src/compiler/translator/ParseContext.cpp

//
// 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.
//

#include "compiler/translator/ParseContext.h"

#include <stdarg.h>
#include <stdio.h>

#include "compiler/preprocessor/SourceLocation.h"
#include "compiler/translator/Cache.h"
#include "compiler/translator/glslang.h"
#include "compiler/translator/ValidateSwitch.h"
#include "compiler/translator/ValidateGlobalInitializer.h"
#include "compiler/translator/util.h"

///////////////////////////////////////////////////////////////////////
//
// Sub- vector and matrix fields
//
////////////////////////////////////////////////////////////////////////

//
// Look at a '.' field selector string and change it into offsets
// for a vector.
//
bool TParseContext::parseVectorFields(const TString &compString, int vecSize, TVectorFields &fields,
                                      const TSourceLoc &line)
{
    fields.num = (int) compString.size();
    if (fields.num > 4)
    {
        error(line, "illegal vector field selection", compString.c_str());
        return false;
    }

    enum {
        exyzw,
        ergba,
        estpq
    } fieldSet[4];

    for (int i = 0; i < fields.num; ++i)
    {
        switch (compString[i])
        {
          case 'x':
            fields.offsets[i] = 0;
            fieldSet[i] = exyzw;
            break;
          case 'r':
            fields.offsets[i] = 0;
            fieldSet[i] = ergba;
            break;
          case 's':
            fields.offsets[i] = 0;
            fieldSet[i] = estpq;
            break;
          case 'y':
            fields.offsets[i] = 1;
            fieldSet[i] = exyzw;
            break;
          case 'g':
            fields.offsets[i] = 1;
            fieldSet[i] = ergba;
            break;
          case 't':
            fields.offsets[i] = 1;
            fieldSet[i] = estpq;
            break;
          case 'z':
            fields.offsets[i] = 2;
            fieldSet[i] = exyzw;
            break;
          case 'b':
            fields.offsets[i] = 2;
            fieldSet[i] = ergba;
            break;
          case 'p':
            fields.offsets[i] = 2;
            fieldSet[i] = estpq;
            break;

          case 'w':
            fields.offsets[i] = 3;
            fieldSet[i] = exyzw;
            break;
          case 'a':
            fields.offsets[i] = 3;
            fieldSet[i] = ergba;
            break;
          case 'q':
            fields.offsets[i] = 3;
            fieldSet[i] = estpq;
            break;
          default:
            error(line, "illegal vector field selection", compString.c_str());
            return false;
        }
    }

    for (int i = 0; i < fields.num; ++i)
    {
        if (fields.offsets[i] >= vecSize)
        {
            error(line, "vector field selection out of range",  compString.c_str());
            return false;
        }

        if (i > 0)
        {
            if (fieldSet[i] != fieldSet[i-1])
            {
                error(line, "illegal - vector component fields not from the same set", compString.c_str());
                return false;
            }
        }
    }

    return true;
}


//
// Look at a '.' field selector string and change it into offsets
// for a matrix.
//
bool TParseContext::parseMatrixFields(const TString &compString, int matCols, int matRows, TMatrixFields &fields,
                                      const TSourceLoc &line)
{
    fields.wholeRow = false;
    fields.wholeCol = false;
    fields.row = -1;
    fields.col = -1;

    if (compString.size() != 2)
    {
        error(line, "illegal length of matrix field selection", compString.c_str());
        return false;
    }

    if (compString[0] == '_')
    {
        if (compString[1] < '0' || compString[1] > '3')
        {
            error(line, "illegal matrix field selection", compString.c_str());
            return false;
        }
        fields.wholeCol = true;
        fields.col = compString[1] - '0';
    }
    else if (compString[1] == '_')
    {
        if (compString[0] < '0' || compString[0] > '3')
        {
            error(line, "illegal matrix field selection", compString.c_str());
            return false;
        }
        fields.wholeRow = true;
        fields.row = compString[0] - '0';
    }
    else
    {
        if (compString[0] < '0' || compString[0] > '3' ||
            compString[1] < '0' || compString[1] > '3')
        {
            error(line, "illegal matrix field selection", compString.c_str());
            return false;
        }
        fields.row = compString[0] - '0';
        fields.col = compString[1] - '0';
    }

    if (fields.row >= matRows || fields.col >= matCols)
    {
        error(line, "matrix field selection out of range", compString.c_str());
        return false;
    }

    return true;
}

///////////////////////////////////////////////////////////////////////
//
// Errors
//
////////////////////////////////////////////////////////////////////////

//
// Track whether errors have occurred.
//
void TParseContext::recover()
{
}

//
// Used by flex/bison to output all syntax and parsing errors.
//
void TParseContext::error(const TSourceLoc &loc,
                          const char *reason, const char *token,
                          const char *extraInfo)
{
    pp::SourceLocation srcLoc;
    srcLoc.file = loc.first_file;
    srcLoc.line = loc.first_line;
    mDiagnostics.writeInfo(pp::Diagnostics::PP_ERROR,
                           srcLoc, reason, token, extraInfo);

}

void TParseContext::warning(const TSourceLoc &loc,
                            const char *reason, const char *token,
                            const char *extraInfo)
{
    pp::SourceLocation srcLoc;
    srcLoc.file = loc.first_file;
    srcLoc.line = loc.first_line;
    mDiagnostics.writeInfo(pp::Diagnostics::PP_WARNING,
                           srcLoc, reason, token, extraInfo);
}

//
// Same error message for all places assignments don't work.
//
void TParseContext::assignError(const TSourceLoc &line, const char *op, TString left, TString right)
{
    std::stringstream extraInfoStream;
    extraInfoStream << "cannot convert from '" << right << "' to '" << left << "'";
    std::string extraInfo = extraInfoStream.str();
    error(line, "", op, extraInfo.c_str());
}

//
// Same error message for all places unary operations don't work.
//
void TParseContext::unaryOpError(const TSourceLoc &line, const char *op, TString operand)
{
    std::stringstream extraInfoStream;
    extraInfoStream << "no operation '" << op << "' exists that takes an operand of type " << operand
                    << " (or there is no acceptable conversion)";
    std::string extraInfo = extraInfoStream.str();
    error(line, " wrong operand type", op, extraInfo.c_str());
}

//
// Same error message for all binary operations don't work.
//
void TParseContext::binaryOpError(const TSourceLoc &line, const char *op, TString left, TString right)
{
    std::stringstream extraInfoStream;
    extraInfoStream << "no operation '" << op << "' exists that takes a left-hand operand of type '" << left
                    << "' and a right operand of type '" << right << "' (or there is no acceptable conversion)";
    std::string extraInfo = extraInfoStream.str();
    error(line, " wrong operand types ", op, extraInfo.c_str());
}

bool TParseContext::precisionErrorCheck(const TSourceLoc &line, TPrecision precision, TBasicType type)
{
    if (!mChecksPrecisionErrors)
        return false;
    switch(type)
    {
      case EbtFloat:
        if( precision == EbpUndefined )
        {
            error( line, "No precision specified for (float)", "" );
            return true;
        }
        break;
      case EbtInt:
        if( precision == EbpUndefined )
        {
            error( line, "No precision specified (int)", "" );
            return true;
        }
        break;
      default:
        return false;
    }
    return false;
}

//
// Both test and if necessary, spit out an error, to see if the node is really
// an l-value that can be operated on this way.
//
// Returns true if the was an error.
//
bool TParseContext::lValueErrorCheck(const TSourceLoc &line, const char *op, TIntermTyped *node)
{
    TIntermSymbol *symNode = node->getAsSymbolNode();
    TIntermBinary *binaryNode = node->getAsBinaryNode();

    if (binaryNode)
    {
        bool errorReturn;

        switch(binaryNode->getOp())
        {
          case EOpIndexDirect:
          case EOpIndexIndirect:
          case EOpIndexDirectStruct:
          case EOpIndexDirectInterfaceBlock:
            return lValueErrorCheck(line, op, binaryNode->getLeft());
          case EOpVectorSwizzle:
            errorReturn = lValueErrorCheck(line, op, binaryNode->getLeft());
            if (!errorReturn)
            {
                int offset[4] = {0,0,0,0};

                TIntermTyped *rightNode = binaryNode->getRight();
                TIntermAggregate *aggrNode = rightNode->getAsAggregate();

                for (TIntermSequence::iterator p = aggrNode->getSequence()->begin();
                                               p != aggrNode->getSequence()->end(); p++)
                {
                    int value = (*p)->getAsTyped()->getAsConstantUnion()->getIConst(0);
                    offset[value]++;
                    if (offset[value] > 1)
                    {
                        error(line, " l-value of swizzle cannot have duplicate components", op);

                        return true;
                    }
                }
            }

            return errorReturn;
          default:
            break;
        }
        error(line, " l-value required", op);

        return true;
    }


    const char *symbol = 0;
    if (symNode != 0)
        symbol = symNode->getSymbol().c_str();

    const char *message = 0;
    switch (node->getQualifier())
    {
      case EvqConst:
        message = "can't modify a const";
        break;
      case EvqConstReadOnly:
        message = "can't modify a const";
        break;
      case EvqAttribute:
        message = "can't modify an attribute";
        break;
      case EvqFragmentIn:
        message = "can't modify an input";
        break;
      case EvqVertexIn:
        message = "can't modify an input";
        break;
      case EvqUniform:
        message = "can't modify a uniform";
        break;
      case EvqVaryingIn:
        message = "can't modify a varying";
        break;
      case EvqFragCoord:
        message = "can't modify gl_FragCoord";
        break;
      case EvqFrontFacing:
        message = "can't modify gl_FrontFacing";
        break;
      case EvqPointCoord:
        message = "can't modify gl_PointCoord";
        break;
      default:
        //
        // Type that can't be written to?
        //
        if (node->getBasicType() == EbtVoid)
        {
            message = "can't modify void";
        }
        if (IsSampler(node->getBasicType()))
        {
            message = "can't modify a sampler";
        }
    }

    if (message == 0 && binaryNode == 0 && symNode == 0)
    {
        error(line, " l-value required", op);

        return true;
    }


    //
    // Everything else is okay, no error.
    //
    if (message == 0)
        return false;

    //
    // If we get here, we have an error and a message.
    //
    if (symNode)
    {
        std::stringstream extraInfoStream;
        extraInfoStream << "\"" << symbol << "\" (" << message << ")";
        std::string extraInfo = extraInfoStream.str();
        error(line, " l-value required", op, extraInfo.c_str());
    }
    else
    {
        std::stringstream extraInfoStream;
        extraInfoStream << "(" << message << ")";
        std::string extraInfo = extraInfoStream.str();
        error(line, " l-value required", op, extraInfo.c_str());
    }

    return true;
}

//
// Both test, and if necessary spit out an error, to see if the node is really
// a constant.
//
// Returns true if the was an error.
//
bool TParseContext::constErrorCheck(TIntermTyped *node)
{
    if (node->getQualifier() == EvqConst)
        return false;

    error(node->getLine(), "constant expression required", "");

    return true;
}

//
// Both test, and if necessary spit out an error, to see if the node is really
// an integer.
//
// Returns true if the was an error.
//
bool TParseContext::integerErrorCheck(TIntermTyped *node, const char *token)
{
    if (node->isScalarInt())
        return false;

    error(node->getLine(), "integer expression required", token);

    return true;
}

//
// Both test, and if necessary spit out an error, to see if we are currently
// globally scoped.
//
// Returns true if the was an error.
//
bool TParseContext::globalErrorCheck(const TSourceLoc &line, bool global, const char *token)
{
    if (global)
        return false;

    error(line, "only allowed at global scope", token);

    return true;
}

//
// For now, keep it simple:  if it starts "gl_", it's reserved, independent
// of scope.  Except, if the symbol table is at the built-in push-level,
// which is when we are parsing built-ins.
// Also checks for "webgl_" and "_webgl_" reserved identifiers if parsing a
// webgl shader.
//
// Returns true if there was an error.
//
bool TParseContext::reservedErrorCheck(const TSourceLoc &line, const TString &identifier)
{
    static const char *reservedErrMsg = "reserved built-in name";
    if (!symbolTable.atBuiltInLevel())
    {
        if (identifier.compare(0, 3, "gl_") == 0)
        {
            error(line, reservedErrMsg, "gl_");
            return true;
        }
        if (IsWebGLBasedSpec(mShaderSpec))
        {
            if (identifier.compare(0, 6, "webgl_") == 0)
            {
                error(line, reservedErrMsg, "webgl_");
                return true;
            }
            if (identifier.compare(0, 7, "_webgl_") == 0)
            {
                error(line, reservedErrMsg, "_webgl_");
                return true;
            }
            if (mShaderSpec == SH_CSS_SHADERS_SPEC && identifier.compare(0, 4, "css_") == 0)
            {
                error(line, reservedErrMsg, "css_");
                return true;
            }
        }
        if (identifier.find("__") != TString::npos)
        {
            error(line,
                  "identifiers containing two consecutive underscores (__) are reserved as possible future keywords",
                  identifier.c_str());
            return true;
        }
    }

    return false;
}

//
// Make sure there is enough data provided to the constructor to build
// something of the type of the constructor.  Also returns the type of
// the constructor.
//
// Returns true if there was an error in construction.
//
bool TParseContext::constructorErrorCheck(const TSourceLoc &line, TIntermNode *node, TFunction &function, TOperator op,
                                          TType *type)
{
    *type = function.getReturnType();

    bool constructingMatrix = false;
    switch(op)
    {
      case EOpConstructMat2:
      case EOpConstructMat2x3:
      case EOpConstructMat2x4:
      case EOpConstructMat3x2:
      case EOpConstructMat3:
      case EOpConstructMat3x4:
      case EOpConstructMat4x2:
      case EOpConstructMat4x3:
      case EOpConstructMat4:
        constructingMatrix = true;
        break;
      default:
        break;
    }

