////////////////////////////////////////////////////////////////////////////
//
//  Full calculator example
//  [ demonstrating grouping parser ]
//
//  [ Hartmut Kaiser 10/7/2002 ]
//
////////////////////////////////////////////////////////////////////////////

//#define SPIRIT_DEBUG        // define this, if debug output is required

#include <boost/spirit/core.hpp>
#include <boost/spirit/attribute.hpp>

#include <iostream>
#include <string>

////////////////////////////////////////////////////////////////////////////
using namespace std;
using namespace spirit;
using namespace phoenix;

////////////////////////////////////////////////////////////////////////////
//
//  Our calculator grammar using phoenix and grouping to do the semantics
//
//  Note:   The top rule propagates the expression result (value) upwards
//          to the calculator grammar self.val closure member which is
//          then visible outside the grammar (i.e. since self.val is the
//          member1 of the closure, it becomes the attribute passed by
//          the calculator to an attached semantic action. See the
//          driver code that uses the calculator below).
//
////////////////////////////////////////////////////////////////////////////
struct calc_closure : spirit::closure<calc_closure, double>
{
    member1 val;
};

struct calculator : public grammar<calculator, calc_closure::context_t>
{
    template <typename ScannerT>
    struct definition
    {
        definition(calculator const& self)
        {
            top = addsub_expr[self.val = arg1];

            addsub_expr 
                =   group_d[muldiv_expr >> '+' >> muldiv_expr]
                    [
                        addsub_expr.val = arg1 + arg3
                    ]
                |   group_d[muldiv_expr >> '-' >> muldiv_expr]
                    [
                        addsub_expr.val = arg1 - arg3
                    ]
                ;
                
            muldiv_expr 
                =   group_d[factor >> '*' >> factor]
                    [
                        muldiv_expr.val = arg1 * arg3
                    ]
                |   group_d[factor >> '/' >> factor]
                    [
                        muldiv_expr.val = arg1 / arg3
                    ]
                |   factor
                    [
                        muldiv_expr.val = arg1
                    ]
                ;

            factor
                =   ureal_p[factor.val = arg1]
                |   '(' >> addsub_expr[factor.val = arg1] >> ')'
                |   '+' >> addsub_expr[factor.val = arg1]
                |   '-' >> addsub_expr[factor.val = -arg1]
                ;

            SPIRIT_DEBUG_NODE(top);
            SPIRIT_DEBUG_NODE(addsub_expr);
            SPIRIT_DEBUG_NODE(muldiv_expr);
            SPIRIT_DEBUG_NODE(factor);
        }

        typedef rule<ScannerT, calc_closure::context_t> rule_t;
        rule_t addsub_expr, muldiv_expr, factor;
        rule<ScannerT> top;

        rule<ScannerT> const&
        start() const { return top; }
    };
};

////////////////////////////////////////////////////////////////////////////
//
//  Main program
//
////////////////////////////////////////////////////////////////////////////
int
main()
{
    cout << "/////////////////////////////////////////////////////////\n\n";
    cout << "\tExpression parser using Phoenix and grouping...\n\n";
    cout << "/////////////////////////////////////////////////////////\n\n";
    cout << "Type an expression...or [q or Q] to quit\n\n";

    calculator calc;    //  Our parser

    for (;;)
    {
        string str;
        getline(cin, str);
        if (str[0] == 'q' || str[0] == 'Q')
            break;

        double n = 0;
        parse_info<> info = parse(str.c_str(), calc[var(n) = arg1], space_p);

        //  calc[var(n) = arg1] invokes the calculator and extracts
        //  the result of the computation. See calculator grammar
        //  note above.

        if (info.full)
        {
            cout << "-------------------------\n";
            cout << "Parsing succeeded\n";
            cout << "result = " << n << endl;
            cout << "-------------------------\n";
        }
        else
        {
            cout << "-------------------------\n";
            cout << "Parsing failed\n";
            cout << "stopped at: \": " << info.stop << "\"\n";
            cout << "-------------------------\n";
        }
    }

    cout << "Bye... :-) \n\n";
    return 0;
}