Compiler/ParseHelper.cpp

//
// Copyright (c) 2002-2010 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 "ParseHelper.h"
#include "InitializeParseContext.h"
#include "osinclude.h"
#include <stdarg.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, int 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 matSize, TMatrixFields& fields, int 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 >= matSize || fields.col >= matSize) {
		error(line, "matrix field selection out of range", compString.c_str(), "");
		return false;
	}

	return true;
}

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

//
// Track whether errors have occurred.
//
void TParseContext::recover()
{
	recoveredFromError = true;
}

//
// Used by flex/bison to output all syntax and parsing errors.
//
void C_DECL TParseContext::error(TSourceLoc nLine, const char *szReason, const char *szToken, 
								 const char *szExtraInfoFormat, ...)
{
	char szExtraInfo[400];
	va_list marker;
	
	va_start(marker, szExtraInfoFormat);
	
	_vsnprintf(szExtraInfo, sizeof(szExtraInfo), szExtraInfoFormat, marker);
	
	/* VC++ format: file(linenum) : error #: 'token' : extrainfo */
	infoSink.info.prefix(EPrefixError);
	infoSink.info.location(nLine);
	infoSink.info << "'" << szToken <<  "' : " << szReason << " " << szExtraInfo << "\n";
	
	va_end(marker);

	++numErrors;
}

//
// Same error message for all places assignments don't work.
//
void TParseContext::assignError(int line, const char* op, TString left, TString right)
{
	error(line, "", op, "cannot convert from '%s' to '%s'",
		  right.c_str(), left.c_str());
}

//
// Same error message for all places unary operations don't work.
//
void TParseContext::unaryOpError(int line, const char* op, TString operand)
{
   error(line, " wrong operand type", op, 
		  "no operation '%s' exists that takes an operand of type %s (or there is no acceptable conversion)",
		  op, operand.c_str());
}

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

//
// 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(int 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:
			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()->getUnionArrayPointer()->getIConst();
					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 EvqUniform:        message = "can't modify a uniform";      break;
	case EvqVaryingIn:      message = "can't modify a varying";      break;
	case EvqInput:          message = "can't modify an input";       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?
		//
		switch (node->getBasicType()) {
		case EbtSampler2D:
		case EbtSamplerCube:
			message = "can't modify a sampler";
			break;
		case EbtVoid:
			message = "can't modify void";
			break;
		default: 
			break;
		}
	}

	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)
		error(line, " l-value required", op, "\"%s\" (%s)", symbol, message);
	else
		error(line, " l-value required", op, "(%s)", message);

	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->getBasicType() == EbtInt && node->getNominalSize() == 1)
		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(int 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.
//
// Returns true if there was an error.
//
bool TParseContext::reservedErrorCheck(int line, const TString& identifier)
{
	if (!symbolTable.atBuiltInLevel()) {
		if (identifier.substr(0, 3) == TString("gl_")) {
			error(line, "reserved built-in name", "gl_", "");
			return true;
		}
		if (identifier.find("__") != TString::npos) {
			//error(line, "Two consecutive underscores are reserved for future use.", identifier.c_str(), "", "");
			//return true;
			infoSink.info.message(EPrefixWarning, "Two consecutive underscores are reserved for future use.", line);
			return false;
		}
	}

	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(int line, TIntermNode* node, TFunction& function, TOperator op, TType* type)
{
	*type = function.getReturnType();

	bool constructingMatrix = false;
	switch(op) {
	case EOpConstructMat2:
	case EOpConstructMat3:
	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.
	//

	int size = 0;
	bool constType = true;
	bool full = false;
	bool overFull = false;
	bool matrixInMatrix = false;
	bool arrayArg = false;
	for (int i = 0; i < function.getParamCount(); ++i) {
		size += function[i].type->getObjectSize();
		
		if (constructingMatrix && function[i].type->isMatrix())
			matrixInMatrix = true;
		if (full)
			overFull = true;
		if (op != EOpConstructStruct && !type->isArray() && size >= type->getObjectSize())
			full = true;
		if (function[i].type->getQualifier() != EvqConst)
			constType = false;
		if (function[i].type->isArray())
			arrayArg = true;
	}
	
	if (constType)
		type->changeQualifier(EvqConst);

	if (type->isArray() && 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()) {
		error(line, "constructing matrix from matrix", "constructor", "(reserved)");
		return true;
	}

