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Merge pull request #7792 from zanderxyz/zanderxyz/priority-dequeue
std: Add Priority Dequeue
This commit is contained in:
Andrew Kelley
GitHub
commit
d780848ae4
972
lib/std/priority_dequeue.zig
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972
lib/std/priority_dequeue.zig
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@ -0,0 +1,972 @@
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// SPDX-License-Identifier: MIT
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// Copyright (c) 2015-2021 Zig Contributors
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// This file is part of [zig](https://ziglang.org/), which is MIT licensed.
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// The MIT license requires this copyright notice to be included in all copies
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// and substantial portions of the software.
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const std = @import("std.zig");
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const Allocator = std.mem.Allocator;
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const assert = std.debug.assert;
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const warn = std.debug.warn;
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const Order = std.math.Order;
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const testing = std.testing;
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const expect = testing.expect;
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const expectEqual = testing.expectEqual;
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const expectError = testing.expectError;
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/// Priority Dequeue for storing generic data. Initialize with `init`.
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pub fn PriorityDequeue(comptime T: type) type {
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return struct {
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const Self = @This();
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items: []T,
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len: usize,
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allocator: *Allocator,
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compareFn: fn (a: T, b: T) Order,
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/// Initialize and return a new priority dequeue. Provide `compareFn`
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/// that returns `Order.lt` when its first argument should
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/// get min-popped before its second argument, `Order.eq` if the
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/// arguments are of equal priority, or `Order.gt` if the second
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/// argument should be min-popped first. Popping the max element works
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/// in reverse. For example, to make `popMin` return the smallest
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/// number, provide
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///
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/// `fn lessThan(a: T, b: T) Order { return std.math.order(a, b); }`
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pub fn init(allocator: *Allocator, compareFn: fn (T, T) Order) Self {
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return Self{
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.items = &[_]T{},
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.len = 0,
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.allocator = allocator,
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.compareFn = compareFn,
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};
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}
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/// Free memory used by the dequeue.
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pub fn deinit(self: Self) void {
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self.allocator.free(self.items);
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}
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/// Insert a new element, maintaining priority.
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pub fn add(self: *Self, elem: T) !void {
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try ensureCapacity(self, self.len + 1);
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addUnchecked(self, elem);
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}
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/// Add each element in `items` to the dequeue.
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pub fn addSlice(self: *Self, items: []const T) !void {
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try self.ensureCapacity(self.len + items.len);
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for (items) |e| {
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self.addUnchecked(e);
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}
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}
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fn addUnchecked(self: *Self, elem: T) void {
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self.items[self.len] = elem;
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if (self.len > 0) {
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const start = self.getStartForSiftUp(elem, self.len);
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self.siftUp(start);
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}
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self.len += 1;
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}
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fn isMinLayer(index: usize) bool {
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// In the min-max heap structure:
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// The first element is on a min layer;
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// next two are on a max layer;
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// next four are on a min layer, and so on.
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const leading_zeros = @clz(usize, index + 1);
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const highest_set_bit = @bitSizeOf(usize) - 1 - leading_zeros;
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return (highest_set_bit & 1) == 0;
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}
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fn nextIsMinLayer(self: Self) bool {
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return isMinLayer(self.len);
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}
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const StartIndexAndLayer = struct {
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index: usize,
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min_layer: bool,
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};
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fn getStartForSiftUp(self: Self, child: T, index: usize) StartIndexAndLayer {
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var child_index = index;
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var parent_index = parentIndex(child_index);
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const parent = self.items[parent_index];
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const min_layer = self.nextIsMinLayer();
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const order = self.compareFn(child, parent);
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if ((min_layer and order == .gt) or (!min_layer and order == .lt)) {
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// We must swap the item with it's parent if it is on the "wrong" layer
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self.items[parent_index] = child;
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self.items[child_index] = parent;
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return .{
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.index = parent_index,
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.min_layer = !min_layer,
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};
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} else {
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return .{
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.index = child_index,
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.min_layer = min_layer,
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};
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}
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}
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fn siftUp(self: *Self, start: StartIndexAndLayer) void {
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if (start.min_layer) {
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doSiftUp(self, start.index, .lt);
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} else {
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doSiftUp(self, start.index, .gt);
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}
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}
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fn doSiftUp(self: *Self, start_index: usize, target_order: Order) void {
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var child_index = start_index;
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while (child_index > 2) {
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var grandparent_index = grandparentIndex(child_index);
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const child = self.items[child_index];
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const grandparent = self.items[grandparent_index];
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// If the grandparent is already better or equal, we have gone as far as we need to
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if (self.compareFn(child, grandparent) != target_order) break;
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// Otherwise swap the item with it's grandparent
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self.items[grandparent_index] = child;
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self.items[child_index] = grandparent;
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child_index = grandparent_index;
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}
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}
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/// Look at the smallest element in the dequeue. Returns
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/// `null` if empty.
