Merge remote-tracking branch 'origin' into libc-wasi-test

1 files changed, 37 insertions, 0 deletions

diff --git a/lib/std/array_hash_map.zig b/lib/std/array_hash_map.zig
index 9bcecab47e..4ca603d2e8 100644
--- a/lib/std/array_hash_map.zig
+++ b/lib/std/array_hash_map.zig
@@ -414,6 +414,12 @@ pub fn ArrayHashMap(
         pub fn pop(self: *Self) KV {
             return self.unmanaged.popContext(self.ctx);
         }
+
+        /// Removes the last inserted `Entry` in the hash map and returns it if count is nonzero.
+        /// Otherwise returns null.
+        pub fn popOrNull(self: *Self) ?KV {
+            return self.unmanaged.popOrNullContext(self.ctx);
+        }
     };
 }
 
@@ -1181,6 +1187,17 @@ pub fn ArrayHashMapUnmanaged(
             };
         }
 
+        /// Removes the last inserted `Entry` in the hash map and returns it if count is nonzero.
+        /// Otherwise returns null.
+        pub fn popOrNull(self: *Self) ?KV {
+            if (@sizeOf(ByIndexContext) != 0)
+                @compileError("Cannot infer context " ++ @typeName(Context) ++ ", call popContext instead.");
+            return self.popOrNullContext(undefined);
+        }
+        pub fn popOrNullContext(self: *Self, ctx: Context) ?KV {
+            return if (self.entries.len == 0) null else self.popContext(ctx);
+        }
+
         // ------------------ No pub fns below this point ------------------
 
         fn fetchRemoveByKey(self: *Self, key: anytype, key_ctx: anytype, ctx: ByIndexContext, comptime removal_type: RemovalType) ?KV {
@@ -2094,6 +2111,26 @@ test "pop" {
     }
 }
 
+test "popOrNull" {
+    var map = AutoArrayHashMap(i32, i32).init(std.testing.allocator);
+    defer map.deinit();
+
+    // Insert just enough entries so that the map expands. Afterwards,
+    // pop all entries out of the map.
+
+    var i: i32 = 0;
+    while (i < 9) : (i += 1) {
+        try testing.expect((try map.fetchPut(i, i)) == null);
+    }
+
+    while (map.popOrNull()) |pop| {
+        try testing.expect(pop.key == i - 1 and pop.value == i - 1);
+        i -= 1;
+    }
+
+    try testing.expect(map.count() == 0);
+}
+
 test "reIndex" {
     var map = ArrayHashMap(i32, i32, AutoContext(i32), true).init(std.testing.allocator);
     defer map.deinit();