exprint.h

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#if !defined( __EXPRINT_H__ )
#define __EXPRINT_H__

namespace Ars
{
class ExprInt   : public Lexer  {

        static const char sr[10][10];


public:

        ExprInt( const string &aBuffer );

        virtual const char      atSr( const int ati , const int atj )   {       return sr[ati][atj];    }
        virtual const int EofId( void ) const;
        virtual const int IdentifierId( void ) const;
        virtual const int NumberId( void ) const;

};

class ExprIntParser     {
private:
        map<icstring,double>    variables;

        class Context   {
        public:

                map<icstring,double>    &variables;
                double  val;

                Context( map<icstring,double> &aVar )
                : variables( aVar ) , val( 0.0 )
                {               }
                
                Context( Context &ctx )
                : variables( ctx.variables ) , val( 0.0 )
                {               }


                Context &operator=( Context &ctx )
                {
                        val = ctx.val;
                        return *this;
                }

                Context &operator+=( Context &ctx )
                {
                        val += ctx.val;
                        return *this;
                }
                Context &operator-=( Context &ctx )
                {
                        val -= ctx.val;
                        return *this;
                }
                Context &operator*=( Context &ctx )
                {
                        val *= ctx.val;
                        return *this;
                }
                Context &operator/=( Context &ctx )
                {
                        val /= ctx.val;
                        return *this;
                }
                Context &operator|=( Context &ctx )
                {
                        val = (int)val | (int)ctx.val;
                        return *this;
                }
        };

        Interpret       *itp;
public:

        ExprIntParser( void )
                : itp( 0 )
        {
                Init();
        }

        ~ExprIntParser( void )
        {
                if( itp )
                        delete itp;
                itp = 0;
        }

        TreeNode *Eval( const string &aBuffer )
        {
                if( itp )
                        delete itp;
                itp = 0;

                ExprInt lex( aBuffer );
                itp = new Interpret( lex );
                itp->Run();
                return itp->back();
        }

        int Apply( TreeNode *tn )
        {
                Context ctx( variables );
                WalkTree( tn , ctx );
                return (int)ctx.val;
        }

private:

        void Init( void )
        {
                Cfg::Handler    &h = Cfg::GetCfg();
                variables.insert( make_pair( icstring( "scrw" ) , h.GetCfgInt( "SetupScreen" , "screenw" ) ) );
                variables.insert( make_pair( icstring( "scrh" ) , h.GetCfgInt( "SetupScreen" , "screenh" ) ) );
        }

        void WalkTree( TreeNode *tn , Context &ctx )
        {
                if( tn )
                {
                        Context lctx( ctx );
                        if( tn->child != 0 )
                                WalkTree( tn->child , lctx );

                        Context rctx( ctx );
                        if( tn->next != 0 )
                                WalkTree( tn->next , rctx );

                        if( tn->symbolId == 9 )         
                                ctx.val = atof( tn->constant.c_str() );
                        else if( tn->symbolId == 5 )
                        {
                                map<icstring,double>::iterator  pos = ctx.variables.find( icstring( tn->constant.c_str() ) );
                                if( pos != ctx.variables.end() )
                                        ctx.val = pos->second;
                        }
                        else
                        {
                                ctx = lctx;     

                                switch( tn->constant.c_str()[0] )
                                {
                                        case '+' : ctx += rctx; break;
                                        case '-' : ctx -= rctx; break;
                                        case '*' : ctx *= rctx; break;
                                        case '/' : ctx /= rctx; break;
                                        case '|' : ctx |= rctx; break;
                                        default:
                                                if( lctx.val != 0 )
                                                        ctx = lctx;
                                                if( rctx.val != 0 )
                                                        if( ctx.val == 0 )
                                                                ctx = rctx;
                                                        else
                                                                printf( "ERROR\n" );
                                                break;
                                }
                        }
                }
        }
};

}

#endif

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