Advice for implementing simple regex (for bbcode/geshi parsing) - php

Question

I had made a personal note software in PHP so I can store and organize my notes and wished for a nice simple format to write them in.
I had done it in Markdown but found it was a little confusing and there was no simple syntax highlighting, so I did bbcode before and wished to implement that.
Now for GeSHi which I really wish to implement (the syntax highlighter), it requires the most simple code like this:
$geshi = new GeSHi($sourcecode, $language);
$geshi->parse_code();
Now this is the easy part , but what I wish to do is allow my bbcode to call it.
My current regular expression to match a made up [syntax=cpp][/syntax] bbcode is the following:
preg_replace('#\[syntax=(.*?)\](.*?)\[/syntax\]#si' , 'geshi(\\2,\\1)????', text);
You will notice I capture the language and the content, how on earth would I connect it to the GeSHi code?
preg_replace seems to just be able to replace it with a string not an 'expression', I am not sure how to use those two lines of code for GeSHi up there with the captured data..
I really am excited about this project and wish to overcome this.

Answer 1

I wrote this class a while back, the reason for the class was to allow easy customization / parsing. Maybe a little overkill, but works well and I needed it overkill for my application. The usage is pretty simple:
$geshiH = new Geshi_Helper();
$text = $geshiH->geshi($text); // this assumes that the text should be parsed (ie inline syntaxes)
---- OR ----
$geshiH = new Geshi_Helper();
$text = $geshiH->geshi($text, $lang); // assumes that you have the language, good for a snippets deal
I had to do some chopping from other custom items I had, but pending no syntax errors from the chopping it should work. Feel free to use it.
<?php
require_once 'Geshi/geshi.php';
class Geshi_Helper
{
/**
* #var array Array of matches from the code block.
*/
private $_codeMatches = array();
private $_token = "";
private $_count = 1;
public function __construct()
{
/* Generate a unique hash token for replacement) */
$this->_token = md5(time() . rand(9999,9999999));
}
/**
* Performs syntax highlights using geshi library to the content.
*
* #param string $content - The context to parse
* #return string Syntax Highlighted content
*/
public function geshi($content, $lang=null)
{
if (!is_null($lang)) {
/* Given the returned results 0 is not set, adding the "" should make this compatible */
$content = $this->_highlightSyntax(array("", strtolower($lang), $content));
}else {
/* Need to replace this prior to the code replace for nobbc */
$content = preg_replace('~\[nobbc\](.+?)\[/nobbc\]~ie', '\'[nobbc]\' . strtr(\'$1\', array(\'[\' => \'[\', \']\' => \']\', \':\' => \':\', \'#\' => \'#\')) . \'[/nobbc]\'', $content);
/* For multiple content we have to handle the br's, hence the replacement filters */
$content = $this->_preFilter($content);
/* Reverse the nobbc markup */
$content = preg_replace('~\[nobbc\](.+?)\[/nobbc\]~ie', 'strtr(\'$1\', array(\'&#91;\' => \'[\', \'&#93;\' => \']\', \'&#58;\' => \':\', \'&#64;\' => \'#\'))', $content);
$content = $this->_postFilter($content);
}
return $content;
}
/**
* Performs syntax highlights using geshi library to the content.
* If it is unknown the number of blocks, use highlightContent
* instead.
*
* #param string $content - The code block to parse
* #param string $language - The language to highlight with
* #return string Syntax Highlighted content
* #todo Add any extra / customization styling here.
*/
private function _highlightSyntax($contentArray)
{
$codeCount = $contentArray[1];
/* If the count is 2 we are working with the filter */
if (count($contentArray) == 2) {
$contentArray = $this->_codeMatches[$contentArray[1]];
}
/* for default [syntax] */
if ($contentArray[1] == "")
$contentArray[1] = "php";
/* Grab the language */
$language = (isset($contentArray[1]))?$contentArray[1]:'text';
/* Remove leading spaces to avoid problems */
$content = ltrim($contentArray[2]);
/* Parse the code to be highlighted */
$geshi = new GeSHi($content, strtolower($language));
return $geshi->parse_code();
}
/**
* Substitute the code blocks for formatting to be done without
* messing up the code.
*
* #param array $match - Referenced array of items to substitute
* #return string Substituted content
*/
private function _substitute(&$match)
{
$index = sprintf("%02d", $this->_count++);
$this->_codeMatches[$index] = $match;
return "----" . $this->_token . $index . "----";
}
/**
* Removes the code from the rest of the content to apply other filters.
*
* #param string $content - The content to filter out the code lines
* #return string Content with code removed.
*/
private function _preFilter($content)
{
return preg_replace_callback("#\s*\[syntax=(.*?)\](.*?)\[/syntax\]\s*#siU", array($this, "_substitute"), $content);
}
/**
* Replaces the code after the filters have been ran.
*
* #param string $content - The content to replace the code lines
* #return string Content with code re-applied.
*/
private function _postFilter($content)
{
/* using dashes to prevent the old filtered tag being escaped */
return preg_replace_callback("/----\s*" . $this->_token . "(\d{2})\s*----/si", array($this, "_highlightSyntax"), $content);
}
}
?>

Answer 2

It looks to me like you already got the regex right. Your problem lies in the invocation, so I suggest making a wrapper function:
function geshi($src, $l) {
$geshi = new GeSHi($sourcecode, $language);
$geshi->parse_code();
return $geshi->how_do_I_get_the_results();
}
Now this would normally suffice, but the source code is likely to contain single or dobule quotes itself. Therefore you cannot write preg_replace(".../e", "geshi('$2','$1')", ...) as you would need. (Note that '$1' and '$2' need quotes because preg_replace just substitutes the $1,$2 placeholders, but this needs to be valid php inline code).
That's why you need to use preg_replace_callback to avoid escaping issues in the /e exec replacement code.
So for example:
preg_replace_callback('#\[syntax=(.*?)\](.*?)\[/syntax\]#si' , 'geshi_replace', $text);
And I'd make a second wrapper, but you can combine it with the original code:
function geshi_replace($uu) {
return geshi($uu[2], $uu[1]);
}

Answer 3

Use preg_match:
$match = preg_match('#\[syntax=(.*?)\](.*?)\[/syntax\]#si', $text);
$geshi = new GeSHi($match[2], $match[1]);