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/*=============================================================================
Copyright (c) 2001-2010 Joel de Guzman
Copyright (c) 2001-2010 Hartmut Kaiser
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 which gets dumped into
// a reverse polish notation afterwards.
//
// [ JDG April 28, 2008 ]
// [ HK April 28, 2008 ]
//
///////////////////////////////////////////////////////////////////////////////
#include <boost/config/warning_disable.hpp>
#include <iostream>
#include <vector>
#include <string>
#include "calc2_ast.hpp"
#include <boost/spirit/include/qi.hpp>
#include <boost/spirit/include/karma.hpp>
#include <boost/fusion/include/adapt_struct.hpp>
using namespace boost::spirit;
using namespace boost::spirit::ascii;
///////////////////////////////////////////////////////////////////////////////
// Our calculator parser grammar
///////////////////////////////////////////////////////////////////////////////
template <typename Iterator>
struct calculator
: qi::grammar<Iterator, expression_ast(), space_type>
{
calculator() : calculator::base_type(expression)
{
expression =
term [_val = _1]
>> *( ('+' >> term [_val += _1])
| ('-' >> term [_val -= _1])
)
;
term =
factor [_val = _1]
>> *( ('*' >> factor [_val *= _1])
| ('/' >> factor [_val /= _1])
)
;
factor =
uint_ [_val = _1]
| '(' >> expression [_val = _1] >> ')'
| ('-' >> factor [_val = neg(_1)])
| ('+' >> factor [_val = pos(_1)])
;
}
qi::rule<Iterator, expression_ast(), space_type> expression, term, factor;
};
// We need to tell fusion about our binary_op and unary_op structs
// to make them a first-class fusion citizen
//
// Note: we register the members exactly in the same sequence as we need them
// in the grammar
BOOST_FUSION_ADAPT_STRUCT(
binary_op,
(expression_ast, left)
(expression_ast, right)
(char, op)
)
BOOST_FUSION_ADAPT_STRUCT(
unary_op,
(expression_ast, right)
(char, op)
)
///////////////////////////////////////////////////////////////////////////////
// Our AST grammar for the generator, this prints the AST in reverse polish
// notation
///////////////////////////////////////////////////////////////////////////////
template <typename OuputIterator>
struct ast_rpn
: karma::grammar<OuputIterator, expression_ast(), space_type>
{
ast_rpn() : ast_rpn::base_type(ast_node)
{
ast_node %= int_ | binary_node | unary_node;
binary_node %= ast_node << ast_node << char_;
unary_node %= '(' << ast_node << char_ << ')';
}
karma::rule<OuputIterator, expression_ast(), space_type> ast_node;
karma::rule<OuputIterator, binary_op(), space_type> binary_node;
karma::rule<OuputIterator, unary_op(), space_type> unary_node;
};
///////////////////////////////////////////////////////////////////////////////
// Main program
///////////////////////////////////////////////////////////////////////////////
int
main()
{
std::cout << "/////////////////////////////////////////////////////////\n\n";
std::cout << "RPN generator for simple expressions...\n\n";
std::cout << "/////////////////////////////////////////////////////////\n\n";
std::cout << "Type an expression...or [q or Q] to quit\n\n";
// Our parser grammar definitions
typedef std::string::const_iterator iterator_type;
typedef calculator<iterator_type> calculator;
calculator calc;
// Our generator grammar definitions
typedef std::back_insert_iterator<std::string> output_iterator_type;
typedef ast_rpn<output_iterator_type> ast_rpn;
ast_rpn ast_grammar;
std::string str;
while (std::getline(std::cin, str))
{
if (str.empty() || str[0] == 'q' || str[0] == 'Q')
break;
expression_ast ast; // this will hold the generated AST
std::string::const_iterator iter = str.begin();
std::string::const_iterator end = str.end();
bool r = qi::phrase_parse(iter, end, calc, space, ast);
if (r && iter == end)
{
std::string generated;
output_iterator_type outit(generated);
r = karma::generate_delimited(outit, ast_grammar, space, ast);
if (r)
{
std::cout << "RPN for '" << str << "': \n" << generated
<< std::endl;
std::cout << "-------------------------\n";
}
else
{
std::cout << "-------------------------\n";
std::cout << "Generating failed\n";
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;
}
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