CodeKicker.BBCode.SyntaxTree.TagNode.ReplaceAttributeValues C# (CSharp) Метод

        string ReplaceAttributeValues(string template, string content)
        {
            var attributesWithValues = (from attr in Tag.Attributes
                                        group attr by attr.ID into gAttrByID
                                        let val = (from attr in gAttrByID
                                                   let val = TryGetValue(attr)
                                                   where val != null
                                                   select new { attr, val }).FirstOrDefault()
                                        select new { attrID = gAttrByID.Key, attrAndVal = val }).ToList();

            var attrValuesByID = attributesWithValues.Where(x => x.attrAndVal != null).ToDictionary(x => x.attrID, x => x.attrAndVal.val);
            if (!attrValuesByID.ContainsKey(BBTag.ContentPlaceholderName))
                attrValuesByID.Add(BBTag.ContentPlaceholderName, content);

            var output = template;
            foreach (var x in attributesWithValues)
            {
                var placeholderStr = "${" + x.attrID + "}";

                if (x.attrAndVal != null)
                {
                    //replace attributes with values
                    var rawValue = x.attrAndVal.val;
                    var attribute = x.attrAndVal.attr;
                    output = ReplaceAttribute(output, attribute, rawValue, placeholderStr, attrValuesByID);
                }
            }

            //replace empty attributes
            var attributeIDsWithValues = new HashSet<string>(attributesWithValues.Where(x => x.attrAndVal != null).Select(x => x.attrID));
            var emptyAttributes = Tag.Attributes.Where(attr => !attributeIDsWithValues.Contains(attr.ID)).ToList();
            
            foreach (var attr in emptyAttributes)
            {
                var placeholderStr = "${" + attr.ID + "}";
                output = ReplaceAttribute(output, attr, null, placeholderStr, attrValuesByID);
            }

            output = output.Replace("${" + BBTag.ContentPlaceholderName + "}", content);
            return output;
        }