Simple JSON Configuration Manager

FMConfigurationManager.php

<?php

/**
  * A Simple JSON Site-wide Configuration manager with key-path access, overriding, inline variables, etc..
  * It might look ugly for some people, most important goal with this is simplicity in the code that uses this.
  * 
  * You can find usage sample at the end of the file
  * 
  * @author Furkan Mustafa <furkan@fume.jp>
  * @version 0.1.3
  * @copyright no, licensed by GPL, please read http://www.gnu.org/licenses/gpl.html
  */

namespace FM;

class ConfigurationManager {
    
    public static $SharedInstance = null;
    public static $Instances = array();
    private $instanceNumber = -1;
    private $___conf = array();
    
    function __construct($configFile = false, $shared = true) {
        if ($configFile) {
            $this->overrideWithContentsOfFile($configFile);
        }
        self::$Instances[] = &$this;
        $this->instanceNumber = count(self::$Instances) - 1;
        if ($shared)
            $this->setShared();
    }
    function overrideWithData($data, $relativeToKeyPath = false, $depth = 0) {
        $depth++;
        if ($depth==1 && !is_array($data))
            return false; // you shouldn't
        $keyPath = array();
        if ($relativeToKeyPath)
            $keyPath = !is_array($relativeToKeyPath) ? explode('.', $relativeToKeyPath) : $relativeToKeyPath;
        
        if (is_array($data)) {
            foreach ($data as $key => $value) {
                if ($key=='@global') {
                    $this->overrideWithData($value, false, $depth);
                    continue;
                }
                $subKeyPath = $keyPath;
                array_push($subKeyPath, $key);
                $this->overrideWithData($value, $subKeyPath, $depth);
            }
            return;
        }
        $this->setConf($keyPath, $data);
    }
    function overrideWithContentsOfFile($file, $relativeToKeyPath = false) {
        if (!file_exists($file))
            throw new \Exception('Config file '.$file.' doesn\'t exist.');
        $this->overrideWithData($this->decode(file_get_contents($file)), $relativeToKeyPath);
    }
    function setShared() {
        self::$SharedInstance = &$this;
    }
    private function decode($configFileContents) {
        // in future this might be pluggable
        return json_decode($configFileContents, true);
    }
    
    private function filter($data) {
        if (is_string($data)) {
            while (preg_match('/\$\{([^\}]+)\}/', $data, $m)) {
                $data = str_replace($m[0], $this->getConf($m[1]), $data);
            }
        }
        else if (is_array($data)) {
            foreach ($data as $n => $i) {
                $data[$n] = $this->filter($i);
            }
        }
        return $data;
    }
    
    public function getConf($itemPath) {
        return $this->conf($itemPath);
    }
    public function setConf($itemPath, $value) {
        return $this->conf($itemPath, $value);
    }
    public function conf($keyPath, $newValue = null) {
        if (!$keyPath)
            return $this->filter($this->___conf);
        $value = &self::GetKeyPath($this->___conf, $keyPath, $newValue!==null);
        if ($newValue!==null) {
            $value = $newValue;
            return;
        }
        // filters for values maybe
        return $this->filter($value);
    }
    private static function &GetKeyPath(&$arr, $keyPath, $create = false) {
        $keyPathParts = !is_array($keyPath) ? explode('.', $keyPath) : $keyPath;
        $subjectKey = array_shift($keyPathParts);
        $array_append = false;
        if (preg_match('/^([^\[]+)\[([^\]]*)\]$/', $subjectKey, $match)) {
            if (isset($match[2]) && strlen(trim($match[2]))>0) {
                array_unshift($keyPathParts, $match[2]);
            } else if ($create) {
                // .. this is for setting/appending
                $array_append = true;
            }
            $subjectKey = $match[1];
        }
        if (!isset($arr[$subjectKey])) {
            if (!$create) {
                $rv = false;
                return $rv;
            }
            $arr[$subjectKey] = null;
            if ($array_append) {
                $arr[$subjectKey] = array();
                array_unshift($keyPathParts, '0');  // first element of array
            }
            if (count($keyPathParts)==0) {
                return $arr[$subjectKey];
            }
            return self::GetKeyPath($arr[$subjectKey], $keyPathParts, true);
        }
        if ($array_append) {
            $count = count($arr[$subjectKey]);
            $arr[$subjectKey][$count] = null;
            $item = &$arr[$subjectKey][$count];
        } else {
            $item = &$arr[$subjectKey];
        }
        if (count($keyPathParts)==0) 
            return $item;
        return self::GetKeyPath($item, $keyPathParts, $create);
    }
    public function registerGlobalFunction($name) {
        $number = $this->instanceNumber;
        $code = 'function '.$name.'($keypath = false, $value = null) { return \FM\ConfigurationManager::$Instances['.$number.']->conf($keypath, $value); }';
        eval($code);
    }
}


/*
// Sample Usage:

$configurationManager = new \FM\ConfigurationManager(__DIR__.'/../config.json');
$configurationManager->registerGlobalFunction('conf');
//$configurationManager->overrideWithContentsOfFile(__DIR__.'/../database.json', 'database');

// detected configuration
conf('path.root', realpath(__DIR__.'/..'));

conf('naber.iyilik', 5);
conf('naber.senden', 'Benden en az ${naber.iyilik} kadar iyiyim be abi');
conf('naber.iyilik', 15);

conf('path.include[].path', 'hey');
conf('path.include[].path', 'mey');

print_r(conf());
*/