lucidtaz\minimax\engine\Evaluation

Complexity

Total Complexity

6

Size/Duplication

Total Lines	40
Duplicated Lines	0 %

Coupling/Cohesion

Components	1
Dependencies	0

Test Coverage

Coverage

100%

Importance

Changes

0

3 Methods

Rating	Name	Duplication	Size	Complexity
A	isBetterThan()	0	8	2
A	getBestComparator()	0	6	2
A	getWorstComparator()	0	6	2

<?php

declare(strict_types=1);

namespace lucidtaz\minimax\engine;

use Closure;

/**
 * Value object containing the result of a decision tree node evaluation
 * These two concepts are used together so often that it warrants a separate
 * class to be able to carry them around easily.
 */
class Evaluation
{
    private const EPSILON = 0.00001;

    /**
     * @var float Score that results from applying the decision
     */
    public $score;

    /**
     * @var integer How deep in the execution tree this result was found. Higher
     * means earlier. This is to prefer earlier solutions to later solutions
     * with the same score, which will make the AI not delay a win without
     * reason.
     */
    public $age;

    public function isBetterThan(Evaluation $other): bool
    {
        if (abs($this->score - $other->score) < self::EPSILON) {
            // Scores are considered the same, prefer earliest decision. (Shallowest node)
            return $this->age > $other->age;
        }
        return $this->score > $other->score;
    }

    public static function getBestComparator(): Closure
    {
        return static function (Evaluation $a, Evaluation $b) {
            return $a->isBetterThan($b) ? 1 : -1;
        };
    }

    public static function getWorstComparator(): Closure
    {
        return static function (Evaluation $a, Evaluation $b) {
            return $b->isBetterThan($a) ? 1 : -1;
        };
    }
}