From c714a3250f57817ea565f0390cecf12025655376 Mon Sep 17 00:00:00 2001
From: Andrew Kelley <andrew@ziglang.org>
Date: Wed, 5 May 2021 16:55:49 -0700
Subject: [PATCH] std.ArrayList: add clearRetainingCapacity and clearAndFree

---
 lib/std/array_list.zig | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)

diff --git a/lib/std/array_list.zig b/lib/std/array_list.zig
index 2ba2e27bba..cd1c09a01b 100644
--- a/lib/std/array_list.zig
+++ b/lib/std/array_list.zig
@@ -294,6 +294,18 @@ pub fn ArrayListAligned(comptime T: type, comptime alignment: ?u29) type {
             self.items.len = new_len;
         }
 
+        /// Invalidates all element pointers.
+        pub fn clearRetainingCapacity(self: *Self) void {
+            self.items.len = 0;
+        }
+
+        /// Invalidates all element pointers.
+        pub fn clearAndFree(self: *Self) void {
+            self.allocator.free(self.allocatedSlice());
+            self.items.len = 0;
+            self.capacity = 0;
+        }
+
         /// Deprecated: call `ensureUnusedCapacity` or `ensureTotalCapacity`.
         pub const ensureCapacity = ensureTotalCapacity;
 
@@ -611,6 +623,18 @@ pub fn ArrayListAlignedUnmanaged(comptime T: type, comptime alignment: ?u29) typ
             self.items.len = new_len;
         }
 
+        /// Invalidates all element pointers.
+        pub fn clearRetainingCapacity(self: *Self) void {
+            self.items.len = 0;
+        }
+
+        /// Invalidates all element pointers.
+        pub fn clearAndFree(self: *Self, allocator: *Allocator) void {
+            allocator.free(self.allocatedSlice());
+            self.items.len = 0;
+            self.capacity = 0;
+        }
+
         /// Deprecated: call `ensureUnusedCapacity` or `ensureTotalCapacity`.
         pub const ensureCapacity = ensureTotalCapacity;