File Source for config_loader.class.php

<?php
// *** Tangra (Application Framework and Tools for PHP)
// $Id$
//
/**
* Contains class Config_Loader
* @package tangra_lib
* @subpackage core
*/
/**
* Loading exception
*/
require_once(TANGRA_MAIN_DIR.'exceptions/te_config_loader_error_key_missing.class.php');
require_once(TANGRA_MAIN_DIR.'exceptions/te_config_loader_error.class.php');
/**
* Base class for configuration loaders.
*
* Base class for all classes of Config_Loader family. Used to define the interface.
* Config_Loader classes are intended to provide unified mechanism for loading configuration from diferent sources as files, db, net connection, etc.
*
*
* @package tangra_lib
* @subpackage core
*
*/
abstract class Config_Loader extends Tangra_Class {
/**
* $pairs holds key - value pairs in associative array. Key is the name of configuration value and value - the value itself.
* @access private
* @var array
*/
protected $pairs = array();
/**
* It is supposed loading of the configuration from external resource as file or DB to be performed at construction time of Config_Loader objects.
* That means that when you createn new instance of Config_Loader class (some descendant of Config_Loader that is not "abstract") your configuration will be loaded and you can use get_conf_value method to extract values.
*
* @param mutable $config_resource Intended to be mutable type, i.e. different Config_Loader descendants may require different paramter type.
*/
abstract function __construct($config_resource);
/**
* Gets coresponding to $key configuration value.
*
* @param string key name of configuration setting
* @param boolean $halt_on_missing if true exception will be trown if configuration setting specified by $key
* @return unknown
* @throws TE_Config_Loader_Error_Key_Missing
*/
final public function get_conf_value($key, $halt_on_missing = true) {
if (array_key_exists($key, $this->pairs)) {
$ret = $this->pairs[$key];
// $ret = trim($this->pairs[$key]);
// $ret = $this->expand($ret, $key);
} else {
if ($halt_on_missing) {
throw new TE_Config_Loader_Error_Key_Missing('Key: '.$key.' is not found.');
} else {
$ret = NULL;
}
}
return $ret;
}
/**
* Auxiliary method that may be used to set the internal private $pairs variable.
* This method normally is not called directly - it is intended to be used by writers of new Config_Loader descendants that require weird approach.
* @param array $pairs Array must be simple associative array with $key => $value structure.
* @throws Tangra_Exception
*/
public function set_pairs($pairs) {
if (is_array($pairs)) {
$this->pairs = $pairs;
} else {
Tangra_Exception('Parameter $pairs is not an array. Current value: '.$pairs);
}
}
/**
* Returns all key-value pairs
*
* @return array
*/
public function get_pairs() {
return $this->pairs;
}
/**
* Expands keys that are present in values
*
* If key starts with _AUTO a global function will be called to return the value. Name of the global function have to be strtolower($key) where $key is the key to be expanded.
* Example:
* If we have in machine_specific.conf the following:
* ROOT=%_AUTO_DETECT_ROOT%
* function with name _auto_detect_root will be called and returned value will be used to replace %_AUTO_DETECT_ROOT%
*
* @param string $value
* @param string $current_key
* @return string
*/
protected function expand($value, $current_key) {
$ret = '';
$keys = $this->extract_keys($value);
if ($keys) {
foreach($keys as $key) {
if ($current_key != $key) {
if (strtoupper(substr($key, 0, 5)) == '_AUTO') {
$global_func = strtolower($key);
$tmp = call_user_func($global_func);
$value = str_replace('%'.$key.'%', $tmp, $value);
} else {
if (array_key_exists($key, $this->pairs)) {
$value = str_replace('%'.$key.'%', trim($this->pairs[$key]), $value);
}
}
} else {
throw new TE_Config_Loader_Error('Fatal error occured while trying to expand value "'.$value.'" for key "'.$current_key.'". Recursion.');
}
}
$ret = $value;
} else {
$ret = $value;
}
return $ret;
}
/**
* Extracts all keys (delimited by % from both sides)
*
* @param string $value
* @return array
* @internal
*/
private function extract_keys($value) {
$ret = array();
$start = strpos($value, '%');
if ($start !== FALSE) {
$ret[] = $this->extract_key($value, $start);
}
return $ret;
}
/**
* Extracts single key that start at position $start in string $value
*
* @param string $value
* @param integer $start
* @return string
* @internal
*/
private function extract_key($value, $start) {
$end = strpos($value, '%', $start + 1);
if ($end !== FALSE) {
$ret = substr($value, $start + 1, $end - $start - 1);
} else {
throw new TE_Config_Loader_Error('Fatal error occured while trying to expand value "'.$value.'". No end delimiter % found.');
}
return $ret;
}
/**
* Adds new key-value pair
*
* @param string $key
* @param string $value
*/
public function add_pair($key, $value) {
if (!array_key_exists($key, $this->pairs)) {
$this->pairs[$key] = $value;
} else {
throw new TE_Config_Loader_Error("Key $key already exists.");
}
}
}

Source for file config_loader.class.php