src/main/php/helpers/LoggerOptionConverter.php - logging-log4php - Git at Google

 <?php
 /**
  * Licensed to the Apache Software Foundation (ASF) under one or more
  * contributor license agreements. See the NOTICE file distributed with
  * this work for additional information regarding copyright ownership.
  * The ASF licenses this file to You under the Apache License, Version 2.0
  * (the "License"); you may not use this file except in compliance with
  * the License. You may obtain a copy of the License at
  *
  *	   http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
  *
  * @package log4php
  */

 /**
  * A convenience class to convert property values to specific types.
  *
  * @version $Revision$
  * @package log4php
  * @subpackage helpers
  * @since 0.5
  */
 class LoggerOptionConverter {

 	const DELIM_START = '${';
 	const DELIM_STOP = '}';
 	const DELIM_START_LEN = 2;
 	const DELIM_STOP_LEN = 1;

 	/** String values which are converted to boolean TRUE. */
 	private static $trueValues = array('1', 'true', 'yes', 'on');

 	/**
 	 * String values which are converted to boolean FALSE.
 	 *
 	 * Note that an empty string must convert to false, because
 	 * parse_ini_file() which is used for parsing configuration
 	 * converts the value _false_ to an empty string.
 	 */
 	private static $falseValues = array('0', 'false', 'no', 'off', '');

 	/**
 	 * Read a predefined var.
 	 *
 	 * It returns a value referenced by <var>$key</var> using this search criteria:
 	 * - if <var>$key</var> is a constant then return it. Else
 	 * - if <var>$key</var> is set in <var>$_ENV</var> then return it. Else
 	 * - return <var>$def</var>.
 	 *
 	 * @param string $key The key to search for.
 	 * @param string $def The default value to return.
 	 * @return string	the string value of the system property, or the default
 	 *					value if there is no property with that key.
 	 */
 	public static function getSystemProperty($key, $def) {
 		if(defined($key)) {
 			return (string)constant($key);
 		} else if(isset($_SERVER[$key])) {
 			return (string)$_SERVER[$key];
 		} else if(isset($_ENV[$key])) {
 			return (string)$_ENV[$key];
 		} else {
 			return $def;
 		}
 	}

 	/**
 	 * If <var>$value</var> is <i>true</i>, then <i>true</i> is
 	 * returned. If <var>$value</var> is <i>false</i>, then
 	 * <i>true</i> is returned. Otherwise, <var>$default</var> is
 	 * returned.
 	 *
 	 * <p>Case of value is unimportant.</p>
 	 *
 	 * @param string $value
 	 * @param boolean $default
 	 * @return boolean
 	 */
 	public static function toBoolean($value, $default=true) {
 		if (is_null($value)) {
 			return $default;
 		} elseif (is_string($value)) {
 			$trimmedVal = strtolower(trim($value));
 			if("1" == $trimmedVal or "true" == $trimmedVal or "yes" == $trimmedVal or "on" == $trimmedVal) {
 				return true;
 			} else if ("" == $trimmedVal or "0" == $trimmedVal or "false" == $trimmedVal or "no" == $trimmedVal or "off" == $trimmedVal) {
 				return false;
 			}
 		} elseif (is_bool($value)) {
 			return $value;
 		} elseif (is_int($value)) {
 			return !($value == 0); // true is everything but 0 like in C
 		}

 		return $default;
 	}

 	/** Converts $value to boolean, or throws an exception if not possible. */
 	public static function toBooleanEx($value) {
 		if (isset($value)) {
 			if (is_bool($value)) {
 				return $value;
 			}
 			$value = strtolower(trim($value));
 			if (in_array($value, self::$trueValues)) {
 				return true;
 			}
 			if (in_array($value, self::$falseValues)) {
 				return false;
 			}
 		}

 		throw new LoggerException("Given value [" . var_export($value, true) . "] cannot be converted to boolean.");
 	}

 	/**
 	 * @param string $value
 	 * @param integer $default
 	 * @return integer
 	 */
 	public static function toInt($value, $default) {
 		$value = trim($value);
 		if(is_numeric($value)) {
 			return (int)$value;
 		} else {
 			return $default;
 		}
 	}


