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Set

Extended Set utilities plus callable and readonly wrappers.

Import

import { DataSet, ReadonlySet, set } from '@stackpress/lib';

When To Use It

Use DataSet when you want Set uniqueness with indexed read helpers and transformation methods. Use ReadonlySet when you want read-only access. Use set() when a callable index-based getter is convenient.

API

Constructor

const tags = new DataSet<string>(['api', 'router', 'queue']);

ReadonlySet accepts the same initial array.

DataSet Methods

Method Returns Notes
filter(callback) new DataSet subclass Filters values by value and insertion index.
find(callback) [number, V] | undefined First matching [index, value].
findIndex(callback) number Returns -1 when no value matches.
findValue(callback) V | undefined First matching value.
first() V | undefined Alias for index(0).
index(index) V | undefined Value by insertion order.
last() V | undefined Value at size - 1.
map(callback) new DataSet<T> Maps each value into a new set.
toArray() V[] Array snapshot.
toString(replacer?, space?) string JSON string of toArray().

ReadonlySet Methods

ReadonlySet exposes the read side of the collection:

  • entries()
  • filter(callback)
  • find(callback)
  • findIndex(callback)
  • findValue(callback)
  • forEach(iterator)
  • has(value)
  • index(index)
  • keys()
  • map(callback)
  • size
  • toArray()
  • toString(replacer?, space?)
  • values()

Callable Helper

const queue = set(['first', 'second']);

queue(0);
queue.index(1);
queue.add('third');

set(data?) returns a CallableSet<V> with the DataSet method surface plus a function signature for indexed reads.

Example

import { DataSet } from '@stackpress/lib';

const flags = new DataSet<number>();
flags.add(1);
flags.add(2);
flags.add(3);

const doubled = flags.map(value => value * 2);
const second = flags.index(1);
const found = flags.findValue(value => value === 3);

Related