<?php
/**
 * FFmpegAutoloader manages lazy autoloading of all FFmpegPHP components
 * 
 * @author huang zengbing
 * @package FFmpegPHP
 * @license New BSD
 * @version 2.6
 */
namespace Phpffmpeg;

class FFmpegAutoloader {
    /**
     * 构造执行函数
     *
     * @var array
     */
    private $directory;
    private $prefix;
    private $prefixLength;

    public function __construct($baseDirectory = __DIR__) {
         // 当前所在的文件夹路径
        $this->directory = $baseDirectory;
        // 当前命名空间
        $this->prefix = __NAMESPACE__.'\\';
        // 当前命名空间的字符串数
        $this->prefixLength = strlen($this->prefix);
    }
    /**
     * Autoloading mechanizm
     * 
     * @param string $className 
     * @return boolean
     */
    public function autoload($className) {
        // new \Phpffmpeg\...
        // 判断如果以\命名空间访问的格式符合
        if (0 === strpos($className, $this->prefix)) {
            //分隔出$this->prefixLength个字符串以后的字符返回，再以\为分隔符分隔
            $parts = explode('\\', substr($className, $this->prefixLength));
            // 组合新的路径
            $filepath = $this->directory.DIRECTORY_SEPARATOR.implode(DIRECTORY_SEPARATOR, $parts).'.php';
            if (is_file($filepath)) {
                require_once $filepath;
            }
        }
    }

    /**
     * Registering autoloading mechanizm
     */     
    public static function register($prepend=false) { 
        if (function_exists('__autoload')) {        
            trigger_error('FFmpegPHP uses spl_autoload_register() which will bypass your __autoload() and may break your autoloading', E_USER_WARNING);    
        } else {     
            // spl_autoload_register(array('FFmpegAutoloader', 'autoload'));
            //spl_autoload_register(array('class_name','function')),即是那个类的function
            spl_autoload_register(array(new self(), 'autoload'), true, $prepend);
        }
    }
}