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

	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->getAsTyped();
	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(int line, const TString& identifier, const TPublicType& pubType)
{
	if (pubType.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(int 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(int line, const TPublicType& pType)
{
	if (pType.type != EbtBool || pType.array || pType.matrix || (pType.size > 1)) {
		error(line, "boolean expression expected", "", "");
		return true;
	} 

	return false;
}

bool TParseContext::samplerErrorCheck(int line, const TPublicType& pType, const char* reason)
{
	if (pType.type == EbtStruct) {
		if (containsSampler(*pType.userDef)) {
			error(line, reason, TType::getBasicString(pType.type), "(structure contains a sampler)");
		
			return true;
		}
		
		return false;
	} else if (IsSampler(pType.type)) {
		error(line, reason, TType::getBasicString(pType.type), "");

		return true;
	}

	return false;
}

bool TParseContext::structQualifierErrorCheck(int line, const TPublicType& pType)
{
	if ((pType.qualifier == EvqVaryingIn || pType.qualifier == EvqVaryingOut || pType.qualifier == EvqAttribute) &&
		pType.type == EbtStruct) {
		error(line, "cannot be used with a structure", getQualifierString(pType.qualifier), "");
		
		return true;
	}

	if (pType.qualifier != EvqUniform && samplerErrorCheck(line, pType, "samplers must be uniform"))
		return true;

	return false;
}

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

	if (type.getBasicType() == EbtStruct) {
		TTypeList& structure = *type.getStruct();
		for (unsigned int i = 0; i < structure.size(); ++i) {
			if (containsSampler(*structure[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(int line, TIntermTyped* expr, int& size)
{
	TIntermConstantUnion* constant = expr->getAsConstantUnion();
	if (constant == 0 || constant->getBasicType() != EbtInt) {
		error(line, "array size must be a constant integer expression", "", "");
		return true;
	}

	size = constant->getUnionArrayPointer()->getIConst();

	if (size <= 0) {
		error(line, "array size must be a positive integer", "", "");
		size = 1;
		return true;
	}

	return false;
}

//
// See if this qualifier can be an array.
//
// Returns true if there is an error.
//
bool TParseContext::arrayQualifierErrorCheck(int line, TPublicType type)
{
	if (type.qualifier == EvqAttribute) {
		error(line, "cannot declare arrays of this qualifier", TType(type).getCompleteString().c_str(), "");
		return true;
	}

	if (type.qualifier == EvqConst && extensionErrorCheck(line, "GL_3DL_array_objects"))
		return true;

	return false;
}

//
// See if this type can be an array.
//
// Returns true if there is an error.
//
bool TParseContext::arrayTypeErrorCheck(int line, 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;
}

//
// Do all the semantic checking for declaring an array, with and 
// without a size, and make the right changes to the symbol table.
//
// size == 0 means no specified size.
//
// Returns true if there was an error.
//
bool TParseContext::arrayErrorCheck(int line, TString& identifier, TPublicType type, TVariable*& variable)
{
	//
	// Don't check for reserved word use until after we know it's not in the symbol table,
	// because reserved arrays can be redeclared.
	//

	bool builtIn = false; 
	bool sameScope = false;
	TSymbol* symbol = symbolTable.find(identifier, &builtIn, &sameScope);
	if (symbol == 0 || !sameScope) {
		if (reservedErrorCheck(line, identifier))
			return true;
		
		variable = new TVariable(&identifier, TType(type));

