README

This small library allows manipulating integer sets.

Requirements

PHP 8.1, 8.2, 8.3.

Installation

composer require remorhaz/int-rangesets

Usage

Introduction

Set is represented in a form of collection of continuous ranges; each range is represented by a pair of integers denoting it's first and last values.

Range

Range cannot be empty, but can contain only one integer; in that case it's first and last values are the same.

<?php

use Remorhaz\IntRangeSets\Range;

// Contains values: 5, 6, 7, 8
$range1 = new Range(5, 8);

// Contains value 12
$range2 = new Range(12);

Ranges are immutable. Any operation on a range creates a new instance, leaving the original one intact.

<?php

use Remorhaz\IntRangeSets\Range;

// Contains values: 5, 6, 7, 8
$range1 = new Range(5, 8);

// New range has first value replaced and contains values: 7, 8
$range2 = $range1->withStart(7);

Range sets

All ranges in a set are normalized: they follow each other in ascending order and are separated by non-empty gaps, so none of them follow immediately after previous one or overlap.

Range sets are also immutable. Any operation on a set creates a new instance, leaving the original one intact.

<?php

use Remorhaz\IntRangeSets\Range;
use Remorhaz\IntRangeSets\RangeSet;

// Contains single range [3..5]
$rangeSet1 = RangeSet::create(new Range(3, 5));

// Added range [4..10] partially overlaps already existing one.
// Resulting range set contains single merged range [3..10].
$rangeSet2 = $rangeSet1->withRanges(new Range(4, 10));

Merging of ranges requires resources, so there's a fast, but unsafe way to initialize set with ranges. In this case constructing code must take full responsibility for normalization of ranges.

<?php

use Remorhaz\IntRangeSets\Range;
use Remorhaz\IntRangeSets\RangeSet;

// Creates range with two ranges: [2..5] and [7..8].
$rangeSet1 = RangeSet::createUnsafe(new Range(2, 5), new Range(7, 8));

WARNING: Operations on non-normalized range sets will return incorrect results! Use create() method with arbitrary range lists.

Available operations

In all examples $a, $b and $result are objects implementing \Remorhaz\IntRangeSets\RangeSetInterface.

Operation	Formula	Example
Union	A ∪ B	`$result = $a->createUnion($b);`
Intersection	A ∩ B	`$result = $a->createIntersection($b);`
Symmetric difference	A ∆ B	`$result = $a->createSymmetricDifference($b);`

License

This library is licensed under MIT license.

remorhaz / int-rangesets

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