sort Statement

Syntax

NONE

sort anArray using <expression with element and nextElement>

Semantics

sort allows you to sort an array by using an expression to compare array elements with each other. The sort algorithm will call the expression each time two elements need to be compared. The expression can return:

an integer	< 0	element precedes nextElement
	= 0	element and nextElement are equal
	> 0	element succeeds nextElement
a boolean	true	element precedes nextElement
a boolean	false	element succeeds nextElement

It is not determined, what sort algorithm will actually be used, though a Quicksort derivative is the most common.

Be aware that sort algorithms are not linear (typically n log n to n² iterations for n elements). Therefore, you should keep the expression as compact as possible.

When using a boolean expression, make sure that equality always returns true (e.g. by using <= instead of <). Otherwise, the implemented sort algorithm may take longer than necessary or not terminate at all.

Substitutables anArray Can be any variable or object attribute having the type Array.

<expression with element and next element> This expression must use the currently evaluated array element and its next neighbor and indicates if the current order is ok or not.

element and nextElement are keywords and allow you to use relative references (as opposed to normal, absolute indices) to single elements of an array (see Get Array Element Operator [ ]).

Examples

NONE

// sort an array of integers in ascending order
set sorted = sort myList using element - nextElement;

//sort an array of strings in ascending order
set sorted = sort myList using element.text < nextElement.text;

//sort an array using dates in descending
set sorted = sort myList using element.date > nextElement.date;

// sort an array using boolean return values
set sorted = sort myList using element <= nextElement;
 
// sort an array with complex elements over 2 sort key
set sorted = sort inputContainer.elements using (element.aString =  nextElement.aString and element.anInteger < nextElement.anInteger) or element.aString < nextElement.aString;

Example File (Builder project E2E Action Language/Array):

<your example path>\E2E Action Language\Array\uml\arraySort.xml