src/OpenGL/compiler/ConstantUnion.h

//
// Copyright (c) 2002-2014 The ANGLE Project Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
//

#ifndef _CONSTANT_UNION_INCLUDED_
#define _CONSTANT_UNION_INCLUDED_

#include <assert.h>

class ConstantUnion {
public:
	POOL_ALLOCATOR_NEW_DELETE();
    ConstantUnion()
    {
        iConst = 0;
        type = EbtVoid;
    }

    bool cast(TBasicType newType, const ConstantUnion &constant)
    {
        switch (newType)
        {
          case EbtFloat:
            switch (constant.type)
            {
              case EbtInt:   setFConst(static_cast<float>(constant.getIConst())); break;
              case EbtUInt:  setFConst(static_cast<float>(constant.getUConst())); break;
              case EbtBool:  setFConst(static_cast<float>(constant.getBConst())); break;
              case EbtFloat: setFConst(static_cast<float>(constant.getFConst())); break;
              default:       return false;
            }
            break;
          case EbtInt:
            switch (constant.type)
            {
              case EbtInt:   setIConst(static_cast<int>(constant.getIConst())); break;
              case EbtUInt:  setIConst(static_cast<int>(constant.getUConst())); break;
              case EbtBool:  setIConst(static_cast<int>(constant.getBConst())); break;
              case EbtFloat: setIConst(static_cast<int>(constant.getFConst())); break;
              default:       return false;
            }
            break;
          case EbtUInt:
            switch (constant.type)
            {
              case EbtInt:   setUConst(static_cast<unsigned int>(constant.getIConst())); break;
              case EbtUInt:  setUConst(static_cast<unsigned int>(constant.getUConst())); break;
              case EbtBool:  setUConst(static_cast<unsigned int>(constant.getBConst())); break;
              case EbtFloat: setUConst(static_cast<unsigned int>(constant.getFConst())); break;
              default:       return false;
            }
            break;
          case EbtBool:
            switch (constant.type)
            {
              case EbtInt:   setBConst(constant.getIConst() != 0);    break;
              case EbtUInt:  setBConst(constant.getUConst() != 0);    break;
              case EbtBool:  setBConst(constant.getBConst());         break;
              case EbtFloat: setBConst(constant.getFConst() != 0.0f); break;
              default:       return false;
            }
            break;
          case EbtStruct:    // Struct fields don't get cast
            switch (constant.type)
            {
              case EbtInt:   setIConst(constant.getIConst()); break;
              case EbtUInt:  setUConst(constant.getUConst()); break;
              case EbtBool:  setBConst(constant.getBConst()); break;
              case EbtFloat: setFConst(constant.getFConst()); break;
              default:       return false;
            }
            break;
          default:
            return false;
        }

        return true;
    }

    void setIConst(int i) {iConst = i; type = EbtInt; }
    void setUConst(unsigned int u) { uConst = u; type = EbtUInt; }
    void setFConst(float f) {fConst = f; type = EbtFloat; }
    void setBConst(bool b) {bConst = b; type = EbtBool; }

    int getIConst() const { return iConst; }
    unsigned int getUConst() const { return uConst; }
    float getFConst() const { return fConst; }
    bool getBConst() const { return bConst; }

	float getAsFloat()
	{
		const int FFFFFFFFh = 0xFFFFFFFF;

		switch(type)
		{
        case EbtInt:   return (float)iConst;
        case EbtFloat: return fConst;
		case EbtBool:  return (bConst == true) ? (float&)FFFFFFFFh : 0;
        default:       return 0;
        }
	}

    bool operator==(const int i) const
    {
        return i == iConst;
    }

    bool operator==(const unsigned int u) const
    {
        return u == uConst;
    }

    bool operator==(const float f) const
    {
        return f == fConst;
    }

    bool operator==(const bool b) const
    {
        return b == bConst;
    }

    bool operator==(const ConstantUnion& constant) const
    {
        if (constant.type != type)
            return false;

        switch (type) {
        case EbtInt:
            return constant.iConst == iConst;
        case EbtUInt:
            return constant.uConst == uConst;
        case EbtFloat:
            return constant.fConst == fConst;
        case EbtBool:
            return constant.bConst == bConst;
        default:
            return false;
        }

        return false;
    }

    bool operator!=(const int i) const
    {
        return !operator==(i);
    }

    bool operator!=(const unsigned int u) const
    {
        return !operator==(u);
    }

    bool operator!=(const float f) const
    {
        return !operator==(f);
    }

    bool operator!=(const bool b) const
    {
        return !operator==(b);
    }

    bool operator!=(const ConstantUnion& constant) const
    {
        return !operator==(constant);
    }

    bool operator>(const ConstantUnion& constant) const
    { 
        assert(type == constant.type);
        switch (type) {
        case EbtInt:
            return iConst > constant.iConst;
        case EbtUInt:
            return uConst > constant.uConst;
        case EbtFloat:
            return fConst > constant.fConst;
        default:
            return false;   // Invalid operation, handled at semantic analysis
        }

        return false;
    }

    bool operator<(const ConstantUnion& constant) const
    { 
        assert(type == constant.type);
        switch (type) {
        case EbtInt:
            return iConst < constant.iConst;
        case EbtUInt:
            return uConst < constant.uConst;
        case EbtFloat:
            return fConst < constant.fConst;
        default:
            return false;   // Invalid operation, handled at semantic analysis
        }

