Add clamp function

[thinkverse]

Like @ryangjchandler, I wanted to experiment with PHP source code a bit, since his live stream showed it was actually quite easy to start messing with it. Got no experience with C but what the heck. Following Ryan's example, I tried to implement my own clamp function based on his own experiment.

Usage example

This is a snippet from Color, where this function would be useful.

Before

class Color
{
    public function __construct(int $red = 0, int $green = 0, int $blue = 0, float $alpha = 1.0)
    {
        $this->red   = max(0, min(255, $red));
        $this->green = max(0, min(255, $green));
        $this->blue  = max(0, min(255, $blue));
        $this->alpha = max(0, min(1.0, $alpha));
    }
}

After

class Color
{
    public function __construct(int $red = 0, int $green = 0, int $blue = 0, float $alpha = 1.0)
    {
        $this->red   = clamp($red, 0, 255);
        $this->green = clamp($green, 0, 255);
        $this->blue  = clamp($blue, 0, 255);
        $this->alpha = clamp($alpha, 0, 1.0);
    }
}