authorgravatar for me@arnavion.devArnavion <me@arnavion.dev> 2021-12-15 17:46:04-08:00
committergravatar for me@arnavion.devArnavion <me@arnavion.dev> 2021-12-15 17:46:04-08:00
log82e893065607cffc1d7ee9d228b8ccdb2bbc61ea
treeb3cbff6ff92f7a881c4d9898605c266f50038dab
parent877a1f2a2986e02269c64a05456dff521da27ac1

std.priority_queue: allow comparator to take a context parameter

1 files changed, 69 insertions(+), 37 deletions(-)

lib/std/priority_queue.zig+69-37
...@@ -8,26 +8,28 @@ const expectEqual = testing.expectEqual;...@@ -8,26 +8,28 @@ const expectEqual = testing.expectEqual;
8const expectError = testing.expectError;8const expectError = testing.expectError;
99
10/// Priority queue for storing generic data. Initialize with `init`.10/// Priority queue for storing generic data. Initialize with `init`.
11/// Provide `compareFn` that returns `Order.lt` when its first11/// Provide `compareFn` that returns `Order.lt` when its second
12/// argument should get popped before its second argument,12/// argument should get popped before its third argument,
13/// `Order.eq` if the arguments are of equal priority, or `Order.gt`13/// `Order.eq` if the arguments are of equal priority, or `Order.gt`
14/// if the second argument should be popped first.14/// if the third argument should be popped first.
15/// For example, to make `pop` return the smallest number, provide15/// For example, to make `pop` return the smallest number, provide
16/// `fn lessThan(a: T, b: T) Order { return std.math.order(a, b); }`16/// `fn lessThan(context: void, a: T, b: T) Order { _ = context; return std.math.order(a, b); }`
17pub fn PriorityQueue(comptime T: type, comptime compareFn: fn (a: T, b: T) Order) type {17pub fn PriorityQueue(comptime T: type, comptime Context: type, comptime compareFn: fn (context: Context, a: T, b: T) Order) type {
18 return struct {18 return struct {
19 const Self = @This();19 const Self = @This();
2020
21 items: []T,21 items: []T,
22 len: usize,22 len: usize,
23 allocator: Allocator,23 allocator: Allocator,
24 context: Context,
2425
25 /// Initialize and return a priority queue.26 /// Initialize and return a priority queue.
26 pub fn init(allocator: Allocator) Self {27 pub fn init(allocator: Allocator, context: Context) Self {
27 return Self{28 return Self{
28 .items = &[_]T{},29 .items = &[_]T{},
29 .len = 0,30 .len = 0,
30 .allocator = allocator,31 .allocator = allocator,
32 .context = context,
31 };33 };
32 }34 }
3335
...@@ -55,7 +57,7 @@ pub fn PriorityQueue(comptime T: type, comptime compareFn: fn (a: T, b: T) Order...@@ -55,7 +57,7 @@ pub fn PriorityQueue(comptime T: type, comptime compareFn: fn (a: T, b: T) Order
55 const child = self.items[child_index];57 const child = self.items[child_index];
56 const parent = self.items[parent_index];58 const parent = self.items[parent_index];
5759
58 if (compareFn(child, parent) != .lt) break;60 if (compareFn(self.context, child, parent) != .lt) break;
5961
60 self.items[parent_index] = child;62 self.items[parent_index] = child;
61 self.items[child_index] = parent;63 self.items[child_index] = parent;
...@@ -127,14 +129,14 @@ pub fn PriorityQueue(comptime T: type, comptime compareFn: fn (a: T, b: T) Order...@@ -127,14 +129,14 @@ pub fn PriorityQueue(comptime T: type, comptime compareFn: fn (a: T, b: T) Order
127 var smallest = self.items[index];129 var smallest = self.items[index];
128130
129 if (left) |e| {131 if (left) |e| {
130 if (compareFn(e, smallest) == .lt) {132 if (compareFn(self.context, e, smallest) == .lt) {
131 smallest_index = left_index;133 smallest_index = left_index;
132 smallest = e;134 smallest = e;
133 }135 }
134 }136 }
135137
136 if (right) |e| {138 if (right) |e| {
137 if (compareFn(e, smallest) == .lt) {139 if (compareFn(self.context, e, smallest) == .lt) {
138 smallest_index = right_index;140 smallest_index = right_index;
139 smallest = e;141 smallest = e;
140 }142 }
...@@ -153,11 +155,12 @@ pub fn PriorityQueue(comptime T: type, comptime compareFn: fn (a: T, b: T) Order...@@ -153,11 +155,12 @@ pub fn PriorityQueue(comptime T: type, comptime compareFn: fn (a: T, b: T) Order
153 /// PriorityQueue takes ownership of the passed in slice. The slice must have been155 /// PriorityQueue takes ownership of the passed in slice. The slice must have been
154 /// allocated with `allocator`.156 /// allocated with `allocator`.
