63 lines
2.5 KiB
C#
63 lines
2.5 KiB
C#
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 AST
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/// records compare by reference for their Terms collections by design (see the
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/// YYC MARK note in SearchNodes.cs), so tests provide equality explicitly.
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/// </summary>
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public sealed class SearchNodeComparer : IEqualityComparer<SearchNode> {
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/// <summary>
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/// Gets the shared comparer instance.
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/// </summary>
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public static SearchNodeComparer Instance { get; } = new();
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/// <summary>
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/// Determines structural equality of two nodes.
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/// </summary>
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/// <param name="x">The first node.</param>
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/// <param name="y">The second node.</param>
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/// <returns><see langword="true"/> when the nodes are structurally equal.</returns>
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public bool Equals(SearchNode? x, SearchNode? y) {
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if (ReferenceEquals(x, y)) {
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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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return false;
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}
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return (x, y) switch {
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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>
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/// Not supported: the comparer exists for assertions, not hashing.
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/// </summary>
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/// <param name="obj">The node.</param>
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/// <returns>Never returns.</returns>
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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>
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/// Order-sensitive element-wise comparison.
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/// </summary>
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/// <param name="x">The first sequence.</param>
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/// <param name="y">The second sequence.</param>
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/// <returns><see langword="true"/> when both sequences match element-wise.</returns>
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private static bool SequencesEqual(IReadOnlyList<SearchNode> x, IReadOnlyList<SearchNode> y) {
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if (x.Count != y.Count) {
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return false;
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}
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return x.Zip(y).All(pair => Instance.Equals(pair.First, pair.Second));
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}
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}
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