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Diffstat (limited to 'src/boost/libs/spirit/example/x3/calc/calc4.cpp')
| -rw-r--r-- | src/boost/libs/spirit/example/x3/calc/calc4.cpp | 273 |
1 files changed, 273 insertions, 0 deletions
diff --git a/src/boost/libs/spirit/example/x3/calc/calc4.cpp b/src/boost/libs/spirit/example/x3/calc/calc4.cpp new file mode 100644 index 00000000..289e2cd9 --- /dev/null +++ b/src/boost/libs/spirit/example/x3/calc/calc4.cpp @@ -0,0 +1,273 @@ +/*============================================================================= + 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) +=============================================================================*/ +/////////////////////////////////////////////////////////////////////////////// +// +// A Calculator example demonstrating generation of AST. The AST, +// once created, is traversed, 1) To print its contents and +// 2) To evaluate the result. +// +// [ JDG April 28, 2008 ] For BoostCon 2008 +// [ JDG February 18, 2011 ] Pure attributes. No semantic actions. +// [ JDG January 9, 2013 ] Spirit X3 +// +/////////////////////////////////////////////////////////////////////////////// + +#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; + }; +}} + +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()(int lhs, operation const& x) 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 + { + return std::accumulate( + x.rest.begin(), x.rest.end() + , boost::apply_visitor(*this, x.first) + , *this); + } + }; +}} + +namespace client +{ + /////////////////////////////////////////////////////////////////////////////// + // The calculator grammar + /////////////////////////////////////////////////////////////////////////////// + namespace calculator_grammar + { + using x3::uint_; + using x3::char_; + + x3::rule<class expression, ast::program> const expression("expression"); + x3::rule<class term, ast::program> const term("term"); + x3::rule<class factor, 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 + ); + + 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::string rest(iter, end); + std::cout << "-------------------------\n"; + std::cout << "Parsing failed\n"; + std::cout << "stopped at: \"" << rest << "\"\n"; + std::cout << "-------------------------\n"; + } + } + + std::cout << "Bye... :-) \n\n"; + return 0; +} |