RuntimeDataReader.php

<?php
 
/*
 *
 *  ____            _        _   __  __ _                  __  __ ____
 * |  _ \ ___   ___| | _____| |_|  \/  (_)_ __   ___      |  \/  |  _ \
 * | |_) / _ \ / __| |/ / _ \ __| |\/| | | '_ \ / _ \_____| |\/| | |_) |
 * |  __/ (_) | (__|   <  __/ |_| |  | | | | | |  __/_____| |  | |  __/
 * |_|   \___/ \___|_|\_\___|\__|_|  |_|_|_| |_|\___|     |_|  |_|_|
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * @author PocketMine Team
 * @link http://www.pocketmine.net/
 *
 *
 */
 
declare(strict_types=1);
 
namespace pocketmine\data\runtime;
 
use pocketmine\block\utils\WallConnectionType;
use pocketmine\math\Axis;
use pocketmine\math\Facing;
use pocketmine\utils\AssumptionFailedError;
use function get_class;
use function intdiv;
use function log;
use function spl_object_id;
 
final class RuntimeDataReader implements RuntimeDataDescriber{
    private int $offset = 0;
 
    public function __construct(
        private int $maxBits,
        private int $value
    ){}
 
    public function readInt(int $bits) : int{
        $bitsLeft = $this->maxBits - $this->offset;
        if($bits > $bitsLeft){
            throw new \InvalidArgumentException("No bits left in buffer (need $bits, have $bitsLeft");
        }
 
        $value = ($this->value >> $this->offset) & ~(~0 << $bits);
        $this->offset += $bits;
        return $value;
    }
 
    public function int(int $bits, int &$value) : void{
        $value = $this->readInt($bits);
    }
 
    private function readBoundedIntAuto(int $min, int $max) : int{
        $bits = ((int) log($max - $min, 2)) + 1;
        $result = $this->readInt($bits) + $min;
        if($result < $min || $result > $max){
            throw new InvalidSerializedRuntimeDataException("Value is outside the range $min - $max");
        }
        return $result;
    }
 
    public function boundedIntAuto(int $min, int $max, int &$value) : void{
        $value = $this->readBoundedIntAuto($min, $max);
    }
 
    protected function readBool() : bool{
        return $this->readInt(1) === 1;
    }
 
    public function bool(bool &$value) : void{
        $value = $this->readBool();
    }
 
    public function facingExcept(Facing &$facing, Facing $except) : void{
        $result = Facing::DOWN;
        $this->enum($result);
        if($result === $except){
            throw new InvalidSerializedRuntimeDataException("Illegal facing value");
        }
 
        $facing = $result;
    }
 
    public function horizontalAxis(Axis &$axis) : void{
        $axis = match($this->readInt(1)){
            0 => Axis::X,
            1 => Axis::Z,
            default => throw new AssumptionFailedError("Unreachable")
        };
    }
 
    public function wallConnections(array &$connections) : void{
        $result = [];
        $offset = 0;
        $packed = $this->readBoundedIntAuto(0, (3 ** 4) - 1);
        foreach(Facing::HORIZONTAL as $facing){
            $type = intdiv($packed,  (3 ** $offset)) % 3;
            if($type !== 0){
                $result[$facing->value] = match($type){
                    1 => WallConnectionType::SHORT,
                    2 => WallConnectionType::TALL,
                    default => throw new AssumptionFailedError("Unreachable")
                };
            }
            $offset++;
        }
 
        $connections = $result;
    }
 
    public function enum(\UnitEnum &$case) : void{
        $metadata = RuntimeEnumMetadata::from($case);
        $raw = $this->readInt($metadata->bits);
        $result = $metadata->intToEnum($raw);
        if($result === null){
            throw new InvalidSerializedRuntimeDataException("Invalid serialized value $raw for " . get_class($case));
        }
 
        $case = $result;
    }
 
    public function enumSet(array &$set, array $allCases) : void{
        $result = [];
        foreach($allCases as $case){
            if($this->readBool()){
                $result[spl_object_id($case)] = $case;
            }
        }
        $set = $result;
    }
 
    public function getOffset() : int{ return $this->offset; }
}