54 lines
2.1 KiB
C#
54 lines
2.1 KiB
C#
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using YKanBan.Search;
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namespace YKanBan.Tests.Search;
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/// <summary>
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/// Structural comparer for search AST nodes, used by assertions only. The
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/// AST records compare by reference for their Terms collections by design
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/// (see the YYC MARK note in SearchNodes.cs), so tests provide equality
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/// explicitly.
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/// </summary>
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public sealed class SearchNodeComparer : IEqualityComparer<SearchNode>
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{
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/// <summary>Shared comparer instance.</summary>
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public static SearchNodeComparer Instance { get; } = new();
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/// <summary>Determines structural equality of two nodes.</summary>
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public bool Equals(SearchNode? x, SearchNode? y)
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{
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if (ReferenceEquals(x, y))
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{
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return true;
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}
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if (x is null || y is null || x.GetType() != y.GetType())
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{
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return false;
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}
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return (x, y) switch
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{
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(SearchNode.Or a, SearchNode.Or b) => SequencesEqual(a.Terms, b.Terms),
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(SearchNode.And a, SearchNode.And b) => SequencesEqual(a.Terms, b.Terms),
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(SearchNode.FreeText a, SearchNode.FreeText b) => a.Text == b.Text,
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(SearchNode.FieldText a, SearchNode.FieldText b) => a.Field == b.Field && a.Text == b.Text,
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(SearchNode.TagName a, SearchNode.TagName b) => a.Name == b.Name,
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(SearchNode.ColumnTitle a, SearchNode.ColumnTitle b) => a.Title == b.Title,
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(SearchNode.CardId a, SearchNode.CardId b) => a.Id == b.Id,
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_ => false,
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};
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}
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/// <summary>Not supported: the comparer exists for assertions, not hashing.</summary>
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public int GetHashCode(SearchNode obj) =>
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throw new NotSupportedException("Structural comparison for assertions only; hashing is not supported.");
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/// <summary>Order-sensitive element-wise comparison.</summary>
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private static bool SequencesEqual(IReadOnlyList<SearchNode> x, IReadOnlyList<SearchNode> y)
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{
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if (x.Count != y.Count)
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{
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return false;
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}
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return Enumerable.Zip(x, y, (a, b) => (a, b)).All(pair => Instance.Equals(pair.a, pair.b));
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}
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}
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