    //
    // Note: It's okay to have too many components available, but not okay to have unused
    // arguments.  'full' will go to true when enough args have been seen.  If we loop
    // again, there is an extra argument, so 'overfull' will become true.
    //

    size_t size = 0;
    bool constType = true;
    bool full = false;
    bool overFull = false;
    bool matrixInMatrix = false;
    bool arrayArg = false;
    for (size_t i = 0; i < function.getParamCount(); ++i)
    {
        const TConstParameter &param = function.getParam(i);
        size += param.type->getObjectSize();

        if (constructingMatrix && param.type->isMatrix())
            matrixInMatrix = true;
        if (full)
            overFull = true;
        if (op != EOpConstructStruct && !type->isArray() && size >= type->getObjectSize())
            full = true;
        if (param.type->getQualifier() != EvqConst)
            constType = false;
        if (param.type->isArray())
            arrayArg = true;
    }

    if (constType)
        type->setQualifier(EvqConst);

    if (type->isArray())
    {
        if (type->isUnsizedArray())
        {
            type->setArraySize(function.getParamCount());
        }
        else if (static_cast<size_t>(type->getArraySize()) != function.getParamCount())
        {
            error(line, "array constructor needs one argument per array element", "constructor");
            return true;
        }
    }

    if (arrayArg && op != EOpConstructStruct)
    {
        error(line, "constructing from a non-dereferenced array", "constructor");
        return true;
    }

    if (matrixInMatrix && !type->isArray())
    {
        if (function.getParamCount() != 1)
        {
          error(line, "constructing matrix from matrix can only take one argument", "constructor");
          return true;
        }
    }

    if (overFull)
    {
        error(line, "too many arguments", "constructor");
        return true;
    }

    if (op == EOpConstructStruct && !type->isArray() && type->getStruct()->fields().size() != function.getParamCount())
    {
        error(line, "Number of constructor parameters does not match the number of structure fields", "constructor");
        return true;
    }

    if (!type->isMatrix() || !matrixInMatrix)
    {
        if ((op != EOpConstructStruct && size != 1 && size < type->getObjectSize()) ||
            (op == EOpConstructStruct && size < type->getObjectSize()))
        {
            error(line, "not enough data provided for construction", "constructor");
            return true;
        }
    }

    TIntermTyped *typed = node ? node->getAsTyped() : 0;
    if (typed == 0)
    {
        error(line, "constructor argument does not have a type", "constructor");
        return true;
    }
    if (op != EOpConstructStruct && IsSampler(typed->getBasicType()))
    {
        error(line, "cannot convert a sampler", "constructor");
        return true;
    }
    if (typed->getBasicType() == EbtVoid)
    {
        error(line, "cannot convert a void", "constructor");
        return true;
    }

    return false;
}

// This function checks to see if a void variable has been declared and raise an error message for such a case
//
// returns true in case of an error
//
bool TParseContext::voidErrorCheck(const TSourceLoc &line, const TString &identifier, const TBasicType &type)
{
    if (type == EbtVoid)
    {
        error(line, "illegal use of type 'void'", identifier.c_str());
        return true;
    }

    return false;
}

// This function checks to see if the node (for the expression) contains a scalar boolean expression or not
//
// returns true in case of an error
//
bool TParseContext::boolErrorCheck(const TSourceLoc &line, const TIntermTyped *type)
{
    if (type->getBasicType() != EbtBool || type->isArray() || type->isMatrix() || type->isVector())
    {
        error(line, "boolean expression expected", "");
        return true;
    }

    return false;
}

// This function checks to see if the node (for the expression) contains a scalar boolean expression or not
//
// returns true in case of an error
//
bool TParseContext::boolErrorCheck(const TSourceLoc &line, const TPublicType &pType)
{
    if (pType.type != EbtBool || pType.isAggregate())
    {
        error(line, "boolean expression expected", "");
        return true;
    }

    return false;
}

bool TParseContext::samplerErrorCheck(const TSourceLoc &line, const TPublicType &pType, const char *reason)
{
    if (pType.type == EbtStruct)
    {
        if (containsSampler(*pType.userDef))
        {
            error(line, reason, getBasicString(pType.type), "(structure contains a sampler)");

            return true;
        }

        return false;
    }
    else if (IsSampler(pType.type))
    {
        error(line, reason, getBasicString(pType.type));

        return true;
    }

    return false;
}

bool TParseContext::locationDeclaratorListCheck(const TSourceLoc &line, const TPublicType &pType)
{
    if (pType.layoutQualifier.location != -1)
    {
        error(line, "location must only be specified for a single input or output variable", "location");
        return true;
    }

    return false;
}

bool TParseContext::parameterSamplerErrorCheck(const TSourceLoc &line, TQualifier qualifier, const TType &type)
{
    if ((qualifier == EvqOut || qualifier == EvqInOut) &&
             type.getBasicType() != EbtStruct && IsSampler(type.getBasicType()))
    {
        error(line, "samplers cannot be output parameters", type.getBasicString());
        return true;
    }

    return false;
}

bool TParseContext::containsSampler(const TType &type)
{
    if (IsSampler(type.getBasicType()))
        return true;

    if (type.getBasicType() == EbtStruct || type.isInterfaceBlock())
    {
        const TFieldList &fields = type.getStruct()->fields();
        for (unsigned int i = 0; i < fields.size(); ++i)
        {
            if (containsSampler(*fields[i]->type()))
                return true;
        }
    }

    return false;
}

//
// Do size checking for an array type's size.
//
// Returns true if there was an error.
//
bool TParseContext::arraySizeErrorCheck(const TSourceLoc &line, TIntermTyped *expr, int &size)
{
    TIntermConstantUnion *constant = expr->getAsConstantUnion();

    if (constant == nullptr || !constant->isScalarInt())
    {
        error(line, "array size must be a constant integer expression", "");
        size = 1;
        return true;
    }

    unsigned int unsignedSize = 0;

    if (constant->getBasicType() == EbtUInt)
    {
        unsignedSize = constant->getUConst(0);
        size = static_cast<int>(unsignedSize);
    }
    else
    {
        size = constant->getIConst(0);

        if (size < 0)
        {
            error(line, "array size must be non-negative", "");
            size = 1;
            return true;
        }

        unsignedSize = static_cast<unsigned int>(size);
    }

    if (size == 0)
    {
        error(line, "array size must be greater than zero", "");
        size = 1;
        return true;
    }

    // The size of arrays is restricted here to prevent issues further down the
    // compiler/translator/driver stack. Shader Model 5 generation hardware is limited to
    // 4096 registers so this should be reasonable even for aggressively optimizable code.
    const unsigned int sizeLimit = 65536;

    if (unsignedSize > sizeLimit)
    {
        error(line, "array size too large", "");
        size = 1;
        return true;
    }

    return false;
}

//
// See if this qualifier can be an array.
//
// Returns true if there is an error.
//
bool TParseContext::arrayQualifierErrorCheck(const TSourceLoc &line, const TPublicType &type)
{
    if ((type.qualifier == EvqAttribute) || (type.qualifier == EvqVertexIn) ||
        (type.qualifier == EvqConst && mShaderVersion < 300))
    {
        error(line, "cannot declare arrays of this qualifier", TType(type).getCompleteString().c_str());
        return true;
    }

    return false;
}

//
// See if this type can be an array.
//
// Returns true if there is an error.
//
bool TParseContext::arrayTypeErrorCheck(const TSourceLoc &line, const TPublicType &type)
{
    //
    // Can the type be an array?
    //
    if (type.array)
    {
        error(line, "cannot declare arrays of arrays", TType(type).getCompleteString().c_str());
        return true;
    }

    return false;
}

//
// Enforce non-initializer type/qualifier rules.
//
// Returns true if there was an error.
//
bool TParseContext::nonInitErrorCheck(const TSourceLoc &line, const TString &identifier, TPublicType *type)
{
    ASSERT(type != nullptr);
    if (type->qualifier == EvqConst)
    {
        // Make the qualifier make sense.
        type->qualifier = EvqTemporary;

        // Generate informative error messages for ESSL1.
        // In ESSL3 arrays and structures containing arrays can be constant.
        if (mShaderVersion < 300 && type->isStructureContainingArrays())
        {
            error(line,
                  "structures containing arrays may not be declared constant since they cannot be initialized",
                  identifier.c_str());
        }
        else
        {
            error(line, "variables with qualifier 'const' must be initialized", identifier.c_str());
        }

        return true;
    }
    if (type->isUnsizedArray())
    {
        error(line, "implicitly sized arrays need to be initialized", identifier.c_str());
        return true;
    }
    return false;
}

// Do some simple checks that are shared between all variable declarations,
// and update the symbol table.
//
// Returns true if declaring the variable succeeded.
//
bool TParseContext::declareVariable(const TSourceLoc &line, const TString &identifier, const TType &type,
                                    TVariable **variable)
{
    ASSERT((*variable) == nullptr);

    bool needsReservedErrorCheck = true;

    // gl_LastFragData may be redeclared with a new precision qualifier
    if (type.isArray() && identifier.compare(0, 15, "gl_LastFragData") == 0)
    {
        const TVariable *maxDrawBuffers =
            static_cast<const TVariable *>(symbolTable.findBuiltIn("gl_MaxDrawBuffers", mShaderVersion));
        if (type.getArraySize() == maxDrawBuffers->getConstPointer()->getIConst())
        {
            if (TSymbol *builtInSymbol = symbolTable.findBuiltIn(identifier, mShaderVersion))
            {
                needsReservedErrorCheck = extensionErrorCheck(line, builtInSymbol->getExtension());
            }
        }
        else
        {
            error(line, "redeclaration of gl_LastFragData with size != gl_MaxDrawBuffers", identifier.c_str());
            return false;
        }
    }

    if (needsReservedErrorCheck && reservedErrorCheck(line, identifier))
        return false;

    (*variable) = new TVariable(&identifier, type);
    if (!symbolTable.declare(*variable))
    {
        error(line, "redefinition", identifier.c_str());
        delete (*variable);
        (*variable) = nullptr;
        return false;
    }

    if (voidErrorCheck(line, identifier, type.getBasicType()))
        return false;

    return true;
}

bool TParseContext::paramErrorCheck(const TSourceLoc &line, TQualifier qualifier, TQualifier paramQualifier,
                                    TType *type)
{
    if (qualifier != EvqConst && qualifier != EvqTemporary)
    {
        error(line, "qualifier not allowed on function parameter", getQualifierString(qualifier));
        return true;
    }
    if (qualifier == EvqConst && paramQualifier != EvqIn)
    {
        error(line, "qualifier not allowed with ", getQualifierString(qualifier), getQualifierString(paramQualifier));
        return true;
    }

    if (qualifier == EvqConst)
        type->setQualifier(EvqConstReadOnly);
    else
        type->setQualifier(paramQualifier);

    return false;
}

bool TParseContext::extensionErrorCheck(const TSourceLoc &line, const TString &extension)
{
    const TExtensionBehavior &extBehavior = extensionBehavior();
    TExtensionBehavior::const_iterator iter = extBehavior.find(extension.c_str());
    if (iter == extBehavior.end())
    {
        error(line, "extension", extension.c_str(), "is not supported");
        return true;
    }
    // In GLSL ES, an extension's default behavior is "disable".
    if (iter->second == EBhDisable || iter->second == EBhUndefined)
    {
        error(line, "extension", extension.c_str(), "is disabled");
        return true;
    }
    if (iter->second == EBhWarn)
    {
        warning(line, "extension", extension.c_str(), "is being used");
        return false;
    }

    return false;
}

// These checks are common for all declarations starting a declarator list, and declarators that follow an empty
// declaration.
//
bool TParseContext::singleDeclarationErrorCheck(const TPublicType &publicType, const TSourceLoc &identifierLocation)
{
    switch (publicType.qualifier)
    {
      case EvqVaryingIn:
      case EvqVaryingOut:
      case EvqAttribute:
      case EvqVertexIn:
      case EvqFragmentOut:
        if (publicType.type == EbtStruct)
        {
            error(identifierLocation, "cannot be used with a structure",
                  getQualifierString(publicType.qualifier));
            return true;
        }

      default: break;
    }

    if (publicType.qualifier != EvqUniform && samplerErrorCheck(identifierLocation, publicType,
                                                                "samplers must be uniform"))
    {
        return true;
    }

    // check for layout qualifier issues
    const TLayoutQualifier layoutQualifier = publicType.layoutQualifier;

    if (layoutQualifier.matrixPacking != EmpUnspecified)
    {
        error(identifierLocation, "layout qualifier", getMatrixPackingString(layoutQualifier.matrixPacking),
              "only valid for interface blocks");
        return true;
    }

    if (layoutQualifier.blockStorage != EbsUnspecified)
    {
        error(identifierLocation, "layout qualifier", getBlockStorageString(layoutQualifier.blockStorage),
              "only valid for interface blocks");
        return true;
    }

    if (publicType.qualifier != EvqVertexIn && publicType.qualifier != EvqFragmentOut &&
        layoutLocationErrorCheck(identifierLocation, publicType.layoutQualifier))
    {
        return true;
    }

    return false;
}

bool TParseContext::layoutLocationErrorCheck(const TSourceLoc &location, const TLayoutQualifier &layoutQualifier)
{
    if (layoutQualifier.location != -1)
    {
        error(location, "invalid layout qualifier:", "location", "only valid on program inputs and outputs");
        return true;
    }

    return false;
}

bool TParseContext::functionCallLValueErrorCheck(const TFunction *fnCandidate, TIntermAggregate *aggregate)
{
    for (size_t i = 0; i < fnCandidate->getParamCount(); ++i)
    {
        TQualifier qual = fnCandidate->getParam(i).type->getQualifier();
        if (qual == EvqOut || qual == EvqInOut)
        {
            TIntermTyped *node = (*(aggregate->getSequence()))[i]->getAsTyped();
            if (lValueErrorCheck(node->getLine(), "assign", node))
            {
                error(node->getLine(),
                    "Constant value cannot be passed for 'out' or 'inout' parameters.", "Error");
                recover();
                return true;
            }
        }
    }
    return false;
}

void TParseContext::es3InvariantErrorCheck(const TQualifier qualifier, const TSourceLoc &invariantLocation)
{
    if (!sh::IsVaryingOut(qualifier) && qualifier != EvqFragmentOut)
    {
        error(invariantLocation, "Only out variables can be invariant.", "invariant");
        recover();
    }
}

bool TParseContext::supportsExtension(const char *extension)
{
    const TExtensionBehavior &extbehavior = extensionBehavior();
    TExtensionBehavior::const_iterator iter = extbehavior.find(extension);
    return (iter != extbehavior.end());
}

bool TParseContext::isExtensionEnabled(const char *extension) const
{
    const TExtensionBehavior &extbehavior = extensionBehavior();
    TExtensionBehavior::const_iterator iter = extbehavior.find(extension);

    if (iter == extbehavior.end())
    {
        return false;
    }

    return (iter->second == EBhEnable || iter->second == EBhRequire);
}

void TParseContext::handleExtensionDirective(const TSourceLoc &loc, const char *extName, const char *behavior)
{
    pp::SourceLocation srcLoc;
    srcLoc.file = loc.first_file;
    srcLoc.line = loc.first_line;
    mDirectiveHandler.handleExtension(srcLoc, extName, behavior);
}

void TParseContext::handlePragmaDirective(const TSourceLoc &loc, const char *name, const char *value, bool stdgl)
{
    pp::SourceLocation srcLoc;
    srcLoc.file = loc.first_file;
    srcLoc.line = loc.first_line;
    mDirectiveHandler.handlePragma(srcLoc, name, value, stdgl);
}

