Antlr4.AntlrTool.ParseGrammar C# (CSharp) Method

        public virtual GrammarRootAST ParseGrammar(string fileName)
        {
            try
            {
                string file = fileName;
                if (!Path.IsPathRooted(file))
                {
                    file = Path.Combine(inputDirectory, fileName);
                }

                string fileContent = File.ReadAllText(file, Encoding.GetEncoding(grammarEncoding));
                char[] fileChars = fileContent.ToCharArray();
                ANTLRStringStream @in = new ANTLRStringStream(fileChars, fileChars.Length, fileName);
                GrammarRootAST t = Parse(fileName, @in);
                return t;
            }
            catch (IOException ioe)
            {
                errMgr.ToolError(ErrorType.CANNOT_OPEN_FILE, ioe, fileName);
            }
            return null;
        }