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pub fn peekMin(self: *Self) ?T {
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return if (self.len > 0) self.items[0] else null;
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}
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/// Look at the largest element in the dequeue. Returns
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/// `null` if empty.
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pub fn peekMax(self: *Self) ?T {
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if (self.len == 0) return null;
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if (self.len == 1) return self.items[0];
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if (self.len == 2) return self.items[1];
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return self.bestItemAtIndices(1, 2, .gt).item;
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}
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fn maxIndex(self: Self) ?usize {
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if (self.len == 0) return null;
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if (self.len == 1) return 0;
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if (self.len == 2) return 1;
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return self.bestItemAtIndices(1, 2, .gt).index;
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}
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/// Pop the smallest element from the dequeue. Returns
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/// `null` if empty.
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pub fn removeMinOrNull(self: *Self) ?T {
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return if (self.len > 0) self.removeMin() else null;
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}
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/// Remove and return the smallest element from the
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/// dequeue.
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pub fn removeMin(self: *Self) T {
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return self.removeIndex(0);
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}
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/// Pop the largest element from the dequeue. Returns
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/// `null` if empty.
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pub fn removeMaxOrNull(self: *Self) ?T {
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return if (self.len > 0) self.removeMax() else null;
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}
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/// Remove and return the largest element from the
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/// dequeue.
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pub fn removeMax(self: *Self) T {
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return self.removeIndex(self.maxIndex().?);
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}
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/// Remove and return element at index. Indices are in the
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/// same order as iterator, which is not necessarily priority
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/// order.
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pub fn removeIndex(self: *Self, index: usize) T {
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assert(self.len > index);
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const item = self.items[index];
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const last = self.items[self.len - 1];
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self.items[index] = last;
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self.len -= 1;
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siftDown(self, index);
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return item;
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}
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fn siftDown(self: *Self, index: usize) void {
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if (isMinLayer(index)) {
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self.doSiftDown(index, .lt);
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} else {
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self.doSiftDown(index, .gt);
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}
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}
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fn doSiftDown(self: *Self, start_index: usize, target_order: Order) void {
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var index = start_index;
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const half = self.len >> 1;
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while (true) {
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const first_grandchild_index = firstGrandchildIndex(index);
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const last_grandchild_index = first_grandchild_index + 3;
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const elem = self.items[index];
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if (last_grandchild_index < self.len) {
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// All four grandchildren exist
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const index2 = first_grandchild_index + 1;
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const index3 = index2 + 1;
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// Find the best grandchild
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const best_left = self.bestItemAtIndices(first_grandchild_index, index2, target_order);
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const best_right = self.bestItemAtIndices(index3, last_grandchild_index, target_order);
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const best_grandchild = self.bestItem(best_left, best_right, target_order);
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// If the item is better than or equal to its best grandchild, we are done
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if (self.compareFn(best_grandchild.item, elem) != target_order) return;
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// Otherwise, swap them
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self.items[best_grandchild.index] = elem;
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self.items[index] = best_grandchild.item;
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index = best_grandchild.index;
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// We might need to swap the element with it's parent
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self.swapIfParentIsBetter(elem, index, target_order);
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} else {
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// The children or grandchildren are the last layer
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const first_child_index = firstChildIndex(index);
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if (first_child_index > self.len) return;
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const best_descendent = self.bestDescendent(first_child_index, first_grandchild_index, target_order);
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// If the item is better than or equal to its best descendant, we are done
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if (self.compareFn(best_descendent.item, elem) != target_order) return;
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// Otherwise swap them
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self.items[best_descendent.index] = elem;
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self.items[index] = best_descendent.item;
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index = best_descendent.index;
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// If we didn't swap a grandchild, we are done
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if (index < first_grandchild_index) return;
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// We might need to swap the element with it's parent
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self.swapIfParentIsBetter(elem, index, target_order);
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return;
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}
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// If we are now in the last layer, we are done
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if (index >= half) return;
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}
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}
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fn swapIfParentIsBetter(self: *Self, child: T, child_index: usize, target_order: Order) void {
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const parent_index = parentIndex(child_index);
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const parent = self.items[parent_index];
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if (self.compareFn(parent, child) == target_order) {
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self.items[parent_index] = child;
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self.items[child_index] = parent;
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}
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}
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const ItemAndIndex = struct {
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item: T,
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index: usize,
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};
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fn getItem(self: Self, index: usize) ItemAndIndex {
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return .{
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.item = self.items[index],
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.index = index,
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};
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}
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fn bestItem(self: Self, item1: ItemAndIndex, item2: ItemAndIndex, target_order: Order) ItemAndIndex {
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if (self.compareFn(item1.item, item2.item) == target_order) {
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return item1;
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} else {
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return item2;
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}
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}
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fn bestItemAtIndices(self: Self, index1: usize, index2: usize, target_order: Order) ItemAndIndex {
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var item1 = self.getItem(index1);
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var item2 = self.getItem(index2);
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return self.bestItem(item1, item2, target_order);
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}
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fn bestDescendent(self: Self, first_child_index: usize, first_grandchild_index: usize, target_order: Order) ItemAndIndex {
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const second_child_index = first_child_index + 1;
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if (first_grandchild_index >= self.len) {
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// No grandchildren, find the best child (second may not exist)
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if (second_child_index >= self.len) {
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return .{
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.item = self.items[first_child_index],
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.index = first_child_index,
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};
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} else {
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return self.bestItemAtIndices(first_child_index, second_child_index, target_order);
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}
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}
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const second_grandchild_index = first_grandchild_index + 1;
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if (second_grandchild_index >= self.len) {
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// One grandchild, so we know there is a second child. Compare first grandchild and second child
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return self.bestItemAtIndices(first_grandchild_index, second_child_index, target_order);
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}
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const best_left_grandchild_index = self.bestItemAtIndices(first_grandchild_index, second_grandchild_index, target_order).index;
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const third_grandchild_index = second_grandchild_index + 1;
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if (third_grandchild_index >= self.len) {
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// Two grandchildren, and we know the best. Compare this to second child.
