feat: add search parser, sql compiler and markdown export

YKanBan.Tests/Search/SearchNodeComparer.cs

@@ -0,0 +1,69 @@
+using YKanBan.Search;
+
+namespace YKanBan.Tests.Search;
+
+/// <summary>
+/// Structural comparer for search AST nodes, used by assertions only. The AST
+/// records compare by reference for their Terms collections by design (see the
+/// YYC MARK note in SearchNodes.cs), so tests provide equality explicitly.
+/// </summary>
+public sealed class SearchNodeComparer : IEqualityComparer<SearchNode>
+{
+    /// <summary>
+    /// Gets the shared comparer instance.
+    /// </summary>
+    public static SearchNodeComparer Instance { get; } = new();
+
+    /// <summary>
+    /// Determines structural equality of two nodes.
+    /// </summary>
+    /// <param name="x">The first node.</param>
+    /// <param name="y">The second node.</param>
+    /// <returns><see langword="true"/> when the nodes are structurally equal.</returns>
+    public bool Equals(SearchNode? x, SearchNode? y)
+    {
+        if (ReferenceEquals(x, y))
+        {
+            return true;
+        }
+        if (x is null || y is null || x.GetType() != y.GetType())
+        {
+            return false;
+        }
+
+        return (x, y) switch
+        {
+            (SearchNode.Or a, SearchNode.Or b) => SequencesEqual(a.Terms, b.Terms),
+            (SearchNode.And a, SearchNode.And b) => SequencesEqual(a.Terms, b.Terms),
+            (SearchNode.FreeText a, SearchNode.FreeText b) => a.Text == b.Text,
+            (SearchNode.FieldText a, SearchNode.FieldText b) => a.Field == b.Field && a.Text == b.Text,
+            (SearchNode.TagName a, SearchNode.TagName b) => a.Name == b.Name,
+            (SearchNode.ColumnTitle a, SearchNode.ColumnTitle b) => a.Title == b.Title,
+            (SearchNode.CardId a, SearchNode.CardId b) => a.Id == b.Id,
+            _ => false,
+        };
+    }
+
+    /// <summary>
+    /// Not supported: the comparer exists for assertions, not hashing.
+    /// </summary>
+    /// <param name="obj">The node.</param>
+    /// <returns>Never returns.</returns>
+    public int GetHashCode(SearchNode obj) =>
+        throw new NotSupportedException("Structural comparison for assertions only; hashing is not supported.");
+
+    /// <summary>
+    /// Order-sensitive element-wise comparison.
+    /// </summary>
+    /// <param name="x">The first sequence.</param>
+    /// <param name="y">The second sequence.</param>
+    /// <returns><see langword="true"/> when both sequences match element-wise.</returns>
+    private static bool SequencesEqual(IReadOnlyList<SearchNode> x, IReadOnlyList<SearchNode> y)
+    {
+        if (x.Count != y.Count)
+        {
+            return false;
+        }
+        return x.Zip(y).All(pair => Instance.Equals(pair.First, pair.Second));
+    }
+}