YamlDotNet.Core.Parser.ProcessDirectives C# (CSharp) Method

        private VersionDirective ProcessDirectives(TagDirectiveCollection tags)
        {
            VersionDirective version = null;
            bool hasOwnDirectives = false;

            while (true)
            {
                VersionDirective currentVersion;
                TagDirective tag;

                if ((currentVersion = GetCurrentToken() as VersionDirective) != null)
                {
                    if (version != null)
                    {
                        throw new SemanticErrorException(currentVersion.Start, currentVersion.End, "Found duplicate %YAML directive.");
                    }

                    if (currentVersion.Version.Major != Constants.MajorVersion || currentVersion.Version.Minor != Constants.MinorVersion)
                    {
                        throw new SemanticErrorException(currentVersion.Start, currentVersion.End, "Found incompatible YAML document.");
                    }

                    version = currentVersion;
                    hasOwnDirectives = true;
                }
                else if ((tag = GetCurrentToken() as TagDirective) != null)
                {
                    if (tags.Contains(tag.Handle))
                    {
                        throw new SemanticErrorException(tag.Start, tag.End, "Found duplicate %TAG directive.");
                    }
                    tags.Add(tag);
                    hasOwnDirectives = true;
                }
                else
                {
                    break;
                }

                Skip();
            }

            AddTagDirectives(tags, Constants.DefaultTagDirectives);

            if (hasOwnDirectives)
            {
                tagDirectives.Clear();
            }

            AddTagDirectives(tagDirectives, tags);

            return version;
        }