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std: Fix update() method in PriorityQueue and PriorityDequeue (#13908)

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Previously the update() method would iterate over its capacity, which may contain uninitialized memory or already removed elements.
This commit is contained in:
Frechdachs 2022-12-13 20:55:41 +01:00 committed by Andrew Kelley
parent b5222f86ee
commit f8ea292d09
2 changed files with 26 additions and 4 deletions
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15
lib/std/priority_dequeue.zig
View File

@ -390,8 +390,10 @@ pub fn PriorityDequeue(comptime T: type, comptime Context: type, comptime compar
pub fn update(self: *Self, elem: T, new_elem: T) !void {
const old_index = blk: {
for (self.items) |item, idx| {
if (compareFn(self.context, item, elem).compare(.eq)) break :blk idx;
var idx: usize = 0;
while (idx < self.len) : (idx += 1) {
const item = self.items[idx];
if (compareFn(self.context, item, elem) == .eq) break :blk idx;
}
return error.ElementNotFound;
};
@ -778,6 +780,15 @@ test "std.PriorityDequeue: update same max queue" {
try expectEqual(@as(u32, 1), queue.removeMax());
}
test "std.PriorityDequeue: update after remove" {
var queue = PDQ.init(testing.allocator, {});
defer queue.deinit();
try queue.add(1);
try expectEqual(@as(u32, 1), queue.removeMin());
try expectError(error.ElementNotFound, queue.update(1, 1));
}
test "std.PriorityDequeue: iterator" {
var queue = PDQ.init(testing.allocator, {});
var map = std.AutoHashMap(u32, void).init(testing.allocator);

15
lib/std/priority_queue.zig
View File

@ -218,8 +218,10 @@ pub fn PriorityQueue(comptime T: type, comptime Context: type, comptime compareF
pub fn update(self: *Self, elem: T, new_elem: T) !void {
const update_index = blk: {
for (self.items) |item, idx| {
if (compareFn(self.context, item, elem).compare(.eq)) break :blk idx;
var idx: usize = 0;
while (idx < self.len) : (idx += 1) {
const item = self.items[idx];
if (compareFn(self.context, item, elem) == .eq) break :blk idx;
}
return error.ElementNotFound;
};
@ -591,6 +593,15 @@ test "std.PriorityQueue: update same max heap" {
try expectEqual(@as(u32, 1), queue.remove());
}
test "std.PriorityQueue: update after remove" {
var queue = PQlt.init(testing.allocator, {});
defer queue.deinit();
try queue.add(1);
try expectEqual(@as(u32, 1), queue.remove());
try expectError(error.ElementNotFound, queue.update(1, 1));
}
test "std.PriorityQueue: siftUp in remove" {
var queue = PQlt.init(testing.allocator, {});
defer queue.deinit();