It is this class that parses conversion patterns and creates * a chained list of {@link LoggerPatternConverter} converters.

* * @version $Revision: 1395467 $ * @package log4php * @subpackage helpers * * @since 0.3 */ class LoggerPatternParser { /** Escape character for conversion words in the conversion pattern. */ const ESCAPE_CHAR = '%'; /** Maps conversion words to relevant converters. */ private $converterMap; /** Conversion pattern used in layout. */ private $pattern; /** Regex pattern used for parsing the conversion pattern. */ private $regex; /** * First converter in the chain. * @var LoggerPatternConverter */ private $head; /** Last converter in the chain. */ private $tail; public function __construct($pattern, $converterMap) { $this->pattern = $pattern; $this->converterMap = $converterMap; // Construct the regex pattern $this->regex = '/' . // Starting regex pattern delimiter self::ESCAPE_CHAR . // Character which marks the start of the conversion pattern '(?P[0-9.-]*)' . // Format modifiers (optional) '(?P[a-zA-Z]+)' . // The conversion word '(?P{[^}]*})?' . // Conversion option in braces (optional) '/'; // Ending regex pattern delimiter } /** * Parses the conversion pattern string, converts it to a chain of pattern * converters and returns the first converter in the chain. * * @return LoggerPatternConverter */ public function parse() { // Skip parsing if the pattern is empty if (empty($this->pattern)) { $this->addLiteral(''); return $this->head; } // Find all conversion words in the conversion pattern $count = preg_match_all($this->regex, $this->pattern, $matches, PREG_OFFSET_CAPTURE); if ($count === false) { $error = error_get_last(); throw new LoggerException("Failed parsing layotut pattern: {$error['message']}"); } $prevEnd = 0; foreach($matches[0] as $key => $item) { // Locate where the conversion command starts and ends $length = strlen($item[0]); $start = $item[1]; $end = $item[1] + $length; // Find any literal expressions between matched commands if ($start > $prevEnd) { $literal = substr($this->pattern, $prevEnd, $start - $prevEnd); $this->addLiteral($literal); } // Extract the data from the matched command $word = !empty($matches['word'][$key]) ? $matches['word'][$key][0] : null; $modifiers = !empty($matches['modifiers'][$key]) ? $matches['modifiers'][$key][0] : null; $option = !empty($matches['option'][$key]) ? $matches['option'][$key][0] : null; // Create a converter and add it to the chain $this->addConverter($word, $modifiers, $option); $prevEnd = $end; } // Add any trailing literals if ($end < strlen($this->pattern)) { $literal = substr($this->pattern, $end); $this->addLiteral($literal); } return $this->head; } /** * Adds a literal converter to the converter chain. * @param string $string The string for the literal converter. */ private function addLiteral($string) { $converter = new LoggerPatternConverterLiteral($string); $this->addToChain($converter); } /** * Adds a non-literal converter to the converter chain. * * @param string $word The conversion word, used to determine which * converter will be used. * @param string $modifiers Formatting modifiers. * @param string $option Option to pass to the converter. */ private function addConverter($word, $modifiers, $option) { $formattingInfo = $this->parseModifiers($modifiers); $option = trim($option, "{} "); if (isset($this->converterMap[$word])) { $converter = $this->getConverter($word, $formattingInfo, $option); $this->addToChain($converter); } else { trigger_error("log4php: Invalid keyword '%$word' in converison pattern. Ignoring keyword.", E_USER_WARNING); } } /** * Determines which converter to use based on the conversion word. Creates * an instance of the converter using the provided formatting info and * option and returns it. * * @param string $word The conversion word. * @param LoggerFormattingInfo $info Formatting info. * @param string $option Converter option. * * @throws LoggerException * * @return LoggerPatternConverter */ private function getConverter($word, $info, $option) { if (!isset($this->converterMap[$word])) { throw new LoggerException("Invalid keyword '%$word' in converison pattern. Ignoring keyword."); } $converterClass = $this->converterMap[$word]; if(!class_exists($converterClass)) { throw new LoggerException("Class '$converterClass' does not exist."); } $converter = new $converterClass($info, $option); if(!($converter instanceof LoggerPatternConverter)) { throw new LoggerException("Class '$converterClass' is not an instance of LoggerPatternConverter."); } return $converter; } /** Adds a converter to the chain and updates $head and $tail pointers. */ private function addToChain(LoggerPatternConverter $converter) { if (!isset($this->head)) { $this->head = $converter; $this->tail = $this->head; } else { $this->tail->next = $converter; $this->tail = $this->tail->next; } } /** * Parses the formatting modifiers and produces the corresponding * LoggerFormattingInfo object. * * @param string $modifier * @return LoggerFormattingInfo * @throws LoggerException */ private function parseModifiers($modifiers) { $info = new LoggerFormattingInfo(); // If no modifiers are given, return default values if (empty($modifiers)) { return $info; } // Validate $pattern = '/^(-?[0-9]+)?\.?-?[0-9]+$/'; if (!preg_match($pattern, $modifiers)) { trigger_error("log4php: Invalid modifier in conversion pattern: [$modifiers]. Ignoring modifier.", E_USER_WARNING); return $info; } $parts = explode('.', $modifiers); if (!empty($parts[0])) { $minPart = (integer) $parts[0]; $info->min = abs($minPart); $info->padLeft = ($minPart > 0); } if (!empty($parts[1])) { $maxPart = (integer) $parts[1]; $info->max = abs($maxPart); $info->trimLeft = ($maxPart < 0); } return $info; } }