freepascal regexp replace - regex

Question

Is there an easy way to do a RegExp replace in FreePascal/Lazarus?
Hunting around I can see that I can do a match fairly easily, but I'm struggling to find functions to do a search and replace.
What I'm trying to acheive is as follows.
I have an XML file loaded into a SynEdit component.
The XML file has a decalaration at the start
The DTD is held in a seperate file.
I don't want to combine the two in one file, but I do wantto validate the XML as it is being editted.
I'm reading the XML into a string variable and I want to insert the DTD between the and the XML content in a temporary string variable (to create a compliant XML with self contained DTD) that can be parsed and validated.
So essentially I have:
<?Line1?>
Line2
Line3
And I want to do a RegExp type search and replace for '<?Line1?>' replaceing with '<?Line1?>\n<![DTD\nINFO WOULD\nGO HERE\n!]' to give me:
<?Line1?>
<![DTD
INFO WOULD
GO HERE
!]
Line2
Line3
For example in PHP I would use:
preg_replace('/(<\?.*\?>)/im','$1
<![DTD
INFO WOULD
GO HERE
!]',$sourcestring);
But there doesn't seem to be an equivalent set of regexp functions for FreePascal / Lazarus - just a simple/basic RegExp match function.
Or is there an easier way without using regular expressions - I don't want to assume that the declaration is always there in the correct position on Line 1 though - just to complicate things.
Thanks,
FM

Answer 1

As far as I know, the PerlRegEx unit isn't compatible with Free Pascal. But you can use the RegExpr unit, which comes with Free Pascal.
If I understand correctly, you want a replacement with substitution. Here is a simple example that you can adapt to your need.
{$APPTYPE CONSOLE}
{$IFDEF FPC}{$MODE DELPHI}{$ENDIF}
uses
regexpr;
var
s: string;
begin
s := 'My name is Bond.';
s := ReplaceRegExpr(
'My name is (\w+?)\.',
s,
'His name is $1.',
TRUE // Use substitution
);
WriteLn(s); // His name is Bond.
ReadLn;
end.