using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Runtime.InteropServices;
using System.Text.RegularExpressions;
using System.Diagnostics;
 
namespace ca
{
    public class Test
    {
        public static void Main()
        {
            Regex trimmer = new Regex(@"\s\s+", RegexOptions.Compiled);
            Random rng = new Random();
            Stopwatch sw = new Stopwatch();
            const int n = 5;
 
            // random 1mb+ string (it's slow enough...)
            StringBuilder ssb = new StringBuilder(1 * 1024 * 1024);
            for (int i = 0; i < 1 * 1024 * 1024; ++i)
                if (rng.Next(5) == 0)
                    ssb.Append(new string(' ', rng.Next(20)));
                else
                    ssb.Append((char)(rng.Next(128 - 32) + 32));
            string s = ssb.ToString();
            StringBuilder tmpbuilder = new StringBuilder(s.Length);
			// ===================
 
 
 
 
            // ========= regex =========
            sw.Start();
            for (int i = 0; i < n; ++i)
            {
                string scopy = s;
                scopy = trimmer.Replace(scopy, " ");
            }
            sw.Stop();
            Console.WriteLine("Regex: " + sw.ElapsedMilliseconds + "ms.");
            
 
            // ========= stringbuilder =========
            sw.Reset(); sw.Start();
            for (int i = 0; i < n; ++i)
            {
                string scopy = s;
                bool inspaces = false;
                tmpbuilder.Length = 0;
 
                for (int k = 0; k < s.Length; ++k)
                {
                    char c = scopy[k];
 
                    if (inspaces)
                    {
                        if (c != ' ')
                        {
                            inspaces = false;
                            tmpbuilder.Append(c);
                        }
                    }
                    else if (c == ' ')
                    {
                        inspaces = true;
                        tmpbuilder.Append(' ');
                    }
                    else
                        tmpbuilder.Append(c);
                }
            }
            sw.Stop();
            Console.WriteLine("Stringbuilder: " + sw.ElapsedMilliseconds + "ms.");
        }
    }
}