast::program> const expression("expression");
x3::rule<expression_class, ast::program> const expression("expression");
x3::rule<term_class, ast::program> const term("term");
x3::rule<term_class, ast::program> const term("term");
x3::rule<factor_class, ast::operand> const factor("factor");
x3::rule<factor_class, ast::operand> const factor("factor");
auto const expression_def =
auto const expression_def =
term
term
>> *( (char_('+') > term)
>> *( (char_('+') > term)
| (char_('-') > term)
| (char_('-') > term)
)
)
;
;
auto const term_def =
auto const term_def =
factor
factor
>> *( (char_('*') > factor)
>> *( (char_('*') > factor)
| (char_('/') > factor)
| (char_('/') > factor)
)
)
;
;
auto const factor_def =
auto const factor_def =
uint_
uint_
| '(' > expression > ')'
| '(' > expression > ')'
| (char_('-') > factor)
| (char_('-') > factor)
| (char_('+') > factor)
| (char_('+') > factor)
;
;
BOOST_SPIRIT_DEFINE(
BOOST_SPIRIT_DEFINE(
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expression
= expression_def
expression
, term
= term_def
, term
, factor
= factor_def
, factor
);
);
struct expression_class
struct expression_class
{
{
// Our error handler
// Our error handler
template <typename Iterator, typename Exception, typename Context>
template <typename Iterator, typename Exception, typename Context>
x3::error_handler_result
x3::error_handler_result
on_error(Iterator&, Iterator const& last, Exception const& x, Context const& context)
on_error(Iterator&, Iterator const& last, Exception const& x, Context const& context)
{
{
std::cout
std::cout
<< "Error! Expecting: "
<< "Error! Expecting: "
<< x.which()
<< x.which()
<< " here: \""
<< " here: \""
<< std::string(x.where(), last)
<< std::string(x.where(), last)
<< "\""
<< "\""
<< std::endl
<< std::endl
;
;
return x3::error_handler_result::fail;
return x3::error_handler_result::fail;
}
}
};
};
auto calculator = expression;
auto calculator = expression;
}
}
using calculator_grammar::calculator;
using calculator_grammar::calculator;
}
}
///////////////////////////////////////////////////////////////////////////////
///////////////////////////////////////////////////////////////////////////////
// Main program
// Main program
///////////////////////////////////////////////////////////////////////////////
///////////////////////////////////////////////////////////////////////////////
int
int
main()
main()
{
{
std::cout << "/////////////////////////////////////////////////////////\n\n";
std::cout << "/////////////////////////////////////////////////////////\n\n";
std::cout << "Expression parser...\n\n";
std::cout << "Expression parser...\n\n";
std::cout << "/////////////////////////////////////////////////////////\n\n";
std::cout << "/////////////////////////////////////////////////////////\n\n";
std::cout << "Type an expression...or [q or Q] to quit\n\n";
std::cout << "Type an expression...or [q or Q] to quit\n\n";
typedef std::string::const_iterator iterator_type;
typedef std::string::const_iterator iterator_type;
typedef client::ast::program ast_program;
typedef client::ast::program ast_program;
typedef client::ast::printer ast_print;
typedef client::ast::printer ast_print;
typedef client::ast::eval ast_eval;
typedef client::ast::eval ast_eval;
std::string str;
std::string str;
while (std::getline(std::cin, str))
while (std::getline(std::cin, str))
{
{
if (str.empty() || str[0] == 'q' || str[0] == 'Q')
if (str.empty() || str[0] == 'q' || str[0] == 'Q')
break;
break;
auto& calc = client::calculator; // Our grammar
auto& calc = client::calculator; // Our grammar
ast_program program; // Our program (AST)
ast_program program; // Our program (AST)
ast_print print; // Prints the program
ast_print print; // Prints the program
ast_eval eval; // Evaluates the program
ast_eval eval; // Evaluates the program
iterator_type iter = str.begin();
iterator_type iter = str.begin();
iterator_type end = str.end();
iterator_type end = str.end();
boost::spirit::x3::ascii::space_type space;
boost::spirit::x3::ascii::space_type space;
bool r = phrase_parse(iter, end, calc, space, program);
bool r = phrase_parse(iter, end, calc, space, program);
if (r && iter == end)
if (r && iter == end)
{
{
std::cout << "-------------------------\n";
std::cout << "-------------------------\n";
std::cout << "Parsing succeeded\n";
std::cout << "Parsing succeeded\n";
print(program);
print(program);
std::cout << "\nResult: " << eval(program) << std::endl;
std::cout << "\nResult: " << eval(program) << std::endl;
std::cout << "-------------------------\n";
std::cout << "-------------------------\n";
}
}
else
else
{
{
std::cout << "-------------------------\n";
std::cout << "-------------------------\n";
