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- /*=============================================================================
- Copyright (c) 2001-2011 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.
- //
- ///////////////////////////////////////////////////////////////////////////////
- ///////////////////////////////////////////////////////////////////////////////
- // Spirit v2.5 allows you to suppress automatic generation
- // of predefined terminals to speed up complation. With
- // BOOST_SPIRIT_NO_PREDEFINED_TERMINALS defined, you are
- // responsible in creating instances of the terminals that
- // you need (e.g. see qi::uint_type uint_ below).
- #define BOOST_SPIRIT_NO_PREDEFINED_TERMINALS
- ///////////////////////////////////////////////////////////////////////////////
- ///////////////////////////////////////////////////////////////////////////////
- // Define this to enable debugging
- #define BOOST_SPIRIT_QI_DEBUG
- ///////////////////////////////////////////////////////////////////////////////
- // Uncomment this if you want to enable debugging
- //#define BOOST_SPIRIT_QI_DEBUG
- ///////////////////////////////////////////////////////////////////////////////
- #if defined(_MSC_VER)
- # pragma warning(disable: 4345)
- #endif
- #include <boost/config/warning_disable.hpp>
- #include <boost/spirit/include/qi.hpp>
- #include <boost/variant/recursive_variant.hpp>
- #include <boost/variant/apply_visitor.hpp>
- #include <boost/fusion/include/adapt_struct.hpp>
- #include <boost/spirit/include/phoenix_function.hpp>
- #include <boost/foreach.hpp>
- #include <iostream>
- #include <string>
- namespace client { namespace ast
- {
- ///////////////////////////////////////////////////////////////////////////
- // The AST
- ///////////////////////////////////////////////////////////////////////////
- struct nil {};
- struct signed_;
- struct program;
- typedef boost::variant<
- nil
- , unsigned int
- , boost::recursive_wrapper<signed_>
- , boost::recursive_wrapper<program>
- >
- operand;
- 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
- {
- namespace qi = boost::spirit::qi;
- namespace ascii = boost::spirit::ascii;
- using boost::phoenix::function;
- ///////////////////////////////////////////////////////////////////////////////
- // Our error handler
- ///////////////////////////////////////////////////////////////////////////////
- struct error_handler_
- {
- template <typename, typename, typename>
- struct result { typedef void type; };
- template <typename Iterator>
- void operator()(
- qi::info const& what
- , Iterator err_pos, Iterator last) const
- {
- std::cout
- << "Error! Expecting "
- << what // what failed?
- << " here: \""
- << std::string(err_pos, last) // iterators to error-pos, end
- << "\""
- << std::endl
- ;
- }
- };
- function<error_handler_> const error_handler = error_handler_();
- ///////////////////////////////////////////////////////////////////////////////
- // Our calculator grammar
- ///////////////////////////////////////////////////////////////////////////////
- template <typename Iterator>
- struct calculator : qi::grammar<Iterator, ast::program(), ascii::space_type>
- {
- calculator() : calculator::base_type(expression)
- {
- qi::char_type char_;
- qi::uint_type uint_;
- qi::_2_type _2;
- qi::_3_type _3;
- qi::_4_type _4;
- using qi::on_error;
- using qi::fail;
- expression =
- term
- >> *( (char_('+') > term)
- | (char_('-') > term)
- )
- ;
- term =
- factor
- >> *( (char_('*') > factor)
- | (char_('/') > factor)
- )
- ;
- factor =
- uint_
- | '(' > expression > ')'
- | (char_('-') > factor)
- | (char_('+') > factor)
- ;
- // Debugging and error handling and reporting support.
- BOOST_SPIRIT_DEBUG_NODE(expression);
- BOOST_SPIRIT_DEBUG_NODE(term);
- BOOST_SPIRIT_DEBUG_NODE(factor);
- // Error handling
- on_error<fail>(expression, error_handler(_4, _3, _2));
- }
- qi::rule<Iterator, ast::program(), ascii::space_type> expression;
- qi::rule<Iterator, ast::program(), ascii::space_type> term;
- qi::rule<Iterator, ast::operand(), ascii::space_type> factor;
- };
- }
- ///////////////////////////////////////////////////////////////////////////////
- // 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::calculator<iterator_type> calculator;
- 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;
- calculator calc; // Our grammar
- ast_program program; // Our program (AST)
- ast_print print; // Prints the program
- ast_eval eval; // Evaluates the program
- std::string::const_iterator iter = str.begin();
- std::string::const_iterator end = str.end();
- boost::spirit::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::string rest(iter, end);
- std::cout << "-------------------------\n";
- std::cout << "Parsing failed\n";
- std::cout << "-------------------------\n";
- }
- }
- std::cout << "Bye... :-) \n\n";
- return 0;
- }
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