authorgravatar for andrew@ziglang.orgAndrew Kelley <andrew@ziglang.org> 2024-10-13 23:43:07-07:00
committergravatar for andrew@ziglang.orgAndrew Kelley <andrew@ziglang.org> 2024-10-14 03:33:23-07:00
log9fd61f7460950a4124f8a9d6eb31a40f03ecd5a7
tree7cef11064e6493b9681034e0fdf7f8979bb740cf
parent3bf89f55c20550ba2acf0c9d904ff040d87979fa

std.MultiArrayList: add clear methods

1 files changed, 20 insertions(+), 5 deletions(-)

lib/std/multi_array_list.zig+20-5
...@@ -346,11 +346,8 @@ pub fn MultiArrayList(comptime T: type) type {...@@ -346,11 +346,8 @@ pub fn MultiArrayList(comptime T: type) type {
346 /// If `new_len` is greater than zero, this may fail to reduce the capacity,346 /// If `new_len` is greater than zero, this may fail to reduce the capacity,
347 /// but the data remains intact and the length is updated to new_len.347 /// but the data remains intact and the length is updated to new_len.
348 pub fn shrinkAndFree(self: *Self, gpa: Allocator, new_len: usize) void {348 pub fn shrinkAndFree(self: *Self, gpa: Allocator, new_len: usize) void {
349 if (new_len == 0) {349 if (new_len == 0) return clearAndFree(self, gpa);
350 gpa.free(self.allocatedBytes());350
351 self.* = .{};
352 return;
353 }
354 assert(new_len <= self.capacity);351 assert(new_len <= self.capacity);
355 assert(new_len <= self.len);352 assert(new_len <= self.len);
356353
...@@ -391,6 +388,11 @@ pub fn MultiArrayList(comptime T: type) type {...@@ -391,6 +388,11 @@ pub fn MultiArrayList(comptime T: type) type {
391 self.* = other;388 self.* = other;
392 }389 }
393390
391 pub fn clearAndFree(self: *Self, gpa: Allocator) void {
392 gpa.free(self.allocatedBytes());
393 self.* = .{};
394 }
395
394 /// Reduce length to `new_len`.396 /// Reduce length to `new_len`.
395 /// Invalidates pointers to elements `items[new_len..]`.397 /// Invalidates pointers to elements `items[new_len..]`.
396 /// Keeps capacity the same.398 /// Keeps capacity the same.
...@@ -398,6 +400,11 @@ pub fn MultiArrayList(comptime T: type) type {...@@ -398,6 +400,11 @@ pub fn MultiArrayList(comptime T: type) type {
398 self.len = new_len;400 self.len = new_len;
399 }401 }
400402
403 /// Invalidates all element pointers.
404 pub fn clearRetainingCapacity(self: *Self) void {
405 self.len = 0;
406 }
407
401 /// Modify the array so that it can hold at least `new_capacity` items.408 /// Modify the array so that it can hold at least `new_capacity` items.
402 /// Implements super-linear growth to achieve amortized O(1) append operations.409 /// Implements super-linear growth to achieve amortized O(1) append operations.
403 /// Invalidates pointers if additional memory is needed.410 /// Invalidates pointers if additional memory is needed.
...@@ -677,6 +684,14 @@ test "basic usage" {...@@ -677,6 +684,14 @@ test "basic usage" {
677 try testing.expectEqual(@as(u32, 2), list.pop().a);684 try testing.expectEqual(@as(u32, 2), list.pop().a);
678 try testing.expectEqual(@as(u8, 'a'), list.pop().c);685 try testing.expectEqual(@as(u8, 'a'), list.pop().c);
679 try testing.expectEqual(@as(?Foo, null), list.popOrNull());686 try testing.expectEqual(@as(?Foo, null), list.popOrNull());
687
688 list.clearRetainingCapacity();
689 try testing.expectEqual(0, list.len);
690 try testing.expect(list.capacity > 0);
691
692 list.clearAndFree(ally);
693 try testing.expectEqual(0, list.len);
694 try testing.expectEqual(0, list.capacity);
680}695}
681696
682// This was observed to fail on aarch64 with LLVM 11, when the capacityInBytes697// This was observed to fail on aarch64 with LLVM 11, when the capacityInBytes