std::cout << "Parsing failed\n";
std::cout << "Parsing failed\n";
std::cout << "-------------------------\n";
std::cout << "-------------------------\n";
}
}
}
}
std::cout << "Bye... :-) \n\n";
std::cout << "Bye... :-) \n\n";
return 0;
return 0;
}
}
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/*============================================================================= Copyright (c) 2001-2014 Joel de Guzman Distributed under the Boost Software License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) =============================================================================*/ /////////////////////////////////////////////////////////////////////////////// // // Same as Calc4, this time, we'll incorporate debugging support, // plus error handling and reporting. // // [ JDG April 28, 2008 ] For BoostCon 2008 // [ JDG February 18, 2011 ] Pure attributes. No semantic actions. // [ JDG April 9, 2014 ] Spirit X3 // /////////////////////////////////////////////////////////////////////////////// /////////////////////////////////////////////////////////////////////////////// // Uncomment this if you want to enable debugging //#define BOOST_SPIRIT_X3_DEBUG #include <boost/config/warning_disable.hpp> #include <boost/spirit/home/x3.hpp> #include <boost/spirit/home/x3/support/ast/variant.hpp> #include <boost/fusion/include/adapt_struct.hpp> #include <iostream> #include <string> #include <list> #include <numeric> namespace x3 = boost::spirit::x3; namespace client { namespace ast { /////////////////////////////////////////////////////////////////////////// // The AST /////////////////////////////////////////////////////////////////////////// struct nil {}; struct signed_; struct program; struct operand : x3::variant< nil , unsigned int , x3::forward_ast<signed_> , x3::forward_ast<program> > { using base_type::base_type; using base_type::operator=; }; struct signed_ { char sign; operand operand_; }; struct operation { char operator_; operand operand_; }; struct program { operand first; std::list<operation> rest; }; // print function for debugging inline std::ostream& operator<<(std::ostream& out, nil) { out << "nil"; return out; } }} BOOST_FUSION_ADAPT_STRUCT( client::ast::signed_, (char, sign) (client::ast::operand, operand_) ) BOOST_FUSION_ADAPT_STRUCT( client::ast::operation, (char, operator_) (client::ast::operand, operand_) ) BOOST_FUSION_ADAPT_STRUCT( client::ast::program, (client::ast::operand, first) (std::list<client::ast::operation>, rest) ) namespace client { namespace ast { /////////////////////////////////////////////////////////////////////////// // The AST Printer /////////////////////////////////////////////////////////////////////////// struct printer { typedef void result_type; void operator()(nil) const {} void operator()(unsigned int n) const { std::cout << n; } void operator()(operation const& x) const { boost::apply_visitor(*this, x.operand_); switch (x.operator_) { case '+': std::cout << " add"; break; case '-': std::cout << " subt"; break; case '*': std::cout << " mult"; break; case '/': std::cout << " div"; break; } } void operator()(signed_ const& x) const { boost::apply_visitor(*this, x.operand_); switch (x.sign) { case '-': std::cout << " neg"; break; case '+': std::cout << " pos"; break; } } void operator()(program const& x) const { boost::apply_visitor(*this, x.first); BOOST_FOREACH(operation const& oper, x.rest) { std::cout << ' '; (*this)(oper); } } }; /////////////////////////////////////////////////////////////////////////// // The AST evaluator /////////////////////////////////////////////////////////////////////////// struct eval { typedef int result_type; int operator()(nil) const { BOOST_ASSERT(0); return 0; } int operator()(unsigned int n) const { return n; } int operator()(operation const& x, int lhs) const { int rhs = boost::apply_visitor(*this, x.operand_); switch (x.operator_) { case '+': return lhs + rhs; case '-': return lhs - rhs; case '*': return lhs * rhs; case '/': return lhs / rhs; } BOOST_ASSERT(0); return 0; } int operator()(signed_ const& x) const { int rhs = boost::apply_visitor(*this, x.operand_); switch (x.sign) { case '-': return -rhs; case '+': return +rhs; } BOOST_ASSERT(0); return 0; } int operator()(program const& x) const { int state = boost::apply_visitor(*this, x.first); BOOST_FOREACH(operation const& oper, x.rest) { state = (*this)(oper, state); } return state; } }; }} namespace client { /////////////////////////////////////////////////////////////////////////////// // The calculator grammar /////////////////////////////////////////////////////////////////////////////// namespace calculator_grammar { using x3::uint_; using x3::char_; struct