SBinary.h

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#ifndef OPAL_SBinary_HH
#define OPAL_SBinary_HH
 
// ------------------------------------------------------------------------
// $RCSfile: SBinary.h,v $
// ------------------------------------------------------------------------
// $Revision: 1.1.1.1 $
// ------------------------------------------------------------------------
// Copyright: see Copyright.readme
// ------------------------------------------------------------------------
//
// Template class: SBinary<T,U>
//
// ------------------------------------------------------------------------
//
// $Date: 2000/03/27 09:33:42 $
// $Author: Andreas Adelmann $
//
// ------------------------------------------------------------------------
 
#include <cerrno>
#include <iosfwd>
#include "AbstractObjects/Expressions.h"
#include "Expressions/SConstant.h"
#include "Expressions/TFunction2.h"
#include "Utilities/DomainError.h"
#include "Utilities/OverflowError.h"
 
namespace Expressions {
 
    // Template class SBinary
    // ----------------------------------------------------------------------
    //  The expression first evaluates the two scalar operands, and then
    //  it applies the given function to the operands and returns the result.
 
    template <class T, class U>
    class SBinary : public Scalar<T> {
    public:
        //  Use scalar function with two operands and two scalars.
        SBinary(const TFunction2<T, U>& function, PtrToScalar<U> left, PtrToScalar<U> right);
 
        SBinary(const SBinary<T, U>&);
        virtual ~SBinary();
 
        virtual Scalar<T>* clone() const;
 
        virtual T evaluate() const;
 
        //  If both operands are constants and the function is not a random
        //  generator, evaluate the expression and  store the result as a
        //  constant.
        static Scalar<T>* make(const TFunction2<T, U>&, PtrToScalar<U> left, PtrToScalar<U> right);
 
        virtual void print(std::ostream& str, int precedence = 99) const;
 
    private:
        // Not implemented.
        SBinary();
        void operator=(const SBinary&);
 
        // The operation object.
        const TFunction2<T, U>& fun;
 
        // The two operands.
        PtrToScalar<U> lft;
        PtrToScalar<U> rgt;
    };
 
    // Implementation
    // ------------------------------------------------------------------------
 
    template <class T, class U>
    inline SBinary<T, U>::SBinary(const SBinary& rhs)
        : Scalar<T>(rhs), fun(rhs.fun), lft(rhs.lft->clone()), rgt(rhs.rgt->clone()) {}
 
    template <class T, class U>
    inline SBinary<T, U>::SBinary(
            const TFunction2<T, U>& function, PtrToScalar<U> left, PtrToScalar<U> right)
        : fun(function), lft(left), rgt(right) {}
 
    template <class T, class U>
    inline SBinary<T, U>::~SBinary() {}
 
    template <class T, class U>
    inline Scalar<T>* SBinary<T, U>::clone() const {
        return new SBinary<T, U>(*this);
    }
 
    template <class T, class U>
    inline T SBinary<T, U>::evaluate() const {
        errno    = 0;
        U op1    = lft->evaluate();
        U op2    = rgt->evaluate();
        T result = (*fun.function)(op1, op2);
 
        // Test for run-time evaluation errors.
        switch (errno) {
            case EDOM:
                throw DomainError("SBinary::evaluate()");
 
            case ERANGE:
                // Ignore underflow.
                if (result == T(0)) return result;
                throw OverflowError("SBinary::evaluate()");
 
            default:
                return result;
        }
    }
 
    template <class T, class U>
    inline Scalar<T>* SBinary<T, U>::make(
            const TFunction2<T, U>& function, PtrToScalar<U> left, PtrToScalar<U> right) {
        // We must pick up the constant flag before the ownerships of "left" and
        // "right" are transferred to "result".
        bool isConst          = left->isConstant() && right->isConstant();
        PtrToScalar<T> result = new SBinary<T, U>(function, left, right);
 
        if (function.precedence != -2) {
            if (isConst) {
                // Replace constant expression by its value.
                result = new SConstant<T>(result->evaluate());
            }
        }
 
        // Other expression.
        return result.release();
    }
 
    template <class T, class U>
    inline void SBinary<T, U>::print(std::ostream& os, int precedence) const {
        if (fun.precedence >= 0) {
            // Binary operation.
            if (fun.precedence <= precedence) os << "(";
            lft->print(os, fun.precedence - 1);
            os << fun.name;
            rgt->print(os, fun.precedence);
            if (fun.precedence <= precedence) os << ")";
        } else {
            // Function.
            os << fun.name << '(';
            lft->print(os, 0);
            os << ',';
            rgt->print(os, 0);
            os << ')';
        }
 
        return;
    }
 
}  // namespace Expressions
 
#endif  // OPAL_SBinary_HH