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easy function memoization in C#
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| // Copyright (c) 2016 Eric Christensen | |
| /* | |
| Permission is hereby granted, free of charge, to any person obtaining a copy of this | |
| software and associated documentation files (the "Software"), to deal in the Software | |
| without restriction, including without limitation the rights to use, copy, modify, merge, | |
| publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons | |
| to whom the Software is furnished to do so, subject to the following conditions: | |
| The above copyright notice and this permission notice shall be included in all copies | |
| or substantial portions of the Software. | |
| THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, | |
| INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR | |
| PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE | |
| FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR | |
| OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER | |
| DEALINGS IN THE SOFTWARE. | |
| */ | |
| using System; | |
| using System.Threading; | |
| namespace FunctionalHelper | |
| { | |
| public class MemoizationTesting | |
| { | |
| Func<int, int> add10; | |
| static int executionSeconds; | |
| static int memorySeconds; | |
| public static void Main(string [] args) | |
| { | |
| executionSeconds = 1; | |
| memorySeconds = 5; | |
| logWithTime("Memoization tests"); | |
| logWithTime(string.Format("Memoized functions will take {0} seconds to compute", executionSeconds)); | |
| logWithTime(string.Format("Memoized functions have memory of {0} seconds", memorySeconds)); | |
| var tester = new MemoizationTesting(); | |
| tester.add10 = Memoizer.Create<int, int>(x => | |
| { | |
| logWithTime("Nothing in memory: computing add10(" + x.ToString() + ")"); | |
| Thread.Sleep(executionSeconds*1000); | |
| return x + 10; | |
| }, memorySeconds); // can remove int parameter for unlimited memory | |
| logWithTime("Executing add10(10)"); | |
| logWithTime("Result is " + tester.add10(10).ToString()); | |
| logWithTime("Executing add10(11)"); | |
| logWithTime("Result is " + tester.add10(11).ToString()); | |
| logWithTime("Executing add10(10)"); | |
| logWithTime("Result is " + tester.add10(10).ToString()); | |
| logWithTime("Executing add10(11)"); | |
| logWithTime("Result is " + tester.add10(11).ToString()); | |
| logWithTime("Executing add10(10)"); | |
| logWithTime("Result is " + tester.add10(10).ToString()); | |
| logWithTime("Executing add10(11)"); | |
| logWithTime("Result is " + tester.add10(11).ToString()); | |
| logWithTime("Executing add10(10)"); | |
| logWithTime("Result is " + tester.add10(10).ToString()); | |
| logWithTime("Executing add10(11)"); | |
| logWithTime("Result is " + tester.add10(11).ToString()); | |
| logWithTime("Taking a nap for 10 seconds!"); | |
| Thread.Sleep(10*1000); | |
| logWithTime("Awake!"); | |
| logWithTime("Executing add10(10)"); | |
| logWithTime("Result is " + tester.add10(10).ToString()); | |
| logWithTime("Executing add10(11)"); | |
| logWithTime("Result is " + tester.add10(11).ToString()); | |
| logWithTime("Executing add10(10)"); | |
| logWithTime("Result is " + tester.add10(10).ToString()); | |
| logWithTime("Executing add10(11)"); | |
| logWithTime("Result is " + tester.add10(11).ToString()); | |
| logWithTime("Executing add10(10)"); | |
| logWithTime("Result is " + tester.add10(10).ToString()); | |
| logWithTime("Executing add10(11)"); | |
| logWithTime("Result is " + tester.add10(11).ToString()); | |
| logWithTime("Executing add10(10)"); | |
| logWithTime("Result is " + tester.add10(10).ToString()); | |
| logWithTime("Executing add10(11)"); | |
| logWithTime("Result is " + tester.add10(11).ToString()); | |
| } | |
| static void logWithTime(string val) | |
| { | |
| Console.WriteLine("[{0}] {1}", DateTime.Now.ToString("yyyy-MM-dd HH:mm:ss.fff"), val); | |
| } | |
| } | |
| } |
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| // Copyright (c) 2016 Eric Christensen | |
| /* | |
| Permission is hereby granted, free of charge, to any person obtaining a copy of this | |
| software and associated documentation files (the "Software"), to deal in the Software | |
| without restriction, including without limitation the rights to use, copy, modify, merge, | |
| publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons | |
| to whom the Software is furnished to do so, subject to the following conditions: | |
| The above copyright notice and this permission notice shall be included in all copies | |
| or substantial portions of the Software. | |
| THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, | |
| INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR | |
| PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE | |
| FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR | |
| OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER | |
| DEALINGS IN THE SOFTWARE. | |
