Expression Operators

Vendor Certification Expressions: Expression Operators, Functions, and Global Variables › Expression Operators

Expression Operators

This section describes operators that you can use in vendor certification expressions.

You can use MVEL syntax in vendor certification expressions. MVEL is a publicly available embeddable Expression Language for Java environments that has a syntax close to Java. MVEL supports expressions similar to Java expressions.

You can build expressions using operators, use braces to control precedence, and terminate statements by semi-colons. For a detailed reference of the MVEL language, see http://mvel.codehaus.org.

The following table summarizes the available operators:

Note: In XML documents, use the XML Named Entities (XNE) presentation.

Operator	XNE	Description	Example
=		Assign	a = 1
==		Equals	"fred" == "fred"
!=		Not Equals	"fred" != "tom"
>	>	Greater Than	1 > 0 is true
<	<	Less Than	0 < 1 is true
>=		Greater Than or Equal	1 >= 0 is true
<=		Less Than or Equal	1 <= 1 is true
contains		Verify if the value on the left side contains the value on the right	"tomcat" contains "cat"
isdef		Tests whether a variable is defined	isdef a
+		Add	1 + 1
+		Concatenate	"one " + "two"
-		Minus	2 - 1
*		Multiply	2 * 2
/		Divide	4 / 2
%		Modulus	5 % 2
&&	&&	Logical AND	(x>-1) && (x<1)
\|\|		Logical OR	(x<-1) \|\| (x>1)
&	&	AND bit operation	17 & 0xF
\|		OR bit operation	4 \| 1
^		Exclusive OR bit operation	5 ^ 1
!		Negate	! True
?		Ternary operator	age > 17 ? "allow" : "deny"