		if (type.arraySize)
			variable->getType().setArraySize(type.arraySize);

		if (! symbolTable.insert(*variable)) {
			delete variable;
			error(line, "INTERNAL ERROR inserting new symbol", identifier.c_str(), "");
			return true;
		}
	} else {
		if (! symbol->isVariable()) {
			error(line, "variable expected", identifier.c_str(), "");
			return true;
		}

		variable = static_cast<TVariable*>(symbol);
		if (! variable->getType().isArray()) {
			error(line, "redeclaring non-array as array", identifier.c_str(), "");
			return true;
		}
		if (variable->getType().getArraySize() > 0) {
			error(line, "redeclaration of array with size", identifier.c_str(), "");
			return true;
		}
		
		if (! variable->getType().sameElementType(TType(type))) {
			error(line, "redeclaration of array with a different type", identifier.c_str(), "");
			return true;
		}

		TType* t = variable->getArrayInformationType();
		while (t != 0) {
			if (t->getMaxArraySize() > type.arraySize) {
				error(line, "higher index value already used for the array", identifier.c_str(), "");
				return true;
			}
			t->setArraySize(type.arraySize);
			t = t->getArrayInformationType();
		}

		if (type.arraySize)
			variable->getType().setArraySize(type.arraySize);
	} 

	if (voidErrorCheck(line, identifier, type))
		return true;

	return false;
}

bool TParseContext::arraySetMaxSize(TIntermSymbol *node, TType* type, int size, bool updateFlag, TSourceLoc line)
{
	bool builtIn = false;
	TSymbol* symbol = symbolTable.find(node->getSymbol(), &builtIn);
	if (symbol == 0) {
		error(line, " undeclared identifier", node->getSymbol().c_str(), "");
		return true;
	}
	TVariable* variable = static_cast<TVariable*>(symbol);

	type->setArrayInformationType(variable->getArrayInformationType());
	variable->updateArrayInformationType(type);

	// special casing to test index value of gl_FragData. If the accessed index is >= gl_MaxDrawBuffers
	// its an error
	if (node->getSymbol() == "gl_FragData") {
		TSymbol* fragData = symbolTable.find("gl_MaxDrawBuffers", &builtIn);
		if (fragData == 0) {
			infoSink.info.message(EPrefixInternalError, "gl_MaxDrawBuffers not defined", line);
			return true;
		}

		int fragDataValue = static_cast<TVariable*>(fragData)->getConstPointer()[0].getIConst();
		if (fragDataValue <= size) {
			error(line, "", "[", "gl_FragData can only have a max array size of up to gl_MaxDrawBuffers", "");
			return true;
		}
	}

	// we dont want to update the maxArraySize when this flag is not set, we just want to include this 
	// node type in the chain of node types so that its updated when a higher maxArraySize comes in.
	if (!updateFlag)
		return false;

	size++;
	variable->getType().setMaxArraySize(size);
	type->setMaxArraySize(size);
	TType* tt = type;

	while(tt->getArrayInformationType() != 0) {
		tt = tt->getArrayInformationType();
		tt->setMaxArraySize(size);
	}

	return false;
}

//
// Enforce non-initializer type/qualifier rules.
//
// Returns true if there was an error.
//
bool TParseContext::nonInitConstErrorCheck(int line, TString& identifier, TPublicType& type)
{
	//
	// Make the qualifier make sense.
	//
	if (type.qualifier == EvqConst) {
		type.qualifier = EvqTemporary;
		error(line, "variables with qualifier 'const' must be initialized", identifier.c_str(), "");
		return true;
	}

	return false;
}

//
// Do semantic checking for a variable declaration that has no initializer,
// and update the symbol table.
//
// Returns true if there was an error.
//
bool TParseContext::nonInitErrorCheck(int line, TString& identifier, TPublicType& type)
{
	if (reservedErrorCheck(line, identifier))
		recover();