/////////////////////////////////////////////////////////////////////////////////
//
// Non-Errors.
//
/////////////////////////////////////////////////////////////////////////////////

const TVariable *TParseContext::getNamedVariable(const TSourceLoc &location,
                                                 const TString *name,
                                                 const TSymbol *symbol)
{
    const TVariable *variable = NULL;

    if (!symbol)
    {
        error(location, "undeclared identifier", name->c_str());
        recover();
    }
    else if (!symbol->isVariable())
    {
        error(location, "variable expected", name->c_str());
        recover();
    }
    else
    {
        variable = static_cast<const TVariable*>(symbol);

        if (symbolTable.findBuiltIn(variable->getName(), mShaderVersion) &&
            !variable->getExtension().empty() &&
            extensionErrorCheck(location, variable->getExtension()))
        {
            recover();
        }

        // Reject shaders using both gl_FragData and gl_FragColor
        TQualifier qualifier = variable->getType().getQualifier();
        if (qualifier == EvqFragData)
        {
            mUsesFragData = true;
        }
        else if (qualifier == EvqFragColor)
        {
            mUsesFragColor = true;
        }

        // This validation is not quite correct - it's only an error to write to
        // both FragData and FragColor. For simplicity, and because users shouldn't
        // be rewarded for reading from undefined varaibles, return an error
        // if they are both referenced, rather than assigned.
        if (mUsesFragData && mUsesFragColor)
        {
            error(location, "cannot use both gl_FragData and gl_FragColor", name->c_str());
            recover();
        }
    }

    if (!variable)
    {
        TType type(EbtFloat, EbpUndefined);
        TVariable *fakeVariable = new TVariable(name, type);
        symbolTable.declare(fakeVariable);
        variable = fakeVariable;
    }

    return variable;
}

//
// Look up a function name in the symbol table, and make sure it is a function.
//
// Return the function symbol if found, otherwise 0.
//
const TFunction *TParseContext::findFunction(const TSourceLoc &line, TFunction *call, int inputShaderVersion,
                                             bool *builtIn)
{
    // First find by unmangled name to check whether the function name has been
    // hidden by a variable name or struct typename.
    // If a function is found, check for one with a matching argument list.
    const TSymbol *symbol = symbolTable.find(call->getName(), inputShaderVersion, builtIn);
    if (symbol == 0 || symbol->isFunction())
    {
        symbol = symbolTable.find(call->getMangledName(), inputShaderVersion, builtIn);
    }

    if (symbol == 0)
    {
        error(line, "no matching overloaded function found", call->getName().c_str());
        return 0;
    }

    if (!symbol->isFunction())
    {
        error(line, "function name expected", call->getName().c_str());
        return 0;
    }

    return static_cast<const TFunction*>(symbol);
}

//
// Initializers show up in several places in the grammar.  Have one set of
// code to handle them here.
//
// Returns true on error, false if no error
//
bool TParseContext::executeInitializer(const TSourceLoc &line, const TString &identifier, const TPublicType &pType,
                                       TIntermTyped *initializer, TIntermNode **intermNode)
{
    ASSERT(intermNode != nullptr);
    TType type = TType(pType);

    TVariable *variable = nullptr;
    if (type.isUnsizedArray())
    {
        type.setArraySize(initializer->getArraySize());
    }
    if (!declareVariable(line, identifier, type, &variable))
    {
        return true;
    }

    bool globalInitWarning = false;
    if (symbolTable.atGlobalLevel() && !ValidateGlobalInitializer(initializer, this, &globalInitWarning))
    {
        // Error message does not completely match behavior with ESSL 1.00, but
        // we want to steer developers towards only using constant expressions.
        error(line, "global variable initializers must be constant expressions", "=");
        return true;
    }
    if (globalInitWarning)
    {
        warning(line, "global variable initializers should be constant expressions "
                "(uniforms and globals are allowed in global initializers for legacy compatibility)", "=");
    }

    //
    // identifier must be of type constant, a global, or a temporary
    //
    TQualifier qualifier = variable->getType().getQualifier();
    if ((qualifier != EvqTemporary) && (qualifier != EvqGlobal) && (qualifier != EvqConst))
    {
        error(line, " cannot initialize this type of qualifier ", variable->getType().getQualifierString());
        return true;
    }
    //
    // test for and propagate constant
    //

    if (qualifier == EvqConst)
    {
        if (qualifier != initializer->getType().getQualifier())
        {
            std::stringstream extraInfoStream;
            extraInfoStream << "'" << variable->getType().getCompleteString() << "'";
            std::string extraInfo = extraInfoStream.str();
            error(line, " assigning non-constant to", "=", extraInfo.c_str());
            variable->getType().setQualifier(EvqTemporary);
            return true;
        }
        if (type != initializer->getType())
        {
            error(line, " non-matching types for const initializer ",
                variable->getType().getQualifierString());
            variable->getType().setQualifier(EvqTemporary);
            return true;
        }
        if (initializer->getAsConstantUnion())
        {
            variable->shareConstPointer(initializer->getAsConstantUnion()->getUnionArrayPointer());
        }
        else if (initializer->getAsSymbolNode())
        {
            const TSymbol *symbol = symbolTable.find(initializer->getAsSymbolNode()->getSymbol(), 0);
            const TVariable *tVar = static_cast<const TVariable*>(symbol);

            TConstantUnion *constArray = tVar->getConstPointer();
            variable->shareConstPointer(constArray);
        }
        else
        {
            std::stringstream extraInfoStream;
            extraInfoStream << "'" << variable->getType().getCompleteString() << "'";
            std::string extraInfo = extraInfoStream.str();
            error(line, " cannot assign to", "=", extraInfo.c_str());
            variable->getType().setQualifier(EvqTemporary);
            return true;
        }
    }

    if (qualifier != EvqConst)
    {
        TIntermSymbol *intermSymbol = intermediate.addSymbol(variable->getUniqueId(), variable->getName(),
                                                             variable->getType(), line);
        *intermNode = createAssign(EOpInitialize, intermSymbol, initializer, line);
        if (*intermNode == nullptr)
        {
            assignError(line, "=", intermSymbol->getCompleteString(), initializer->getCompleteString());
            return true;
        }
    }
    else
    {
        *intermNode = nullptr;
    }

    return false;
}

bool TParseContext::areAllChildConst(TIntermAggregate *aggrNode)
{
    ASSERT(aggrNode != NULL);
    if (!aggrNode->isConstructor())
        return false;

    bool allConstant = true;

    // check if all the child nodes are constants so that they can be inserted into
    // the parent node
    TIntermSequence *sequence = aggrNode->getSequence() ;
    for (TIntermSequence::iterator p = sequence->begin(); p != sequence->end(); ++p)
    {
        if (!(*p)->getAsTyped()->getAsConstantUnion())
            return false;
    }

    return allConstant;
}

TPublicType TParseContext::addFullySpecifiedType(TQualifier qualifier, bool invariant, TLayoutQualifier layoutQualifier,
                                                 const TPublicType &typeSpecifier)
{
    TPublicType returnType = typeSpecifier;
    returnType.qualifier = qualifier;
    returnType.invariant = invariant;
    returnType.layoutQualifier = layoutQualifier;

    if (mShaderVersion < 300)
    {
        if (typeSpecifier.array)
        {
            error(typeSpecifier.line, "not supported", "first-class array");
            recover();
            returnType.clearArrayness();
        }

        if (qualifier == EvqAttribute && (typeSpecifier.type == EbtBool || typeSpecifier.type == EbtInt))
        {
            error(typeSpecifier.line, "cannot be bool or int", getQualifierString(qualifier));
            recover();
        }

        if ((qualifier == EvqVaryingIn || qualifier == EvqVaryingOut) &&
            (typeSpecifier.type == EbtBool || typeSpecifier.type == EbtInt))
        {
            error(typeSpecifier.line, "cannot be bool or int", getQualifierString(qualifier));
            recover();
        }
    }
    else
    {
        if (!layoutQualifier.isEmpty())
        {
            if (globalErrorCheck(typeSpecifier.line, symbolTable.atGlobalLevel(), "layout"))
            {
                recover();
            }
        }
        switch (qualifier)
        {
          case EvqSmoothIn:
          case EvqSmoothOut:
          case EvqVertexOut:
          case EvqFragmentIn:
          case EvqCentroidOut:
          case EvqCentroidIn:
            if (typeSpecifier.type == EbtBool)
            {
                error(typeSpecifier.line, "cannot be bool", getQualifierString(qualifier));
                recover();
            }
            if (typeSpecifier.type == EbtInt || typeSpecifier.type == EbtUInt)
            {
                error(typeSpecifier.line, "must use 'flat' interpolation here", getQualifierString(qualifier));
                recover();
            }
            break;

          case EvqVertexIn:
          case EvqFragmentOut:
          case EvqFlatIn:
          case EvqFlatOut:
            if (typeSpecifier.type == EbtBool)
            {
                error(typeSpecifier.line, "cannot be bool", getQualifierString(qualifier));
                recover();
            }
            break;

          default: break;
        }
    }

    return returnType;
}

TIntermAggregate *TParseContext::parseSingleDeclaration(TPublicType &publicType,
                                                        const TSourceLoc &identifierOrTypeLocation,
                                                        const TString &identifier)
{
    TIntermSymbol *symbol = intermediate.addSymbol(0, identifier, TType(publicType), identifierOrTypeLocation);

    bool emptyDeclaration = (identifier == "");

    mDeferredSingleDeclarationErrorCheck = emptyDeclaration;

    if (emptyDeclaration)
    {
        if (publicType.isUnsizedArray())
        {
            // ESSL3 spec section 4.1.9: Array declaration which leaves the size unspecified is an error.
            // It is assumed that this applies to empty declarations as well.
            error(identifierOrTypeLocation, "empty array declaration needs to specify a size", identifier.c_str());
        }
    }
    else
    {
        if (singleDeclarationErrorCheck(publicType, identifierOrTypeLocation))
            recover();

        if (nonInitErrorCheck(identifierOrTypeLocation, identifier, &publicType))
            recover();

        TVariable *variable = nullptr;
        if (!declareVariable(identifierOrTypeLocation, identifier, TType(publicType), &variable))
            recover();

        if (variable && symbol)
            symbol->setId(variable->getUniqueId());
    }

    return intermediate.makeAggregate(symbol, identifierOrTypeLocation);
}

TIntermAggregate *TParseContext::parseSingleArrayDeclaration(TPublicType &publicType,
                                                             const TSourceLoc &identifierLocation,
                                                             const TString &identifier,
                                                             const TSourceLoc &indexLocation,
                                                             TIntermTyped *indexExpression)
{
    mDeferredSingleDeclarationErrorCheck = false;

    if (singleDeclarationErrorCheck(publicType, identifierLocation))
        recover();

    if (nonInitErrorCheck(identifierLocation, identifier, &publicType))
        recover();

    if (arrayTypeErrorCheck(indexLocation, publicType) || arrayQualifierErrorCheck(indexLocation, publicType))
    {
        recover();
    }

    TType arrayType(publicType);

    int size;
    if (arraySizeErrorCheck(identifierLocation, indexExpression, size))
    {
        recover();
    }
    // Make the type an array even if size check failed.
    // This ensures useless error messages regarding the variable's non-arrayness won't follow.
    arrayType.setArraySize(size);

    TVariable *variable = nullptr;
    if (!declareVariable(identifierLocation, identifier, arrayType, &variable))
        recover();

    TIntermSymbol *symbol = intermediate.addSymbol(0, identifier, arrayType, identifierLocation);
    if (variable && symbol)
        symbol->setId(variable->getUniqueId());

    return intermediate.makeAggregate(symbol, identifierLocation);
}

TIntermAggregate *TParseContext::parseSingleInitDeclaration(const TPublicType &publicType,
                                                            const TSourceLoc &identifierLocation,
                                                            const TString &identifier,
                                                            const TSourceLoc &initLocation,
                                                            TIntermTyped *initializer)
{
    mDeferredSingleDeclarationErrorCheck = false;

    if (singleDeclarationErrorCheck(publicType, identifierLocation))
        recover();

    TIntermNode *intermNode = nullptr;
    if (!executeInitializer(identifierLocation, identifier, publicType, initializer, &intermNode))
    {
        //
        // Build intermediate representation
        //
        return intermNode ? intermediate.makeAggregate(intermNode, initLocation) : nullptr;
    }
    else
    {
        recover();
        return nullptr;
    }
}

TIntermAggregate *TParseContext::parseSingleArrayInitDeclaration(TPublicType &publicType,
                                                                 const TSourceLoc &identifierLocation,
                                                                 const TString &identifier,
                                                                 const TSourceLoc &indexLocation,
                                                                 TIntermTyped *indexExpression,
                                                                 const TSourceLoc &initLocation,
                                                                 TIntermTyped *initializer)
{
    mDeferredSingleDeclarationErrorCheck = false;

    if (singleDeclarationErrorCheck(publicType, identifierLocation))
        recover();

    if (arrayTypeErrorCheck(indexLocation, publicType) || arrayQualifierErrorCheck(indexLocation, publicType))
    {
        recover();
    }

