WikiFunctions.Parse.Parsers.TemplateRedirectsHashSet C# (CSharp) Method

        private static string TemplateRedirectsHashSet(string articleText, Dictionary<Regex, string> TemplateRedirects)
        {
            // performance: first check there's a match between templates used in article and listed template redirects
            // using intersection of HashSet lists of the two
            HashSet<string> TemplatesFound = new HashSet<string>(GetAllTemplates(articleText));
            TemplatesFound.IntersectWith(WikiRegexes.AllTemplateRedirectsHS);

            // run replacements only if matches found
            if (TemplatesFound.Any())
            {
                // performance: secondly filter the TemplateRedirects dictionary down to those rules matching templates used in article
                string all = String.Join(" ", TemplatesFound.Select(s => "{{" + s + "}}").ToArray());
                TemplateRedirects = TemplateRedirects.Where(s => s.Key.IsMatch(all))
                    .ToDictionary(x => x.Key, y => y.Value);

                // performance: thirdly then run replacement for only those matching templates, and only against the matching rules, handle nested templates
                Regex MatchedTemplates = Tools.NestedTemplateRegex(TemplatesFound.ToList());

                articleText = MatchedTemplates.Replace(articleText, m2 =>
                {
                    string res = m2.Value;
                    string valBefore = "";

                    // inner loop to handle nested templates
                    while(res != valBefore)
                    {
                        valBefore = res;
                        foreach (KeyValuePair<Regex, string> kvp in TemplateRedirects)
                        {
                            res = kvp.Key.Replace(res, m => TemplateRedirectsME(m, kvp.Value));

                            // if template name changed and not nested template, done, so break out
                            if (!res.Equals(m2.Value) && !m2.Groups[3].Value.Contains("{{"))
                                break;
                        }
                    }
                    return res;
                });
            }
            return articleText;
        }