preg_replace question...

Perculator · #1 12-Feb-2004, 19:42

Hello -

I've put together a little php script to grab forum posts and parse the bulletin codes into html, however one particular transition seems to be making it screw up. I just wanted to figure out whats going on, cause I seem to be missing something completely with this.

Heres a little snippet of the preg_replace portion....

PHP Code:


$original = array( // All tags are "/\[ start tag text \] between tag text \[\/ end tag text \]/"
                           "/\[[B|b]\](.*)\[\/[B|b]\]/",                        // Bold
                           "/\[[I|i]\](.*)\[\/[I|i]\]/",                        // Italic
                           "/\[[U|u]\](.*)\[\/[U|u]\]/",                        // Underline
                           "/\[[S|s][I|i][Z|z][E|e]=(\d*)\](.*)\[\/[S|s][I|i][Z|z][E|e]\]/",        // Size
                           "/\[[F|f][O|o][N|n][T|t]=(.*)\](.*)\[\/[F|f][O|o][N|n][T|t]\]/",        // Font
                           "/\[[C|c][O|o][L|l][O|o][R|r]=(\w*)\](.*)\[\/[C|c][O|o][L|l][O|o][R|r]\]/",    // Color
                           "/\[[U|u][R|r][L|l]=(.*)\](.*)\[\/[U|u][R|r][L|l]\]/",            // URL
                           "/\[[E|e][M|m][A|a][I|i][L|l]=(.*)\](.*)\[\/[E|e][M|m][A|a][I|i][L|l]\]/",    // Email
                           "/\[[I|i][M|m][G|g]\](.*)\[\/[I|i][M|m][G|g]\]/",                // Image
                           "/\[[C|c][O|o][D|d][E|e]\]([\s\S]*)\[\/[C|c][O|o][D|d][E|e]\]/",        // Code
                           "/\[[P|p][H|h][P|p]\]([\s\S]*)\[\/[P|p][H|h][P|p]\]/",            // PHP
                           "/\[[L|l][I|i][S|s][T|t]=[1]\]([\s\S]*)\[\/[L|l][I|i][S|s][T|t]=[1]\]/",    // Numberd List
                           "/\[[L|l][I|i][S|s][T|t]=[A|a]\]([\s\S]*)\[\/[L|l][I|i][S|s][T|t]=[A|a]\]/",    // Alpha List
                           "/\[[L|l][I|i][S|s][T|t]\]([\s\S]*)\[\/[L|l][I|i][S|s][T|t]\]/",        // Bullet List
                           "/\[\*\](.*)/",                                // List element
                           "/\[[Q|q][U|u][O|o][T|t][E|e]\]([\s\S]*)\[\/[Q|q][U|u][O|o][T|t][E|e]\]/"    // Quote
                         );
        $replace = array(
                           "<B>\\1</B>",                                // Bold
                           "<I>\\1</I>",                                // Italic
                           "<U>\\1</U>",                                // Underline
                           "<FONT SIZE=\\1>\\2</FONT>",                            // Size
                           "<FONT FACE=\"\\1\">\\2</FONT>",                        // Font
                           "<FONT COLOR=\\1>\\2</FONT>",                        // Color
                           "<A HREF=\"\\1\">\\2</A>",                            // URL
                           "<A HREF=\"mailto:\\1\">\\2</A>",                        // Email
                           "<IMG SRC=\"\\1\">",                                // Image
                           "<BLOCKQUOTE><PRE><FONT FACE=\"verdana,arial,helvetica\"
                 SIZE=\"1\">code:</FONT><HR>\\1<HR></PRE></BLOCKQUOTE>",         // Code
                           "<BLOCKQUOTE><PRE><FONT FACE=\"verdana,arial,helvetica\"
                 SIZE=\"1\">php:</FONT><HR>\\1<HR></PRE></BLOCKQUOTE>",            // PHP
                           "<OL TYPE=\"1\">\\1</OL>",                            // Numberd List
                           "<OL TYPE=\"A\">\\1</OL>",                            // Alpha List
                           "<UL>\\1</UL>",                                // Bullet List
                           "<LI>\\1",                                    // List element
                           "<BLOCKQUOTE><PRE><FONT FACE=\"verdana,arial,helvetica\"
                 SIZE=\"1\">quote:</FONT><HR>\\1<HR></PRE></BLOCKQUOTE>"        // Quote
                        );

        $pagetext = preg_replace($original, $replace, $pagetext);

For the most part this works great, however the URL (and possibly email too) seem to have problems working properly. For the following BB post:

Code:

...about it www.mysite.com.  For more information, check out the post 
www.mysite.com.  Do your...