    TPublicType arrayType(publicType);

    int size = 0;
    // If indexExpression is nullptr, then the array will eventually get its size implicitly from the initializer.
    if (indexExpression != nullptr && arraySizeErrorCheck(identifierLocation, indexExpression, size))
    {
        recover();
    }
    // Make the type an array even if size check failed.
    // This ensures useless error messages regarding the variable's non-arrayness won't follow.
    arrayType.setArraySize(size);

    // initNode will correspond to the whole of "type b[n] = initializer".
    TIntermNode *initNode = nullptr;
    if (!executeInitializer(identifierLocation, identifier, arrayType, initializer, &initNode))
    {
        return initNode ? intermediate.makeAggregate(initNode, initLocation) : nullptr;
    }
    else
    {
        recover();
        return nullptr;
    }
}

TIntermAggregate *TParseContext::parseInvariantDeclaration(const TSourceLoc &invariantLoc,
                                                           const TSourceLoc &identifierLoc,
                                                           const TString *identifier,
                                                           const TSymbol *symbol)
{
    // invariant declaration
    if (globalErrorCheck(invariantLoc, symbolTable.atGlobalLevel(), "invariant varying"))
    {
        recover();
    }

    if (!symbol)
    {
        error(identifierLoc, "undeclared identifier declared as invariant", identifier->c_str());
        recover();
        return nullptr;
    }
    else
    {
        const TString kGlFrontFacing("gl_FrontFacing");
        if (*identifier == kGlFrontFacing)
        {
            error(identifierLoc, "identifier should not be declared as invariant", identifier->c_str());
            recover();
            return nullptr;
        }
        symbolTable.addInvariantVarying(std::string(identifier->c_str()));
        const TVariable *variable = getNamedVariable(identifierLoc, identifier, symbol);
        ASSERT(variable);
        const TType &type = variable->getType();
        TIntermSymbol *intermSymbol = intermediate.addSymbol(variable->getUniqueId(),
                                                             *identifier, type, identifierLoc);

        TIntermAggregate *aggregate = intermediate.makeAggregate(intermSymbol, identifierLoc);
        aggregate->setOp(EOpInvariantDeclaration);
        return aggregate;
    }
}

TIntermAggregate *TParseContext::parseDeclarator(TPublicType &publicType, TIntermAggregate *aggregateDeclaration,
                                                 const TSourceLoc &identifierLocation, const TString &identifier)
{
    // If the declaration starting this declarator list was empty (example: int,), some checks were not performed.
    if (mDeferredSingleDeclarationErrorCheck)
    {
        if (singleDeclarationErrorCheck(publicType, identifierLocation))
            recover();
        mDeferredSingleDeclarationErrorCheck = false;
    }

    if (locationDeclaratorListCheck(identifierLocation, publicType))
        recover();

    if (nonInitErrorCheck(identifierLocation, identifier, &publicType))
        recover();

    TVariable *variable = nullptr;
    if (!declareVariable(identifierLocation, identifier, TType(publicType), &variable))
        recover();

    TIntermSymbol *symbol = intermediate.addSymbol(0, identifier, TType(publicType), identifierLocation);
    if (variable && symbol)
        symbol->setId(variable->getUniqueId());

    return intermediate.growAggregate(aggregateDeclaration, symbol, identifierLocation);
}

TIntermAggregate *TParseContext::parseArrayDeclarator(TPublicType &publicType, TIntermAggregate *aggregateDeclaration,
                                                      const TSourceLoc &identifierLocation, const TString &identifier,
                                                      const TSourceLoc &arrayLocation, TIntermTyped *indexExpression)
{
    // If the declaration starting this declarator list was empty (example: int,), some checks were not performed.
    if (mDeferredSingleDeclarationErrorCheck)
    {
        if (singleDeclarationErrorCheck(publicType, identifierLocation))
            recover();
        mDeferredSingleDeclarationErrorCheck = false;
    }

    if (locationDeclaratorListCheck(identifierLocation, publicType))
        recover();

    if (nonInitErrorCheck(identifierLocation, identifier, &publicType))
        recover();

    if (arrayTypeErrorCheck(arrayLocation, publicType) || arrayQualifierErrorCheck(arrayLocation, publicType))
    {
        recover();
    }
    else
    {
        TType arrayType = TType(publicType);
        int size;
        if (arraySizeErrorCheck(arrayLocation, indexExpression, size))
        {
            recover();
        }
        arrayType.setArraySize(size);

        TVariable *variable = nullptr;
        if (!declareVariable(identifierLocation, identifier, arrayType, &variable))
            recover();

        TIntermSymbol *symbol = intermediate.addSymbol(0, identifier, arrayType, identifierLocation);
        if (variable && symbol)
            symbol->setId(variable->getUniqueId());

        return intermediate.growAggregate(aggregateDeclaration, symbol, identifierLocation);
    }

    return nullptr;
}

TIntermAggregate *TParseContext::parseInitDeclarator(const TPublicType &publicType, TIntermAggregate *aggregateDeclaration,
                                                     const TSourceLoc &identifierLocation, const TString &identifier,
                                                     const TSourceLoc &initLocation, TIntermTyped *initializer)
{
    // If the declaration starting this declarator list was empty (example: int,), some checks were not performed.
    if (mDeferredSingleDeclarationErrorCheck)
    {
        if (singleDeclarationErrorCheck(publicType, identifierLocation))
            recover();
        mDeferredSingleDeclarationErrorCheck = false;
    }

    if (locationDeclaratorListCheck(identifierLocation, publicType))
        recover();

    TIntermNode *intermNode = nullptr;
    if (!executeInitializer(identifierLocation, identifier, publicType, initializer, &intermNode))
    {
        //
        // build the intermediate representation
        //
        if (intermNode)
        {
            return intermediate.growAggregate(aggregateDeclaration, intermNode, initLocation);
        }
        else
        {
            return aggregateDeclaration;
        }
    }
    else
    {
        recover();
        return nullptr;
    }
}

TIntermAggregate *TParseContext::parseArrayInitDeclarator(const TPublicType &publicType,
                                                          TIntermAggregate *aggregateDeclaration,
                                                          const TSourceLoc &identifierLocation,
                                                          const TString &identifier,
                                                          const TSourceLoc &indexLocation,
                                                          TIntermTyped *indexExpression,
                                                          const TSourceLoc &initLocation, TIntermTyped *initializer)
{
    // If the declaration starting this declarator list was empty (example: int,), some checks were not performed.
    if (mDeferredSingleDeclarationErrorCheck)
    {
        if (singleDeclarationErrorCheck(publicType, identifierLocation))
            recover();
        mDeferredSingleDeclarationErrorCheck = false;
    }

    if (locationDeclaratorListCheck(identifierLocation, publicType))
        recover();

    if (arrayTypeErrorCheck(indexLocation, publicType) || arrayQualifierErrorCheck(indexLocation, publicType))
    {
        recover();
    }

    TPublicType arrayType(publicType);

    int size = 0;
    // If indexExpression is nullptr, then the array will eventually get its size implicitly from the initializer.
    if (indexExpression != nullptr && arraySizeErrorCheck(identifierLocation, indexExpression, size))
    {
        recover();
    }
    // Make the type an array even if size check failed.
    // This ensures useless error messages regarding the variable's non-arrayness won't follow.
    arrayType.setArraySize(size);

    // initNode will correspond to the whole of "b[n] = initializer".
    TIntermNode *initNode = nullptr;
    if (!executeInitializer(identifierLocation, identifier, arrayType, initializer, &initNode))
    {
        if (initNode)
        {
            return intermediate.growAggregate(aggregateDeclaration, initNode, initLocation);
        }
        else
        {
            return aggregateDeclaration;
        }
    }
    else
    {
        recover();
        return nullptr;
    }
}

void TParseContext::parseGlobalLayoutQualifier(const TPublicType &typeQualifier)
{
    if (typeQualifier.qualifier != EvqUniform)
    {
        error(typeQualifier.line,
              "invalid qualifier:",
              getQualifierString(typeQualifier.qualifier), "global layout must be uniform");
        recover();
        return;
    }

    const TLayoutQualifier layoutQualifier = typeQualifier.layoutQualifier;
    ASSERT(!layoutQualifier.isEmpty());

    if (mShaderVersion < 300)
    {
        error(typeQualifier.line, "layout qualifiers supported in GLSL ES 3.00 only", "layout");
        recover();
        return;
    }

    if (layoutLocationErrorCheck(typeQualifier.line, typeQualifier.layoutQualifier))
    {
        recover();
        return;
    }

    if (layoutQualifier.matrixPacking != EmpUnspecified)
    {
        mDefaultMatrixPacking = layoutQualifier.matrixPacking;
    }

    if (layoutQualifier.blockStorage != EbsUnspecified)
    {
        mDefaultBlockStorage = layoutQualifier.blockStorage;
    }
}

void TParseContext::parseFunctionPrototype(const TSourceLoc &location,
                                           TFunction *function,
                                           TIntermAggregate **aggregateOut)
{
    const TSymbol *builtIn = symbolTable.findBuiltIn(function->getMangledName(), getShaderVersion());

    if (builtIn)
    {
        error(location, "built-in functions cannot be redefined", function->getName().c_str());
        recover();
    }

    TFunction* prevDec = static_cast<TFunction*>(symbolTable.find(function->getMangledName(), getShaderVersion()));
    //
    // Note:  'prevDec' could be 'function' if this is the first time we've seen function
    // as it would have just been put in the symbol table.  Otherwise, we're looking up
    // an earlier occurance.
    //
    if (prevDec->isDefined())
    {
        // Then this function already has a body.
        error(location, "function already has a body", function->getName().c_str());
        recover();
    }
    prevDec->setDefined();
    //
    // Overload the unique ID of the definition to be the same unique ID as the declaration.
    // Eventually we will probably want to have only a single definition and just swap the
    // arguments to be the definition's arguments.
    //
    function->setUniqueId(prevDec->getUniqueId());

    // Raise error message if main function takes any parameters or return anything other than void
    if (function->getName() == "main")
    {
        if (function->getParamCount() > 0)
        {
            error(location, "function cannot take any parameter(s)", function->getName().c_str());
            recover();
        }
        if (function->getReturnType().getBasicType() != EbtVoid)
        {
            error(location, "", function->getReturnType().getBasicString(), "main function cannot return a value");
            recover();
        }
    }

    //
    // Remember the return type for later checking for RETURN statements.
    //
    setCurrentFunctionType(&(prevDec->getReturnType()));
    setFunctionReturnsValue(false);

    //
    // Insert parameters into the symbol table.
    // If the parameter has no name, it's not an error, just don't insert it
    // (could be used for unused args).
    //
    // Also, accumulate the list of parameters into the HIL, so lower level code
    // knows where to find parameters.
    //
    TIntermAggregate *paramNodes = new TIntermAggregate;
    for (size_t i = 0; i < function->getParamCount(); i++)
    {
        const TConstParameter &param = function->getParam(i);
        if (param.name != 0)
        {
            TVariable *variable = new TVariable(param.name, *param.type);
            //
            // Insert the parameters with name in the symbol table.
            //
            if (!symbolTable.declare(variable)) {
                error(location, "redefinition", variable->getName().c_str());
                recover();
                delete variable;
            }

            //
            // Add the parameter to the HIL
            //
            TIntermSymbol *symbol = intermediate.addSymbol(variable->getUniqueId(),
                                                           variable->getName(),
                                                           variable->getType(), location);

            paramNodes = intermediate.growAggregate(paramNodes, symbol, location);
        }
        else
        {
            paramNodes = intermediate.growAggregate(paramNodes, intermediate.addSymbol(0, "", *param.type, location), location);
        }
    }
    intermediate.setAggregateOperator(paramNodes, EOpParameters, location);
    *aggregateOut = paramNodes;
    setLoopNestingLevel(0);
}

TFunction *TParseContext::parseFunctionDeclarator(const TSourceLoc &location,
                                                  TFunction *function)
{
    //
    // Multiple declarations of the same function are allowed.
    //
    // If this is a definition, the definition production code will check for redefinitions
    // (we don't know at this point if it's a definition or not).
    //
    // Redeclarations are allowed.  But, return types and parameter qualifiers must match.
    //
    TFunction *prevDec = static_cast<TFunction*>(symbolTable.find(function->getMangledName(), getShaderVersion()));
    if (prevDec)
    {
        if (prevDec->getReturnType() != function->getReturnType())
        {
            error(location,
                  "overloaded functions must have the same return type",
                  function->getReturnType().getBasicString());
            recover();
        }
        for (size_t i = 0; i < prevDec->getParamCount(); ++i)
        {
            if (prevDec->getParam(i).type->getQualifier() != function->getParam(i).type->getQualifier())
            {
                error(location,
                      "overloaded functions must have the same parameter qualifiers",
                      function->getParam(i).type->getQualifierString());
                recover();
            }
        }
    }

    //
    // Check for previously declared variables using the same name.
    //
    TSymbol *prevSym = symbolTable.find(function->getName(), getShaderVersion());
    if (prevSym)
    {
        if (!prevSym->isFunction())
        {
            error(location, "redefinition", function->getName().c_str(), "function");
            recover();
        }
    }
    else
    {
        // Insert the unmangled name to detect potential future redefinition as a variable.
        TFunction *newFunction = new TFunction(NewPoolTString(function->getName().c_str()), &function->getReturnType());
        symbolTable.getOuterLevel()->insertUnmangled(newFunction);
    }

    // We're at the inner scope level of the function's arguments and body statement.
    // Add the function prototype to the surrounding scope instead.
    symbolTable.getOuterLevel()->insert(function);

    //
    // If this is a redeclaration, it could also be a definition,
    // in which case, we want to use the variable names from this one, and not the one that's
    // being redeclared.  So, pass back up this declaration, not the one in the symbol table.
    //
    return function;
}