 	/**
 	 * Converts $value to integer, or throws an exception if not possible.
 	 * Floats cannot be converted to integer.
 	 */
 	public static function toIntegerEx($value) {
 		if (is_integer($value)) {
 			return $value;
 		}
 		if (is_numeric($value) && ($value == (integer) $value)) {
 			return (integer) $value;
 		}

 		throw new LoggerException("Given value [" . var_export($value, true) . "] cannot be converted to integer.");
 	}

 	/**
 	 * Converts $value to integer, or throws an exception if not possible.
 	 * Floats cannot be converted to integer.
 	 */
 	public static function toPositiveIntegerEx($value) {
 		if (is_integer($value) && $value > 0) {
 			return $value;
 		}
 		if (is_numeric($value) && ($value == (integer) $value) && $value > 0) {
 			return (integer) $value;
 		}

 		throw new LoggerException("Given value [" . var_export($value, true) . "] cannot be converted to a positive integer.");
 	}

 	/**
 	 * Converts a standard or custom priority level to a Level
 	 * object.
 	 *
 	 * <p> If <var>$value</var> is of form "<b>level#full_file_classname</b>",
 	 * where <i>full_file_classname</i> means the class filename with path
 	 * but without php extension, then the specified class' <i>toLevel()</i> method
 	 * is called to process the specified level string; if no '#'
 	 * character is present, then the default {@link LoggerLevel}
 	 * class is used to process the level value.</p>
 	 *
 	 * <p>As a special case, if the <var>$value</var> parameter is
 	 * equal to the string "NULL", then the value <i>null</i> will
 	 * be returned.</p>
 	 *
 	 * <p>If any error occurs while converting the value to a level,
 	 * the <var>$defaultValue</var> parameter, which may be
 	 * <i>null</i>, is returned.</p>
 	 *
 	 * <p>Case of <var>$value</var> is insignificant for the level level, but is
 	 * significant for the class name part, if present.</p>
 	 *
 	 * @param string $value
 	 * @param LoggerLevel $defaultValue
 	 * @return LoggerLevel a {@link LoggerLevel} or null
 	 */
 	public static function toLevel($value, $defaultValue) {
 		if($value === null) {
 			return $defaultValue;
 		}
 		$hashIndex = strpos($value, '#');
 		if($hashIndex === false) {
 			if("NULL" == strtoupper($value)) {
 				return null;
 			} else {
 				// no class name specified : use standard Level class
 				return LoggerLevel::toLevel($value, $defaultValue);
 			}
 		}

 		$result = $defaultValue;

 		$clazz = substr($value, ($hashIndex + 1));
 		$levelName = substr($value, 0, $hashIndex);

 		// This is degenerate case but you never know.
 		if("NULL" == strtoupper($levelName)) {
 			return null;
 		}

 		$clazz = basename($clazz);

 		if(class_exists($clazz)) {
 			$result = @call_user_func(array($clazz, 'toLevel'), $levelName, $defaultValue);
 			if(!$result instanceof LoggerLevel) {
 				$result = $defaultValue;
 			}
 		}
 		return $result;
 	}


 	/** Converts the value to a level. Throws an exception if not possible. */
 	public static function toLevelEx($value) {
 		if ($value instanceof LoggerLevel) {
 			return $value;
 		}
 		$level = LoggerLevel::toLevel($value);
 		if ($level === null) {
 			throw new LoggerException("Given value [" . var_export($value, true) . "] cannot be converted to a logger level.");
 		}
 		return $level;
 	}

 	/**
 	 * @param string $value
 	 * @param float $default
 	 * @return float
 	 */
 	public static function toFileSize($value, $default) {
 		if($value === null) {
 			return $default;
 		}

