一个用PHP实现的UBB类！

  <?php
  /*
  如有转载，请注明作者
  
  作者: 何志强
  文件: ubb.php
  备注: 说是改进，其实核心函数parse()已经完全重写了，而且思路也是不一样的。
  不过仍是受何志强的例子的启发，而且测试的例子还有URLCHECK等几个函数也是沿用的何志强的程序，谢谢何志强。
  目前还没有颜色的功能，但我会加入的。
  如果在程序上有什么BUG或不便的地方，请给我MAIL。
  谢谢！
  改进功能:
  对字符串进行UBB编码,该类目前只支持下列几个简单且实用的编码:
  1. URL裢接
  http://www.phpexe.com/
  http://头可以不需要
  如phpexe.com也是可以的。
  2. Email裢接
  demo@163.net
  3. 图片裢接
  
  同URL链接一样，前面的http也可以不要。
  4. 文字方面
  粗体字
  斜体字
  加下划线
  
  1号标题字
  ...
  6号标题字
  
  
  
  [tt][/tt]
  [s][/s]
  
  [em][/em]
  [strong][/strong]
  [code][/code]
  [samp][/samp]
  [kbd][/kbd]
  [var][/var]
  [dfn][/dfn]
  [cite][/cite]
  
  
  
  注意以下几点:
  1. url,email,img等标签是不分大小写的.
  2. 在标签中不允许有TAB键出现，但空格允许。
  3. 该类要调用htmlencode,htmlencode4textarea,emailcheck函数和urlcheck类.
  4. 修改后支持嵌套，但url,email,img这三个标签不是允许嵌套的。
  技术资料:
  Ultimate Bulletin Board
  http://www.ultimatebb.com/
  What is UBB Code
  http://www.scriptkeeper.com/ubb/ubbcode.html
  */
  
  include("urlcheck.php");
  include("otherfunc.php"); //这两个文件的内容，附在最后。
  
  //ubbcode类
  class ubbcode{
  var $call_time=0;
  //可处理标签及处理函数对应表
  var $tags = array( //小写的标签 => 对应的处理函数
  @#url@# => @#$this->url@#,
  @#email@# => @#$this->email@#,
  @#img@# => @#$this->img@#,
  @#b@# => @#$this->simple@#,
  @#i@# => @#$this->simple@#,
  @#u@# => @#$this->simple@#,
  @#tt@# => @#$this->simple@#,
  @#s@# => @#$this->simple@#,
  @#strike@# => @#$this->simple@#,
  @#h1@# => @#$this->simple@#,
  @#h2@# => @#$this->simple@#,
  @#h3@# => @#$this->simple@#,
  @#h4@# => @#$this->simple@#,
  @#h5@# => @#$this->simple@#,
  @#h6@# => @#$this->simple@#,
  @#sup@# => @#$this->simple@#,
  @#sub@# => @#$this->simple@#,
  @#em@# => @#$this->simple@#,
  @#strong@# => @#$this->simple@#,
  @#code@# => @#$this->simple@#,
  @#samp@# => @#$this->simple@#,
  @#kbd@# => @#$this->simple@#,
  @#var@# => @#$this->simple@#,
  @#dfn@# => @#$this->simple@#,
  @#cite@# => @#$this->simple@#,
  @#small@# => @#$this->simple@#,
  @#big@# => @#$this->simple@#,
  @#blink@# => @#$this->simple@#
  );
  //url裢接属性
  var $attr_url;
  //url合法性检查对象
  var $urlcheck;
  
  function ubbcode($attr_url){
  $this->attr_url = @#@#.$attr_url;
  $this->urlcheck = new urlcheck();
  }
  
  //对$str进行UBB编码解析
  function parse($str){
  $this->call_time++;
  $parse = @#@#.htmlencode($str);
  
  $ret = @#@#;
  while(true){
  $eregi_ret=eregi("\[[#]{0,1}[[:alnum:]]{1,7}\]",$parse,$eregi_arr); //查找[xx]
  if(!$eregi_ret){
  $ret .= $parse;
  break; //如果没有，返回
  }
  $pos = @strpos($parse,$eregi_arr[0]);
  $tag_len=strlen($eregi_arr[0])-2;//标记长度
  $tag_start=substr($eregi_arr[0],1,$tag_len);
  $tag=strtolower($tag_start);
  
  if((($tag=="url") or ($tag=="email") or ($tag=="img")) and ($this->call_time>1)){
  echo $this->call_time."<br>";
  return $parse;//如果不能是不能嵌套的标记，直接返回
  }
  
