9.4 Compile-Time Expressions and Operators

The HLA CTL supports constant expressions in the CTL assignment statement. Unlike the runtime language (where you have to translate algebraic notation into a sequence of machine instructions), the HLA CTL allows a full set of arithmetic operations using familiar expression syntax. This gives the HLA CTL considerable power, especially when combined with the built-in compile-time functions the next section discusses.

Table 9-1 and Table 9-2 list operators that the HLA CTL supports in compile-time expressions.

Table 9-1. Compile-Time Operators

Operator(s)	Operand Types[a]	Description
- (unary)	numeric	Negates the specific numeric value (int, uns, real).
	cset	Returns the complement of the specified character set.
! (unary)	integer	Inverts all the bits in the operand (bitwise not).
	boolean	Boolean not of the operand.
*	numericL * numericR	Multiplies the two operands.
	csetL * csetR	Computes the intersection of the two sets.
div	integerL divintegerR	Computes the integer quotient of the two integer (int/uns/dword) operands.
mod	integerL modintegerR	Computes the remainder of the division of the two integer (int/uns/dword) operands.
/	numericL / numericR	Computes the real quotient of the two numeric operands. Returns a real result even if both operands are integers.
<<	integerL << integerR	Shifts integerL operand to the left the number of bits specified by the integerR operand.
>>	integerL >> integerR	Shifts integerL operand to the right the number of bits specified by the integerR operand.
+	numericL + numericR	Adds the two numeric operands.
	csetL + csetR	Computes the union of the two sets.
	strL + strR	Concatenates the two strings.
-	numericL numericR	Computes the difference between numericL and numericR.
	csetL - csetR	Computes the set difference of csetL - csetR.
= or ==	numericL = numericR	Returns true if the two operands have the same value.
	csetL = csetR	Returns true if the two sets are equal.
	strL = strR	Returns true if the two strings/chars are equal.
	typeL = typeR	Returns true if the two values are equal. They must be the same type.
<> or !=	typeL <> typeR (sameas !=)	Returns false if the two (compatible) operands are not equal to one another (numeric, cset, or string).
<	numericL < numericR	Returns true if numericL is less than numericR.
	csetL < csetR	Returns true if csetL is a proper subset of csetR.
	strL < strR	Returns true if strL is less than strR.
	booleanL < booleanR	Returns true if the left operand is less than the right operand (note: false < true).
	enumL < enumR	Returns true if enumL appears in the same enumlist as enumR and enumL appears first.
<=	Same as <	Returns true if the left operand is less than or equal to the right operand. For character sets, this means that the left operand is a subset of the right operand.
>	Same as <	Returns true if the left operand is greater than the right operand. For character sets, this means that the left operand is a proper superset of the right operand.
>=	Same as <=	Returns true if the left operand is greater than or equal to the right operand. For character sets, this means that the left operand is a superset of the right operand.
&	integerL & integerR	Computes the bitwise and of the two operands.
	booleanL & booleanR	Computes the logical and of the two operands.
|	integerL | integerR	Computes the bitwise or of the two operands.
	booleanL | booleanR	Computes the logical or of the two operands.
^	integerL ^ integerR	Computes the bitwise xor of the two operands.
	booleanL ^ booleanR	Computes the logical xor of the two operands. Note that this is equivalent to booleanL <> booleanR.
in	charL in csetR	Returns true if charL is a member of csetR.
[a] Type numeric is {intXX, unsXX, byte, word, dword, and realXX} values. Type cset is a character set operand. Type integer is {intXX, unsXX, byte, word, dword}. Type str is any string or character value. Type indicates an arbitrary HLA type. Other types specify an explicit HLA data type.

Table 9-2. Operator Precedence and Associativity

Associativity	Precedence (Highest to Lowest)	Operator
Right to left	6	! (unary)
		- (unary)
Left to right	5	*
		div
		mod
		/
		>>
		<<
Left to right	4	+
		-
Left to right	3	= or ==
		<> or !=
		<
		<=
		>
		>=
Left to right	2	&
		|
		^
Nonassociative	1	in

Of course, you can always override the default precedence and associativity of an operator by using parentheses in an expression.