CI框架源码完全分析之核心文件Common.php

 0)
		{
			foreach ($replace as $key => $val)
			{
				if (isset($config[$key]))
				{
					$config[$key] = $val;
				}
			}
		}

		return $_config[0] =& $config;
	}
}

// ------------------------------------------------------------------------

/**
* 这个就简单啦，返回配置数组中某个键名的配置值
*
* @access	public
* @return	mixed
*/
if ( ! function_exists('config_item'))
{
	function config_item($item)
	{
		static $_config_item = array();

		if ( ! isset($_config_item[$item]))
		{
			$cOnfig=& get_config();

			if ( ! isset($config[$item]))
			{
				return FALSE;
			}
			$_config_item[$item] = $config[$item];
		}

		return $_config_item[$item];
	}
}

// ------------------------------------------------------------------------

/**
* 错误处理
*
* 直接显示错误信息到浏览器，都是使用core/Exception.php的方法
* 默认的view文件 application/errors/errors.php
*
* @access	public
* @return	void
*/
if ( ! function_exists('show_error'))
{
	function show_error($message, $status_code = 500, $heading = 'An Error Was Encountered')
	{
		$_error =& load_class('Exceptions', 'core');
		echo $_error->show_error($heading, $message, 'error_general', $status_code);
		exit;
	}
}

// ------------------------------------------------------------------------

/**
* 404页面处理
 * 如上相同
*
* @access	public
* @return	void
*/
if ( ! function_exists('show_404'))
{
	function show_404($page = '', $log_error = TRUE)
	{
		$_error =& load_class('Exceptions', 'core');
		$_error->show_404($page, $log_error);
		exit;
	}
}

// ------------------------------------------------------------------------

/**
* 记录错误日志，默认是libraries/log.php类库处理
*
* @access	public
* @return	void
*/
if ( ! function_exists('log_message'))
{
	function log_message($level = 'error', $message, $php_error = FALSE)
	{
		static $_log;

		if (config_item('log_threshold') == 0)
		{
			return;
		}

		$_log =& load_class('Log');
		$_log->write_log($level, $message, $php_error);
	}
}

// ------------------------------------------------------------------------

/**
 * 响应一个http头，数组是常见的http头的状态码
 *
 * @access	public
 * @param	int		the status code
 * @param	string
 * @return	void
 */
if ( ! function_exists('set_status_header'))
{
	function set_status_header($code = 200, $text = '')
	{
		$stati = array(
							200	=> 'OK',
							201	=> 'Created',
							202	=> 'Accepted',
							203	=> 'Non-Authoritative Information',
							204	=> 'No Content',
							205	=> 'Reset Content',
							206	=> 'Partial Content',

							300	=> 'Multiple Choices',
							301	=> 'Moved Permanently',
							302	=> 'Found',
							304	=> 'Not Modified',
							305	=> 'Use Proxy',
							307	=> 'Temporary Redirect',

							400	=> 'Bad Request',
							401	=> 'Unauthorized',
							403	=> 'Forbidden',
							404	=> 'Not Found',
							405	=> 'Method Not Allowed',
							406	=> 'Not Acceptable',
							407	=> 'Proxy Authentication Required',
							408	=> 'Request Timeout',
							409	=> 'Conflict',
							410	=> 'Gone',
							411	=> 'Length Required',
							412	=> 'Precondition Failed',
							413	=> 'Request Entity Too Large',
							414	=> 'Request-URI Too Long',
							415	=> 'Unsupported Media Type',
							416	=> 'Requested Range Not Satisfiable',
							417	=> 'Expectation Failed',

							500	=> 'Internal Server Error',
							501	=> 'Not Implemented',
							502	=> 'Bad Gateway',
							503	=> 'Service Unavailable',
							504	=> 'Gateway Timeout',
							505	=> 'HTTP Version Not Supported'
						);

		if ($code == '' OR ! is_numeric($code))
		{
			show_error('Status codes must be numeric', 500);
		}

		if (isset($stati[$code]) AND $text == '')
		{
			$text = $stati[$code];
		}

		if ($text == '')
		{
			show_error('No status text available.  Please check your status code number or supply your own message text.', 500);
		}

		$server_protocol = (isset($_SERVER['SERVER_PROTOCOL'])) ? $_SERVER['SERVER_PROTOCOL'] : FALSE;

		if (substr(php_sapi_name(), 0, 3) == 'cgi')
		{
			header("Status: {$code} {$text}", TRUE);
		}
		elseif ($server_protocol == 'HTTP/1.1' OR $server_protocol == 'HTTP/1.0')
		{
			header($server_protocol." {$code} {$text}", TRUE, $code);
		}
		else
		{
			header("HTTP/1.1 {$code} {$text}", TRUE, $code);
		}
	}
}

// --------------------------------------------------------------------

/**
* 异常或错误出力
*
* @access	private
* @return	void
*/
if ( ! function_exists('_exception_handler'))
{
	function _exception_handler($severity, $message, $filepath, $line)
	{
		 //E_STRICT的错误信息没用就不要了
		if ($severity == E_STRICT)
		{
			return;
		}

		$_error =& load_class('Exceptions', 'core');

		//这里是位运算哦，你可以看看PHP的错误级别(http://www.phpddt.com/php/error_reporting.html)
                //很显然1,2,4,8...（1,10,100,1000）中任意一个与1111进行&都是它本身，根据结果显示错误
		if (($severity & error_reporting()) == $severity)
		{
			$_error->show_php_error($severity, $message, $filepath, $line);
		}

		//根据配置信息是否记录错误信息日志
		if (config_item('log_threshold') == 0)
		{
			return;
		}

		$_error->log_exception($severity, $message, $filepath, $line);
	}
}

// --------------------------------------------------------------------

/**
 * 防止在ASCII字符之间插入空字符，如Java\0script.
 *
 * @access	public
 * @param	string
 * @return	string
 */
if ( ! function_exists('remove_invisible_characters'))
{
	function remove_invisible_characters($str, $url_encoded = TRUE)
	{
		$non_displayables = array();
		
		// every control character except newline (dec 10)
		// carriage return (dec 13), and horizontal tab (dec 09)
		
		if ($url_encoded)
		{
			$non_displayables[] = '/%0[0-8bcef]/';	// url encoded 00-08, 11, 12, 14, 15
			$non_displayables[] = '/%1[0-9a-f]/';	// url encoded 16-31
		}
		
		$non_displayables[] = '/[\x00-\x08\x0B\x0C\x0E-\x1F\x7F]+/S';	// 00-08, 11, 12, 14-31, 127

		do
		{
			$str = preg_replace($non_displayables, '', $str, -1, $count);
		}
		while ($count);

		return $str;
	}
}

// ------------------------------------------------------------------------

/**
* 将特殊字符转化成html实体，如单引号，双引号等
*
* @access	public
* @param	mixed
* @return	mixed
*/
if ( ! function_exists('html_escape'))
{
	function html_escape($var)
	{
		if (is_array($var))
		{
			return array_map('html_escape', $var);
		}
		else
		{
			return htmlspecialchars($var, ENT_QUOTES, config_item('charset'));
		}
	}
}