TFunction *TParseContext::addConstructorFunc(const TPublicType &publicTypeIn)
{
    TPublicType publicType = publicTypeIn;
    TOperator op = EOpNull;
    if (publicType.userDef)
    {
        op = EOpConstructStruct;
    }
    else
    {
        switch (publicType.type)
        {
          case EbtFloat:
            if (publicType.isMatrix())
            {
                switch(publicType.getCols())
                {
                  case 2:
                    switch(publicType.getRows())
                    {
                      case 2: op = EOpConstructMat2;   break;
                      case 3: op = EOpConstructMat2x3; break;
                      case 4: op = EOpConstructMat2x4; break;
                    }
                    break;
                  case 3:
                    switch(publicType.getRows())
                    {
                      case 2: op = EOpConstructMat3x2; break;
                      case 3: op = EOpConstructMat3;   break;
                      case 4: op = EOpConstructMat3x4; break;
                    }
                    break;
                  case 4:
                    switch(publicType.getRows())
                    {
                      case 2: op = EOpConstructMat4x2; break;
                      case 3: op = EOpConstructMat4x3; break;
                      case 4: op = EOpConstructMat4;   break;
                    }
                    break;
                }
            }
            else
            {
                switch(publicType.getNominalSize())
                {
                  case 1: op = EOpConstructFloat; break;
                  case 2: op = EOpConstructVec2;  break;
                  case 3: op = EOpConstructVec3;  break;
                  case 4: op = EOpConstructVec4;  break;
                }
            }
            break;

          case EbtInt:
            switch(publicType.getNominalSize())
            {
              case 1: op = EOpConstructInt;   break;
              case 2: op = EOpConstructIVec2; break;
              case 3: op = EOpConstructIVec3; break;
              case 4: op = EOpConstructIVec4; break;
            }
            break;

          case EbtUInt:
            switch(publicType.getNominalSize())
            {
              case 1: op = EOpConstructUInt;  break;
              case 2: op = EOpConstructUVec2; break;
              case 3: op = EOpConstructUVec3; break;
              case 4: op = EOpConstructUVec4; break;
            }
            break;

          case EbtBool:
            switch(publicType.getNominalSize())
            {
                case 1: op = EOpConstructBool;  break;
                case 2: op = EOpConstructBVec2; break;
                case 3: op = EOpConstructBVec3; break;
                case 4: op = EOpConstructBVec4; break;
            }
            break;

          default: break;
        }

        if (op == EOpNull)
        {
            error(publicType.line, "cannot construct this type", getBasicString(publicType.type));
            recover();
            publicType.type = EbtFloat;
            op = EOpConstructFloat;
        }
    }

    TString tempString;
    const TType *type = new TType(publicType);
    return new TFunction(&tempString, type, op);
}

// This function is used to test for the correctness of the parameters passed to various constructor functions
// and also convert them to the right datatype if it is allowed and required.
//
// Returns 0 for an error or the constructed node (aggregate or typed) for no error.
//
TIntermTyped *TParseContext::addConstructor(TIntermNode *arguments, TType *type, TOperator op, TFunction *fnCall,
                                            const TSourceLoc &line)
{
    TIntermAggregate *aggregateArguments = arguments->getAsAggregate();

    if (!aggregateArguments)
    {
        aggregateArguments = new TIntermAggregate;
        aggregateArguments->getSequence()->push_back(arguments);
    }

    if (type->isArray())
    {
        // GLSL ES 3.00 section 5.4.4: Each argument must be the same type as the element type of the array.
        TIntermSequence *args = aggregateArguments->getSequence();
        for (size_t i = 0; i < args->size(); i++)
        {
            const TType &argType = (*args)[i]->getAsTyped()->getType();
            // It has already been checked that the argument is not an array.
            ASSERT(!argType.isArray());
            if (!argType.sameElementType(*type))
            {
                error(line, "Array constructor argument has an incorrect type", "Error");
                recover();
                return nullptr;
            }
        }
    }
    else if (op == EOpConstructStruct)
    {
        const TFieldList &fields = type->getStruct()->fields();
        TIntermSequence *args = aggregateArguments->getSequence();

        for (size_t i = 0; i < fields.size(); i++)
        {
            if (i >= args->size() || (*args)[i]->getAsTyped()->getType() != *fields[i]->type())
            {
                error(line, "Structure constructor arguments do not match structure fields", "Error");
                recover();

                return 0;
            }
        }
    }

    // Turn the argument list itself into a constructor
    TIntermAggregate *constructor = intermediate.setAggregateOperator(aggregateArguments, op, line);
    TIntermTyped *constConstructor = foldConstConstructor(constructor, *type);
    if (constConstructor)
    {
        return constConstructor;
    }

    // Structs should not be precision qualified, the individual members may be.
    // Built-in types on the other hand should be precision qualified.
    if (op != EOpConstructStruct)
    {
        constructor->setPrecisionFromChildren();
        type->setPrecision(constructor->getPrecision());
    }

    return constructor;
}

TIntermTyped *TParseContext::foldConstConstructor(TIntermAggregate *aggrNode, const TType &type)
{
    // TODO: Add support for folding array constructors
    bool canBeFolded = areAllChildConst(aggrNode) && !type.isArray();
    aggrNode->setType(type);
    if (canBeFolded)
    {
        bool returnVal = false;
        TConstantUnion *unionArray = new TConstantUnion[type.getObjectSize()];
        if (aggrNode->getSequence()->size() == 1)
        {
            returnVal = intermediate.parseConstTree(aggrNode->getLine(), aggrNode, unionArray, aggrNode->getOp(), type,
                                                    true);
        }
        else
        {
            returnVal = intermediate.parseConstTree(aggrNode->getLine(), aggrNode, unionArray, aggrNode->getOp(),
                                                    type);
        }
        if (returnVal)
            return 0;

        return intermediate.addConstantUnion(unionArray, type, aggrNode->getLine());
    }

    return 0;
}

//
// This function returns the tree representation for the vector field(s) being accessed from contant vector.
// If only one component of vector is accessed (v.x or v[0] where v is a contant vector), then a contant node is
// returned, else an aggregate node is returned (for v.xy). The input to this function could either be the symbol
// node or it could be the intermediate tree representation of accessing fields in a constant structure or column of
// a constant matrix.
//
TIntermTyped *TParseContext::addConstVectorNode(TVectorFields &fields, TIntermTyped *node, const TSourceLoc &line)
{
    TIntermTyped *typedNode;
    TIntermConstantUnion *tempConstantNode = node->getAsConstantUnion();

    const TConstantUnion *unionArray;
    if (tempConstantNode)
    {
        unionArray = tempConstantNode->getUnionArrayPointer();

        if (!unionArray)
        {
            return node;
        }
    }
    else
    { // The node has to be either a symbol node or an aggregate node or a tempConstant node, else, its an error
        error(line, "Cannot offset into the vector", "Error");
        recover();

        return 0;
    }

    TConstantUnion *constArray = new TConstantUnion[fields.num];

    for (int i = 0; i < fields.num; i++)
    {
        if (fields.offsets[i] >= node->getType().getNominalSize())
        {
            std::stringstream extraInfoStream;
            extraInfoStream << "vector field selection out of range '" << fields.offsets[i] << "'";
            std::string extraInfo = extraInfoStream.str();
            error(line, "", "[", extraInfo.c_str());
            recover();
            fields.offsets[i] = 0;
        }

        constArray[i] = unionArray[fields.offsets[i]];

    }
    typedNode = intermediate.addConstantUnion(constArray, node->getType(), line);
    return typedNode;
}

//
// This function returns the column being accessed from a constant matrix. The values are retrieved from
// the symbol table and parse-tree is built for a vector (each column of a matrix is a vector). The input
// to the function could either be a symbol node (m[0] where m is a constant matrix)that represents a
// constant matrix or it could be the tree representation of the constant matrix (s.m1[0] where s is a constant structure)
//
TIntermTyped *TParseContext::addConstMatrixNode(int index, TIntermTyped *node, const TSourceLoc &line)
{
    TIntermTyped *typedNode;
    TIntermConstantUnion *tempConstantNode = node->getAsConstantUnion();

    if (index >= node->getType().getCols())
    {
        std::stringstream extraInfoStream;
        extraInfoStream << "matrix field selection out of range '" << index << "'";
        std::string extraInfo = extraInfoStream.str();
        error(line, "", "[", extraInfo.c_str());
        recover();
        index = 0;
    }

    if (tempConstantNode)
    {
         TConstantUnion *unionArray = tempConstantNode->getUnionArrayPointer();
         int size = tempConstantNode->getType().getCols();
         typedNode = intermediate.addConstantUnion(&unionArray[size*index], tempConstantNode->getType(), line);
    }
    else
    {
        error(line, "Cannot offset into the matrix", "Error");
        recover();

        return 0;
    }

    return typedNode;
}


//
// This function returns an element of an array accessed from a constant array. The values are retrieved from
// the symbol table and parse-tree is built for the type of the element. The input
// to the function could either be a symbol node (a[0] where a is a constant array)that represents a
// constant array or it could be the tree representation of the constant array (s.a1[0] where s is a constant structure)
//
TIntermTyped *TParseContext::addConstArrayNode(int index, TIntermTyped *node, const TSourceLoc &line)
{
    TIntermTyped *typedNode;
    TIntermConstantUnion *tempConstantNode = node->getAsConstantUnion();
    TType arrayElementType = node->getType();
    arrayElementType.clearArrayness();

    if (index >= node->getType().getArraySize())
    {
        std::stringstream extraInfoStream;
        extraInfoStream << "array field selection out of range '" << index << "'";
        std::string extraInfo = extraInfoStream.str();
        error(line, "", "[", extraInfo.c_str());
        recover();
        index = 0;
    }

    if (tempConstantNode)
    {
        size_t arrayElementSize = arrayElementType.getObjectSize();
        TConstantUnion *unionArray = tempConstantNode->getUnionArrayPointer();
        typedNode = intermediate.addConstantUnion(&unionArray[arrayElementSize * index], tempConstantNode->getType(),
                                                  line);
    }
    else
    {
        error(line, "Cannot offset into the array", "Error");
        recover();

        return 0;
    }

    return typedNode;
}


//
// This function returns the value of a particular field inside a constant structure from the symbol table.
// If there is an embedded/nested struct, it appropriately calls addConstStructNested or addConstStructFromAggr
// function and returns the parse-tree with the values of the embedded/nested struct.
//
TIntermTyped *TParseContext::addConstStruct(const TString &identifier, TIntermTyped *node, const TSourceLoc &line)
{
    const TFieldList &fields = node->getType().getStruct()->fields();
    size_t instanceSize = 0;

    for (size_t index = 0; index < fields.size(); ++index)
    {
        if (fields[index]->name() == identifier)
        {
            break;
        }
        else
        {
            instanceSize += fields[index]->type()->getObjectSize();
        }
    }

    TIntermTyped *typedNode;
    TIntermConstantUnion *tempConstantNode = node->getAsConstantUnion();
    if (tempConstantNode)
    {
         TConstantUnion *constArray = tempConstantNode->getUnionArrayPointer();

         // type will be changed in the calling function
         typedNode = intermediate.addConstantUnion(constArray+instanceSize, tempConstantNode->getType(), line);
    }
    else
    {
        error(line, "Cannot offset into the structure", "Error");
        recover();

        return 0;
    }

    return typedNode;
}

//
// Interface/uniform blocks
//
TIntermAggregate *TParseContext::addInterfaceBlock(const TPublicType &typeQualifier, const TSourceLoc &nameLine,
                                                   const TString &blockName, TFieldList *fieldList,
                                                   const TString *instanceName, const TSourceLoc &instanceLine,
                                                   TIntermTyped *arrayIndex, const TSourceLoc &arrayIndexLine)
{
    if (reservedErrorCheck(nameLine, blockName))
        recover();

    if (typeQualifier.qualifier != EvqUniform)
    {
        error(typeQualifier.line, "invalid qualifier:", getQualifierString(typeQualifier.qualifier),
              "interface blocks must be uniform");
        recover();
    }

    TLayoutQualifier blockLayoutQualifier = typeQualifier.layoutQualifier;
    if (layoutLocationErrorCheck(typeQualifier.line, blockLayoutQualifier))
    {
        recover();
    }

    if (blockLayoutQualifier.matrixPacking == EmpUnspecified)
    {
        blockLayoutQualifier.matrixPacking = mDefaultMatrixPacking;
    }

    if (blockLayoutQualifier.blockStorage == EbsUnspecified)
    {
        blockLayoutQualifier.blockStorage = mDefaultBlockStorage;
    }

    TSymbol *blockNameSymbol = new TInterfaceBlockName(&blockName);
    if (!symbolTable.declare(blockNameSymbol))
    {
        error(nameLine, "redefinition", blockName.c_str(), "interface block name");
        recover();
    }

    // check for sampler types and apply layout qualifiers
    for (size_t memberIndex = 0; memberIndex < fieldList->size(); ++memberIndex)
    {
        TField *field = (*fieldList)[memberIndex];
        TType *fieldType = field->type();
        if (IsSampler(fieldType->getBasicType()))
        {
            error(field->line(), "unsupported type", fieldType->getBasicString(),
                  "sampler types are not allowed in interface blocks");
            recover();
        }

        const TQualifier qualifier = fieldType->getQualifier();
        switch (qualifier)
        {
          case EvqGlobal:
          case EvqUniform:
            break;
          default:
            error(field->line(), "invalid qualifier on interface block member", getQualifierString(qualifier));
            recover();
            break;
        }

        // check layout qualifiers
        TLayoutQualifier fieldLayoutQualifier = fieldType->getLayoutQualifier();
        if (layoutLocationErrorCheck(field->line(), fieldLayoutQualifier))
        {
            recover();
        }

        if (fieldLayoutQualifier.blockStorage != EbsUnspecified)
        {
            error(field->line(), "invalid layout qualifier:", getBlockStorageString(fieldLayoutQualifier.blockStorage),
                  "cannot be used here");
            recover();
        }

        if (fieldLayoutQualifier.matrixPacking == EmpUnspecified)
        {
            fieldLayoutQualifier.matrixPacking = blockLayoutQualifier.matrixPacking;
        }
        else if (!fieldType->isMatrix() && fieldType->getBasicType() != EbtStruct)
        {
            warning(field->line(), "extraneous layout qualifier:",
                    getMatrixPackingString(fieldLayoutQualifier.matrixPacking), "only has an effect on matrix types");
        }

        fieldType->setLayoutQualifier(fieldLayoutQualifier);
    }

    // add array index
    int arraySize = 0;
    if (arrayIndex != NULL)
    {
        if (arraySizeErrorCheck(arrayIndexLine, arrayIndex, arraySize))
            recover();
    }

