<?php

/**
 * Copyright (c) 2005 Richard Heyes (http://www.phpguru.org/)
 *
 * All rights reserved.
 *
 * This script is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * The GNU General Public License can be found at
 * http://www.gnu.org/copyleft/gpl.html.
 *
 * This script is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU General Public License for more details.
 */

/**
 * Implements an object which iterates over each line in a file.
 *
 * Eg:
 *
 * foreach(new FileIterator('myFile.txt') as $line) {
 *      // Do stuff with $line...
 * }
 *
 * Or:
 *
 * foreach(new FileIterator('myFile.txt', 2048) as $key => $line) { //
 * Possibly long lines
 *      $lineNum = $key + 1;
 *
 *      // Do stuff...
 * }
 */

class FileIterator implements Iterator {
    /**
     * Name of file
     *
     * @var string
     */
    private $filename;

    /**
     * Size of read buffer
     *
     * @var int
     */
    private $buffer;

    /**
     * File pointer
     *
     * @var resource
     */
    private $fp;

    /**
     * Current line of file
     *
     * @var string
     */
    private $current;

    /**
     * Current line number of file
     *
     * @var int
     */
    private $key;

    /**
     * Whether current element is valid or not
     */
    private $valid;

    /**
     * Constructor. Takes the name of the file
     *
     * @param string $filename Name of file to go thru
     */
    public function __construct($filename, $buffer = 1024) {
        $this->filename = $filename;
        $this->buffer = $buffer;
        $this->key = -1;

        if(!($this->fp = fopen($filename, 'rb')))
            throw new Exception("Error when opening file: $filename");
    }

    /**
     * Iterator::current() - Returns the current line of the file.
     *
     * @return string Current line of file
     */
    public function current() {
        return $this->current;
    }

    /**
     * Iterator::key() - Returns the current "key". In this instance,
     * key() + 1 would
     * give you the current line number.
     *
     * @return string Current elements key
     */
    public function key() {
        return $this->key;
    }

    /**
     * Iterator::next() - Advances the iterator to the next "element"
     */
    public function next() {
        if (is_resource($this->fp)) {
            if (!feof($this->fp)) {
                $this->key++;
                $this->current = fgets($this->fp, $this->buffer);
                $this->valid = true;
            } else {
                $this->valid = false;
            }
        }
    }

    /**
     * Iterator::rewind() - Resets the iterator to the "beginning"
     */
    public function rewind() {
        if (is_resource($this->fp)) {
            $this->key = -1;
            fseek($this->fp, 0);

            $this->next();
        }
    }

    /**
     * Iterator::valid() - Returns true/false as to whether a call to
     * current()
     * is valid/possible or not.
     *
     * @return bool Whether current element is valid or not
     */
    public function valid() {
        return $this->valid;
    }
}

?>