 		$string = strtoupper(trim($value));
 		$multiplier = (float)1;
 		if(($index = strpos($string, 'KB')) !== false) {
 			$multiplier = 1024;
 			$string = substr($string, 0, $index);
 		} else if(($index = strpos($string, 'MB')) !== false) {
 			$multiplier = 1024 * 1024;
 			$string = substr($string, 0, $index);
 		} else if(($index = strpos($string, 'GB')) !== false) {
 			$multiplier = 1024 * 1024 * 1024;
 			$string = substr($string, 0, $index);
 		}
 		if(is_numeric($string)) {
 			return (float)$string * $multiplier;
 		}
 		return $default;
 	}


 	/**
 	 * Converts a value to a valid file size (integer).
 	 *
 	 * Supports 'KB', 'MB' and 'GB' suffixes, where KB = 1024 B etc.
 	 *
 	 * The final value will be rounded to the nearest integer.
 	 *
 	 * Examples:
 	 * - '100' => 100
 	 * - '100.12' => 100
 	 * - '100KB' => 102400
 	 * - '1.5MB' => 1572864
 	 *
 	 * @param mixed $value File size (optionally with suffix).
 	 * @return integer Parsed file size.
 	 */
 	public static function toFileSizeEx($value) {

 		if (empty($value)) {
 			throw new LoggerException("Empty value cannot be converted to a file size.");
 		}

 		if (is_numeric($value)) {
 			return (integer) $value;
 		}

 		if (!is_string($value)) {
 			throw new LoggerException("Given value [" . var_export($value, true) . "] cannot be converted to a file size.");
 		}

 		$str = strtoupper(trim($value));
 		$count = preg_match('/^([0-9.]+)(KB|MB|GB)?$/', $str, $matches);

 		if ($count > 0) {
 			$size = $matches[1];
 			$unit = $matches[2];

 			switch($unit) {
 				case 'KB': $size *= pow(1024, 1); break;
 				case 'MB': $size *= pow(1024, 2); break;
 				case 'GB': $size *= pow(1024, 3); break;
 			}

 			return (integer) $size;
 		}

 		throw new LoggerException("Given value [$value] cannot be converted to a file size.");
 	}

 	/**
 	 * Converts a value to string, or throws an exception if not possible.
 	 *
 	 * Objects can be converted to string if they implement the magic
 	 * __toString() method.
 	 *
 	 */
 	public static function toStringEx($value) {
 		if (is_string($value)) {
 			return $value;
 		}
 		if (is_numeric($value)) {
 			return (string) $value;
 		}
 		if (is_object($value) && method_exists($value, '__toString')) {
 			return (string) $value;
 		}

 		throw new LoggerException("Given value [" . var_export($value, true) . "] cannot be converted to string.");
 	}


 	/**
 	 * Find the value corresponding to <var>$key</var> in
 	 * <var>$props</var>. Then perform variable substitution on the
 	 * found value.
 	 *
 	 * @param string $key
 	 * @param array $props
 	 * @return string
 	 */
 	public static function findAndSubst($key, $props) {
 		$value = @$props[$key];

 		// If coming from the LoggerConfiguratorIni, some options were
 		// already mangled by parse_ini_file:
 		//
 		// not specified      => never reaches this code
 		// ""|off|false|null  => string(0) ""
 		// "1"|on|true        => string(1) "1"
 		// "true"             => string(4) "true"
 		// "false"            => string(5) "false"
 		//
 		// As the integer 1 and the boolean true are therefore indistinguable
 		// it's up to the setter how to deal with it, they can not be cast
 		// into a boolean here. {@see toBoolean}
 		// Even an empty value has to be given to the setter as it has been
 		// explicitly set by the user and is different from an option which
 		// has not been specified and therefore keeps its default value.
 		//
 		// if(!empty($value)) {
 			return LoggerOptionConverter::substVars($value, $props);
 		// }
 	}

