<?php
// netstrings.php - PHP netstrings implementation
// Version 0.2  Sun, 25 Jun 2006 22:20:19 -0600
//
// Copyright (C) 2006  Dwayne C. Litzenberger <dlitz@dlitz.net>
// 
// Permission is hereby granted, free of charge, to any person obtaining
// a copy of this software and associated documentation files (the
// "Software"), to deal in the Software without restriction, including
// without limitation the rights to use, copy, modify, merge, publish,
// distribute, sublicense, and/or sell copies of the Software, and to
// permit persons to whom the Software is furnished to do so.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

// See http://cr.yp.to/proto/netstrings.txt for the format specification.

function netstrings_shift(&$string)
{
    // Note: We limit to 9 digits to avoid overflowing a 32-bit signed integer
    $m = array();
    if (!preg_match('#^(\d{1,9}):(.*)$#s', $string, $m)) {
        trigger_error("Invalid data passed to netstrings_shift", E_USER_NOTICE);
        return FALSE;
    }
    $count = $m[1];
    $data = $m[2];
    $retval = substr($data, 0, $count);
    if (substr($data, $count, 1) !== ',') {
        trigger_error("Invalid data passed to netstrings_shift", E_USER_NOTICE);
        return FALSE;
    }
    $string = substr($data, $count+1);
    return $retval;
}

function netstrings_decode($string)
{
    $retval = @netstrings_shift($string);
    if ($retval === FALSE or strlen($string) != 0) {
        trigger_error("Invalid data passed to netstrings_decode", E_USER_NOTICE);
        return FALSE;
    }
    return $retval;
}

function netstrings_encode($string)
{
    return strlen($string) . ':' . $string . ',';
}

function netstrings_implode($array)
{
    $retval = array();
    foreach($array as $item) {
        $retval[] = netstrings_encode($item);
    }
    return implode('', $retval);
}

function netstrings_explode($string)
{
    if (!isset($string)) {
        trigger_error("Undefined variable passed to netstrings_explode", E_USER_WARNING);
        return FALSE;
    }
    $retval = array();
    while (!empty($string)) {
        $r = netstrings_shift($string);
        if ($r === FALSE) {
            return FALSE;
        }
        $retval[] = $r;
    }
    return $retval;
}

// vim:set ts=4 sw=4 sts=4 expandtab: