The string tokenizer class allows an application to break a string into tokens.

StringTokenizer.class.php

<?php

/**
 * The string tokenizer class allows an application to break a string into tokens.
 *
 * @author Azeem Michael
 * @example The following is one example of the use of the tokenizer. The code:
 * <code>
 * <?php
 *    $str = "this is:@\t\n a test!";
 *    $delim = " !@:'\t\n\0"; // remove these chars
 *    $st = new StringTokenizer($str, $delim);
 *    echo 'Total tokens: '.$st->countTokens().'<br/>';
 *    while ($st->hasMoreTokens()) {
 *        echo $st->nextToken() . '<br/>';
 *    }
 *    prints the following output:
 *      Total tokens: 4
 *      this
 *      is
 *      a
 *      test
 * ?>
 * </code>
 */
class StringTokenizer {

    /** @var string
     */
    private $string;

    /** @var string
     */
    private $token;

    /** @var string
     */
    private $delim;

    /**
     * Constructs a string tokenizer for the specified string.
     * @param string $str String to tokenize
     * @param string $delim The set of delimiters (the characters that separate tokens)
     * specified at creation time, default to " \n\r\t\0"
     */
    public function __construct($str, $delim=" \n\r\t\0") {
        $this->string = $str;
        $this->delim = $delim;
        $this->token = strtok($str, $delim);        
    }

    /**
     * Destructor to prevent memory leaks
     */
    public function __destruct() {
        unset($this);
    }

    /**
     * Calculates the number of times that this tokenizer's nextToken method can
     * be called before it generates an exception
     * @return int - number of tokens
     */
    public function countTokens() {
        $counter = 0;
        while($this->hasMoreTokens()) {
            $counter++;
            $this->nextToken();
        }
        $this->token = strtok($this->string, $this->delim);
        return $counter;        
    }

    /**
     * Tests if there are more tokens available from this tokenizer's string. It
     * does not move the internal pointer in any way. To move the internal pointer
     * to the next element call nextToken()
     * @return boolean - true if has more tokens, false otherwise
     */
    public function hasMoreTokens() {
        return ($this->token !== false);
    }

    /**
     * Returns the next token from this string tokenizer and advances the internal
     * pointer by one.
     * @return string - next element in the tokenized string
     */
    public function nextToken() {
        $hold = $this->token; //hold current pointer value
        $this->token = strtok($this->delim); //increment pointer
        return $hold; //return current pointer value
    }
}
?>