  $parse2 = substr($parse,0,$pos);//标记之前
  $parse = substr($parse,$pos+$tag_len+2);//标记之后
  if(!isset($this->tags[$tag])){
  echo "$tag_start<br>";
  $ret .= $parse2.@#[@#.$tag_start.@#]@#;
  continue;//如果是不支持的标记
  }
  
  //查找对对应的结束标记
  $eregi_ret=eregi("\[\/".$tag."\]",$parse,$eregi_arr);
  if(!$eregi_ret){
  $ret .= $parse2.@#[@#.$tag_start.@#]@#;
  continue;//如果没有对应该的结束标记
  }
  $pos=strpos($parse,$eregi_arr[0]);
  $value=substr($parse,0,$pos);//这是起止标记之间的内容
  $tag_end=substr($parse,$pos+2,$tag_len);
  $parse=substr($parse,$pos+$tag_len+3);//结束标记之后的内容
  
  if(($tag!="url") and ($tag!="email") and ($tag!="img")){
  $value=$this->parse($value);
  }
  
  $ret .= $parse2;
  eval(@#$ret .= @#.$this->tags[$tag].@#("@#.$tag_start.@#","@#.$tag_end.@#","@#.$value.@#");@#);
  }
  $this->call_time--;
  return $ret;
  }
  
  function simple($start,$end,$value){
  return @#<@#.$start.@#>@#.$value.@#</@#.$end.@#>@#;
  }
  
  function url($start,$end,$value){
  $trim_value=trim($value);
  if (strtolower(substr($trim_value,0,7))!="http://")
  $trim_value="http://".$trim_value;
  if($this->urlcheck->check($trim_value)) return @#<a href="@#.$trim_value.@#" @#.$this->attr_url.@#>@#.$value.@#</a>@#;
  else return @#[@#.$start.@#]@#.$value.@#[/@#.$end.@#]@#;
  }
  
  function email($start,$end,$value){
  if(emailcheck($value)) return @#<a href="mailto:@#.$value.@#">@#.$value.@#</a>@#;
  else return @#[@#.$start.@#]@#.$value.@#[/@#.$end.@#]@#;
  }
  
  function img($start,$end,$value){
  $trim_value=trim($value);
  if ((strtolower(substr($trim_value,0,7))!="http://") or ($this->urlcheck->check($trim_value)))
  return @#<img src="@#.$trim_value.@#"></img>@#;
  else return @#[@#.$start.@#]@#.$value.@#[/@#.$end.@#]@#;
  }
  }
  
  //测试
  echo @#<html>@#;
  echo @#<head><title>测试</title></head>@#;
  echo @#<body>@#;
  echo @#<form action="@#.str2url($PATH_INFO).@#" method="post">@#;
  echo @#<textarea cols="100" rows="10" name="ubb">@#.htmlencode4textarea($ubb).@#</textarea><br>@#;
  echo @#<input type="submit" value="转换">@#;
  echo @#</form>@#;
  
  if(isset($ubb)){
  $ubbcode = new ubbcode(@#target="_blank"@#);
  echo @#<hr>@#.$ubbcode->parse($ubb);
  }
  
  echo @#</body>@#;
  echo @#</html>@#;
  
  ?>
  
  文件urlcheck.php的内容
  <?php
  //urlcheck.php
  class urlcheck{
  var $regex = array(//协议名(注意在这里必须写成小写) => 对应的正则表达式
  @#ftp@# => @#$this->ftpurl@#,
  @#file@# => @#$this->fileurl@#,
  @#http@# => @#$this->httpurl@#,
  @#https@# => @#$this->httpurl@#,
  @#gopher@# => @#$this->gopherurl@#,
  @#news@# => @#$this->newsurl@#,
  @#nntp@# => @#$this->nntpurl@#,
  @#telnet@# => @#$this->telneturl@#,
  @#wais@# => @#$this->waisurl@#
  );
  
  var $lowalpha;
  var $hialpha;
  var $alpha;
  var $digit;
  var $safe;
  var $extra;
  var $national;
  var $punctuation;
  var $reserved;
  var $hex;
  var $escape;
  var $unreserved;
  var $uchar;
  var $xchar;
  var $digits;
  
  var $urlpath;
  var $password;
  var $user;
  var $port;
  var $hostnumber;
  var $alphadigit;
  var $toplabel;
  var $domainlabel;
  var $hostname;
  var $host;
  var $hostport;
  var $login;
  
  //ftp
  var $ftptype;
  var $fsegment;
  var $fpath;
  var $ftpurl;
  
  //file
  var $fileurl;
  
  //http,https
  var $search;
  var $hsegment;
  var $hpath;
  var $httpurl;
  