        return false;
    }

    ConstantUnion operator+(const ConstantUnion& constant) const
    { 
        ConstantUnion returnValue;
        assert(type == constant.type);
        switch (type) {
        case EbtInt: returnValue.setIConst(iConst + constant.iConst); break;
        case EbtUInt: returnValue.setUConst(uConst + constant.uConst); break;
        case EbtFloat: returnValue.setFConst(fConst + constant.fConst); break;
        default: assert(false && "Default missing");
        }

        return returnValue;
    }

    ConstantUnion operator-(const ConstantUnion& constant) const
    { 
        ConstantUnion returnValue;
        assert(type == constant.type);
        switch (type) {
        case EbtInt: returnValue.setIConst(iConst - constant.iConst); break;
        case EbtUInt: returnValue.setUConst(uConst - constant.uConst); break;
        case EbtFloat: returnValue.setFConst(fConst - constant.fConst); break;
        default: assert(false && "Default missing");
        }

        return returnValue;
    }

    ConstantUnion operator*(const ConstantUnion& constant) const
    { 
        ConstantUnion returnValue;
        assert(type == constant.type);
        switch (type) {
        case EbtInt: returnValue.setIConst(iConst * constant.iConst); break;
        case EbtUInt: returnValue.setUConst(uConst * constant.uConst); break;
        case EbtFloat: returnValue.setFConst(fConst * constant.fConst); break; 
        default: assert(false && "Default missing");
        }

        return returnValue;
    }

    ConstantUnion operator%(const ConstantUnion& constant) const
    { 
        ConstantUnion returnValue;
        assert(type == constant.type);
        switch (type) {
        case EbtInt: returnValue.setIConst(iConst % constant.iConst); break;
        case EbtUInt: returnValue.setUConst(uConst % constant.uConst); break;
        default:     assert(false && "Default missing");
        }

        return returnValue;
    }

    ConstantUnion operator>>(const ConstantUnion& constant) const
    { 
        ConstantUnion returnValue;
        assert(type == constant.type);
        switch (type) {
        case EbtInt: returnValue.setIConst(iConst >> constant.iConst); break;
        case EbtUInt: returnValue.setUConst(uConst >> constant.uConst); break;
        default:     assert(false && "Default missing");
        }

        return returnValue;
    }

    ConstantUnion operator<<(const ConstantUnion& constant) const
    { 
        ConstantUnion returnValue;
        // The signedness of the second parameter might be different, but we
        // don't care, since the result is undefined if the second parameter is
        // negative, and aliasing should not be a problem with unions.
        assert(constant.type == EbtInt || constant.type == EbtUInt);
        switch (type) {
        case EbtInt: returnValue.setIConst(iConst << constant.iConst); break;
        case EbtUInt: returnValue.setUConst(uConst << constant.uConst); break;
        default:     assert(false && "Default missing");
        }

        return returnValue;
    }

    ConstantUnion operator&(const ConstantUnion& constant) const
    { 
        ConstantUnion returnValue;
        assert(constant.type == EbtInt || constant.type == EbtUInt);
        switch (type) {
        case EbtInt:  returnValue.setIConst(iConst & constant.iConst); break;
        case EbtUInt:  returnValue.setUConst(uConst & constant.uConst); break;
        default:     assert(false && "Default missing");
        }

        return returnValue;
    }

    ConstantUnion operator|(const ConstantUnion& constant) const
    { 
        ConstantUnion returnValue;
        assert(type == constant.type);
        switch (type) {
        case EbtInt:  returnValue.setIConst(iConst | constant.iConst); break;
        case EbtUInt:  returnValue.setUConst(uConst | constant.uConst); break;
        default:     assert(false && "Default missing");
        }

        return returnValue;
    }

    ConstantUnion operator^(const ConstantUnion& constant) const
    { 
        ConstantUnion returnValue;
        assert(type == constant.type);
        switch (type) {
        case EbtInt:  returnValue.setIConst(iConst ^ constant.iConst); break;
        case EbtUInt:  returnValue.setUConst(uConst ^ constant.uConst); break;
        default:     assert(false && "Default missing");
        }

        return returnValue;
    }

    ConstantUnion operator&&(const ConstantUnion& constant) const
    { 
        ConstantUnion returnValue;
        assert(type == constant.type);
        switch (type) {
        case EbtBool: returnValue.setBConst(bConst && constant.bConst); break;
        default:     assert(false && "Default missing");
        }

        return returnValue;
    }

    ConstantUnion operator||(const ConstantUnion& constant) const
    { 
        ConstantUnion returnValue;
        assert(type == constant.type);
        switch (type) {
        case EbtBool: returnValue.setBConst(bConst || constant.bConst); break;
        default:     assert(false && "Default missing");
        }

        return returnValue;
    }

    TBasicType getType() const { return type; }
private:

    union  {
        int iConst;  // used for ivec, scalar ints
        unsigned int uConst; // used for uvec, scalar uints
        bool bConst; // used for bvec, scalar bools
        float fConst;   // used for vec, mat, scalar floats
    } ;

    TBasicType type;
};

#endif // _CONSTANT_UNION_INCLUDED_