	TVariable* variable = new TVariable(&identifier, TType(type));

	if (! symbolTable.insert(*variable)) {
		error(line, "redefinition", variable->getName().c_str(), "");
		delete variable;
		return true;
	}

	if (voidErrorCheck(line, identifier, type))
		return true;

	return false;
}

bool TParseContext::paramErrorCheck(int 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->changeQualifier(EvqConstReadOnly);
	else
		type->changeQualifier(paramQualifier);

	return false;
}

bool TParseContext::extensionErrorCheck(int line, const char* extension)
{       
	if (extensionBehavior[extension] == EBhWarn) {
		infoSink.info.message(EPrefixWarning, ("extension " + TString(extension) + " is being used").c_str(), line);
		return false;
	}
	if (extensionBehavior[extension] == EBhDisable) {
		error(line, "extension", extension, "is disabled");
		return true;
	}

	return false;
}

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

//
// 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(int line, TFunction* call, bool *builtIn)
{
	const TSymbol* symbol = symbolTable.find(call->getMangledName(), 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;
	}
	
	const TFunction* function = static_cast<const TFunction*>(symbol);
	
	return function;
}

//
// Initializers show up in several places in the grammar.  Have one set of
// code to handle them here.
//
bool TParseContext::executeInitializer(TSourceLoc line, TString& identifier, TPublicType& pType, 
									   TIntermTyped* initializer, TIntermNode*& intermNode, TVariable* variable)
{
	TType type = TType(pType);

	if (variable == 0) {
		if (reservedErrorCheck(line, identifier))
			return true;

		if (voidErrorCheck(line, identifier, pType))
			return true;

		//
		// add variable to symbol table
		//
		variable = new TVariable(&identifier, type);
		if (! symbolTable.insert(*variable)) {
			error(line, "redefinition", variable->getName().c_str(), "");
			return true;
			// don't delete variable, it's used by error recovery, and the pool 
			// pop will take care of the memory
		}
	}

	//
	// 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()) {
			error(line, " assigning non-constant to", "=", "'%s'", variable->getType().getCompleteString().c_str());
			variable->getType().changeQualifier(EvqTemporary);
			return true;
		}
		if (type != initializer->getType()) {
			error(line, " non-matching types for const initializer ", 
				variable->getType().getQualifierString(), "");
			variable->getType().changeQualifier(EvqTemporary);
			return true;
		}
		if (initializer->getAsConstantUnion()) { 
			constUnion* unionArray = variable->getConstPointer();

			if (type.getObjectSize() == 1 && type.getBasicType() != EbtStruct) {
				*unionArray = (initializer->getAsConstantUnion()->getUnionArrayPointer())[0];
			} else {
				variable->shareConstPointer(initializer->getAsConstantUnion()->getUnionArrayPointer());
			}
		} else if (initializer->getAsSymbolNode()) {
			const TSymbol* symbol = symbolTable.find(initializer->getAsSymbolNode()->getSymbol());
			const TVariable* tVar = static_cast<const TVariable*>(symbol);

			constUnion* constArray = tVar->getConstPointer();
			variable->shareConstPointer(constArray);
		} else {
			error(line, " cannot assign to", "=", "'%s'", variable->getType().getCompleteString().c_str());
			variable->getType().changeQualifier(EvqTemporary);
			return true;
		}
	}
 
	if (qualifier != EvqConst) {
		TIntermSymbol* intermSymbol = intermediate.addSymbol(variable->getUniqueId(), variable->getName(), variable->getType(), line);
		intermNode = intermediate.addAssign(EOpInitialize, intermSymbol, initializer, line);
		if (intermNode == 0) {
			assignError(line, "=", intermSymbol->getCompleteString(), initializer->getCompleteString());
			return true;
		}
	} else 
		intermNode = 0;

	return false;
}

bool TParseContext::areAllChildConst(TIntermAggregate* aggrNode)
{
	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
	if (aggrNode) {
		TIntermSequence &childSequenceVector = aggrNode->getSequence() ;
		for (TIntermSequence::iterator p = childSequenceVector.begin(); 
									p != childSequenceVector.end(); p++) {
			if (!(*p)->getAsTyped()->getAsConstantUnion())
				return false;
		}
	}

	return allConstant;
}

// 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* node, const TType* type, TOperator op, TFunction* fnCall, TSourceLoc line)
{
	if (node == 0)
		return 0;

