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| // Copyright (c) 2001-2011 Hartmut Kaiser
//
// Distributed under the Boost Software License, Version 1.0. (See accompanying
// file LICENSE_1_0.txt or copy at [url]http://www.boost.org/LICENSE_1_0.txt[/url])
//#include "spirit_test.h"
//#include "spirit_parser.h"
//#include "recursive.h"
//#include "cpptest.h"
#include <iostream>
#include <vector>
#include <cmath>
#include <boost/proto/proto.hpp>
#include <boost/proto/core.hpp>
#include <boost/proto/context.hpp>
#include <boost/typeof/std/ostream.hpp>
#include <boost/type.hpp>
#include <complex>
using namespace boost;
template<typename Expr>
struct calculator;
// Define a placeholder type
template<int I>
struct placeholder
{};
struct calculator_grammar
: proto::or_<
proto::plus< calculator_grammar, calculator_grammar >
, proto::minus< calculator_grammar, calculator_grammar >
, proto::multiplies< calculator_grammar, calculator_grammar >
, proto::divides< calculator_grammar, calculator_grammar >
, proto::terminal< proto::_ >
>
{};
// the calculator domain will be wrapped in the
// calculator<> expression wrapper.
struct calculator_domain
: proto::domain< proto::generator<calculator>,calculator_grammar >
{};
struct calculator_context
: proto::callable_context< calculator_context const >
{
// Values to replace the placeholders
std::vector<double> args;
// Define the result type of the calculator.
// (This makes the calculator_context "callable".)
typedef double result_type;
// Handle the placeholders:
template<int I>
// Define a calculator domain. Expression within
double operator()(proto::tag::terminal, placeholder<I>) const
{
return this->args[I];
}
};
// Define a calculator expression wrapper. It behaves just like
// the expression it wraps, but with an extra operator() member
// function that evaluates the expression.
template<typename Expr>
struct calculator
: proto::extends<Expr, calculator<Expr>, calculator_domain>
{
typedef
proto::extends<Expr, calculator<Expr>, calculator_domain>
base_type;
calculator(Expr const &expr = Expr())
: base_type(expr)
{}
typedef double result_type;
// Overload operator() to invoke proto::eval() with
// our calculator_context.
double operator()(double a1 = 0, double a2 = 0) const
{
calculator_context ctx;
ctx.args.push_back(a1);
ctx.args.push_back(a2);
return proto::eval(*this, ctx);
}
};
int main()
{
// Define the Protofied placeholder terminals
calculator<proto::terminal<placeholder<0> >::type > const _1;
calculator<proto::terminal<placeholder<1> >::type > const _2 ;
calculator_context ctx;
double d = ((_2 - _1) / _2 * 100)(31,32),k;
std::cout << d << std::endl;
return 0;
} |
(
