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Topological Sort algorithm for sorting items based on dependencies
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| using System; | |
| using System.Collections.Generic; | |
| using System.Linq; | |
| using System.Text; | |
| using System.Threading.Tasks; | |
| namespace Application | |
| { | |
| public static class TopologicalSorter | |
| { | |
| /// <summary> | |
| /// Returns a set of items sorted by topological order. | |
| /// </summary> | |
| /// <typeparam name="T">The element type of the sequence.</typeparam> | |
| /// <param name="source">The source.</param> | |
| /// <param name="dependencies">The dependencies.</param> | |
| /// <param name="throwOnCycle">If set to <c>true</c> cyclic dependency is not allowed.</param> | |
| /// <returns>The sorted sequence.</returns> | |
| public static IEnumerable<T> TplgSort<T>(this IEnumerable<T> source, Func<T, IEnumerable<T>> dependencies, bool throwOnCycle = false) | |
| { | |
| var sorted = new List<T>(); | |
| var visited = new HashSet<T>(); | |
| foreach (var item in source) | |
| { | |
| Visit(item, visited, sorted, dependencies, throwOnCycle); | |
| } | |
| return sorted; | |
| } | |
| private static void Visit<T>(T item, HashSet<T> visited, List<T> sorted, Func<T, IEnumerable<T>> dependencies, bool throwOnCycle) | |
| { | |
| if (visited.Contains(item) == false) | |
| { | |
| visited.Add(item); | |
| foreach (var dep in dependencies(item)) | |
| { | |
| Visit(dep, visited, sorted, dependencies, throwOnCycle); | |
| } | |
| sorted.Add(item); | |
| } | |
| else | |
| { | |
| if (throwOnCycle && sorted.Contains(item) == false) | |
| { | |
| throw new Exception("Cyclic dependency found"); | |
| } | |
| } | |
| } | |
| } | |
| } |
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