	TIntermAggregate* aggrNode = node->getAsAggregate();
	
	TTypeList::iterator memberTypes;
	if (op == EOpConstructStruct)
		memberTypes = type->getStruct()->begin();
	
	TType elementType = *type;
	if (type->isArray())
		elementType.clearArrayness();

	bool singleArg;
	if (aggrNode) {
		if (aggrNode->getOp() != EOpNull || aggrNode->getSequence().size() == 1)
			singleArg = true;
		else
			singleArg = false;
	} else
		singleArg = true;

	TIntermTyped *newNode;
	if (singleArg) {
		// If structure constructor or array constructor is being called 
		// for only one parameter inside the structure, we need to call constructStruct function once.
		if (type->isArray())
			newNode = constructStruct(node, &elementType, 1, node->getLine(), false);
		else if (op == EOpConstructStruct)
			newNode = constructStruct(node, (*memberTypes).type, 1, node->getLine(), false);
		else
			newNode = constructBuiltIn(type, op, node, node->getLine(), false);

		if (newNode && newNode->getAsAggregate()) {
			TIntermTyped* constConstructor = foldConstConstructor(newNode->getAsAggregate(), *type);
			if (constConstructor)
				return constConstructor;
		}

		return newNode;
	}
	
	//
	// Handle list of arguments.
	//
	TIntermSequence &sequenceVector = aggrNode->getSequence() ;    // Stores the information about the parameter to the constructor
	// if the structure constructor contains more than one parameter, then construct
	// each parameter
	
	int paramCount = 0;  // keeps a track of the constructor parameter number being checked    
	
	// for each parameter to the constructor call, check to see if the right type is passed or convert them 
	// to the right type if possible (and allowed).
	// for structure constructors, just check if the right type is passed, no conversion is allowed.
	
	for (TIntermSequence::iterator p = sequenceVector.begin(); 
								   p != sequenceVector.end(); p++, paramCount++) {
		if (type->isArray())
			newNode = constructStruct(*p, &elementType, paramCount+1, node->getLine(), true);
		else if (op == EOpConstructStruct)
			newNode = constructStruct(*p, (memberTypes[paramCount]).type, paramCount+1, node->getLine(), true);
		else
			newNode = constructBuiltIn(type, op, *p, node->getLine(), true);
		
		if (newNode) {
			*p = newNode;
		}
	}

	TIntermTyped* constructor = intermediate.setAggregateOperator(aggrNode, op, line);
	TIntermTyped* constConstructor = foldConstConstructor(constructor->getAsAggregate(), *type);
	if (constConstructor)
		return constConstructor;

	return constructor;
}

TIntermTyped* TParseContext::foldConstConstructor(TIntermAggregate* aggrNode, const TType& type)
{
	bool canBeFolded = areAllChildConst(aggrNode);
	aggrNode->setType(type);
	if (canBeFolded) {
		bool returnVal = false;
		constUnion* unionArray = new constUnion[type.getObjectSize()];
		if (aggrNode->getSequence().size() == 1)  {
			returnVal = intermediate.parseConstTree(aggrNode->getLine(), aggrNode, unionArray, aggrNode->getOp(), symbolTable,  type, true);
		}
		else {
			returnVal = intermediate.parseConstTree(aggrNode->getLine(), aggrNode, unionArray, aggrNode->getOp(), symbolTable,  type);
		}
		if (returnVal)
			return 0;

