Talk In Code

I talked a while ago about Adding Code To WordPress Blogs And Comments, but I decided that it needed a bit of code to do this automatically.

So here it is, prepared by the text processor.

<form method="post" action="http://talkincode.com/examples/text-process/text.php">
    <textarea name="text" rows="10" cols="80" wrap="off"></textarea>
    <input type="submit" value="Process" />
</form>
 
<?php
if ( isset($_POST["text"]) ) {
    $text   = $_POST["text"];
    $text   = stripslashes( $text );
    $input  = array ( "/&/", "/'/", "/"/", "/</", "/>/", "/t/", "/(?<=s)x20|x20(?=s)/", "/^\s$/m", "/&/", "/rn/" );
    $output = array ( "&amp;", "&#39;", "&quot;", "&lt;", "&gt;", "&nbsp;&nbsp;&nbsp;&nbsp;", "&nbsp;", "&nbsp;<br />", "&amp;", "<br />" );
    $temp = preg_replace($input, $output, $text);
    echo '<div style="border:1px solid grey;">'.$temp.'</div>';
}
?>

There seems to be rather a lot going on here, but the process is quite simple. The preg_replace() function can take an array as an argument for the input and output parameters. When you do this the arrays will be matched up so that the second item in the input array will be replaced by the second item in the output array.

So here is a list of the things I am matching for and what they are replaced with.

• /&/ This matches for any ampersand, we replace this with the encoded variant of &.
• /'/ Find single quotes and encode them with '.
• /\"/ Find double quotes and encode them with ".
• /
• />/ Same as above but the other way around, in this case the equivalent is >.
• /\t/ Next we start matching for white space, the first is to find all tab characters and replace them with four   characters, like this     
• /(?<=\s)\x20|\x20(?=\s)/ Next we look for any space character that has white space characters before and after it and replace with a single white space character &nbsp;.
• /^\s$/m This matches for any line with nothing on it. These must be replaced with a single &nbsp; character, but in order to keep the code as it was posted we add a <br /> tag, the final output would be &nbsp;<br />.
• /&/ Now that we have all of our tags encoded we need to re encode all of the & characters so that when the script prints out the content to a HTML page with all & translated to &amp;.
• /\r\n/ Finally, we find all of the new line characters and convert them to <br /> tags. You might want to change this to just \n if you are using a Linux format.

Before we do any of this we pass the text through the stripslashes() function. This is because sending the text over POST might add slashes to the " and ' characters. This call just removes them.

You can try out the processor if you want by copying some code into the following text box.

The PHP function preg_replace() has powerful functionality in its own right, but extra depth can be added with the inclusion of the e modifier. Take the following bit of code, which just picks out the letters of a string and replaces them with the letter X.

$something = 'df1gdf2gdf3sgdfg';
$something = preg_replace("/([a-z]*)/", "X", $something);
echo $something; // XX1XX2XX3XX

This is simple enough, but using the e modifier allows us to use PHP functions within the replace parameters. The following bit of code turns all letters upper case in a string of random letters by using the strtoupper() PHP function.

$something = 'df1gdf2gdf3sgdfg';
$something = preg_replace("/([a-z]*)/e", "strtoupper('\\1')", $something);
echo $something; // DF1GDF2GDF3SGDFG

Here is another example, but in this case the full string is repeated after the modified string.

$something = 'df1gdf2gdf3sgdfg';
$something = preg_replace("/([a-z0-9]*)/e", "strtoupper('\\1').'\\1'", $something);
echo $something; // DF1GDF2GDF3SGDFGdf1gdf2gdf3sgdfg

Notice that when using the e modifier it is important to properly escape the string with single and doulbe quotes. This is because the string as a whole is parsed as PHP and so if you don’t put single quotes around the backreferences then you will get PHP complaining about constants.

For a more complex example I modified the createTextLinks() function that wrote about recently on the site. The function originally found any URL strings within a larger string and turned them into links. The modified function now returns the same thing, except that the link text has been shortened using the shortenurl() function.

$longurl = "there is the new site http://www.google.co.uk/search?aq=f&num=100&hl=en&client=firefox-a&channel=s&rls=org.mozilla%3Aen-US%3Aofficial";
 
function createShortTextLinks($str='') {
 
 if($str=='' or !preg_match('/(http|www\.|@)/im', $str)){
  return $str;
 }
 
 // replace links:
 $str = preg_replace("/([ \t]|^)www\./im", "\\1http://www.", $str);
 $str = preg_replace("/([ \t]|^)ftp\./im", "\\1ftp://ftp.", $str);
 
 $str = preg_replace("/(https?:\/\/[^ )\r\n!]+)/eim", "'<a href=\"\\1\" title=\"\\1\">'.shortenurl('\\1').'</a>'", $str);
 
 $str = preg_replace("/(ftp:\/\/[^ )\r\n!]+)/eim", "'<a href=\"\\1\" title=\"\\1\">'.shortenurl('\\1').'</a>'", $str);
 
 $str = preg_replace("/([-a-z0-9_]+(\.[_a-z0-9-]+)*@([a-z0-9-]+(\.[a-z0-9-]+)+))/eim", "'<a href=\"mailto:\\1\" title=\"Email \\1\">'.shortenurl('\\1').'</a>'", $str);
 
 $str = preg_replace("/(\&)/im","\\1amp;", $str);
 
 return $str;
}
 
function shortenurl($url){
 if(strlen($url) > 45){
  return substr($url, 0, 30)."[...]".substr($url, -15);
 }else{
  return $url;
 }
}
 
echo createShortTextLinks($longurl);

Using the strip_tags() function on any user generated input should be common practice in order to stop users putting in odd bits of HTML and messing up your nicely coded HTML. You might want to allow anchor tags to be used, but some users might use this to include onmouseover and other events in order to run JavaScript annoyances on the page.

So after stripping all tags from your text you can then run the following function to turn any links into anchor elements. This will work with any plain text that you want to use it on.

function createTextLinks($str='') {
 
 if($str=='' or !preg_match('/(http|www\.|@)/im', $str)){
  return $str;
 }
 
 // replace links:
 $str = preg_replace("/([ \t]|^)www\./im", "\\1http://www.", $str);
 $str = preg_replace("/([ \t]|^)ftp\./im", "\\1ftp://ftp.", $str);
 
 $str = preg_replace("/(https?:\/\/[^ )\r\n!]+)/im", "<a href=\"\\1\" title=\"\\1\">\\1</a>", $str);
 
 $str = preg_replace("/(ftp:\/\/[^ )\r\n!]+)/im", "<a href=\"\\1\" title=\"\\1\">\\1</a>", $str);
 
 $str = preg_replace("/([-a-z0-9_]+(\.[_a-z0-9-]+)*@([a-z0-9-]+(\.[a-z0-9-]+)+))/im", "<a href=\"mailto:\\1\" title=\"Email \\1\">\\1</a>", $str);
 
 $str = preg_replace("/(\&)/im","\\1amp;", $str);
 
 return $str;
}