EnumerableUtils.ChunkWhile()

Nixill · Dec 7, 2022 · d951ef3 · d951ef3
1 parent 5af89a0
commit d951ef3
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diff --git a/CSharp.Nixill.Test/src/NixLibTests.cs b/CSharp.Nixill.Test/src/NixLibTests.cs
@@ -4,6 +4,7 @@
 using Nixill.Objects;
 using System.Text.RegularExpressions;
 using Nixill.Collections;
+using System.Linq;
 
 namespace Nixill.Test {
   public class NixLibTests {
@@ -75,6 +76,20 @@ public void AVLSearchAroundTest() {
       TestValues(set.SearchAround(16), 14, 16, 18);
     }
 
+    [Test]
+    public void ChunkWhileTest() {
+      string[] words = EnumerableUtils
+        .Of('a', 'b', 'c', ' ', 'd', 'e', ' ', 'f')
+        .ChunkWhile(chr => chr != ' ')
+        .Select(chunk => chunk.FormString())
+        .ToArray();
+
+      Assert.AreEqual(words.Length, 3);
+      Assert.AreEqual(words[0], "abc");
+      Assert.AreEqual(words[1], "de");
+      Assert.AreEqual(words[2], "f");
+    }
+
     public void TestValues(NodeTriplet<int> ints, int? lower, int? equal, int? higher) {
       if (lower.HasValue) {
         Assert.True(ints.HasLesserValue);

diff --git a/CSharp.Nixill/src/Utils/EnumerableUtils.cs b/CSharp.Nixill/src/Utils/EnumerableUtils.cs
@@ -212,4 +212,26 @@ public static IEnumerable<TSource> MinManyBy<TSource, TResult>(this IEnumerable<
     return allItems;
   }
 
+  public static IEnumerable<IEnumerable<TSource>> ChunkWhile<TSource>(this IEnumerable<TSource> items,
+      Func<TSource, bool> predicate) {
+    List<TSource> list = null;
+
+    foreach (TSource item in items) {
+      if (predicate(item)) {
+        if (list == null) list = new();
+        list.Add(item);
+      }
+      else {
+        if (list == null) yield return Enumerable.Empty<TSource>();
+        else {
+          yield return list;
+          list = null;
+        }
+      }
+    }
+
+    if (list != null) yield return list;
+  }
+
+  public static string FormString(this IEnumerable<char> chars) => new string(chars.ToArray());
 }