expression_class; struct term_class; struct factor_class; x3::rule<expression_class, ast::program> const expression("expression"); x3::rule<term_class, ast::program> const term("term"); x3::rule<factor_class, ast::operand> const factor("factor"); auto const expression_def = term >> *( (char_('+') > term) | (char_('-') > term) ) ; auto const term_def = factor >> *( (char_('*') > factor) | (char_('/') > factor) ) ; auto const factor_def = uint_ | '(' > expression > ')' | (char_('-') > factor) | (char_('+') > factor) ; BOOST_SPIRIT_DEFINE( expression = expression_def , term = term_def , factor = factor_def ); struct expression_class { // Our error handler template <typename Iterator, typename Exception, typename Context> x3::error_handler_result on_error(Iterator&, Iterator const& last, Exception const& x, Context const& context) { std::cout << "Error! Expecting: " << x.which() << " here: \"" << std::string(x.where(), last) << "\"" << std::endl ; return x3::error_handler_result::fail; } }; auto calculator = expression; } using calculator_grammar::calculator; } /////////////////////////////////////////////////////////////////////////////// // Main program /////////////////////////////////////////////////////////////////////////////// int main() { std::cout << "/////////////////////////////////////////////////////////\n\n"; std::cout << "Expression parser...\n\n"; std::cout << "/////////////////////////////////////////////////////////\n\n"; std::cout << "Type an expression...or [q or Q] to quit\n\n"; typedef std::string::const_iterator iterator_type; typedef client::ast::program ast_program; typedef client::ast::printer ast_print; typedef client::ast::eval ast_eval; std::string str; while (std::getline(std::cin, str)) { if (str.empty() || str[0] == 'q' || str[0] == 'Q') break; auto& calc = client::calculator; // Our grammar ast_program program; // Our program (AST) ast_print print; // Prints the program ast_eval eval; // Evaluates the program iterator_type iter = str.begin(); iterator_type end = str.end(); boost::spirit::x3::ascii::space_type space; bool r = phrase_parse(iter, end, calc, space, program); if (r && iter == end) { std::cout << "-------------------------\n"; std::cout << "Parsing succeeded\n"; print(program); std::cout << "\nResult: " << eval(program) << std::endl; std::cout << "-------------------------\n"; } else { std::cout << "-------------------------\n"; std::cout << "Parsing failed\n"; std::cout << "-------------------------\n"; } } std::cout << "Bye... :-) \n\n"; return 0; }
更改后文本
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/*============================================================================= Copyright (c) 2001-2014 Joel de Guzman Distributed under the Boost Software License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) =============================================================================*/ /////////////////////////////////////////////////////////////////////////////// // // Same as Calc4, this time, we'll incorporate debugging support, // plus error handling and reporting. // // [ JDG April 28, 2008 ] For BoostCon 2008 // [ JDG February 18, 2011 ] Pure attributes. No semantic actions. // [ JDG April 9, 2014 ] Spirit X3 // /////////////////////////////////////////////////////////////////////////////// /////////////////////////////////////////////////////////////////////////////// // Uncomment this if you want to enable debugging //#define BOOST_SPIRIT_X3_DEBUG #include <boost/config/warning_disable.hpp> #include <boost/spirit/home/x3.hpp> #include <boost/spirit/home/x3/support/ast/variant.hpp> #include <boost/fusion/include/adapt_struct.hpp> #include <iostream> #include <string> #include <list> #include <numeric> namespace x3 = boost::spirit::x3; namespace client { namespace ast { /////////////////////////////////////////////////////////////////////////// // The AST /////////////////////////////////////////////////////////////////////////// struct nil {}; struct signed_; struct program; struct operand : x3::variant< nil , unsigned int , x3::forward_ast<signed_> , x3::forward_ast<program> > { using base_type::base_type; using base_type::operator=; }; struct signed_ { char sign; operand operand_; }; struct operation { char operator_; operand operand_; }; struct program { operand first; std::list<operation> rest; }; // print function for debugging inline std::ostream& operator<<(std::ostream& out, nil) { out << "nil"; return out; } }} BOOST_FUSION_ADAPT_STRUCT(client::ast::signed_, sign, operand_ ) BOOST_FUSION_ADAPT_STRUCT(client::ast::operation, operator_, operand_ ) BOOST_FUSION_ADAPT_STRUCT(client::ast::program, first, rest ) namespace client { namespace ast { /////////////////////////////////////////////////////////////////////////// // The AST Printer /////////////////////////////////////////////////////////////////////////// struct printer { typedef void result_type; void operator()(nil) const {} void operator()(unsigned int n) const { std::cout << n; } void operator()(operation const& x) const { boost::apply_visitor(*this, x.operand_); switch (x.operator_) { case '+': std::cout << " add"; break; case '-': std::cout << " subt"; break; case '*': std::cout << " mult"; break; case '/': std::cout << " div"; break; } } void operator()(signed_ const& x) const { boost::apply_visitor(*this, x.operand_); switch (x.sign) { case '-': std::cout << " neg"; break; case '+': std::cout << " pos"; break; } } void operator()(program const& x) const { boost::apply_visitor(*this, x.first); for (operation const& oper : x.rest) { std::cout << ' '; (*this)(oper); } } }; /////////////////////////////////////////////////////////////////////////// // The AST evaluator /////////////////////////////////////////////////////////////////////////// struct eval { typedef int result_type; int operator()(nil) const { BOOST_ASSERT(0); return 0; } int operator()(unsigned int n) const { return n; } int operator()(operation const& x, int lhs) const { int rhs = boost::apply_visitor(*this, x.operand_); switch (x.operator_) { case '+': return lhs + rhs; case '-': return lhs - rhs; case '*': return lhs * rhs; case '/': return lhs / rhs; } BOOST_ASSERT(0); return 0; } int operator()(signed_ const& x) const { int rhs = boost::apply_visitor(*this, x.operand_); switch (x.sign) { case '-': return -rhs; case '+': return +rhs; } BOOST_ASSERT(0); return 0; } int operator()(program const& x) const { int state = boost::apply_visitor(*this, x.first); for (operation const& oper : x.rest) { state = (*this)(oper, state); } return state; } }; }} namespace client { /////////////////////////////////////////////////////////////////////////////// // The calculator grammar /////////////////////////////////////////////////////////////////////////////// namespace calculator_grammar { using x3::uint_; using x3::char_; struct expression_class; struct term_class; struct factor_class; x3::rule<expression_class, ast::program> const expression("expression"); x3::rule<term_class, ast::program> const term("term"); x3::rule<factor_class, ast::operand> const factor("factor"); auto const expression_def = term >> *( (char_('+') > term) | (char_('-') > term) ) ; auto const term_def = factor >> *( (char_('*') > factor) | (char_('/') > factor) ) ; auto const factor_def = uint_ | '(' > expression > ')' | (char_('-') > factor) | (char_('+') > factor) ; BOOST_SPIRIT_DEFINE( expression , term , factor ); struct expression_class { // Our error handler template <typename Iterator, typename Exception, typename Context> x3::error_handler_result on_error(Iterator&, Iterator const& last, Exception const& x, Context const& context) { std::cout << "Error! Expecting: " << x.which() << " here: \"" << std::string(x.where(), last) << "\"" << std::endl ; return x3::error_handler_result::fail; } }; auto calculator = expression; } using calculator_grammar::calculator; } /////////////////////////////////////////////////////////////////////////////// // Main program /////////////////////////////////////////////////////////////////////////////// int main() { std::cout << "/////////////////////////////////////////////////////////\n\n"; std::cout << "Expression parser...\n\n"; std::cout << "/////////////////////////////////////////////////////////\n\n"; std::cout << "Type an expression...or [q or Q] to quit\n\n"; typedef std::string::const_iterator iterator_type; typedef client::ast::program ast_program; typedef client::ast::printer ast_print; typedef client::ast::eval ast_eval; std::string str; while (std::getline(std::cin, str)) { if (str.empty() || str[0] == 'q' || str[0] == 'Q') break; auto& calc = client::calculator; // Our grammar ast_program program; // Our program (AST) ast_print print; // Prints the program ast_eval eval; // Evaluates the program iterator_type iter = str.begin(); iterator_type end = str.end(); boost::spirit::x3::ascii::space_type space; bool r = phrase_parse(iter, end, calc, space, program); if (r && iter == end) { std::cout << "-------------------------\n"; std::cout << "Parsing succeeded\n"; print(program); std::cout << "\nResult: " << eval(program) << std::endl; std::cout << "-------------------------\n"; } else { std::cout << "-------------------------\n"; std::cout << "Parsing failed\n"; std::cout << "-------------------------\n"; } } std::cout << "Bye... :-) \n\n"; return 0; }
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