using System;
using System.Diagnostics;
using System.Collections.Generic;

class ForEachBenchmark
{
    const int Iterations = 10000;
    const int Size = 100000;

    static void Main()        
    {
        Console.WriteLine ("Test parameters: Size={0}; Iterations={1}",
                           Size, Iterations);
        List<string> list = new List<string>();
        for (int i=0; i < Size; i++)
        {
            list.Add("x");
        }
        
        RunTest(list, LanguageForEach);
        RunTest(list, NewDelegateEachTime);
        RunTest(list, CachedDelegate);
        RunTest(list, LanguageForEachWithCopy1);
        RunTest(list, LanguageForEachWithCopy2);
    }
    
    delegate int ForEachTest(List<string> list);
    
    static void RunTest(List<string> list, ForEachTest test)
    {
        Stopwatch stopwatch = new Stopwatch();
        stopwatch.Start();
        int sum = test(list);
        TimeSpan time = stopwatch.Elapsed;
        if (sum != Iterations*Size)
        {
            Console.WriteLine ("Error in test {0}", test.Method.Name);
        }
        Console.WriteLine ("Test {0}: {1}", time, test.Method.Name);        
    }
    
    static int LanguageForEach(List<string> list)
    {
        int sum = 0;
        
        for (int i=0; i < Iterations; i++)
        {
            foreach (string s in list)
            {
                sum += s.Length;
            }
        }
        return sum;
    }
    
    static int LanguageForEachWithCopy1(List<string> list)
    {
        int sum = 0;
        
        for (int i=0; i < Iterations; i++)
        {
            string[] array = new string[list.Count];
            list.CopyTo(array, 0);
            foreach (string s in array)
            {
                sum += s.Length;
            }
        }
        return sum;
    }

    static int LanguageForEachWithCopy2(List<string> list)
    {
        string[] array = new string[list.Count];
        list.CopyTo(array, 0);

        int sum = 0;        

        for (int i=0; i < Iterations; i++)
        {
            foreach (string s in array)
            {
                sum += s.Length;
            }
        }
        return sum;
    }

    static int NewDelegateEachTime(List<string> list)
    {
        int sum = 0;
        for (int i=0; i < Iterations; i++)
        {
            // Note: Just using sum instead isn't good enough,
            // as then a single delegate is used (equivalent to
            // CachedDelegate). In this test, "count" is captured
            // separately for each outer iteration.
            int count=0;
            list.ForEach (delegate(string s) { count += s.Length; });
            sum += count;
        }
        return sum;
    }

    static int CachedDelegate(List<string> list)
    {
        int sum = 0;
        
        Action<string> action = delegate(string s)
        {
            sum += s.Length;
        };
        
        for (int i=0; i < Iterations; i++)
        {
            list.ForEach (action);
        }
        return sum;
    }
}