  //gopher
  var $gopher_string;
  var $selector;
  var $gtype;
  var $gopherurl;
  
  //news
  var $article;
  var $group;
  var $grouppart;
  var $newsurl;
  
  //nntp
  var $nntpurl;
  
  //telnet
  var $telneturl;
  
  //wais
  var $wpath;
  var $wtype;
  var $database;
  var $waisdoc;
  var $waisindex;
  var $waisdatabase;
  var $waisurl;
  
  function check($url){
  $pos = @strpos($url,@#:@#,1);
  if($pos<1) return false;
  $prot = substr($url,0,$pos);
  if(!isset($this->regex[$prot])) return false;
  eval(@#$regex = @#.$this->regex[$prot].@#;@#);
  return ereg(@#^@#.$regex.@#$@#,$url);
  }
  
  function urlcheck(){
  $this->lowalpha = @#[a-z]@#;
  $this->hialpha = @#[A-Z]@#;
  $this->alpha = @#(@#.$this->lowalpha.@#|@#.$this->hialpha.@#)@#;
  $this->digit = @#[0-9]@#;
  $this->safe = @#[$.+_-]@#;
  $this->extra = @#[*()\@#!,]@#;
  $this->national = @#([{}|\^~`]|\\[|\\])@#;
  $this->punctuation = @#[<>#%"]@#;
  $this->reserved = @#[?;/:@&=]@#;
  $this->hex = @#(@#.$this->digit.@#|[a-fA-F])@#;
  $this->escape = @#(%@#.$this->hex.@#{2})@#;
  $this->unreserved = @#(@#.$this->alpha.@#|@#.$this->digit.@#|@#.$this->safe.@#|@#.$this->extra.@#)@#;
  $this->uchar = @#(@#.$this->unreserved.@#|@#.$this->escape.@#)@#;
  $this->xchar = @#(@#.$this->unreserved.@#|@#.$this->reserved.@#|@#.$this->escape.@#)@#;
  $this->digits = @#(@#.$this->digit.@#+)@#;
  
  $this->urlpath = @#(@#.$this->xchar.@#*)@#;
  $this->password = @#((@#.$this->uchar.@#|[?;&=]@#.@#)*)@#;
  $this->user = @#((@#.$this->uchar.@#|[?;&=]@#.@#)*)@#;
  $this->port = $this->digits;
  $this->hostnumber = @#(@#.$this->digits.@#.@#.$this->digits.@#.@#.$this->digits.@#.@#.$this->digits.@#)@#;
  $this->alphadigit = @#(@#.$this->alpha.@#|@#.$this->digit.@#)@#;
  $this->toplabel = @#(@#.$this->alpha.@#|(@#.$this->alpha.@#(@#.$this->alphadigit.@#|-)*@#.$this->alphadigit.@#))@#;
  $this->domainlabel = @#(@#.$this->alphadigit.@#|(@#.$this->alphadigit.@#(@#.$this->alphadigit.@#|-)*@#.$this->alphadigit.@#))@#;
  $this->hostname = @#((@#.$this->domainlabel.@#\\.)*@#.$this->toplabel.@#)@#;
  $this->host = @#(@#.$this->hostname.@#|@#.$this->hostnumber.@#)@#;
  $this->hostport = @#(@#.$this->host.@#(:@#.$this->port.@#)?)@#;
  $this->login = @#((@#.$this->user.@#(:@#.$this->password.@#)?@)?@#.$this->hostport.@#)@#;
  
  $this->ftptype = @#[aidAID]@#;
  $this->fsegment = @#((@#.$this->uchar.@#|[?:@&=])*)@#;
  $this->fpath = @#(@#.$this->fsegment.@#(/@#.$this->fsegment.@#)*)@#;
  $this->ftpurl = @#([fF][tT][pP]://@#.$this->login.@#(/@#.$this->fpath.@#(;[tT][yY][pP][eE]=@#.$this->ftptype.@#)?)?)@#;
  
  $this->fileurl = @#([fF][iI][lL][eE]://(@#.$this->host.@#|[lL][oO][cC][aA][lL][hH][oO][sS][tT])?/@#.$this->fpath.@#)@#;
  
  $this->search = @#((@#.$this->uchar.@#|[;:@&=])*)@#;
  $this->hsegment = @#((@#.$this->uchar.@#|[;:@&=])*)@#;
  $this->hpath = @#(@#.$this->hsegment.@#(/@#.$this->hsegment.@#)*)@#;
  $this->httpurl = @#([hH][tT][tT][pP][sS]?://@#.$this->hostport.@#(/@#.$this->hpath.@#([?]@#.$this->search.@#)?)?)@#;
  