 	/**
 	 * Perform variable substitution in string <var>$val</var> from the
 	 * values of keys found with the {@link getSystemProperty()} method.
 	 *
 	 * <p>The variable substitution delimeters are <b>${</b> and <b>}</b>.
 	 *
 	 * <p>For example, if the "MY_CONSTANT" contains "value", then
 	 * the call
 	 * <code>
 	 * $s = LoggerOptionConverter::substVars("Value of key is ${MY_CONSTANT}.");
 	 * </code>
 	 * will set the variable <i>$s</i> to "Value of key is value.".</p>
 	 *
 	 * <p>If no value could be found for the specified key, then the
 	 * <var>$props</var> parameter is searched, if the value could not
 	 * be found there, then substitution defaults to the empty string.</p>
 	 *
 	 * <p>For example, if {@link getSystemProperty()} cannot find any value for the key
 	 * "inexistentKey", then the call
 	 * <code>
 	 * $s = LoggerOptionConverter::substVars("Value of inexistentKey is [${inexistentKey}]");
 	 * </code>
 	 * will set <var>$s</var> to "Value of inexistentKey is []".</p>
 	 *
 	 * <p>A warn is thrown if <var>$val</var> contains a start delimeter "${"
 	 * which is not balanced by a stop delimeter "}" and an empty string is returned.</p>
 	 *
 	 * @param string $val The string on which variable substitution is performed.
 	 * @param array $props
 	 * @return string
 	 */
 	 // TODO: this method doesn't work correctly with key = true, it needs key = "true" which is odd
 	public static function substVars($val, $props = null) {
 		$sbuf = '';
 		$i = 0;
 		while(true) {
 			$j = strpos($val, self::DELIM_START, $i);
 			if($j === false) {
 				// no more variables
 				if($i == 0) { // this is a simple string
 					return $val;
 				} else { // add the tail string which contails no variables and return the result.
 					$sbuf .= substr($val, $i);
 					return $sbuf;
 				}
 			} else {

 				$sbuf .= substr($val, $i, $j-$i);
 				$k = strpos($val, self::DELIM_STOP, $j);
 				if($k === false) {
 					// LoggerOptionConverter::substVars() has no closing brace. Opening brace
 					return '';
 				} else {
 					$j += self::DELIM_START_LEN;
 					$key = substr($val, $j, $k - $j);
 					// first try in System properties
 					$replacement = LoggerOptionConverter::getSystemProperty($key, null);
 					// then try props parameter
 					if($replacement == null and $props !== null) {
 						$replacement = @$props[$key];
 					}

 					if(!empty($replacement)) {
 						// Do variable substitution on the replacement string
 						// such that we can solve "Hello ${x2}" as "Hello p1"
 						// the where the properties are
 						// x1=p1
 						// x2=${x1}
 						$recursiveReplacement = LoggerOptionConverter::substVars($replacement, $props);
 						$sbuf .= $recursiveReplacement;
 					}
 					$i = $k + self::DELIM_STOP_LEN;
 				}
 			}
 		}
 	}

 }
	<?php
	/**
	* Licensed to the Apache Software Foundation (ASF) under one or more
	* contributor license agreements. See the NOTICE file distributed with
	* this work for additional information regarding copyright ownership.
	* The ASF licenses this file to You under the Apache License, Version 2.0
	* (the "License"); you may not use this file except in compliance with
	* the License. You may obtain a copy of the License at
	*
	* http://www.apache.org/licenses/LICENSE-2.0
	*
	* Unless required by applicable law or agreed to in writing, software
	* distributed under the License is distributed on an "AS IS" BASIS,
	* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	* See the License for the specific language governing permissions and
	* limitations under the License.
	*
	* @package log4php
	*/

	/**
	* A convenience class to convert property values to specific types.
	*
	* @version $Revision$
	* @package log4php
	* @subpackage helpers
	* @since 0.5
	*/
	class LoggerOptionConverter {

	const DELIM_START = '${';
	const DELIM_STOP = '}';
	const DELIM_START_LEN = 2;
	const DELIM_STOP_LEN = 1;

	/** String values which are converted to boolean TRUE. */
	private static $trueValues = array('1', 'true', 'yes', 'on');

	/**
	* String values which are converted to boolean FALSE.
	*
	* Note that an empty string must convert to false, because
	* parse_ini_file() which is used for parsing configuration
	* converts the value _false_ to an empty string.
	*/
	private static $falseValues = array('0', 'false', 'no', 'off', '');

	/**
	* Read a predefined var.
	*
	* It returns a value referenced by <var>$key</var> using this search criteria:
	* - if <var>$key</var> is a constant then return it. Else
	* - if <var>$key</var> is set in <var>$_ENV</var> then return it. Else
	* - return <var>$def</var>.
	*
	* @param string $key The key to search for.
	* @param string $def The default value to return.
	* @return string the string value of the system property, or the default
	* value if there is no property with that key.
	*/
	public static function getSystemProperty($key, $def) {
	if(defined($key)) {
	return (string)constant($key);
	} else if(isset($_SERVER[$key])) {
	return (string)$_SERVER[$key];
	} else if(isset($_ENV[$key])) {
	return (string)$_ENV[$key];
	} else {
	return $def;
	}
	}

	/**
	* If <var>$value</var> is <i>true</i>, then <i>true</i> is
	* returned. If <var>$value</var> is <i>false</i>, then
	* <i>true</i> is returned. Otherwise, <var>$default</var> is
	* returned.
	*
	* <p>Case of value is unimportant.</p>
	*
	* @param string $value
	* @param boolean $default
	* @return boolean
	*/
	public static function toBoolean($value, $default=true) {
	if (is_null($value)) {
	return $default;
	} elseif (is_string($value)) {
	$trimmedVal = strtolower(trim($value));
	if("1" == $trimmedVal or "true" == $trimmedVal or "yes" == $trimmedVal or "on" == $trimmedVal) {
	return true;
	} else if ("" == $trimmedVal or "0" == $trimmedVal or "false" == $trimmedVal or "no" == $trimmedVal or "off" == $trimmedVal) {
	return false;
	}
	} elseif (is_bool($value)) {
	return $value;
	} elseif (is_int($value)) {
	return !($value == 0); // true is everything but 0 like in C
	}

	return $default;
	}

	/** Converts $value to boolean, or throws an exception if not possible. */
	public static function toBooleanEx($value) {
	if (isset($value)) {
	if (is_bool($value)) {
	return $value;
	}
	$value = strtolower(trim($value));
	if (in_array($value, self::$trueValues)) {
	return true;
	}
	if (in_array($value, self::$falseValues)) {
	return false;
	}
	}

	throw new LoggerException("Given value [" . var_export($value, true) . "] cannot be converted to boolean.");
	}

	/**
	* @param string $value
	* @param integer $default
	* @return integer
	*/
	public static function toInt($value, $default) {
	$value = trim($value);
	if(is_numeric($value)) {
	return (int)$value;
	} else {
	return $default;
	}
	}


	/**
	* Converts $value to integer, or throws an exception if not possible.
	* Floats cannot be converted to integer.
	*/
	public static function toIntegerEx($value) {
	if (is_integer($value)) {
	return $value;
	}
	if (is_numeric($value) && ($value == (integer) $value)) {
	return (integer) $value;
	}

	throw new LoggerException("Given value [" . var_export($value, true) . "] cannot be converted to integer.");
	}

	/**
	* Converts $value to integer, or throws an exception if not possible.
	* Floats cannot be converted to integer.
	*/
	public static function toPositiveIntegerEx($value) {
	if (is_integer($value) && $value > 0) {
	return $value;
	}
	if (is_numeric($value) && ($value == (integer) $value) && $value > 0) {
	return (integer) $value;
	}

	throw new LoggerException("Given value [" . var_export($value, true) . "] cannot be converted to a positive integer.");
	}