    TInterfaceBlock *interfaceBlock = new TInterfaceBlock(&blockName, fieldList, instanceName, arraySize,
                                                          blockLayoutQualifier);
    TType interfaceBlockType(interfaceBlock, typeQualifier.qualifier, blockLayoutQualifier, arraySize);

    TString symbolName = "";
    int symbolId = 0;

    if (!instanceName)
    {
        // define symbols for the members of the interface block
        for (size_t memberIndex = 0; memberIndex < fieldList->size(); ++memberIndex)
        {
            TField *field = (*fieldList)[memberIndex];
            TType *fieldType = field->type();

            // set parent pointer of the field variable
            fieldType->setInterfaceBlock(interfaceBlock);

            TVariable *fieldVariable = new TVariable(&field->name(), *fieldType);
            fieldVariable->setQualifier(typeQualifier.qualifier);

            if (!symbolTable.declare(fieldVariable))
            {
                error(field->line(), "redefinition", field->name().c_str(), "interface block member name");
                recover();
            }
        }
    }
    else
    {
        if (reservedErrorCheck(instanceLine, *instanceName))
            recover();

        // add a symbol for this interface block
        TVariable *instanceTypeDef = new TVariable(instanceName, interfaceBlockType, false);
        instanceTypeDef->setQualifier(typeQualifier.qualifier);

        if (!symbolTable.declare(instanceTypeDef))
        {
            error(instanceLine, "redefinition", instanceName->c_str(), "interface block instance name");
            recover();
        }

        symbolId = instanceTypeDef->getUniqueId();
        symbolName = instanceTypeDef->getName();
    }

    TIntermAggregate *aggregate = intermediate.makeAggregate(intermediate.addSymbol(symbolId, symbolName,
                                                                                    interfaceBlockType,
                                                                                    typeQualifier.line),
                                                             nameLine);
    aggregate->setOp(EOpDeclaration);

    exitStructDeclaration();
    return aggregate;
}

bool TParseContext::enterStructDeclaration(const TSourceLoc &line, const TString &identifier)
{
    ++mStructNestingLevel;

    // Embedded structure definitions are not supported per GLSL ES spec.
    // They aren't allowed in GLSL either, but we need to detect this here
    // so we don't rely on the GLSL compiler to catch it.
    if (mStructNestingLevel > 1)
    {
        error(line, "", "Embedded struct definitions are not allowed");
        return true;
    }

    return false;
}

void TParseContext::exitStructDeclaration()
{
    --mStructNestingLevel;
}

namespace {

const int kWebGLMaxStructNesting = 4;

}  // namespace

bool TParseContext::structNestingErrorCheck(const TSourceLoc &line, const TField &field)
{
    if (!IsWebGLBasedSpec(mShaderSpec))
    {
        return false;
    }

    if (field.type()->getBasicType() != EbtStruct)
    {
        return false;
    }

    // We're already inside a structure definition at this point, so add
    // one to the field's struct nesting.
    if (1 + field.type()->getDeepestStructNesting() > kWebGLMaxStructNesting)
    {
        std::stringstream reasonStream;
        reasonStream << "Reference of struct type "
                     << field.type()->getStruct()->name().c_str()
                     << " exceeds maximum allowed nesting level of "
                     << kWebGLMaxStructNesting;
        std::string reason = reasonStream.str();
        error(line, reason.c_str(), field.name().c_str(), "");
        return true;
    }

    return false;
}

//
// Parse an array index expression
//
TIntermTyped *TParseContext::addIndexExpression(TIntermTyped *baseExpression, const TSourceLoc &location,
                                                TIntermTyped *indexExpression)
{
    TIntermTyped *indexedExpression = NULL;

    if (!baseExpression->isArray() && !baseExpression->isMatrix() && !baseExpression->isVector())
    {
        if (baseExpression->getAsSymbolNode())
        {
            error(location, " left of '[' is not of type array, matrix, or vector ",
                  baseExpression->getAsSymbolNode()->getSymbol().c_str());
        }
        else
        {
            error(location, " left of '[' is not of type array, matrix, or vector ", "expression");
        }
        recover();
    }

    TIntermConstantUnion *indexConstantUnion = indexExpression->getAsConstantUnion();

    if (indexExpression->getQualifier() == EvqConst && indexConstantUnion)
    {
        int index = indexConstantUnion->getIConst(0);
        if (index < 0)
        {
            std::stringstream infoStream;
            infoStream << index;
            std::string info = infoStream.str();
            error(location, "negative index", info.c_str());
            recover();
            index = 0;
        }
        if (baseExpression->getType().getQualifier() == EvqConst)
        {
            if (baseExpression->isArray())
            {
                // constant folding for arrays
                indexedExpression = addConstArrayNode(index, baseExpression, location);
            }
            else if (baseExpression->isVector())
            {
                // constant folding for vectors
                TVectorFields fields;
                fields.num = 1;
                fields.offsets[0] = index; // need to do it this way because v.xy sends fields integer array
                indexedExpression = addConstVectorNode(fields, baseExpression, location);
            }
            else if (baseExpression->isMatrix())
            {
                // constant folding for matrices
                indexedExpression = addConstMatrixNode(index, baseExpression, location);
            }
        }
        else
        {
            int safeIndex = -1;

            if (baseExpression->isArray())
            {
                if (index >= baseExpression->getType().getArraySize())
                {
                    std::stringstream extraInfoStream;
                    extraInfoStream << "array index out of range '" << index << "'";
                    std::string extraInfo = extraInfoStream.str();
                    error(location, "", "[", extraInfo.c_str());
                    recover();
                    safeIndex = baseExpression->getType().getArraySize() - 1;
                }
                else if (baseExpression->getQualifier() == EvqFragData && index > 0 &&
                         !isExtensionEnabled("GL_EXT_draw_buffers"))
                {
                    error(location, "",
                          "[", "array indexes for gl_FragData must be zero when GL_EXT_draw_buffers is disabled");
                    recover();
                    safeIndex = 0;
                }
            }
            else if ((baseExpression->isVector() || baseExpression->isMatrix()) &&
                      baseExpression->getType().getNominalSize() <= index)
            {
                std::stringstream extraInfoStream;
                extraInfoStream << "field selection out of range '" << index << "'";
                std::string extraInfo = extraInfoStream.str();
                error(location, "", "[", extraInfo.c_str());
                recover();
                safeIndex = baseExpression->getType().getNominalSize() - 1;
            }

            // Don't modify the data of the previous constant union, because it can point
            // to builtins, like gl_MaxDrawBuffers. Instead use a new sanitized object.
            if (safeIndex != -1)
            {
                TConstantUnion *safeConstantUnion = new TConstantUnion();
                safeConstantUnion->setIConst(safeIndex);
                indexConstantUnion->replaceConstantUnion(safeConstantUnion);
            }

            indexedExpression = intermediate.addIndex(EOpIndexDirect, baseExpression, indexExpression, location);
        }
    }
    else
    {
        if (baseExpression->isInterfaceBlock())
        {
            error(location, "",
                  "[", "array indexes for interface blocks arrays must be constant integral expressions");
            recover();
        }
        else if (baseExpression->getQualifier() == EvqFragmentOut)
        {
            error(location, "", "[", "array indexes for fragment outputs must be constant integral expressions");
            recover();
        }

        indexedExpression = intermediate.addIndex(EOpIndexIndirect, baseExpression, indexExpression, location);
    }

    if (indexedExpression == 0)
    {
        TConstantUnion *unionArray = new TConstantUnion[1];
        unionArray->setFConst(0.0f);
        indexedExpression = intermediate.addConstantUnion(unionArray, TType(EbtFloat, EbpHigh, EvqConst), location);
    }
    else if (baseExpression->isArray())
    {
        const TType &baseType = baseExpression->getType();
        if (baseType.getStruct())
        {
            TType copyOfType(baseType.getStruct());
            indexedExpression->setType(copyOfType);
        }
        else if (baseType.isInterfaceBlock())
        {
            TType copyOfType(baseType.getInterfaceBlock(), baseType.getQualifier(), baseType.getLayoutQualifier(), 0);
            indexedExpression->setType(copyOfType);
        }
        else
        {
            indexedExpression->setType(TType(baseExpression->getBasicType(), baseExpression->getPrecision(),
                                             EvqTemporary, static_cast<unsigned char>(baseExpression->getNominalSize()),
                                             static_cast<unsigned char>(baseExpression->getSecondarySize())));
        }

        if (baseExpression->getType().getQualifier() == EvqConst)
        {
            indexedExpression->getTypePointer()->setQualifier(EvqConst);
        }
    }
    else if (baseExpression->isMatrix())
    {
        TQualifier qualifier = baseExpression->getType().getQualifier() == EvqConst ? EvqConst : EvqTemporary;
        indexedExpression->setType(TType(baseExpression->getBasicType(), baseExpression->getPrecision(),
                                         qualifier, static_cast<unsigned char>(baseExpression->getRows())));
    }
    else if (baseExpression->isVector())
    {
        TQualifier qualifier = baseExpression->getType().getQualifier() == EvqConst ? EvqConst : EvqTemporary;
        indexedExpression->setType(TType(baseExpression->getBasicType(), baseExpression->getPrecision(), qualifier));
    }
    else
    {
        indexedExpression->setType(baseExpression->getType());
    }

    return indexedExpression;
}

TIntermTyped *TParseContext::addFieldSelectionExpression(TIntermTyped *baseExpression, const TSourceLoc &dotLocation,
                                                         const TString &fieldString, const TSourceLoc &fieldLocation)
{
    TIntermTyped *indexedExpression = NULL;

    if (baseExpression->isArray())
    {
        error(fieldLocation, "cannot apply dot operator to an array", ".");
        recover();
    }

    if (baseExpression->isVector())
    {
        TVectorFields fields;
        if (!parseVectorFields(fieldString, baseExpression->getNominalSize(), fields, fieldLocation))
        {
            fields.num = 1;
            fields.offsets[0] = 0;
            recover();
        }

        if (baseExpression->getType().getQualifier() == EvqConst)
        {
            // constant folding for vector fields
            indexedExpression = addConstVectorNode(fields, baseExpression, fieldLocation);
            if (indexedExpression == 0)
            {
                recover();
                indexedExpression = baseExpression;
            }
            else
            {
                indexedExpression->setType(TType(baseExpression->getBasicType(), baseExpression->getPrecision(),
                                                 EvqConst, (unsigned char) (fieldString).size()));
            }
        }
        else
        {
            TString vectorString = fieldString;
            TIntermTyped *index = intermediate.addSwizzle(fields, fieldLocation);
            indexedExpression = intermediate.addIndex(EOpVectorSwizzle, baseExpression, index, dotLocation);
            indexedExpression->setType(TType(baseExpression->getBasicType(), baseExpression->getPrecision(),
                                             EvqTemporary, (unsigned char) vectorString.size()));
        }
    }
    else if (baseExpression->isMatrix())
    {
        TMatrixFields fields;
        if (!parseMatrixFields(fieldString, baseExpression->getCols(), baseExpression->getRows(), fields,
                               fieldLocation))
        {
            fields.wholeRow = false;
            fields.wholeCol = false;
            fields.row = 0;
            fields.col = 0;
            recover();
        }

        if (fields.wholeRow || fields.wholeCol)
        {
            error(dotLocation, " non-scalar fields not implemented yet", ".");
            recover();
            TConstantUnion *unionArray = new TConstantUnion[1];
            unionArray->setIConst(0);
            TIntermTyped *index = intermediate.addConstantUnion(unionArray, TType(EbtInt, EbpUndefined, EvqConst),
                                                                fieldLocation);
            indexedExpression = intermediate.addIndex(EOpIndexDirect, baseExpression, index, dotLocation);
            indexedExpression->setType(TType(baseExpression->getBasicType(), baseExpression->getPrecision(),
                                             EvqTemporary, static_cast<unsigned char>(baseExpression->getCols()),
                                             static_cast<unsigned char>(baseExpression->getRows())));
        }
        else
        {
            TConstantUnion *unionArray = new TConstantUnion[1];
            unionArray->setIConst(fields.col * baseExpression->getRows() + fields.row);
            TIntermTyped *index = intermediate.addConstantUnion(unionArray, TType(EbtInt, EbpUndefined, EvqConst),
                                                                fieldLocation);
            indexedExpression = intermediate.addIndex(EOpIndexDirect, baseExpression, index, dotLocation);
            indexedExpression->setType(TType(baseExpression->getBasicType(), baseExpression->getPrecision()));
        }
    }
    else if (baseExpression->getBasicType() == EbtStruct)
    {
        bool fieldFound = false;
        const TFieldList &fields = baseExpression->getType().getStruct()->fields();
        if (fields.empty())
        {
            error(dotLocation, "structure has no fields", "Internal Error");
            recover();
            indexedExpression = baseExpression;
        }
        else
        {
            unsigned int i;
            for (i = 0; i < fields.size(); ++i)
            {
                if (fields[i]->name() == fieldString)
                {
                    fieldFound = true;
                    break;
                }
            }
            if (fieldFound)
            {
                if (baseExpression->getType().getQualifier() == EvqConst)
                {
                    indexedExpression = addConstStruct(fieldString, baseExpression, dotLocation);
                    if (indexedExpression == 0)
                    {
                        recover();
                        indexedExpression = baseExpression;
                    }
                    else
                    {
                        indexedExpression->setType(*fields[i]->type());
                        // change the qualifier of the return type, not of the structure field
                        // as the structure definition is shared between various structures.
                        indexedExpression->getTypePointer()->setQualifier(EvqConst);
                    }
                }
                else
                {
                    TConstantUnion *unionArray = new TConstantUnion[1];
                    unionArray->setIConst(i);
                    TIntermTyped *index = intermediate.addConstantUnion(unionArray, *fields[i]->type(), fieldLocation);
                    indexedExpression = intermediate.addIndex(EOpIndexDirectStruct, baseExpression, index, dotLocation);
                    indexedExpression->setType(*fields[i]->type());
                }
            }
            else
            {
                error(dotLocation, " no such field in structure", fieldString.c_str());
                recover();
                indexedExpression = baseExpression;
            }
        }
    }
    else if (baseExpression->isInterfaceBlock())
    {
        bool fieldFound = false;
        const TFieldList &fields = baseExpression->getType().getInterfaceBlock()->fields();
        if (fields.empty())
        {
            error(dotLocation, "interface block has no fields", "Internal Error");
            recover();
            indexedExpression = baseExpression;
        }
        else
        {
            unsigned int i;
            for (i = 0; i < fields.size(); ++i)
            {
                if (fields[i]->name() == fieldString)
                {
                    fieldFound = true;
                    break;
                }
            }
            if (fieldFound)
            {
                TConstantUnion *unionArray = new TConstantUnion[1];
                unionArray->setIConst(i);
                TIntermTyped *index = intermediate.addConstantUnion(unionArray, *fields[i]->type(), fieldLocation);
                indexedExpression = intermediate.addIndex(EOpIndexDirectInterfaceBlock, baseExpression, index,
                                                          dotLocation);
                indexedExpression->setType(*fields[i]->type());
            }
            else
            {
                error(dotLocation, " no such field in interface block", fieldString.c_str());
                recover();
                indexedExpression = baseExpression;
            }
        }
    }
    else
    {
        if (mShaderVersion < 300)
        {
            error(dotLocation, " field selection requires structure, vector, or matrix on left hand side",
                  fieldString.c_str());
        }
        else
        {
            error(dotLocation,
                  " field selection requires structure, vector, matrix, or interface block on left hand side",
                  fieldString.c_str());
        }
        recover();
        indexedExpression = baseExpression;
    }

