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xc

SortDescriptor

SortDescriptor sorts records by keys (NSSortDescriptor in shape). Filter with a Predicate, then sort with descriptors: what a table does to its rows. From 0.72.

#import "SortDescriptor.xc"   // not in the Foundation umbrella: import it by name

Overview

Section titled “Overview”
Array* rows = SortDescriptor.sorted(people, SortDescriptor.list2(
    SortDescriptor.withKey(String.withCString("age"), false),     // oldest first
    SortDescriptor.withKey(String.withCString("name"), true)));   // then by name

A descriptor names a key (a dotted path through nested Maps, as a predicate reads one), a direction, and whether Strings compare ignoring ASCII case. A list of descriptors sorts by the first and breaks ties with the next.

Values order as a predicate compares them (Predicate.compareValues): Numbers as numbers, with Strings that hold numbers; Strings by bytes. A missing or null value, or one with no order against the other, sorts before every other value when ascending, and after when descending.

The sort is stable: records every descriptor finds equal keep their order.

Topics

Section titled “Topics”

Describing · withKey · key / ascending / caseInsensitive · reversed · list1 / list2

Sorting · sorted · sortedWith · compare / compareValues

Describing

Section titled “Describing”

withKey

Section titled “withKey”
static SortDescriptor* withKey(String* key, bool ascending)

key / ascending / caseInsensitive

Section titled “key / ascending / caseInsensitive”
String* key;
bool ascending;
bool caseInsensitive;

Public fields.

reversed

Section titled “reversed”
SortDescriptor* reversed(void)

A copy with the direction turned round: for a column header clicked again.

list1 / list2

Section titled “list1 / list2”
static Array* list1(SortDescriptor* a)
static Array* list2(SortDescriptor* a, SortDescriptor* b)

A list of one or two descriptors, for the common cases; any Array of descriptors will do.

↑ Topics

Sorting

Section titled “Sorting”

sorted

Section titled “sorted”
static Array* sorted(Array* items, Array* descriptors)

A sorted copy of items (Maps).

sortedWith

Section titled “sortedWith”
static Array* sortedWith(Array* items, Array* descriptors, callback read Object*(Object* item, String* key))

The same for any objects, reading each key through read.

compare / compareValues

Section titled “compare / compareValues”
i8 compare(Object* a, Object* b)
i8 compareValues(Object* a, Object* b)

How two records, or two values, order under this one descriptor: -1, 0 or 1.

↑ Topics