	/**
	* Converts a standard or custom priority level to a Level
	* object.
	*
	* <p> If <var>$value</var> is of form "<b>level#full_file_classname</b>",
	* where <i>full_file_classname</i> means the class filename with path
	* but without php extension, then the specified class' <i>toLevel()</i> method
	* is called to process the specified level string; if no '#'
	* character is present, then the default {@link LoggerLevel}
	* class is used to process the level value.</p>
	*
	* <p>As a special case, if the <var>$value</var> parameter is
	* equal to the string "NULL", then the value <i>null</i> will
	* be returned.</p>
	*
	* <p>If any error occurs while converting the value to a level,
	* the <var>$defaultValue</var> parameter, which may be
	* <i>null</i>, is returned.</p>
	*
	* <p>Case of <var>$value</var> is insignificant for the level level, but is
	* significant for the class name part, if present.</p>
	*
	* @param string $value
	* @param LoggerLevel $defaultValue
	* @return LoggerLevel a {@link LoggerLevel} or null
	*/
	public static function toLevel($value, $defaultValue) {
	if($value === null) {
	return $defaultValue;
	}
	$hashIndex = strpos($value, '#');
	if($hashIndex === false) {
	if("NULL" == strtoupper($value)) {
	return null;
	} else {
	// no class name specified : use standard Level class
	return LoggerLevel::toLevel($value, $defaultValue);
	}
	}

	$result = $defaultValue;

	$clazz = substr($value, ($hashIndex + 1));
	$levelName = substr($value, 0, $hashIndex);

	// This is degenerate case but you never know.
	if("NULL" == strtoupper($levelName)) {
	return null;
	}

	$clazz = basename($clazz);

	if(class_exists($clazz)) {
	$result = @call_user_func(array($clazz, 'toLevel'), $levelName, $defaultValue);
	if(!$result instanceof LoggerLevel) {
	$result = $defaultValue;
	}
	}
	return $result;
	}


	/** Converts the value to a level. Throws an exception if not possible. */
	public static function toLevelEx($value) {
	if ($value instanceof LoggerLevel) {
	return $value;
	}
	$level = LoggerLevel::toLevel($value);
	if ($level === null) {
	throw new LoggerException("Given value [" . var_export($value, true) . "] cannot be converted to a logger level.");
	}
	return $level;
	}

	/**
	* @param string $value
	* @param float $default
	* @return float
	*/
	public static function toFileSize($value, $default) {
	if($value === null) {
	return $default;
	}

	$string = strtoupper(trim($value));
	$multiplier = (float)1;
	if(($index = strpos($string, 'KB')) !== false) {
	$multiplier = 1024;
	$string = substr($string, 0, $index);
	} else if(($index = strpos($string, 'MB')) !== false) {
	$multiplier = 1024 * 1024;
	$string = substr($string, 0, $index);
	} else if(($index = strpos($string, 'GB')) !== false) {
	$multiplier = 1024 * 1024 * 1024;
	$string = substr($string, 0, $index);
	}
	if(is_numeric($string)) {
	return (float)$string * $multiplier;
	}
	return $default;
	}


	/**
	* Converts a value to a valid file size (integer).
	*
	* Supports 'KB', 'MB' and 'GB' suffixes, where KB = 1024 B etc.
	*
	* The final value will be rounded to the nearest integer.
	*
	* Examples:
	* - '100' => 100
	* - '100.12' => 100
	* - '100KB' => 102400
	* - '1.5MB' => 1572864
	*
	* @param mixed $value File size (optionally with suffix).
	* @return integer Parsed file size.
	*/
	public static function toFileSizeEx($value) {

	if (empty($value)) {
	throw new LoggerException("Empty value cannot be converted to a file size.");
	}

	if (is_numeric($value)) {
	return (integer) $value;
	}

	if (!is_string($value)) {
	throw new LoggerException("Given value [" . var_export($value, true) . "] cannot be converted to a file size.");
	}

	$str = strtoupper(trim($value));
	$count = preg_match('/^([0-9.]+)(KB\|MB\|GB)?$/', $str, $matches);

	if ($count > 0) {
	$size = $matches[1];
	$unit = $matches[2];

	switch($unit) {
	case 'KB': $size *= pow(1024, 1); break;
	case 'MB': $size *= pow(1024, 2); break;
	case 'GB': $size *= pow(1024, 3); break;
	}

	return (integer) $size;
	}

	throw new LoggerException("Given value [$value] cannot be converted to a file size.");
	}