It returns this result:

[html]
...about it <A HREF="http://www.mysite.com/forums/showthread.php?s=&threadid=3357]here[/url]. For more information, check out the post
[url=http://www.mysite.com/forums/showthread.php?s=&threadid=3598">here</A>. Do your...
[/HTML]

So what I would like to know is why its skipping the first match for the url regex? Anyone got any possible ideas?

Much thanks.

-Perc

Perculator · #2 12-Feb-2004, 19:47

Oh, and on an odd side note of cleaning that above php up, is there a better way to check for both caps and lowercase in a regex than [U|u][R|r][L|l]?

Thanks.

-Perc

JdS · #3 13-Feb-2004, 02:54

Hello Perculator,

You need what is known as PCRE Pattern Modifiers in your patterns above.

An example:

PHP Code:


<?php

// the 2 following patterns do the same thing
$find[0] = "/[a-zA-Z]+/";
$find[1] = "/[a-z]+/i"; // by simply appending the "i" modifier to the pattern,
                        // we match both, upper and lower case letters!

// so... to edit one of your existing patterns e.g.
$original[0] = "/\[[B|b]\](.*)\[\/[B|b]\]/";
// you can instead do this..
$original[0] = "/\[b\](.*)\[\/b\]/i";
?>

As for your second problem, this again is a PATTERN MODIFIER issue, the Ungreedy pattern modifier specifically.

Again, to show you how you could use these PCRE pattern modifiers more efficiently in your existing PHP script snippet above, refer to the example code below:

PHP Code:


<?php
$original[6] = "/\[[U|u][R|r][L|l]=(.*)\](.*)\[\/[U|u][R|r][L|l]\]/";  // URL
// you can change this to something like...
$original[6] = "/\[url=(.*)\](.*)\[\/url\]/iU"; // "iU" pattern modifiers
?>

For more detailed information on the various available PCRE Pattern Modifiers, please refer to this page: http://www.php.net/manual/en/pcre.pattern.modifiers.php

Garth Farley · #4 13-Feb-2004, 05:58

Yup, that's exactly it. Preg functions, by default, are supposed to be as greedy as possible, so using the U modifier tells it not to be.
GF

Perculator · #5 13-Feb-2004, 22:19

Spectacular. Worked like a charm.

My last question as a follow up, is why were the bold and italic replacements not being greedy? There were several bold and italic sections, but they all converted properly. I think that's what was throwing me off the most....how it was working for some, and not others.

Reguardless, thank you very much for the quick and useful reply...

-Perc

JdS · #6 15-Feb-2004, 05:05

Quote:

Originally Posted by Perculator

... is why were the bold and italic replacements not being greedy?...

I am quite certain they are (being GREEDY)... as long as they are in a single line.

What I mean actually: since you did NOT use the "s" (or PCRE_dotall) pattern modifier in your patterns, multiple [b] tags will work quite well, as LONG as each pair appear in separate lines - but the minute there are multiple

PHP Code:


<?php

$find[0]        =  '/\[b\](.*)\[\/b\]/i';
$replace[0]     =  "<strong>$1</strong>";

$before         =  "[b]Bold<strong> tags in a single line, you're screwed! <img src="/images/gid/smilies/icon_lol.gif" border="0" alt="" title="Laughing" class="inlineimg" />

Example follows:

</strong> this.\r\nAnd [b]this[/b].";

$after          =  preg_replace( $find, $replace, $before );

[/b]

PHP Code:


this. And [b]this</strong>.

*/

// So, ideally, $find[0] should look like this:
$find[0]       =  "#\[b\](.*)\[/b\]#isU";
?>

Perculator · #7 16-Feb-2004, 22:25

Very interesting, and very cool. Much thanks JDS...

-Perc

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preg_replace question...

PCRE (Perl Compatible Regular Expressions) Pattern Modifiers