Antlr4.Parse.ScopeParser._ParsePrefixDecl C# (CSharp) Method

        public static System.Tuple<int, int> _ParsePrefixDecl(Attribute attr, string decl, ActionAST a, Grammar g)
        {
            // walk backwards looking for start of an ID
            bool inID = false;
            int start = -1;
            for (int i = decl.Length - 1; i >= 0; i--)
            {
                char ch = decl[i];
                // if we haven't found the end yet, keep going
                if (!inID && char.IsLetterOrDigit(ch))
                {
                    inID = true;
                }
                else if (inID && !(char.IsLetterOrDigit(ch) || ch == '_'))
                {
                    start = i + 1;
                    break;
                }
            }
            if (start < 0 && inID)
            {
                start = 0;
            }
            if (start < 0)
            {
                g.tool.errMgr.GrammarError(ErrorType.CANNOT_FIND_ATTRIBUTE_NAME_IN_DECL, g.fileName, a.Token, decl);
            }

            // walk forward looking for end of an ID
            int stop = -1;
            for (int i = start; i < decl.Length; i++)
            {
                char ch = decl[i];
                // if we haven't found the end yet, keep going
                if (!(char.IsLetterOrDigit(ch) || ch == '_'))
                {
                    stop = i;
                    break;
                }
                if (i == decl.Length - 1)
                {
                    stop = i + 1;
                }
            }

            // the name is the last ID
            attr.name = decl.Substring(start, stop - start);

            // the type is the decl minus the ID (could be empty)
            attr.type = decl.Substring(0, start);
            if (stop <= decl.Length - 1)
            {
                attr.type += decl.Substring(stop, decl.Length - stop);
            }

            attr.type = attr.type.Trim();
            if (attr.type.Length == 0)
            {
                attr.type = null;
            }

            return Tuple.Create(start, stop);
        }