drupol\phpermutations\Iterators\FiniteGroup

Complexity

Total Complexity

18

Size/Duplication

Total Lines	174
Duplicated Lines	0 %

Coupling/Cohesion

Dependencies

1

Test Coverage

Coverage

85.11%

Importance

Changes	2
Bugs	0	Features	0

13 Methods

Rating	Name	Duplication	Size	Complexity
A	current()	0	4	1
A	key()	0	4	1
A	valid()	0	4	1
A	count()	0	4	1
A	toArray()	0	10	2
A	getSize()	0	4	1
A	__construct()	0	4	1
A	next()	0	5	1
A	rewind()	0	4	1
A	setSize()	0	5	1
A	order()	0	11	2
A	computeGroup()	0	10	3
A	gcd()	0	4	2

<?php

namespace drupol\phpermutations\Iterators;

use drupol\phpermutations\Combinatorics;

/**
 * Class FiniteGroup.
 *
 * The finite group is an abelian finite cyclic group.
 *
 * @package drupol\phpermutations\Iterators
 */
class FiniteGroup extends Combinatorics implements \Iterator, \Countable
{
    /**
     * The group size.
     *
     * @var int
     */
    protected $size;

    /**
     * The group.
     *
     * @var int[]
     */
    protected $group;

    /**
     * The key.
     *
     * @var int
     */
    protected $key;

    /**
     * Combinatorics constructor.
     */
    public function __construct()
    {
        parent::__construct([], null);
    }

    /**
     * {@inheritdoc}
     */
    public function current()
    {
        return current($this->group);
    }

    /**
     * {@inheritdoc}
     */
    public function next()
    {
        $this->key++;
        next($this->group);
    }

    /**
     * {@inheritdoc}
     */
    public function key()
    {
        return $this->key;
    }

    /**
     * {@inheritdoc}
     */
    public function valid()
    {
        return isset($this->group[$this->key()]);
    }

    /**
     * {@inheritdoc}
     */
    public function rewind()
    {
        $this->key = 0;
    }

    /**
     * Count elements of an object.
     *
     * @return int
     *   The number of element.
     */
    public function count()
    {
        return count($this->group);
    }

    /**
     * Convert the iterator into an array.
     *
     * @return array
     *   The elements.
     */
    public function toArray()
    {
        $data = [];

        for ($this->rewind(); $this->valid(); $this->next()) {
            $data[] = $this->current();
        }

        return $data;
    }

    /**
     * Set the group size.
     *
     * @param int $size
     *   The size.
     */
    public function setSize($size)
    {
        $this->size = $size;
        $this->computeGroup();
    }

    /**
     * Get the group size.
     *
     * @return int
     *   The size.
     */
    public function getSize()
    {
        return intval($this->size);
    }

    /**
     * Get the order.
     *
     * @param int $generator
     *   The generator.
     *
     * @return int
     *   The order.
     */
    public function order($generator)
    {
        $result = [];

        foreach (range(1, $this->getSize() - 1) as $number) {
            $value = pow($generator, $number) % $this->getSize();
            $result[$value] = $value;
        }

        return count($result);
    }

    /**
     * Clean out the group from unwanted values.
     */
    private function computeGroup()
    {
        $this->group = [];

        foreach (range(1, $this->getSize() - 1) as $number) {
            if ($this->gcd($number, $this->getSize() - 1) === 1) {
                $this->group[] = $number;
            }
        }
    }

    /**
     * Get the greater common divisor between two numbers.
     *
     * @param int $a
     *   The first number.
     * @param int $b
     *   The second number.
     *
     * @return int
     *   The greater common divisor between $a and $b.
     */
    private function gcd($a, $b)

Avoid variables with short names like $a. Configured minimum length is 3.

Avoid variables with short names like $b. Configured minimum length is 3.

    {
        return $b ? $this->gcd($b, $a % $b) : $a;
    }
}