155 /// Deinitialize with `deinit`.157 /// Deinitialize with `deinit`.
156 pub fn fromOwnedSlice(allocator: Allocator, items: []T) Self {158 pub fn fromOwnedSlice(allocator: Allocator, items: []T, context: Context) Self {
157 var queue = Self{159 var queue = Self{
158 .items = items,160 .items = items,
159 .len = items.len,161 .len = items.len,
160 .allocator = allocator,162 .allocator = allocator,
163 .context = context,
161 };164 };
162165
163 if (queue.len <= 1) return queue;166 if (queue.len <= 1) return queue;
...@@ -207,7 +210,7 @@ pub fn PriorityQueue(comptime T: type, comptime compareFn: fn (a: T, b: T) Order...@@ -207,7 +210,7 @@ pub fn PriorityQueue(comptime T: type, comptime compareFn: fn (a: T, b: T) Order
207 var update_index: usize = std.mem.indexOfScalar(T, self.items[0..self.len], elem) orelse return error.ElementNotFound;210 var update_index: usize = std.mem.indexOfScalar(T, self.items[0..self.len], elem) orelse return error.ElementNotFound;
208 const old_elem: T = self.items[update_index];211 const old_elem: T = self.items[update_index];
209 self.items[update_index] = new_elem;212 self.items[update_index] = new_elem;
210 switch (compareFn(new_elem, old_elem)) {213 switch (compareFn(self.context, new_elem, old_elem)) {
211 .lt => siftUp(self, update_index),214 .lt => siftUp(self, update_index),
212 .gt => siftDown(self, update_index),215 .gt => siftDown(self, update_index),
213 .eq => {}, // Nothing to do as the items have equal priority216 .eq => {}, // Nothing to do as the items have equal priority
...@@ -215,7 +218,7 @@ pub fn PriorityQueue(comptime T: type, comptime compareFn: fn (a: T, b: T) Order...@@ -215,7 +218,7 @@ pub fn PriorityQueue(comptime T: type, comptime compareFn: fn (a: T, b: T) Order
215 }218 }
216219
217 pub const Iterator = struct {220 pub const Iterator = struct {
218 queue: *PriorityQueue(T, compareFn),221 queue: *PriorityQueue(T, Context, compareFn),
219 count: usize,222 count: usize,
220223
221 pub fn next(it: *Iterator) ?T {224 pub fn next(it: *Iterator) ?T {
...@@ -258,19 +261,20 @@ pub fn PriorityQueue(comptime T: type, comptime compareFn: fn (a: T, b: T) Order...@@ -258,19 +261,20 @@ pub fn PriorityQueue(comptime T: type, comptime compareFn: fn (a: T, b: T) Order
258 };261 };
259}262}
260263
261fn lessThan(a: u32, b: u32) Order {264fn lessThan(context: void, a: u32, b: u32) Order {
265 _ = context;
262 return std.math.order(a, b);266 return std.math.order(a, b);
263}267}
264268
265fn greaterThan(a: u32, b: u32) Order {269fn greaterThan(context: void, a: u32, b: u32) Order {
266 return lessThan(a, b).invert();270 return lessThan(context, a, b).invert();
267}271}
268272
269const PQlt = PriorityQueue(u32, lessThan);273const PQlt = PriorityQueue(u32, void, lessThan);
270const PQgt = PriorityQueue(u32, greaterThan);274const PQgt = PriorityQueue(u32, void, greaterThan);
271275
272test "std.PriorityQueue: add and remove min heap" {276test "std.PriorityQueue: add and remove min heap" {
273 var queue = PQlt.init(testing.allocator);277 var queue = PQlt.init(testing.allocator, {});
274 defer queue.deinit();278 defer queue.deinit();
275279
276 try queue.add(54);280 try queue.add(54);
...@@ -288,7 +292,7 @@ test "std.PriorityQueue: add and remove min heap" {...@@ -288,7 +292,7 @@ test "std.PriorityQueue: add and remove min heap" {
288}292}
289293
290test "std.PriorityQueue: add and remove same min heap" {294test "std.PriorityQueue: add and remove same min heap" {
291 var queue = PQlt.init(testing.allocator);295 var queue = PQlt.init(testing.allocator, {});
292 defer queue.deinit();296 defer queue.deinit();
293297
294 try queue.add(1);298 try queue.add(1);
