Sort (Arraylist subroutine)

<section begin=dpl_desc/>Sort the input Arraylist<section end=dpl_desc/>

Sort is a member of the Arraylist class.

This subroutine sorts the method object Arraylist and replaces it with the sorted result. The sort is based on one or more sort criteria which consist of a sorting direction (ascending or descending) paired with a sort key (a function that gets applied to each Arraylist item). Each sort criterion pair is a SortOrder object, and multiple pairs are a SortOrder collection.

The sort key function that gets applied to each Arraylist item, which you identify in the Sort parameter, must operate on the item type and return a User Language intrinsic datatype (Float, String, Longstring, or Unicode) value. The values returned by the function are sorted into ascending or descending order to determine the position of their associated item in the Arraylist.

The system intrinsic classes are discussed in "Intrinsic classes".

Sort is available in Sirius Mods version 7.3 and later.

Syntax

  [Call] %arrayl:Sort(sortCriteria)

Syntax Terms

%arrayl

The input Arraylist object.

sortCriteria

One or more SortOrder objects, which consist of an ordering direction for the sort and an attribute, or key, to sort by. The ordering direction and sort key are specified in the form: order(key). The order is either Ascending or Descending, and the key is a function that is applied to each item in the Arraylist. The values returned by the function are sorted into ascending or descending order to determine the position of their associated item in the rearranged Arraylist. For example:

    %arrayl:sortnew(descending(length))

The function is a method value (a method or class member name literal, or a method variable) for a method that operates on items of the type specified on the %arrayl declaration and that returns a numeric or string value. This is described further in "Specifying a SortOrder's sort key method".

Usage Notes

• If the function applied by Sort returns string values, Sort uses the decimal-equivalent value of the character bytes to determine the ascending or descending alphabetic order of the associated arraylist items. In ascending order, the highest or last lowercase letter is “z”; the highest or last uppercase letter is “Z”; “z” ranks lower than all the uppercase letters; and all letters rank lower than any number.
• If two or more Arraylist items have equal values after all sort criteria are applied, Sort places them in the same order in which they appear in the input Arraylist.
• The function in the parameter for Sort is a method value, not a User Language expression. That is, you cannot provide a function that itself has an argument (say, ToIntegerPower(2)) as the Sort parameter.
• As of Sirius Mods version 7.6, the default sortCriteria argument is the SortOrder Ascending(This), where This is the identity function described further in "Using the This function as the Maximum parameter". Therefore, %arrayl:sort(ascending(this)) can be specified simply as %arrayl:sort. See "SortNew example".
• SortNew is a function that works like Sort but returns a new Arraylist instead of replacing the method object.
• For examples of the Sort method, see Finding collection maxima and minima, and sorting.