    return indexedExpression;
}

TLayoutQualifier TParseContext::parseLayoutQualifier(const TString &qualifierType, const TSourceLoc &qualifierTypeLine)
{
    TLayoutQualifier qualifier;

    qualifier.location = -1;
    qualifier.matrixPacking = EmpUnspecified;
    qualifier.blockStorage = EbsUnspecified;

    if (qualifierType == "shared")
    {
        qualifier.blockStorage = EbsShared;
    }
    else if (qualifierType == "packed")
    {
        qualifier.blockStorage = EbsPacked;
    }
    else if (qualifierType == "std140")
    {
        qualifier.blockStorage = EbsStd140;
    }
    else if (qualifierType == "row_major")
    {
        qualifier.matrixPacking = EmpRowMajor;
    }
    else if (qualifierType == "column_major")
    {
        qualifier.matrixPacking = EmpColumnMajor;
    }
    else if (qualifierType == "location")
    {
        error(qualifierTypeLine, "invalid layout qualifier", qualifierType.c_str(), "location requires an argument");
        recover();
    }
    else
    {
        error(qualifierTypeLine, "invalid layout qualifier", qualifierType.c_str());
        recover();
    }

    return qualifier;
}

TLayoutQualifier TParseContext::parseLayoutQualifier(const TString &qualifierType, const TSourceLoc &qualifierTypeLine,
                                                     const TString &intValueString, int intValue,
                                                     const TSourceLoc &intValueLine)
{
    TLayoutQualifier qualifier;

    qualifier.location = -1;
    qualifier.matrixPacking = EmpUnspecified;
    qualifier.blockStorage = EbsUnspecified;

    if (qualifierType != "location")
    {
        error(qualifierTypeLine, "invalid layout qualifier", qualifierType.c_str(),
              "only location may have arguments");
        recover();
    }
    else
    {
        // must check that location is non-negative
        if (intValue < 0)
        {
            error(intValueLine, "out of range:", intValueString.c_str(), "location must be non-negative");
            recover();
        }
        else
        {
            qualifier.location = intValue;
        }
    }

    return qualifier;
}

TLayoutQualifier TParseContext::joinLayoutQualifiers(TLayoutQualifier leftQualifier, TLayoutQualifier rightQualifier)
{
    TLayoutQualifier joinedQualifier = leftQualifier;

    if (rightQualifier.location != -1)
    {
        joinedQualifier.location = rightQualifier.location;
    }
    if (rightQualifier.matrixPacking != EmpUnspecified)
    {
        joinedQualifier.matrixPacking = rightQualifier.matrixPacking;
    }
    if (rightQualifier.blockStorage != EbsUnspecified)
    {
        joinedQualifier.blockStorage = rightQualifier.blockStorage;
    }

    return joinedQualifier;
}

TPublicType TParseContext::joinInterpolationQualifiers(const TSourceLoc &interpolationLoc,
                                                       TQualifier interpolationQualifier,
                                                       const TSourceLoc &storageLoc,
                                                       TQualifier storageQualifier)
{
    TQualifier mergedQualifier = EvqSmoothIn;

    if (storageQualifier == EvqFragmentIn)
    {
        if (interpolationQualifier == EvqSmooth)
            mergedQualifier = EvqSmoothIn;
        else if (interpolationQualifier == EvqFlat)
            mergedQualifier = EvqFlatIn;
        else UNREACHABLE();
    }
    else if (storageQualifier == EvqCentroidIn)
    {
        if (interpolationQualifier == EvqSmooth)
            mergedQualifier = EvqCentroidIn;
        else if (interpolationQualifier == EvqFlat)
            mergedQualifier = EvqFlatIn;
        else UNREACHABLE();
    }
    else if (storageQualifier == EvqVertexOut)
    {
        if (interpolationQualifier == EvqSmooth)
            mergedQualifier = EvqSmoothOut;
        else if (interpolationQualifier == EvqFlat)
            mergedQualifier = EvqFlatOut;
        else UNREACHABLE();
    }
    else if (storageQualifier == EvqCentroidOut)
    {
        if (interpolationQualifier == EvqSmooth)
            mergedQualifier = EvqCentroidOut;
        else if (interpolationQualifier == EvqFlat)
            mergedQualifier = EvqFlatOut;
        else UNREACHABLE();
    }
    else
    {
        error(interpolationLoc, "interpolation qualifier requires a fragment 'in' or vertex 'out' storage qualifier",
              getInterpolationString(interpolationQualifier));
        recover();

        mergedQualifier = storageQualifier;
    }

    TPublicType type;
    type.setBasic(EbtVoid, mergedQualifier, storageLoc);
    return type;
}

TFieldList *TParseContext::addStructDeclaratorList(const TPublicType &typeSpecifier, TFieldList *fieldList)
{
    if (voidErrorCheck(typeSpecifier.line, (*fieldList)[0]->name(), typeSpecifier.type))
    {
        recover();
    }

    for (unsigned int i = 0; i < fieldList->size(); ++i)
    {
        //
        // Careful not to replace already known aspects of type, like array-ness
        //
        TType *type = (*fieldList)[i]->type();
        type->setBasicType(typeSpecifier.type);
        type->setPrimarySize(typeSpecifier.primarySize);
        type->setSecondarySize(typeSpecifier.secondarySize);
        type->setPrecision(typeSpecifier.precision);
        type->setQualifier(typeSpecifier.qualifier);
        type->setLayoutQualifier(typeSpecifier.layoutQualifier);

        // don't allow arrays of arrays
        if (type->isArray())
        {
            if (arrayTypeErrorCheck(typeSpecifier.line, typeSpecifier))
                recover();
        }
        if (typeSpecifier.array)
            type->setArraySize(typeSpecifier.arraySize);
        if (typeSpecifier.userDef)
        {
            type->setStruct(typeSpecifier.userDef->getStruct());
        }

        if (structNestingErrorCheck(typeSpecifier.line, *(*fieldList)[i]))
        {
            recover();
        }
    }

    return fieldList;
}

TPublicType TParseContext::addStructure(const TSourceLoc &structLine, const TSourceLoc &nameLine,
                                        const TString *structName, TFieldList *fieldList)
{
    TStructure *structure = new TStructure(structName, fieldList);
    TType *structureType = new TType(structure);

    // Store a bool in the struct if we're at global scope, to allow us to
    // skip the local struct scoping workaround in HLSL.
    structure->setUniqueId(TSymbolTable::nextUniqueId());
    structure->setAtGlobalScope(symbolTable.atGlobalLevel());

    if (!structName->empty())
    {
        if (reservedErrorCheck(nameLine, *structName))
        {
            recover();
        }
        TVariable *userTypeDef = new TVariable(structName, *structureType, true);
        if (!symbolTable.declare(userTypeDef))
        {
            error(nameLine, "redefinition", structName->c_str(), "struct");
            recover();
        }
    }

    // ensure we do not specify any storage qualifiers on the struct members
    for (unsigned int typeListIndex = 0; typeListIndex < fieldList->size(); typeListIndex++)
    {
        const TField &field = *(*fieldList)[typeListIndex];
        const TQualifier qualifier = field.type()->getQualifier();
        switch (qualifier)
        {
          case EvqGlobal:
          case EvqTemporary:
            break;
          default:
            error(field.line(), "invalid qualifier on struct member", getQualifierString(qualifier));
            recover();
            break;
        }
    }

    TPublicType publicType;
    publicType.setBasic(EbtStruct, EvqTemporary, structLine);
    publicType.userDef = structureType;
    exitStructDeclaration();

    return publicType;
}

TIntermSwitch *TParseContext::addSwitch(TIntermTyped *init, TIntermAggregate *statementList, const TSourceLoc &loc)
{
    TBasicType switchType = init->getBasicType();
    if ((switchType != EbtInt && switchType != EbtUInt) ||
        init->isMatrix() ||
        init->isArray() ||
        init->isVector())
    {
        error(init->getLine(), "init-expression in a switch statement must be a scalar integer", "switch");
        recover();
        return nullptr;
    }

    if (statementList)
    {
        if (!ValidateSwitch::validate(switchType, this, statementList, loc))
        {
            recover();
            return nullptr;
        }
    }

    TIntermSwitch *node = intermediate.addSwitch(init, statementList, loc);
    if (node == nullptr)
    {
        error(loc, "erroneous switch statement", "switch");
        recover();
        return nullptr;
    }
    return node;
}

TIntermCase *TParseContext::addCase(TIntermTyped *condition, const TSourceLoc &loc)
{
    if (mSwitchNestingLevel == 0)
    {
        error(loc, "case labels need to be inside switch statements", "case");
        recover();
        return nullptr;
    }
    if (condition == nullptr)
    {
        error(loc, "case label must have a condition", "case");
        recover();
        return nullptr;
    }
    if ((condition->getBasicType() != EbtInt && condition->getBasicType() != EbtUInt) ||
        condition->isMatrix() ||
        condition->isArray() ||
        condition->isVector())
    {
        error(condition->getLine(), "case label must be a scalar integer", "case");
        recover();
    }
    TIntermConstantUnion *conditionConst = condition->getAsConstantUnion();
    if (conditionConst == nullptr)
    {
        error(condition->getLine(), "case label must be constant", "case");
        recover();
    }
    TIntermCase *node = intermediate.addCase(condition, loc);
    if (node == nullptr)
    {
        error(loc, "erroneous case statement", "case");
        recover();
        return nullptr;
    }
    return node;
}

TIntermCase *TParseContext::addDefault(const TSourceLoc &loc)
{
    if (mSwitchNestingLevel == 0)
    {
        error(loc, "default labels need to be inside switch statements", "default");
        recover();
        return nullptr;
    }
    TIntermCase *node = intermediate.addCase(nullptr, loc);
    if (node == nullptr)
    {
        error(loc, "erroneous default statement", "default");
        recover();
        return nullptr;
    }
    return node;
}

TIntermTyped *TParseContext::createUnaryMath(TOperator op, TIntermTyped *child, const TSourceLoc &loc,
    const TType *funcReturnType)
{
    if (child == nullptr)
    {
        return nullptr;
    }

    switch (op)
    {
      case EOpLogicalNot:
        if (child->getBasicType() != EbtBool ||
            child->isMatrix() ||
            child->isArray() ||
            child->isVector())
        {
            return nullptr;
        }
        break;
      case EOpBitwiseNot:
        if ((child->getBasicType() != EbtInt && child->getBasicType() != EbtUInt) ||
            child->isMatrix() ||
            child->isArray())
        {
            return nullptr;
        }
        break;
      case EOpPostIncrement:
      case EOpPreIncrement:
      case EOpPostDecrement:
      case EOpPreDecrement:
      case EOpNegative:
      case EOpPositive:
        if (child->getBasicType() == EbtStruct ||
            child->getBasicType() == EbtBool ||
            child->isArray())
        {
            return nullptr;
        }
      // Operators for built-ins are already type checked against their prototype.
      default:
        break;
    }

    return intermediate.addUnaryMath(op, child, loc, funcReturnType);
}

TIntermTyped *TParseContext::addUnaryMath(TOperator op, TIntermTyped *child, const TSourceLoc &loc)
{
    TIntermTyped *node = createUnaryMath(op, child, loc, nullptr);
    if (node == nullptr)
    {
        unaryOpError(loc, GetOperatorString(op), child->getCompleteString());
        recover();
        return child;
    }
    return node;
}

TIntermTyped *TParseContext::addUnaryMathLValue(TOperator op, TIntermTyped *child, const TSourceLoc &loc)
{
    if (lValueErrorCheck(loc, GetOperatorString(op), child))
        recover();
    return addUnaryMath(op, child, loc);
}

bool TParseContext::binaryOpCommonCheck(TOperator op, TIntermTyped *left, TIntermTyped *right,
    const TSourceLoc &loc)
{
    if (left->isArray() || right->isArray())
    {
        if (mShaderVersion < 300)
        {
            error(loc, "Invalid operation for arrays", GetOperatorString(op));
            return false;
        }

        if (left->isArray() != right->isArray())
        {
            error(loc, "array / non-array mismatch", GetOperatorString(op));
            return false;
        }

        switch (op)
        {
          case EOpEqual:
          case EOpNotEqual:
          case EOpAssign:
          case EOpInitialize:
            break;
          default:
            error(loc, "Invalid operation for arrays", GetOperatorString(op));
            return false;
        }
        // At this point, size of implicitly sized arrays should be resolved.
        if (left->getArraySize() != right->getArraySize())
        {
            error(loc, "array size mismatch", GetOperatorString(op));
            return false;
        }
    }