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

	return 0;
}

// Function for constructor implementation. Calls addUnaryMath with appropriate EOp value
// for the parameter to the constructor (passed to this function). Essentially, it converts
// the parameter types correctly. If a constructor expects an int (like ivec2) and is passed a 
// float, then float is converted to int.
//
// Returns 0 for an error or the constructed node.
//
TIntermTyped* TParseContext::constructBuiltIn(const TType* type, TOperator op, TIntermNode* node, TSourceLoc line, bool subset)
{
	TIntermTyped* newNode;
	TOperator basicOp;

	//
	// First, convert types as needed.
	//
	switch (op) {
	case EOpConstructVec2:
	case EOpConstructVec3:
	case EOpConstructVec4:
	case EOpConstructMat2:
	case EOpConstructMat3:
	case EOpConstructMat4:
	case EOpConstructFloat:
		basicOp = EOpConstructFloat;
		break;

	case EOpConstructIVec2:
	case EOpConstructIVec3:
	case EOpConstructIVec4:
	case EOpConstructInt:
		basicOp = EOpConstructInt;
		break;

	case EOpConstructBVec2:
	case EOpConstructBVec3:
	case EOpConstructBVec4:
	case EOpConstructBool:
		basicOp = EOpConstructBool;
		break;

	default:
		error(line, "unsupported construction", "", "");
		recover();

		return 0;
	}
	newNode = intermediate.addUnaryMath(basicOp, node, node->getLine(), symbolTable);
	if (newNode == 0) {
		error(line, "can't convert", "constructor", "");
		return 0;
	}

	//
	// Now, if there still isn't an operation to do the construction, and we need one, add one.
	//
	
	// Otherwise, skip out early.
	if (subset || (newNode != node && newNode->getType() == *type))
		return newNode;

	// setAggregateOperator will insert a new node for the constructor, as needed.
	return intermediate.setAggregateOperator(newNode, op, line);
}

// This function tests for the type of the parameters to the structures constructors. Raises
// an error message if the expected type does not match the parameter passed to the constructor.
//
// Returns 0 for an error or the input node itself if the expected and the given parameter types match.
//
TIntermTyped* TParseContext::constructStruct(TIntermNode* node, TType* type, int paramCount, TSourceLoc line, bool subset)
{
	if (*type == node->getAsTyped()->getType()) {
		if (subset)
			return node->getAsTyped();
		else
			return intermediate.setAggregateOperator(node->getAsTyped(), EOpConstructStruct, line);
	} else {
		error(line, "", "constructor", "cannot convert parameter %d from '%s' to '%s'", paramCount,
				node->getAsTyped()->getType().getBasicString(), type->getBasicString());
		recover();
	}

	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, TSourceLoc line)
{
	TIntermTyped* typedNode;
	TIntermConstantUnion* tempConstantNode = node->getAsConstantUnion();

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

		if (!unionArray) {  // this error message should never be raised
			infoSink.info.message(EPrefixInternalError, "constUnion not initialized in addConstVectorNode function", line);
			recover();

			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;
	}

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

	for (int i = 0; i < fields.num; i++) {
		if (fields.offsets[i] >= node->getType().getObjectSize()) {
			error(line, "", "[", "vector field selection out of range '%d'", fields.offsets[i]);
			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, TSourceLoc line)
{
	TIntermTyped* typedNode;
	TIntermConstantUnion* tempConstantNode = node->getAsConstantUnion();

	if (index >= node->getType().getNominalSize()) {
		error(line, "", "[", "matrix field selection out of range '%d'", index);
		recover();
		index = 0;
	}

	if (tempConstantNode) {
		 constUnion* unionArray = tempConstantNode->getUnionArrayPointer();
		 int size = tempConstantNode->getType().getNominalSize();
		 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, TSourceLoc line)
{
	TIntermTyped* typedNode;
	TIntermConstantUnion* tempConstantNode = node->getAsConstantUnion();
	TType arrayElementType = node->getType();
	arrayElementType.clearArrayness();