  $this->gopher_string = @#(@#.$this->xchar.@#*)@#;
  $this->selector = @#(@#.$this->xchar.@#*)@#;
  $this->gtype = $this->xchar;
  $this->gopherurl = @#([gG][oO][pP][hH][eE][rR]://@#.$this->hostport.@#(/(@#.$this->gtype.@#(@#.$this->selector.@#(%09@#.$this->search.@#(%09@#.$this->gopher_string.@#)?)?)?)?)?)@#;
  
  $this->article = @#((@#.$this->uchar.@#|[;/?:&=])+@@#.$this->host.@#)@#;
  $this->group = @#(@#.$this->alpha.@#(@#.$this->alpha.@#|@#.$this->digit.@#|[-.+_])*)@#;
  $this->grouppart = @#([*]|@#.$this->group.@#|@#.$this->article.@#)@#;
  $this->newsurl = @#([nN][eE][wW][sS]:@#.$this->grouppart.@#)@#;
  
  $this->nntpurl = @#([nN][nN][tT][pP]://@#.$this->hostport.@#/@#.$this->group.@#(/@#.$this->digits.@#)?)@#;
  
  $this->telneturl = @#([tT][eE][lL][nN][eE][tT]://@#.$this->login.@#/?)@#;
  
  $this->wpath = @#(@#.$this->uchar.@#*)@#;
  $this->wtype = @#(@#.$this->uchar.@#*)@#;
  $this->database = @#(@#.$this->uchar.@#*)@#;
  $this->waisdoc = @#([wW][aA][iI][sS]://@#.$this->hostport.@#/@#.$this->database.@#/@#.$this->wtype.@#/@#.$this->wpath.@#)@#;
  $this->waisindex = @#([wW][aA][iI][sS]://@#.$this->hostport.@#/@#.$this->database.@#[?]@#.$this->search.@#)@#;
  $this->waisdatabase = @#([wW][aA][iI][sS]://@#.$this->hostport.@#/@#.$this->database.@#)@#;
  $this->waisurl = @#(@#.$this->waisdatabase.@#|@#.$this->waisindex.@#|@#.$this->waisdoc.@#)@#;
  }
  }
  
  ?>
  
  
  文件otherfunc.php的内容
  <?php
  //otherfunc.php
  function htmlencode($str){
  $str = (string)$str;
  
  $ret = @#@#;
  $len = strlen($str);
  $nl = false;
  for($i=0;$i<$len;$i++){
  $chr = $str[$i];
  switch($chr){
  case @#<@#:
  $ret .= @#<@#;
  $nl = false;
  break;
  case @#>@#:
  $ret .= @#>@#;
  $nl = false;
  break;
  case @#"@#:
  $ret .= @#"@#;
  $nl = false;
  break;
  case @#&@#:
  $ret .= @#&@#;
  $nl = false;
  break;
  /*
  case @# @#:
  $ret .= @# @#;
  $nl = false;
  break;
  */
  case chr(9):
  $ret .= @#    @#;
  $nl = false;
  break;
  case chr(10):
  if($nl) $nl = false;
  else{
  $ret .= @#<br>@#;
  $nl = true;
  }
  break;
  case chr(13):
  if($nl) $nl = false;
  else{
  $ret .= @#<br>@#;
  $nl = true;
  }
  break;
  default:
  $ret .= $chr;
  $nl = false;
  break;
  }
  }
  
  return $ret;
  }
  
  
  function htmlencode4textarea($str){
  $str = (string)$str;
  
  $ret = @#@#;
  $len = strlen($str);
  for($i=0;$i<$len;$i++){
  $chr = $str[$i];
  switch($chr){
  case @#<@#:
  $ret .= @#<@#;
  break;
  case @#>@#:
  $ret .= @#>@#;
  break;
  case @#"@#:
  $ret .= @#"@#;
  break;
  case @#&@#:
  $ret .= @#&@#;
  break;
  case @# @#:
  $ret .= @# @#;
  break;
  case chr(9):
  $ret .= @#    @#;
  break;
  default:
  $ret .= $chr;
  break;
  }
  }
  
  return $ret;
  }
  
  function emailcheck($email){
  $ret=false;
  if(strstr($email, @#@@#) && strstr($email, @#.@#)){
  if(eregi("^([_a-z0-9]+([\\._a-z0-9-]+)*)@([a-z0-9]{2,}(\\.[a-z0-9-]{2,})*\\.[a-z]{2,3})$", $email)){
  $ret=true;
  }
  }
  return $ret;
  }
  
  function str2url($path){
  return eregi_replace("%2f","/",urlencode($path));
  }
  ?>

原文转自：http://www.ltesting.net