    // Check ops which require integer / ivec parameters
    bool isBitShift = false;
    switch (op)
    {
      case EOpBitShiftLeft:
      case EOpBitShiftRight:
      case EOpBitShiftLeftAssign:
      case EOpBitShiftRightAssign:
        // Unsigned can be bit-shifted by signed and vice versa, but we need to
        // check that the basic type is an integer type.
        isBitShift = true;
        if (!IsInteger(left->getBasicType()) || !IsInteger(right->getBasicType()))
        {
            return false;
        }
        break;
      case EOpBitwiseAnd:
      case EOpBitwiseXor:
      case EOpBitwiseOr:
      case EOpBitwiseAndAssign:
      case EOpBitwiseXorAssign:
      case EOpBitwiseOrAssign:
        // It is enough to check the type of only one operand, since later it
        // is checked that the operand types match.
        if (!IsInteger(left->getBasicType()))
        {
            return false;
        }
        break;
      default:
        break;
    }

    // GLSL ES 1.00 and 3.00 do not support implicit type casting.
    // So the basic type should usually match.
    if (!isBitShift && left->getBasicType() != right->getBasicType())
    {
        return false;
    }

    // Check that type sizes match exactly on ops that require that.
    // Also check restrictions for structs that contain arrays or samplers.
    switch(op)
    {
      case EOpAssign:
      case EOpInitialize:
      case EOpEqual:
      case EOpNotEqual:
        // ESSL 1.00 sections 5.7, 5.8, 5.9
        if (mShaderVersion < 300 && left->getType().isStructureContainingArrays())
        {
            error(loc, "undefined operation for structs containing arrays", GetOperatorString(op));
            return false;
        }
        // Samplers as l-values are disallowed also in ESSL 3.00, see section 4.1.7,
        // we interpret the spec so that this extends to structs containing samplers,
        // similarly to ESSL 1.00 spec.
        if ((mShaderVersion < 300 || op == EOpAssign || op == EOpInitialize) &&
            left->getType().isStructureContainingSamplers())
        {
            error(loc, "undefined operation for structs containing samplers", GetOperatorString(op));
            return false;
        }
      case EOpLessThan:
      case EOpGreaterThan:
      case EOpLessThanEqual:
      case EOpGreaterThanEqual:
        if ((left->getNominalSize() != right->getNominalSize()) ||
            (left->getSecondarySize() != right->getSecondarySize()))
        {
            return false;
        }
      default:
        break;
    }

    return true;
}

TIntermTyped *TParseContext::addBinaryMathInternal(TOperator op, TIntermTyped *left, TIntermTyped *right,
    const TSourceLoc &loc)
{
    if (!binaryOpCommonCheck(op, left, right, loc))
        return nullptr;

    switch (op)
    {
      case EOpEqual:
      case EOpNotEqual:
        break;
      case EOpLessThan:
      case EOpGreaterThan:
      case EOpLessThanEqual:
      case EOpGreaterThanEqual:
        ASSERT(!left->isArray() && !right->isArray());
        if (left->isMatrix() || left->isVector() ||
            left->getBasicType() == EbtStruct)
        {
            return nullptr;
        }
        break;
      case EOpLogicalOr:
      case EOpLogicalXor:
      case EOpLogicalAnd:
        ASSERT(!left->isArray() && !right->isArray());
        if (left->getBasicType() != EbtBool ||
            left->isMatrix() || left->isVector())
        {
            return nullptr;
        }
        break;
      case EOpAdd:
      case EOpSub:
      case EOpDiv:
      case EOpMul:
        ASSERT(!left->isArray() && !right->isArray());
        if (left->getBasicType() == EbtStruct || left->getBasicType() == EbtBool)
        {
            return nullptr;
        }
        break;
      case EOpIMod:
        ASSERT(!left->isArray() && !right->isArray());
        // Note that this is only for the % operator, not for mod()
        if (left->getBasicType() == EbtStruct || left->getBasicType() == EbtBool || left->getBasicType() == EbtFloat)
        {
            return nullptr;
        }
        break;
      // Note that for bitwise ops, type checking is done in promote() to
      // share code between ops and compound assignment
      default:
        break;
    }

    return intermediate.addBinaryMath(op, left, right, loc);
}

TIntermTyped *TParseContext::addBinaryMath(TOperator op, TIntermTyped *left, TIntermTyped *right,
    const TSourceLoc &loc)
{
    TIntermTyped *node = addBinaryMathInternal(op, left, right, loc);
    if (node == 0)
    {
        binaryOpError(loc, GetOperatorString(op), left->getCompleteString(), right->getCompleteString());
        recover();
        return left;
    }
    return node;
}

TIntermTyped *TParseContext::addBinaryMathBooleanResult(TOperator op, TIntermTyped *left, TIntermTyped *right,
    const TSourceLoc &loc)
{
    TIntermTyped *node = addBinaryMathInternal(op, left, right, loc);
    if (node == 0)
    {
        binaryOpError(loc, GetOperatorString(op), left->getCompleteString(), right->getCompleteString());
        recover();
        TConstantUnion *unionArray = new TConstantUnion[1];
        unionArray->setBConst(false);
        return intermediate.addConstantUnion(unionArray, TType(EbtBool, EbpUndefined, EvqConst), loc);
    }
    return node;
}

TIntermTyped *TParseContext::createAssign(TOperator op, TIntermTyped *left, TIntermTyped *right,
    const TSourceLoc &loc)
{
    if (binaryOpCommonCheck(op, left, right, loc))
    {
        return intermediate.addAssign(op, left, right, loc);
    }
    return nullptr;
}

TIntermTyped *TParseContext::addAssign(TOperator op, TIntermTyped *left, TIntermTyped *right,
    const TSourceLoc &loc)
{
    TIntermTyped *node = createAssign(op, left, right, loc);
    if (node == nullptr)
    {
        assignError(loc, "assign", left->getCompleteString(), right->getCompleteString());
        recover();
        return left;
    }
    return node;
}

TIntermBranch *TParseContext::addBranch(TOperator op, const TSourceLoc &loc)
{
    switch (op)
    {
      case EOpContinue:
        if (mLoopNestingLevel <= 0)
        {
            error(loc, "continue statement only allowed in loops", "");
            recover();
        }
        break;
      case EOpBreak:
        if (mLoopNestingLevel <= 0 && mSwitchNestingLevel <= 0)
        {
            error(loc, "break statement only allowed in loops and switch statements", "");
            recover();
        }
        break;
      case EOpReturn:
        if (mCurrentFunctionType->getBasicType() != EbtVoid)
        {
            error(loc, "non-void function must return a value", "return");
            recover();
        }
        break;
      default:
        // No checks for discard
        break;
    }
    return intermediate.addBranch(op, loc);
}

TIntermBranch *TParseContext::addBranch(TOperator op, TIntermTyped *returnValue, const TSourceLoc &loc)
{
    ASSERT(op == EOpReturn);
    mFunctionReturnsValue = true;
    if (mCurrentFunctionType->getBasicType() == EbtVoid)
    {
        error(loc, "void function cannot return a value", "return");
        recover();
    }
    else if (*mCurrentFunctionType != returnValue->getType())
    {
        error(loc, "function return is not matching type:", "return");
        recover();
    }
    return intermediate.addBranch(op, returnValue, loc);
}

TIntermTyped *TParseContext::addFunctionCallOrMethod(TFunction *fnCall, TIntermNode *paramNode, TIntermNode *thisNode,
                                                     const TSourceLoc &loc, bool *fatalError)
{
    *fatalError = false;
    TOperator op = fnCall->getBuiltInOp();
    TIntermTyped *callNode = nullptr;

    if (thisNode != nullptr)
    {
        TConstantUnion *unionArray = new TConstantUnion[1];
        int arraySize = 0;
        TIntermTyped *typedThis = thisNode->getAsTyped();
        if (fnCall->getName() != "length")
        {
            error(loc, "invalid method", fnCall->getName().c_str());
            recover();
        }
        else if (paramNode != nullptr)
        {
            error(loc, "method takes no parameters", "length");
            recover();
        }
        else if (typedThis == nullptr || !typedThis->isArray())
        {
            error(loc, "length can only be called on arrays", "length");
            recover();
        }
        else
        {
            arraySize = typedThis->getArraySize();
            if (typedThis->getAsSymbolNode() == nullptr)
            {
                // This code path can be hit with expressions like these:
                // (a = b).length()
                // (func()).length()
                // (int[3](0, 1, 2)).length()
                // ESSL 3.00 section 5.9 defines expressions so that this is not actually a valid expression.
                // It allows "An array name with the length method applied" in contrast to GLSL 4.4 spec section 5.9
                // which allows "An array, vector or matrix expression with the length method applied".
                error(loc, "length can only be called on array names, not on array expressions", "length");
                recover();
            }
        }
        unionArray->setIConst(arraySize);
        callNode = intermediate.addConstantUnion(unionArray, TType(EbtInt, EbpUndefined, EvqConst), loc);
    }
    else if (op != EOpNull)
    {
        //
        // Then this should be a constructor.
        // Don't go through the symbol table for constructors.
        // Their parameters will be verified algorithmically.
        //
        TType type(EbtVoid, EbpUndefined);  // use this to get the type back
        if (!constructorErrorCheck(loc, paramNode, *fnCall, op, &type))
        {
            //
            // It's a constructor, of type 'type'.
            //
            callNode = addConstructor(paramNode, &type, op, fnCall, loc);
        }

        if (callNode == nullptr)
        {
            recover();
            callNode = intermediate.setAggregateOperator(nullptr, op, loc);
        }
        callNode->setType(type);
    }
    else
    {
        //
        // Not a constructor.  Find it in the symbol table.
        //
        const TFunction *fnCandidate;
        bool builtIn;
        fnCandidate = findFunction(loc, fnCall, mShaderVersion, &builtIn);
        if (fnCandidate)
        {
            //
            // A declared function.
            //
            if (builtIn && !fnCandidate->getExtension().empty() &&
                extensionErrorCheck(loc, fnCandidate->getExtension()))
            {
                recover();
            }
            op = fnCandidate->getBuiltInOp();
            if (builtIn && op != EOpNull)
            {
                //
                // A function call mapped to a built-in operation.
                //
                if (fnCandidate->getParamCount() == 1)
                {
                    //
                    // Treat it like a built-in unary operator.
                    //
                    callNode = createUnaryMath(op, paramNode->getAsTyped(), loc, &fnCandidate->getReturnType());
                    if (callNode == nullptr)
                    {
                        std::stringstream extraInfoStream;
                        extraInfoStream << "built in unary operator function.  Type: "
                            << static_cast<TIntermTyped*>(paramNode)->getCompleteString();
                        std::string extraInfo = extraInfoStream.str();
                        error(paramNode->getLine(), " wrong operand type", "Internal Error", extraInfo.c_str());
                        *fatalError = true;
                        return nullptr;
                    }
                }
                else
                {
                    TIntermAggregate *aggregate = intermediate.setAggregateOperator(paramNode, op, loc);
                    aggregate->setType(fnCandidate->getReturnType());
                    aggregate->setPrecisionFromChildren();

                    // Some built-in functions have out parameters too.
                    functionCallLValueErrorCheck(fnCandidate, aggregate);

                    // See if we can constant fold a built-in.
                    TIntermTyped *foldedNode = intermediate.foldAggregateBuiltIn(aggregate);
                    if (foldedNode)
                    {
                        callNode = foldedNode;
                    }
                    else
                    {
                        callNode = aggregate;
                    }
                }
            }
            else
            {
                // This is a real function call

                TIntermAggregate *aggregate = intermediate.setAggregateOperator(paramNode, EOpFunctionCall, loc);
                aggregate->setType(fnCandidate->getReturnType());

                // this is how we know whether the given function is a builtIn function or a user defined function
                // if builtIn == false, it's a userDefined -> could be an overloaded builtIn function also
                // if builtIn == true, it's definitely a builtIn function with EOpNull
                if (!builtIn)
                    aggregate->setUserDefined();
                aggregate->setName(fnCandidate->getMangledName());
                aggregate->setFunctionId(fnCandidate->getUniqueId());

                // This needs to happen after the name is set
                if (builtIn)
                    aggregate->setBuiltInFunctionPrecision();

                callNode = aggregate;

                functionCallLValueErrorCheck(fnCandidate, aggregate);
            }
        }
        else
        {
            // error message was put out by findFunction()
            // Put on a dummy node for error recovery
            TConstantUnion *unionArray = new TConstantUnion[1];
            unionArray->setFConst(0.0f);
            callNode = intermediate.addConstantUnion(unionArray, TType(EbtFloat, EbpUndefined, EvqConst), loc);
            recover();
        }
    }
    delete fnCall;
    return callNode;
}

TIntermTyped *TParseContext::addTernarySelection(TIntermTyped *cond, TIntermTyped *trueBlock, TIntermTyped *falseBlock,
                                                 const TSourceLoc &loc)
{
    if (boolErrorCheck(loc, cond))
        recover();

    if (trueBlock->getType() != falseBlock->getType())
    {
        binaryOpError(loc, ":", trueBlock->getCompleteString(), falseBlock->getCompleteString());
        recover();
        return falseBlock;
    }
    // ESSL1 sections 5.2 and 5.7:
    // ESSL3 section 5.7:
    // Ternary operator is not among the operators allowed for structures/arrays.
    if (trueBlock->isArray() || trueBlock->getBasicType() == EbtStruct)
    {
        error(loc, "ternary operator is not allowed for structures or arrays", ":");
        recover();
        return falseBlock;
    }
    return intermediate.addSelection(cond, trueBlock, falseBlock, loc);
}

//
// Parse an array of strings using yyparse.
//
// Returns 0 for success.
//
int PaParseStrings(size_t count, const char *const string[], const int length[],
                   TParseContext *context)
{
    if ((count == 0) || (string == NULL))
        return 1;

    if (glslang_initialize(context))
        return 1;

    int error = glslang_scan(count, string, length, context);
    if (!error)
        error = glslang_parse(context);

    glslang_finalize(context);

    return (error == 0) && (context->numErrors() == 0) ? 0 : 1;
}