| */ | |
| using System; | |
| using System.Collections.Generic; | |
| namespace FunctionalHelper | |
| { | |
| public static class Memoizer | |
| { | |
| // create an inner class to store the results | |
| class Result<T1, T2> | |
| { | |
| public T1 input; | |
| public T2 output; | |
| DateTime expireDate; | |
| public bool Expired() | |
| { | |
| return (expireDate.CompareTo(DateTime.Now) < 0); | |
| } | |
| public Result(T1 input, T2 output, int validSeconds) | |
| { | |
| this.input = input; | |
| this.output = output; | |
| expireDate = DateTime.Now.AddSeconds(validSeconds); | |
| } | |
| } | |
| // create an inner class to store the results | |
| class Result<T> | |
| { | |
| public T output; | |
| DateTime expireDate; | |
| public bool Expired() | |
| { | |
| return (expireDate.CompareTo(DateTime.Now) < 0); | |
| } | |
| public Result() | |
| { | |
| expireDate = DateTime.Now.AddSeconds(-99); | |
| } | |
| public Result(T output, int validSeconds) | |
| { | |
| this.output = output; | |
| expireDate = DateTime.Now.AddSeconds(validSeconds); | |
| } | |
| } | |
| // input and output, finite memory | |
| public static Func<T1, T2> Create<T1, T2>(Func<T1, T2> fn, int memorySeconds) | |
| { | |
| Dictionary<T1, Result<T1, T2>> memory = new Dictionary<T1, Result<T1, T2>>(); | |
| return x => | |
| { | |
| Result<T1, T2> foundInMemory; | |
| if (memory.TryGetValue(x, out foundInMemory)) | |
| { | |
| if (!foundInMemory.Expired()) | |
| { | |
| return foundInMemory.output; | |
| } | |
| } | |
| T2 val = fn(x); | |
| memory[x] = new Result<T1, T2>(x, val, memorySeconds); | |
| return val; | |
| }; | |
| } | |
| // input and output, infinite memory | |
| public static Func<T1, T2> Create<T1, T2>(Func<T1, T2> fn) | |
| { | |
| Dictionary<T1, T2> memory = new Dictionary<T1, T2>(); | |
| return x => | |
| { | |
| T2 val; | |
| if (memory.TryGetValue(x, out val)) | |
| { | |
| return val; | |
| } | |
| val = fn(x); | |
| memory[x] = val; | |
| return val; | |
| }; | |
| } | |
| // output only, finite memory | |
| public static Func<T1> Create<T1>(Func<T1> fn, int memorySeconds) | |
| { | |
| Result<T1> memory = new Result<T1>(); | |
| return () => | |
| { | |
| T1 val; | |
| if (!memory.Expired()) | |
| { | |
| return memory.output; | |
| } | |
| val = fn(); | |
| memory = new Result<T1>(val, memorySeconds); | |
| return val; | |
| }; | |
| } | |
| // output only, infinite memory | |
| public static Func<T1> Create<T1>(Func<T1> fn) | |
| { | |
| Result<T1> memory = new Result<T1>(); | |
| return () => | |
| { | |
| T1 val; | |
| if (!memory.Expired()) | |
| { | |
| return memory.output; | |
| } | |
| val = fn(); | |
| memory = new Result<T1>(val, 999999999); // 31 years | |
| return val; | |
| }; | |
| } | |
| } | |
| } |
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| [2016-06-16 22:17:26.706] Memoization tests | |
| [2016-06-16 22:17:26.715] Memoized functions will take 1 seconds to compute | |
| [2016-06-16 22:17:26.715] Memoized functions have memory of 5 seconds | |
| [2016-06-16 22:17:26.716] Executing add10(10) | |
| [2016-06-16 22:17:26.717] Nothing in memory: computing add10(10) | |
| [2016-06-16 22:17:27.718] Result is 20 | |
| [2016-06-16 22:17:27.718] Executing add10(11) | |
| [2016-06-16 22:17:27.719] Nothing in memory: computing add10(11) | |
| [2016-06-16 22:17:28.719] Result is 21 | |
| [2016-06-16 22:17:28.719] Executing add10(10) | |
| [2016-06-16 22:17:28.720] Result is 20 | |
| [2016-06-16 22:17:28.720] Executing add10(11) | |
| [2016-06-16 22:17:28.720] Result is 21 | |
| [2016-06-16 22:17:28.721] Executing add10(10) | |
| [2016-06-16 22:17:28.721] Result is 20 | |
| [2016-06-16 22:17:28.721] Executing add10(11) | |
| [2016-06-16 22:17:28.721] Result is 21 | |
| [2016-06-16 22:17:28.722] Executing add10(10) | |
| [2016-06-16 22:17:28.722] Result is 20 | |
| [2016-06-16 22:17:28.722] Executing add10(11) | |
| [2016-06-16 22:17:28.722] Result is 21 | |
| [2016-06-16 22:17:28.723] Taking a nap for 10 seconds! | |
| [2016-06-16 22:17:38.735] Awake! | |
| [2016-06-16 22:17:38.735] Executing add10(10) | |
| [2016-06-16 22:17:38.735] Nothing in memory: computing add10(10) | |
| [2016-06-16 22:17:39.735] Result is 20 | |
| [2016-06-16 22:17:39.735] Executing add10(11) | |
| [2016-06-16 22:17:39.735] Nothing in memory: computing add10(11) | |
| [2016-06-16 22:17:40.735] Result is 21 | |
| [2016-06-16 22:17:40.735] Executing add10(10) | |
| [2016-06-16 22:17:40.736] Result is 20 | |
| [2016-06-16 22:17:40.736] Executing add10(11) | |
| [2016-06-16 22:17:40.737] Result is 21 | |
| [2016-06-16 22:17:40.737] Executing add10(10) | |
| [2016-06-16 22:17:40.737] Result is 20 | |
| [2016-06-16 22:17:40.738] Executing add10(11) | |
| [2016-06-16 22:17:40.738] Result is 21 | |
| [2016-06-16 22:17:40.738] Executing add10(10) | |
| [2016-06-16 22:17:40.738] Result is 20 | |
| [2016-06-16 22:17:40.738] Executing add10(11) | |
| [2016-06-16 22:17:40.738] Result is 21 |
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