alexandre-spieser
62 lines
2.4 KiB
C#
62 lines
2.4 KiB
C#
using System;
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namespace CoreIntegrationTests.Infrastructure
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{
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// Thanks BlueRaja - Danny Pflughoeft https://stackoverflow.com/a/13095144/5103354
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/// <summary>
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/// Extensions for the random number generator <see cref="Random"/>
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/// </summary>
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public static class RandomExtensions
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{
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/// <summary>
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/// Returns a random long from min (inclusive) to max (exclusive)
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/// </summary>
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/// <param name="random">The given random instance</param>
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/// <param name="min">The inclusive minimum bound</param>
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/// <param name="max">The exclusive maximum bound. Must be greater than min</param>
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public static long NextLong(this Random random, long min, long max)
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{
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if (max <= min)
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throw new ArgumentOutOfRangeException("max", "max must be > min!");
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//Working with ulong so that modulo works correctly with values > long.MaxValue
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ulong uRange = (ulong)(max - min);
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//Prevent a modulo bias; see https://stackoverflow.com/a/10984975/238419
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//for more information.
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//In the worst case, the expected number of calls is 2 (though usually it's
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//much closer to 1) so this loop doesn't really hurt performance at all.
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ulong ulongRand;
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do
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{
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byte[] buf = new byte[8];
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random.NextBytes(buf);
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ulongRand = (ulong)BitConverter.ToInt64(buf, 0);
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} while (ulongRand > ulong.MaxValue - ((ulong.MaxValue % uRange) + 1) % uRange);
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return (long)(ulongRand % uRange) + min;
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}
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/// <summary>
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/// Returns a random long from 0 (inclusive) to max (exclusive)
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/// </summary>
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/// <param name="random">The given random instance</param>
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/// <param name="max">The exclusive maximum bound. Must be greater than 0</param>
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public static long NextLong(this Random random, long max)
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{
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return random.NextLong(0, max);
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}
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/// <summary>
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/// Returns a random long over all possible values of long (except long.MaxValue, similar to
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/// random.Next())
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/// </summary>
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/// <param name="random">The given random instance</param>
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public static long NextLong(this Random random)
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{
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return random.NextLong(long.MinValue, long.MaxValue);
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}
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}
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}
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