On Sat, Aug 03, 2002 at 05:03:36PM +0100, Phil Ewington wrote:
> Hi,
>
> I am am writing a function to color code and indent JavaScript source using
> regular expressions and cannot seem to get back referencing working.
What you're using isn't "back referencing," it's utilizing "substrings."
Back referencing is when you bring the substrings back into the regular
expression definition.
> $string = eregi_replace("<(/?)(scr[^>]*)>", "�font color=maroon�\1�/font�",
> $string);
Here's what your command asks PHP to do: Find any opening or
closing script tag and replace it with "�font color=maroon�\1�/font�."
That's not what you intend. Let's make a test script:
<?php
$string = 'begin <script>java is dumb</script> end';
$string = eregi_replace("<(/?)(scr[^>]*)>",
"�font color=maroon�\1�/font�", $string);
echo "$string\n";
?>
This is what comes out:
begin �font color=maroon��/font�java is dumb�font color=maroon��/font�
end
First off, if you want to utilize substrings, you need to use two
backslashes. "\\1" instead of "\1". Second, \\1 refers to the first
parenthesized part of the pattern, which in the pattern you set up is the
forward slash at the beginning of the script tag. So, let's modify the
pattern accordingly and see what happens:
$string = eregi_replace("<(/?)(scr[^>]*)>",
"�font color=maroon�\\1�/font�", $string);
Creates:
begin �font color=maroon��/font�java is dumb�font color=maroon�/�/font�
end
But, that's still not what you intend. I think you're really looking to
surround the scripts with maroon font tags. To do that, you need to tweak
the expression to grab the script tags, the script itself and the closing
script tag.
$string = eregi_replace('(<script[^>]*>[^<]*</script>)',
'<font color="maroon">\\1</font>', $string);
Outputs:
begin <font color="maroon"><script>java is dumb</script></font> end
Notice the use of ' rather than ", which saves a little processor time by
not evaluaing the strings for variables.
One final improvement. Font tags are obnoxious. They cause problems for
people that choose their own background colors in their browsers. Read
http://www.analysisandsolutions.com/code/weberror.htm?ft=y for more info
on that. Anyway, I suggest using Cascading Style Sheets,
http://www.w3.org/TR/REC-CSS1, for the colroing instead:
$string = eregi_replace('(<script[^>]*>[^<]*</script>)',
'<code class="js">\\1</code>', $string);
echo "<style>code.js {color: maroon;}</style>\n";
echo "$string\n";
Yields:
<style>code.js {color: maroon;}</style>
begin <code class="js"><script>java is dumb</script></code> end
Voila!
--Dan
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