	if (index >= node->getType().getArraySize()) {
		error(line, "", "[", "array field selection out of range '%d'", index);
		recover();
		index = 0;
	}

	int arrayElementSize = arrayElementType.getObjectSize();

	if (tempConstantNode) {
		 constUnion* 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(TString& identifier, TIntermTyped* node, TSourceLoc line)
{
	TTypeList* fields = node->getType().getStruct();
	TIntermTyped *typedNode;
	int instanceSize = 0;
	unsigned int index = 0;
	TIntermConstantUnion *tempConstantNode = node->getAsConstantUnion();

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

	if (tempConstantNode) {
		 constUnion* constArray = tempConstantNode->getUnionArrayPointer();

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

		return 0;
	}

	return typedNode;
}

//
// Initialize all supported extensions to disable
//
void TParseContext::initializeExtensionBehavior()
{
	//
	// example code: extensionBehavior["test"] = EBhDisable; // where "test" is the name of 
	// supported extension
	//
	extensionBehavior["GL_ARB_texture_rectangle"] = EBhRequire;
	extensionBehavior["GL_3DL_array_objects"] = EBhDisable;
}

OS_TLSIndex GlobalParseContextIndex = OS_INVALID_TLS_INDEX;

bool InitializeParseContextIndex()
{
	if (GlobalParseContextIndex != OS_INVALID_TLS_INDEX) {
		assert(0 && "InitializeParseContextIndex(): Parse Context already initalised");
		return false;
	}

	//
	// Allocate a TLS index.
	//
	GlobalParseContextIndex = OS_AllocTLSIndex();
	
	if (GlobalParseContextIndex == OS_INVALID_TLS_INDEX) {
		assert(0 && "InitializeParseContextIndex(): Parse Context already initalised");
		return false;
	}

	return true;
}

bool InitializeGlobalParseContext()
{
	if (GlobalParseContextIndex == OS_INVALID_TLS_INDEX) {
		assert(0 && "InitializeGlobalParseContext(): Parse Context index not initalised");
		return false;
	}

	TThreadParseContext *lpParseContext = static_cast<TThreadParseContext *>(OS_GetTLSValue(GlobalParseContextIndex));
	if (lpParseContext != 0) {
		assert(0 && "InitializeParseContextIndex(): Parse Context already initalised");
		return false;
	}

	TThreadParseContext *lpThreadData = new TThreadParseContext();
	if (lpThreadData == 0) {
		assert(0 && "InitializeGlobalParseContext(): Unable to create thread parse context");
		return false;
	}

	lpThreadData->lpGlobalParseContext = 0;
	OS_SetTLSValue(GlobalParseContextIndex, lpThreadData);

	return true;
}

TParseContextPointer& GetGlobalParseContext()
{
	//
	// Minimal error checking for speed
	//

	TThreadParseContext *lpParseContext = static_cast<TThreadParseContext *>(OS_GetTLSValue(GlobalParseContextIndex));

	return lpParseContext->lpGlobalParseContext;
}

bool FreeParseContext()
{
	if (GlobalParseContextIndex == OS_INVALID_TLS_INDEX) {
		assert(0 && "FreeParseContext(): Parse Context index not initalised");
		return false;
	}

	TThreadParseContext *lpParseContext = static_cast<TThreadParseContext *>(OS_GetTLSValue(GlobalParseContextIndex));
	if (lpParseContext)
		delete lpParseContext;

	return true;
}

bool FreeParseContextIndex()
{
	OS_TLSIndex tlsiIndex = GlobalParseContextIndex;

	if (GlobalParseContextIndex == OS_INVALID_TLS_INDEX) {
		assert(0 && "FreeParseContextIndex(): Parse Context index not initalised");
		return false;
	}

	GlobalParseContextIndex = OS_INVALID_TLS_INDEX;

	return OS_FreeTLSIndex(tlsiIndex);
}