1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191
|
/*=============================================================================
Copyright (c) 2001-2014 Joel de Guzman
Copyright (c) 2013-2014 Agustin Berge
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
//
///////////////////////////////////////////////////////////////////////////////
#if defined(_MSC_VER)
# pragma warning(disable: 4345)
#endif
#include <boost/spirit/home/x3.hpp>
#include <boost/spirit/home/x3/support/ast/variant.hpp>
#include <boost/variant/recursive_variant.hpp>
#include <boost/variant/apply_visitor.hpp>
#include <boost/fusion/include/adapt_struct.hpp>
#include <list>
#include <numeric>
namespace x3 = boost::spirit::x3;
namespace client { namespace ast
{
///////////////////////////////////////////////////////////////////////////
// The AST
///////////////////////////////////////////////////////////////////////////
struct nil {};
struct signed_;
struct program;
typedef x3::variant<
nil
, unsigned int
, x3::forward_ast<signed_>
, x3::forward_ast<program>
>
operand;
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 parser_type =
x3::any_parser<
std::string::const_iterator
, ast::program
, decltype(x3::make_context<x3::skipper_tag>(x3::ascii::space))
>;
parser_type calculator();
}
auto const calculator = calculator_grammar::calculator();
}
|