glslang/glslang/MachineIndependent/parseConst.cpp

//
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//
// Travarse a tree of constants to create a single folded constant.
// It should only be used when the whole tree is known to be constant.
//

#include "ParseHelper.h"

namespace glslang {

class TConstTraverser : public TIntermTraverser {
public:
    TConstTraverser(TConstUnion* cUnion, bool singleConstParam, TOperator constructType, const TType& t) : unionArray(cUnion), type(t),
        constructorType(constructType), singleConstantParam(singleConstParam), error(false), isMatrix(false), 
        matrixCols(0), matrixRows(0) {  index = 0; tOp = EOpNull;}
    int index ;
    TConstUnion *unionArray;
    TOperator tOp;
    const TType& type;
    TOperator constructorType;
    bool singleConstantParam;
    bool error;
    int size; // size of the constructor ( 4 for vec4)
    bool isMatrix;
    int matrixCols;
    int matrixRows;
};

bool ParseAggregate(bool /* preVisit */, TIntermAggregate* node, TIntermTraverser* it)
{
    TConstTraverser* oit = static_cast<TConstTraverser*>(it);

    if (! node->isConstructor() && node->getOp() != EOpComma) {
        oit->error = true;

        return false;  
    }

    if (node->getSequence().size() == 0) {
        oit->error = true;

        return false;
    }

    bool flag = node->getSequence().size() == 1 && node->getSequence()[0]->getAsTyped()->getAsConstantUnion();
    if (flag) {
        oit->singleConstantParam = true; 
        oit->constructorType = node->getOp();
        oit->size = node->getType().getObjectSize();

        if (node->getType().isMatrix()) {
            oit->isMatrix = true;
            oit->matrixCols = node->getType().getMatrixCols();
            oit->matrixRows = node->getType().getMatrixRows();
        }
    }       

    for (TIntermSequence::iterator p = node->getSequence().begin(); 
                                   p != node->getSequence().end(); p++) {

        if (node->getOp() == EOpComma)
            oit->index = 0;           

        (*p)->traverse(oit);
    }   
    if (flag) 
    {
        oit->singleConstantParam = false;   
        oit->constructorType = EOpNull;
        oit->size = 0;
        oit->isMatrix = false;
        oit->matrixCols = 0;
        oit->matrixRows = 0;
    }

    return false;
}

void ParseConstantUnion(TIntermConstantUnion* node, TIntermTraverser* it)
{
    TConstTraverser* oit = static_cast<TConstTraverser*>(it);
    TConstUnion* leftUnionArray = oit->unionArray;
    int instanceSize = oit->type.getObjectSize();

    if (oit->index >= instanceSize)
        return;

    if (!oit->singleConstantParam) {
        int size = node->getType().getObjectSize();
    
        TConstUnion *rightUnionArray = node->getUnionArrayPointer();
        for (int i=0; i < size; i++) {
            if (oit->index >= instanceSize)
                return;
            leftUnionArray[oit->index] = rightUnionArray[i];

            (oit->index)++;
        }
    } else {
        int size, totalSize, matrixCols, matrixRows;
        bool isMatrix = false;
        size = oit->size;
        matrixCols = oit->matrixCols;
        matrixRows = oit->matrixRows;
        isMatrix = oit->isMatrix;
        totalSize = oit->index + size;
        TConstUnion *rightUnionArray = node->getUnionArrayPointer();
        if (! isMatrix) {
            int count = 0;
            for (int i = oit->index; i < totalSize; i++) {
                if (i >= instanceSize)
                    return;

                leftUnionArray[i] = rightUnionArray[count];

                (oit->index)++;
                
                if (node->getType().getObjectSize() > 1)
                    count++;
            }
        } else {  // for matrix constructors
            int count = 0;
            int index = oit->index;
            for (int i = index; i < totalSize; i++) {
                if (i >= instanceSize)
                    return;
                if (index - i == 0 || (i - index) % (matrixRows + 1) == 0 )
                    leftUnionArray[i] = rightUnionArray[count];
                else 
                    leftUnionArray[i].setDConst(0.0);

                (oit->index)++;

                if (node->getType().getObjectSize() > 1)
                    count++;                
            }
        }
    }
}

bool TIntermediate::parseConstTree(TSourceLoc line, TIntermNode* root, TConstUnion* unionArray, TOperator constructorType, const TType& t, bool singleConstantParam)
{
    if (root == 0)
        return false;

    TConstTraverser it(unionArray, singleConstantParam, constructorType, t);
    
    it.visitAggregate = ParseAggregate;
    it.visitConstantUnion = ParseConstantUnion;

    root->traverse(&it);
    if (it.error)
        return true;
    else
        return false;
}

} // end namespace glslang