System.Text.RegularExpressions.RegexRunnerFactory.CreateInstance C# (CSharp) Method

        protected internal abstract RegexRunner CreateInstance();

        /*
         * Internal worker called by all the public APIs
         */
        internal Match Run(bool quick, int prevlen, string input, int beginning, int length, int startat)
        {
            Match       match;
            RegexRunner runner = null;

            if (startat < 0 || startat > input.Length)
            {
                throw new ArgumentOutOfRangeException(nameof(startat), SR.BeginIndexNotNegative);
            }

            if (length < 0 || length > input.Length)
            {
                throw new ArgumentOutOfRangeException(nameof(length), SR.LengthNotNegative);
            }

            // There may be a cached runner; grab ownership of it if we can.

            runner = (RegexRunner)_runnerref.Get();

            // Create a RegexRunner instance if we need to

            if (runner == null)
            {
                // Use the compiled RegexRunner factory if the code was compiled to MSIL

                if (factory != null)
                {
                    runner = factory.CreateInstance();
                }
                else
                {
                    runner = new RegexInterpreter(_code, UseOptionInvariant() ? CultureInfo.InvariantCulture : CultureInfo.CurrentCulture);
                }
            }

            try
            {
                // Do the scan starting at the requested position
                match = runner.Scan(this, input, beginning, beginning + length, startat, prevlen, quick, internalMatchTimeout);
            }
            finally
            {
                // Release or fill the cache slot
                _runnerref.Release(runner);
            }

#if DEBUG
            if (Debug && match != null)
            {
                match.Dump();
            }
#endif
            return(match);
        }