基本满足所有配置相关的需求，此处贴代码

1.类代码

class Config {
 /**
 * 解析后的配置文件
 *
 * @var stdClass
 */
 private $config;
 /**
 * 一个二维数组，键是配置文件的section
 * 值是一个数组或回调函数
 * 如果是数组则计算hostname是否在数组中决定是否使用该section
 * 如果是回调函数通过返回值true或false来确定是否使用该section
 *
 * @var array
 */
 private $map = array ();
  
 /**
 * section会被解析，:表示继承
 * 配置项中的'.'用来区分层级关系
 * section中的'.'不会被解析，配置中的数组不受影响。
 *
 * @param string $conf     
 * @throws ErrorException
 * @return stdClass
 */
 function __construct($conf, $map) {
 $config = $this->parseIni ( ( object ) parse_ini_string ( $conf, true ) );
 if (array_key_exists ( 'production', $map )) {
  $production = $map ['production'];
  unset ( $map ['production'] );
  $map = array_merge ( array (
   'production' => $production ), $map );
 } else {
  throw new ErrorException ( 'production section not found in config' );
 }
 $section = 'production';
 $hostname = gethostname ();
 foreach ( $map as $k => $v ) {
  if (is_array ( $v )) {
  foreach ( $v as $v1 ) {
   if ($v1 == $hostname) {
   $section = $k;
   break 2;
   }
  }
  } elseif (is_callable ( $v )) {
  if (true == call_user_func ( $v )) {
   $section = $k;
   break;
  }
  } else {
  throw new ErrorException ( 'Wrong map value in ' . __CLASS__ );
  }
 }
 $this->config = $config->$section;
 }
  
 /**
 * 总是返回配置对象
 *
 * @return mixed
 */
 function __get($key) {
 if (isset ( $this->config->$key )) {
  return $this->config->$key;
 }
 }
  
 /**
 * 切分
 *
 * @param stdClass $v     
 * @param string $k1     
 * @param mixed $v1     
 */
 private function split($v, $k1, $v1) {
 $keys = explode ( '.', $k1 );
 $last = array_pop ( $keys );
 $node = $v;
 foreach ( $keys as $v2 ) {
  if (! isset ( $node->$v2 )) {
  $node->$v2 = new stdClass ();
  }
  $node = $node->$v2;
 }
 $node->$last = $v1;
 if (count ( $keys ) > 0) {
  unset ( $v->$k1 );
 }
 }
  
 /**
 * parseIni
 *
 * @param object $conf     
 * @return stdClass
 */
 private function parseIni($conf) {
 $confObj = new stdClass ();
 foreach ( $conf as $k => $v ) {
  // 是section
  if (is_array ( $v )) {
  $confObj->$k = ( object ) $v;
  foreach ( $v as $k1 => $v1 ) {
   call_user_func ( array (
    $this,
    'split' ), $confObj->$k, $k1, $v1 );
  }
  } else {
  call_user_func ( array (
   $this,
   'split' ), $confObj, $k, $v );
  }
 }
 unset ( $conf );
 // 处理继承
 foreach ( $confObj as $k => $v ) {
  if (false !== strpos ( $k, ':' )) {
  if (0 === strpos ( $k, ':' )) {
   throw new ErrorException ( 'config ' . $k . ' is invalid, ':' can't be the first char' );
  } elseif (1 < substr_count ( $k, ':' )) {
   throw new ErrorException ( 'config ' . $k . ' is invalid, ':' can appear only once' );
  } else {
   $keys = explode ( ':', $k );
   if (! isset ( $confObj->$keys [1] )) {
   throw new ErrorException ( 'parent section ' . $keys [1] . ' doesn't exist in config file' );
   } else {
   if (isset ( $confObj->$keys [0] )) {
    throw new ErrorException ( 'config is invalid, ' . $keys [0] . ' and ' . $k . ' conflicts' );
   } else {
    $confObj->$keys [0] = $this->deepCloneR ( $confObj->$keys [1] );
    $this->objectMergeR ( $confObj->$keys [0], $v );
    unset ( $confObj->$k );
   }
   }
  }
  }
 }
 return $confObj;
 }
  
 /**
 * php默认是浅克隆，函数实现深克隆
 *
 * @param object $obj     
 * @return object $obj
 */
 private function deepCloneR($obj) {
 $objClone = clone $obj;
 foreach ( $objClone as $k => $v ) {
  if (is_object ( $v )) {
  $objClone->$k = $this->deepCloneR ( $v );
  }
 }
 return $objClone;
 }
  
 /**
 * 递归的合并两个对象
 *
 * @param unknown $obj1     
 * @param unknown $obj2     
 */
 private function objectMergeR($obj1, $obj2) {
 foreach ( $obj2 as $k => $v ) {
  if (is_object ( $v ) && isset ( $obj1->$k ) && is_object ( $obj1->$k )) {
  $this->objectMergeR ( $obj1->$k, $v );
  } else {
  $obj1->$k = $v;
  }
 }
 }
}

2.测试代码

$_ENV ['config'] = new Config ( file_get_contents ( __DIR__ . '/config.ini' ), array (
 'development' => array (
  'localhost.localdomain',
  'localhost'
 ),
 'production' => array ()
) );

3.配置文件

[product]
db.default.dsn="mysql:host=127.0.0.1;dbname=default"
db.default.username=root
db.default.password=123456
 
admin.username=admin
admin.password=123456
 
php.error_reporting=E_ALL
php.display_errors=no
php.log_errors=yes
php.error_log=APP_PATH'/resource/log/phpError.log'
php.session.save_path=APP_PATH'/resource/data/session'
 
[development:product]
db.test1.dsn="mysql:host=127.0.0.1;dbname=test1"
db.test1.username=root
db.test1.password=123456
php.display_errors=yes
 
[url]
url.root = http://www.lai18.com/
url.resource = /resourc