...@@ -306,14 +310,14 @@ test "std.PriorityQueue: add and remove same min heap" {...@@ -306,14 +310,14 @@ test "std.PriorityQueue: add and remove same min heap" {
306}310}
307311
308test "std.PriorityQueue: removeOrNull on empty" {312test "std.PriorityQueue: removeOrNull on empty" {
309 var queue = PQlt.init(testing.allocator);313 var queue = PQlt.init(testing.allocator, {});
310 defer queue.deinit();314 defer queue.deinit();
311315
312 try expect(queue.removeOrNull() == null);316 try expect(queue.removeOrNull() == null);
313}317}
314318
315test "std.PriorityQueue: edge case 3 elements" {319test "std.PriorityQueue: edge case 3 elements" {
316 var queue = PQlt.init(testing.allocator);320 var queue = PQlt.init(testing.allocator, {});
317 defer queue.deinit();321 defer queue.deinit();
318322
319 try queue.add(9);323 try queue.add(9);
...@@ -325,7 +329,7 @@ test "std.PriorityQueue: edge case 3 elements" {...@@ -325,7 +329,7 @@ test "std.PriorityQueue: edge case 3 elements" {
325}329}
326330
327test "std.PriorityQueue: peek" {331test "std.PriorityQueue: peek" {
328 var queue = PQlt.init(testing.allocator);332 var queue = PQlt.init(testing.allocator, {});
329 defer queue.deinit();333 defer queue.deinit();
330334
331 try expect(queue.peek() == null);335 try expect(queue.peek() == null);
...@@ -337,7 +341,7 @@ test "std.PriorityQueue: peek" {...@@ -337,7 +341,7 @@ test "std.PriorityQueue: peek" {
337}341}
338342
339test "std.PriorityQueue: sift up with odd indices" {343test "std.PriorityQueue: sift up with odd indices" {
340 var queue = PQlt.init(testing.allocator);344 var queue = PQlt.init(testing.allocator, {});
341 defer queue.deinit();345 defer queue.deinit();
342 const items = [_]u32{ 15, 7, 21, 14, 13, 22, 12, 6, 7, 25, 5, 24, 11, 16, 15, 24, 2, 1 };346 const items = [_]u32{ 15, 7, 21, 14, 13, 22, 12, 6, 7, 25, 5, 24, 11, 16, 15, 24, 2, 1 };
343 for (items) |e| {347 for (items) |e| {
...@@ -351,7 +355,7 @@ test "std.PriorityQueue: sift up with odd indices" {...@@ -351,7 +355,7 @@ test "std.PriorityQueue: sift up with odd indices" {
351}355}
352356
353test "std.PriorityQueue: addSlice" {357test "std.PriorityQueue: addSlice" {
354 var queue = PQlt.init(testing.allocator);358 var queue = PQlt.init(testing.allocator, {});
355 defer queue.deinit();359 defer queue.deinit();
356 const items = [_]u32{ 15, 7, 21, 14, 13, 22, 12, 6, 7, 25, 5, 24, 11, 16, 15, 24, 2, 1 };360 const items = [_]u32{ 15, 7, 21, 14, 13, 22, 12, 6, 7, 25, 5, 24, 11, 16, 15, 24, 2, 1 };
357 try queue.addSlice(items[0..]);361 try queue.addSlice(items[0..]);
...@@ -365,7 +369,7 @@ test "std.PriorityQueue: addSlice" {...@@ -365,7 +369,7 @@ test "std.PriorityQueue: addSlice" {
365test "std.PriorityQueue: fromOwnedSlice trivial case 0" {369test "std.PriorityQueue: fromOwnedSlice trivial case 0" {
366 const items = [0]u32{};370 const items = [0]u32{};
367 const queue_items = try testing.allocator.dupe(u32, &items);371 const queue_items = try testing.allocator.dupe(u32, &items);
368 var queue = PQlt.fromOwnedSlice(testing.allocator, queue_items[0..]);372 var queue = PQlt.fromOwnedSlice(testing.allocator, queue_items[0..], {});
369 defer queue.deinit();373 defer queue.deinit();
370 try expectEqual(@as(usize, 0), queue.len);374 try expectEqual(@as(usize, 0), queue.len);
371 try expect(queue.removeOrNull() == null);375 try expect(queue.removeOrNull() == null);
...@@ -374,7 +378,7 @@ test "std.PriorityQueue: fromOwnedSlice trivial case 0" {...@@ -374,7 +378,7 @@ test "std.PriorityQueue: fromOwnedSlice trivial case 0" {
374test "std.PriorityQueue: fromOwnedSlice trivial case 1" {378test "std.PriorityQueue: fromOwnedSlice trivial case 1" {
375 const items = [1]u32{1};379 const items = [1]u32{1};
