Hi Ty,
Wow. I can almost read this program. I'm proud of myself. Maybe I'm starting to
learn this OO stuff. I'm happy.
Jim
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-----Original Message-----
From: programmingblind-bounce@xxxxxxxxxxxxx
[mailto:programmingblind-bounce@xxxxxxxxxxxxx] On Behalf Of Littlefield, Tyler
Sent: Thursday, April 07, 2011 9:09 AM
To: programmingblind@xxxxxxxxxxxxx
Subject: boost::spirit and boost in general for c++ people.
hello all:
Recently I got into using boost a bit and started finding uses for it
all over the place. I would like to encourage those who haven't yet and
use c++ to check it out; it is quite powerful and can eas some of your
work and provide really cool features along the way. For example:
boost::function lets you take callbacks in multiple forms; boost::bind
will let you bind a functor to it's arguments and pass that as your
callback, which means you can bind to a static member function, a member
function (and pass the object with boost::ref), a global function and
you can also use boost::lambda.
There are many more utilities out there; I highly recommend checking out
boost::asio, boost::fusion, boost::function and boost::bind.
In the spirit of convincing you all, I wrote a small calculator program
that does single operations (1+3, 3*5), etc and returns the result.
My next step is to split up my parsing into different rulesets and then
work on generating an AST so that I can handle larger more complex
calculations.
/*
A simple calculator, supports multiplication, division, addition and
subtraction.
*/
#include<boost/spirit/include/qi.hpp>
#include<boost/spirit/include/phoenix_core.hpp>
#include<boost/spirit/include/phoenix_operator.hpp>
#include<boost/spirit/include/phoenix_operator.hpp>
#include<iostream>
#include<string>
#include<boost/fusion/include/adapt_struct.hpp>
#include<boost/fusion/container/vector.hpp>
#include<boost/fusion/container/vector/convert.hpp>
#include<boost/fusion/include/io.hpp>
namespace qi = boost::spirit::qi;
namespace ascii = boost::spirit::ascii;
namespace phoenix = boost::phoenix;
struct calculation
{
int a, b;
char op;
};
BOOST_FUSION_ADAPT_STRUCT(calculation, (int, a) (char, op) (int, b) )
template<typename iterator>
class CParser:public qi::grammar<iterator, calculation(),
qi::ascii::space_type>
{
qi::rule<iterator, calculation(), qi::ascii::space_type> crule;
public:
CParser():CParser::base_type(crule)
{
using qi::ascii::char_;
using qi::int_;
crule %= (int_>>
(char_('+')|char_('-')|char_('*')|char_('/'))>>
int_);
}
};
int main()
{
CParser<std::string::iterator> p;
std::string str;
calculation result;
std::cout<< "Enter your calculation>";
getline(std::cin, str);
bool r = phrase_parse(str.begin(), str.end(), p, qi::ascii::space,
result);
if (r)
{
std::cout<< "a: "<< result.a<< " b: "<< result.b<< " op:"
<< result.op<< std::endl;
switch(result.op)
{
case '+':
std::cout<< "Result: "<< (result.a + result.b)<< std::endl;
break;
case '-':
std::cout<< "result: "<< (result.a - result.b)<< std::endl;
break;
case '*':
std::cout<< "Result: "<< (result.a * result.b)<< std::endl;
break;
case '/':
if (result.a == 0)
{
std::cout<< "Division by zero error."<< std::endl;
break;
}
std::cout<< "result: "<< (result.a / result.b)<< std::endl;
break;
default:
std::cout<< "Invalid operation."<< std::endl;
}
}
else
{
std::cout<< "Invalid input."<< std::endl;
}
return 0;
}
--
Thanks,
Ty
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