How to replace pairs tags with regexp

[Suliman via Digitalmars-d-learn]

I have got next code:

import std.stdio;
import std.regex;
import std.file;

void main()
{
	auto text = readText("book.txt");
	
	auto inlineCodeBlock = regex("`([^`\n]+)`");
	auto bigCodeBlock = regex(r"`{3}[\s\S]*?`{3}");
	
	foreach(t; text.matchAll(bigCodeBlock))
	{
		string t1 = t.hit.replaceFirst(regex("`"),`<code>`);
		string t2 = t1.replaceFirst(regex("`"),`</code>`);
	}
	
}

Here I am replacing `foo` to <code>foo</code>. But got replaced 
data as copy, not in original document. But I need to get 
replacing in original document.

replaceAll is not suitable for it because it's not clear how to 
get open and close tags (<code> and </code>).