PHP DocAnnotation Code

<?php
abstract class Parser {
	

	public $string;
	
	public $symbol = '';
	public $symbols = array();
	public $forwardSymbol = '';
	public $stack = array();
	protected $pos = 0;
	
	
	/**
	 * s the input string and returns the next symbol.
	 * 
	 * @return string
	 */
	protected function sieve() {
		$buffer = '';
		
		$len = strlen($this->string);
		
		// For all chars, do:
		while($this->pos < $len) {
			$whitespaces = 0;
				
			// eat whitespace
			for($char = $this->string[$this->pos];
			
				($this->pos < $len) &&
				($char == ' ' || $char == "\n" || $char == "\t" || $char == '*' || $char == '/');
				
				$char = $this->string[++$this->pos], $whitespaces++); 
			
			if ($whitespaces != 0 && $buffer != '')
				return $buffer;
				
			// for all no whitespace chars to: 
			switch($this->string[$this->pos]) {
				case '@': /*case '$':*/
					if ($buffer != '') {
						if ($whitespaces == 0)
							throw new ParsingException('Syntaxmissmatch: need a space between "' . $buffer . '" and "' . $this->string[$this->pos] .'"');

						return $buffer;
					} 
					  
				case '=': case '(':	case ')':
				case '{': case '}': case ',':
					
					// if there is no buffer to return,
					// return the delimeter/char
					
					if ($buffer == '')					
						return $this->string[$this->pos++];
					
					return $buffer;
					break;
				case '$':
					// if there are no whitespaces
					// between the last collected string
					// and the $, thats a syntax missmatch.
					if ($buffer != '') {
						if ($whitespaces == 0)
							throw new ParsingException('Syntaxmissmatch: need a space between "' . $buffer . '" and "$"');

						return $buffer;
					}

					// collect the quoted string
					$this->pos++;
					while($this->pos < $len) {
						$char = $this->string[$this->pos];
						$ch = ord(strtolower($char));
						
						if ($char != '_' 
							&& (($ch < ord('0') || $ch > ord('9')) 
							&& ($ch < ord('a') || $ch > ord('z'))))
							break;									
							
						$buffer .= $char;
						$this->pos++;
					}
					
					if ($buffer == '')
						throw new ParsingException('Invalid variable name: Must not be empty.');
							
					if (is_numeric($buffer[0]))
						throw new ParsingException('Invalid variable name: "' . $buffer . '". Variablenames must not begin with a number.');
				
					return '$'.$buffer;
					break;
				case "'": case '"': case '`':
					// remember the quoting char
					$quote = $this->string[$this->pos];
					
					// if there are no whitespaces
					// between the last collected string
					// and the quote, thats a syntax missmatch.
					if ($buffer != '') {
						if ($whitespaces == 0)
							throw new ParsingException('Syntaxmissmatch: need a space between "' . $buffer . '" and "' . $quote .'"');

						return $buffer;
					}

					// collect the quoted string
					while($this->pos < $len) {
						$this->pos++;
						

						if ($this->string[$this->pos] == $quote) {
							// if quote appears, this means the end
							// of collecting the string.
							
							$this->pos++; 
							return $buffer; 
						} else if ($this->string[$this->pos] == '\\') {
							// if a \ appears, we have a escape sequence
							
							$this->pos++; 
							
							if ($this->string[$this->pos] == '\\')
								// a second \ means that we have to
								// collect that \
								$buffer .= '\\';
							else if ($this->string[$this->pos] == $quote)
								// collect the quote
								$buffer .= $quote;
							else
								throw new ParsingException('Invalid escape sequence');
								
						} else {
							// just collect
							$buffer .= $this->string[$this->pos];
						} 
					}
					break;
									
				default:					
					// just collect
					$buffer .= $this->string[$this->pos++];
					 
			}
			
		}
				
		return $buffer;					
	}
	
	public function parse($string) {
		$this->string = $string;
		$this->pos = 0;
		$this->symbol = '';
		$this->symbols = array();
		$this->nextSymbol();
		$this->nextSymbol();
		$this->read('START');	
		return true;
	}
	
	abstract protected function read_START();
	
	protected function testFollowOf($name) {
		if (in_array($this->symbol, $this->follow[$name])) {			
			return true;
		}
		return false;
	}
	
	protected function isSymbol($expected) {
		if ($expected == $this->symbol) {			
			return true;
		}
		return false;
	}

	protected function assertSymbol($expected) {
		
		if ($this->symbol != $expected)
			throw new ParsingException("Parsing-Error: '$expected' expected, but '$this->symbol' found.");
		$this->nextSymbol();
	}
	
	protected function nextSymbol() {
		$this->symbol = $this->forwardSymbol;		
		$this->symbols[] = $this->forwardSymbol = $this->sieve();
		return $this->symbol; 
	}
	
	protected function read($symbol) {
		$osp = count($this->stack);
		$pos = count($this->symbols) - 2;
		
		$this->{'read_'.$symbol}();
		
		if (method_exists($this, 'handle_'.$symbol))
			$this->{'handle_'.$symbol}($pos, max(0, count($this->stack) - $osp));
	}

}

class ParsingException extends RuntimeException {
	
}
?>