Algo-Web / POData

    ) {

        //for null operands only equality operators are allowed

        $null = new Null1();

        if ($leftArgument->typeIs($null) || $rightArgument->typeIs($null)) {

            if ((strcmp($expressionToken->Text, ODataConstants::KEYWORD_EQUAL) != 0)

                && (strcmp($expressionToken->Text, ODataConstants::KEYWORD_NOT_EQUAL) != 0)

            ) {

                throw ODataException::createSyntaxError(

                    Messages::expressionParserOperatorNotSupportNull(

                        $expressionToken->Text,

                        $expressionToken->Position

                    )

                );

            }

            return;

        }

        //for guid operands only equality operators are allowed

        $guid = new Guid();

        //for guid operands only equality operators are allowed

        $guid = new Guid();

        if ($leftArgument->typeIs($guid) && $rightArgument->typeIs($guid)) {

            if ((strcmp($expressionToken->Text, ODataConstants::KEYWORD_EQUAL) != 0)

                && (strcmp($expressionToken->Text, ODataConstants::KEYWORD_NOT_EQUAL) != 0)

            ) {

                throw ODataException::createSyntaxError(

                    Messages::expressionParserOperatorNotSupportGuid(

                        $expressionToken->Text,

                        $expressionToken->Position

                    )

                );

            }

            return;

        }

        //for binary operands only equality operators are allowed

        //for binary operands only equality operators are allowed

        $binary = new Binary();

        if ($leftArgument->typeIs($binary) && $rightArgument->typeIs($binary)) {

            if ((strcmp($expressionToken->Text, ODataConstants::KEYWORD_EQUAL) != 0)

                && (strcmp($expressionToken->Text, ODataConstants::KEYWORD_NOT_EQUAL) != 0)

            ) {

                throw ODataException::createSyntaxError(

                    Messages::expressionParserOperatorNotSupportBinary(

                        $expressionToken->Text,

                        $expressionToken->Position

                    )

                );

            }

            return;

        }

        //TODO: eq and ne is valid for 'resource reference'