Color value object

Color.php

<?php
final class Color
{
    private $name;

    /**
     * @param integer $r [0, 255]
     * @param integer $g [0, 255]
     * @param integer $b [0, 255]
     * @return Color
     */
    public static function fromRGB($r, $g, $b)
    {
        if ($r < 0 || $r > 255) {
            throw new \InvalidArgumentException('Invalid value for R component');
        }

        if ($g < 0 || $g > 255) {
            throw new \InvalidArgumentException('Invalid value for G component');
        }

        if ($b < 0 || $b > 255) {
            throw new \InvalidArgumentException('Invalid value for B component');
        }

        $color = new self();
        $color->name = sprintf('%02X%02X%02X', $r, $g, $b);

        return $color;
    }

    /**
     * @param integer $h [0, 360]
     * @param float $s [0, 1]
     * @param float $l [0, 1]
     * @return Color
     */
    public static function fromHSL($h, $s, $l)
    {
        if ($h < 0 || $h > 360) {
            throw new \InvalidArgumentException('Invalid value for H component');
        }

        if ($s < 0 || $s > 1) {
            throw new \InvalidArgumentException('Invalid value for S component');
        }

        if ($s < 0 || $s > 1) {
            throw new \InvalidArgumentException('Invalid value for L component');
        }

        $h = $h / 360;

        if ($s == 0) {
            return self::fromRGB(round($l * 255), round($l * 255), round($l * 255));
        }

        $q = $l < 0.5 ? $l * (1 + $s) : $l + $s - $l * $s;
        $p = 2 * $l - $q;

        $r = self::HUEtoRGB($p, $q, $h + 1/3);
        $g = self::HUEtoRGB($p, $q, $h);
        $b = self::HUEtoRGB($p, $q, $h - 1/3);

        return self::fromRGB(round($r * 255), round($g * 255), round($b * 255));
    }

    /**
     * @param float $p
     * @param float $q
     * @param float $t
     * @return float
     */
    private static function HUEtoRGB($p, $q, $t)
    {
        if($t < 0) {
            $t += 1;
        }
        if($t > 1) {
            $t -= 1;
        }
        if($t < 1/6) {
            return $p + ($q - $p) * 6 * $t;
        }
        if($t < 1/2) {
            return $q;
        }
        if($t < 2/3) {
            return $p + ($q - $p) * (2/3 - $t) * 6;
        }

        return $p;
    }

    public function __toString()
    {
        return $this->name;
    }

    private function __construct()
    {
    }
}

$d = 360 / 5;

$colors = [];

for ($i = 0; $i < 360; $i += $d) {
    $color = Color::fromHSL($i, 0.7, 0.5);
    $colors[] = (string)$color;
}

echo json_encode(array_map(function($value){
    return '#'.$value;
}, $colors)) . "\n\n";