	/**
	* Converts a value to string, or throws an exception if not possible.
	*
	* Objects can be converted to string if they implement the magic
	* __toString() method.
	*
	*/
	public static function toStringEx($value) {
	if (is_string($value)) {
	return $value;
	}
	if (is_numeric($value)) {
	return (string) $value;
	}
	if (is_object($value) && method_exists($value, '__toString')) {
	return (string) $value;
	}

	throw new LoggerException("Given value [" . var_export($value, true) . "] cannot be converted to string.");
	}


	/**
	* Find the value corresponding to <var>$key</var> in
	* <var>$props</var>. Then perform variable substitution on the
	* found value.
	*
	* @param string $key
	* @param array $props
	* @return string
	*/
	public static function findAndSubst($key, $props) {
	$value = @$props[$key];

	// If coming from the LoggerConfiguratorIni, some options were
	// already mangled by parse_ini_file:
	//
	// not specified => never reaches this code
	// ""\|off\|false\|null => string(0) ""
	// "1"\|on\|true => string(1) "1"
	// "true" => string(4) "true"
	// "false" => string(5) "false"
	//
	// As the integer 1 and the boolean true are therefore indistinguable
	// it's up to the setter how to deal with it, they can not be cast
	// into a boolean here. {@see toBoolean}
	// Even an empty value has to be given to the setter as it has been
	// explicitly set by the user and is different from an option which
	// has not been specified and therefore keeps its default value.
	//
	// if(!empty($value)) {
	return LoggerOptionConverter::substVars($value, $props);
	// }
	}

	/**
	* Perform variable substitution in string <var>$val</var> from the
	* values of keys found with the {@link getSystemProperty()} method.
	*
	* <p>The variable substitution delimeters are <b>${</b> and <b>}</b>.
	*
	* <p>For example, if the "MY_CONSTANT" contains "value", then
	* the call
	* <code>
	* $s = LoggerOptionConverter::substVars("Value of key is ${MY_CONSTANT}.");
	* </code>
	* will set the variable <i>$s</i> to "Value of key is value.".</p>
	*
	* <p>If no value could be found for the specified key, then the
	* <var>$props</var> parameter is searched, if the value could not
	* be found there, then substitution defaults to the empty string.</p>
	*
	* <p>For example, if {@link getSystemProperty()} cannot find any value for the key
	* "inexistentKey", then the call
	* <code>
	* $s = LoggerOptionConverter::substVars("Value of inexistentKey is [${inexistentKey}]");
	* </code>
	* will set <var>$s</var> to "Value of inexistentKey is []".</p>
	*
	* <p>A warn is thrown if <var>$val</var> contains a start delimeter "${"
	* which is not balanced by a stop delimeter "}" and an empty string is returned.</p>
	*
	* @param string $val The string on which variable substitution is performed.
	* @param array $props
	* @return string
	*/
	// TODO: this method doesn't work correctly with key = true, it needs key = "true" which is odd
	public static function substVars($val, $props = null) {
	$sbuf = '';
	$i = 0;
	while(true) {
	$j = strpos($val, self::DELIM_START, $i);
	if($j === false) {
	// no more variables
	if($i == 0) { // this is a simple string
	return $val;
	} else { // add the tail string which contails no variables and return the result.
	$sbuf .= substr($val, $i);
	return $sbuf;
	}
	} else {

	$sbuf .= substr($val, $i, $j-$i);
	$k = strpos($val, self::DELIM_STOP, $j);
	if($k === false) {
	// LoggerOptionConverter::substVars() has no closing brace. Opening brace
	return '';
	} else {
	$j += self::DELIM_START_LEN;
	$key = substr($val, $j, $k - $j);
	// first try in System properties
	$replacement = LoggerOptionConverter::getSystemProperty($key, null);
	// then try props parameter
	if($replacement == null and $props !== null) {
	$replacement = @$props[$key];
	}

	if(!empty($replacement)) {
	// Do variable substitution on the replacement string
	// such that we can solve "Hello ${x2}" as "Hello p1"
	// the where the properties are
	// x1=p1
	// x2=${x1}
	$recursiveReplacement = LoggerOptionConverter::substVars($replacement, $props);
	$sbuf .= $recursiveReplacement;
	}
	$i = $k + self::DELIM_STOP_LEN;
	}
	}
	}
	}

	}