376 const queue_items = try testing.allocator.dupe(u32, &items);380 const queue_items = try testing.allocator.dupe(u32, &items);
377 var queue = PQlt.fromOwnedSlice(testing.allocator, queue_items[0..]);381 var queue = PQlt.fromOwnedSlice(testing.allocator, queue_items[0..], {});
378 defer queue.deinit();382 defer queue.deinit();
379383
380 try expectEqual(@as(usize, 1), queue.len);384 try expectEqual(@as(usize, 1), queue.len);
...@@ -385,7 +389,7 @@ test "std.PriorityQueue: fromOwnedSlice trivial case 1" {...@@ -385,7 +389,7 @@ test "std.PriorityQueue: fromOwnedSlice trivial case 1" {
385test "std.PriorityQueue: fromOwnedSlice" {389test "std.PriorityQueue: fromOwnedSlice" {
386 const items = [_]u32{ 15, 7, 21, 14, 13, 22, 12, 6, 7, 25, 5, 24, 11, 16, 15, 24, 2, 1 };390 const items = [_]u32{ 15, 7, 21, 14, 13, 22, 12, 6, 7, 25, 5, 24, 11, 16, 15, 24, 2, 1 };
387 const heap_items = try testing.allocator.dupe(u32, items[0..]);391 const heap_items = try testing.allocator.dupe(u32, items[0..]);
388 var queue = PQlt.fromOwnedSlice(testing.allocator, heap_items[0..]);392 var queue = PQlt.fromOwnedSlice(testing.allocator, heap_items[0..], {});
389 defer queue.deinit();393 defer queue.deinit();
390394
391 const sorted_items = [_]u32{ 1, 2, 5, 6, 7, 7, 11, 12, 13, 14, 15, 15, 16, 21, 22, 24, 24, 25 };395 const sorted_items = [_]u32{ 1, 2, 5, 6, 7, 7, 11, 12, 13, 14, 15, 15, 16, 21, 22, 24, 24, 25 };
...@@ -395,7 +399,7 @@ test "std.PriorityQueue: fromOwnedSlice" {...@@ -395,7 +399,7 @@ test "std.PriorityQueue: fromOwnedSlice" {
395}399}
396400
397test "std.PriorityQueue: add and remove max heap" {401test "std.PriorityQueue: add and remove max heap" {
398 var queue = PQgt.init(testing.allocator);402 var queue = PQgt.init(testing.allocator, {});
399 defer queue.deinit();403 defer queue.deinit();
400404
401 try queue.add(54);405 try queue.add(54);
...@@ -413,7 +417,7 @@ test "std.PriorityQueue: add and remove max heap" {...@@ -413,7 +417,7 @@ test "std.PriorityQueue: add and remove max heap" {
413}417}
414418
415test "std.PriorityQueue: add and remove same max heap" {419test "std.PriorityQueue: add and remove same max heap" {
416 var queue = PQgt.init(testing.allocator);420 var queue = PQgt.init(testing.allocator, {});
417 defer queue.deinit();421 defer queue.deinit();
418422
419 try queue.add(1);423 try queue.add(1);
...@@ -431,7 +435,7 @@ test "std.PriorityQueue: add and remove same max heap" {...@@ -431,7 +435,7 @@ test "std.PriorityQueue: add and remove same max heap" {
431}435}
432436
433test "std.PriorityQueue: iterator" {437test "std.PriorityQueue: iterator" {
434 var queue = PQlt.init(testing.allocator);438 var queue = PQlt.init(testing.allocator, {});
435 var map = std.AutoHashMap(u32, void).init(testing.allocator);439 var map = std.AutoHashMap(u32, void).init(testing.allocator);
436 defer {440 defer {
437 queue.deinit();441 queue.deinit();
...@@ -453,7 +457,7 @@ test "std.PriorityQueue: iterator" {...@@ -453,7 +457,7 @@ test "std.PriorityQueue: iterator" {
453}457}
454458
455test "std.PriorityQueue: remove at index" {459test "std.PriorityQueue: remove at index" {
456 var queue = PQlt.init(testing.allocator);460 var queue = PQlt.init(testing.allocator, {});
457 defer queue.deinit();461 defer queue.deinit();
458462
459 try queue.add(3);463 try queue.add(3);
...@@ -476,7 +480,7 @@ test "std.PriorityQueue: remove at index" {...@@ -476,7 +480,7 @@ test "std.PriorityQueue: remove at index" {
476}480}
477481
478test "std.PriorityQueue: iterator while empty" {482test "std.PriorityQueue: iterator while empty" {
479 var queue = PQlt.init(testing.allocator);483 var queue = PQlt.init(testing.allocator, {});
