XSL - Does evaluating conditional expressions “sho

Question

Given an XSL 'If' statement:

<xsl:if test="a = 'some value' and b = 'another value'">

If a does not equal 'some value', is the value of b still checked? (As if the first test is false, the only outcome of the and is false.) This is what languages like C# do - I was wondering if the same goes in XSL. Does it depend on the engine/parser?

Answer 1

Yes, this is depending on the implementation. But since XSLT is side-effect-free (as opposed to C# and other languages, where a function call chainging some state or even an assignment can be in the expression), this does not matter.

Answer 2

Yes, it is called lazy-evaluation or short-circuiting, and xsl supports it. See: http://www.w3.org/TR/xpath#booleans

An and expression is evaluated by evaluating each operand and converting its value to a boolean as if by a call to the boolean function. The result is true if both values are true and false otherwise. The right operand is not evaluated if the left operand evaluates to false.