480 defer queue.deinit();484 defer queue.deinit();
481485
482 var it = queue.iterator();486 var it = queue.iterator();
...@@ -485,7 +489,7 @@ test "std.PriorityQueue: iterator while empty" {...@@ -485,7 +489,7 @@ test "std.PriorityQueue: iterator while empty" {
485}489}
486490
487test "std.PriorityQueue: shrinkAndFree" {491test "std.PriorityQueue: shrinkAndFree" {
488 var queue = PQlt.init(testing.allocator);492 var queue = PQlt.init(testing.allocator, {});
489 defer queue.deinit();493 defer queue.deinit();
490494
491 try queue.ensureTotalCapacity(4);495 try queue.ensureTotalCapacity(4);
...@@ -508,7 +512,7 @@ test "std.PriorityQueue: shrinkAndFree" {...@@ -508,7 +512,7 @@ test "std.PriorityQueue: shrinkAndFree" {
508}512}
509513
510test "std.PriorityQueue: update min heap" {514test "std.PriorityQueue: update min heap" {
511 var queue = PQlt.init(testing.allocator);515 var queue = PQlt.init(testing.allocator, {});
512 defer queue.deinit();516 defer queue.deinit();
513517
514 try queue.add(55);518 try queue.add(55);
...@@ -523,7 +527,7 @@ test "std.PriorityQueue: update min heap" {...@@ -523,7 +527,7 @@ test "std.PriorityQueue: update min heap" {
523}527}
524528
525test "std.PriorityQueue: update same min heap" {529test "std.PriorityQueue: update same min heap" {
526 var queue = PQlt.init(testing.allocator);530 var queue = PQlt.init(testing.allocator, {});
527 defer queue.deinit();531 defer queue.deinit();
528532
529 try queue.add(1);533 try queue.add(1);
...@@ -539,7 +543,7 @@ test "std.PriorityQueue: update same min heap" {...@@ -539,7 +543,7 @@ test "std.PriorityQueue: update same min heap" {
539}543}
540544
541test "std.PriorityQueue: update max heap" {545test "std.PriorityQueue: update max heap" {
542 var queue = PQgt.init(testing.allocator);546 var queue = PQgt.init(testing.allocator, {});
543 defer queue.deinit();547 defer queue.deinit();
544548
545 try queue.add(55);549 try queue.add(55);
...@@ -554,7 +558,7 @@ test "std.PriorityQueue: update max heap" {...@@ -554,7 +558,7 @@ test "std.PriorityQueue: update max heap" {
554}558}
555559
556test "std.PriorityQueue: update same max heap" {560test "std.PriorityQueue: update same max heap" {
557 var queue = PQgt.init(testing.allocator);561 var queue = PQgt.init(testing.allocator, {});
558 defer queue.deinit();562 defer queue.deinit();
559563
560 try queue.add(1);564 try queue.add(1);
...@@ -568,3 +572,31 @@ test "std.PriorityQueue: update same max heap" {...@@ -568,3 +572,31 @@ test "std.PriorityQueue: update same max heap" {
568 try expectEqual(@as(u32, 2), queue.remove());572 try expectEqual(@as(u32, 2), queue.remove());
569 try expectEqual(@as(u32, 1), queue.remove());573 try expectEqual(@as(u32, 1), queue.remove());
570}574}
575
576fn contextLessThan(context: []const u32, a: usize, b: usize) Order {
577 return std.math.order(context[a], context[b]);
578}
579
580const CPQlt = PriorityQueue(usize, []const u32, contextLessThan);
581
582test "std.PriorityQueue: add and remove min heap with contextful comparator" {
583 const context = [_]u32{ 5, 3, 4, 2, 2, 8, 0 };
584
585 var queue = CPQlt.init(testing.allocator, context[0..]);
586 defer queue.deinit();
587
588 try queue.add(0);
589 try queue.add(1);
590 try queue.add(2);
591 try queue.add(3);
592 try queue.add(4);
593 try queue.add(5);
594 try queue.add(6);
595 try expectEqual(@as(usize, 6), queue.remove());
596 try expectEqual(@as(usize, 4), queue.remove());
597 try expectEqual(@as(usize, 3), queue.remove());
598 try expectEqual(@as(usize, 1), queue.remove());
599 try expectEqual(@as(usize, 2), queue.remove());
600 try expectEqual(@as(usize, 0), queue.remove());
601 try expectEqual(@as(usize, 5), queue.remove());
602}