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return self.bestItemAtIndices(best_left_grandchild_index, second_child_index, target_order);
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} else {
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// Three grandchildren, compare the min of the first two with the third
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return self.bestItemAtIndices(best_left_grandchild_index, third_grandchild_index, target_order);
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}
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}
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/// Return the number of elements remaining in the dequeue
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pub fn count(self: Self) usize {
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return self.len;
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}
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/// Return the number of elements that can be added to the
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/// dequeue before more memory is allocated.
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pub fn capacity(self: Self) usize {
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return self.items.len;
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}
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/// Dequeue takes ownership of the passed in slice. The slice must have been
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/// allocated with `allocator`.
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/// De-initialize with `deinit`.
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pub fn fromOwnedSlice(allocator: *Allocator, compareFn: fn (T, T) Order, items: []T) Self {
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var queue = Self{
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.items = items,
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.len = items.len,
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.allocator = allocator,
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.compareFn = compareFn,
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};
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if (queue.len <= 1) return queue;
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const half = (queue.len >> 1) - 1;
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var i: usize = 0;
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while (i <= half) : (i += 1) {
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const index = half - i;
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queue.siftDown(index);
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}
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return queue;
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}
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pub fn ensureCapacity(self: *Self, new_capacity: usize) !void {
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var better_capacity = self.capacity();
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if (better_capacity >= new_capacity) return;
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while (true) {
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better_capacity += better_capacity / 2 + 8;
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if (better_capacity >= new_capacity) break;
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}
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self.items = try self.allocator.realloc(self.items, better_capacity);
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}
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/// Reduce allocated capacity to `new_len`.
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pub fn shrinkAndFree(self: *Self, new_len: usize) void {
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assert(new_len <= self.items.len);
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// Cannot shrink to smaller than the current queue size without invalidating the heap property
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assert(new_len >= self.len);
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self.items = self.allocator.realloc(self.items[0..], new_len) catch |e| switch (e) {
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error.OutOfMemory => { // no problem, capacity is still correct then.
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self.items.len = new_len;
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return;
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},
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};
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self.len = new_len;
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}
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/// Reduce length to `new_len`.
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pub fn shrinkRetainingCapacity(self: *Self, new_len: usize) void {
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assert(new_len <= self.items.len);
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// Cannot shrink to smaller than the current queue size without invalidating the heap property
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assert(new_len >= self.len);
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self.len = new_len;
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}
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pub fn update(self: *Self, elem: T, new_elem: T) !void {
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var old_index: usize = std.mem.indexOfScalar(T, self.items[0..self.len], elem) orelse return error.ElementNotFound;
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_ = self.removeIndex(old_index);
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self.addUnchecked(new_elem);
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}
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pub const Iterator = struct {
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queue: *PriorityDequeue(T),
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count: usize,
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pub fn next(it: *Iterator) ?T {
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if (it.count >= it.queue.len) return null;
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const out = it.count;
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it.count += 1;
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return it.queue.items[out];
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}
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pub fn reset(it: *Iterator) void {
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it.count = 0;
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}
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};
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/// Return an iterator that walks the queue without consuming
|
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/// it. Invalidated if the queue is modified.
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pub fn iterator(self: *Self) Iterator {
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return Iterator{
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.queue = self,
|
||||
.count = 0,
|
||||
};
|
||||
}
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||||
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fn dump(self: *Self) void {
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warn("{{ ", .{});
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warn("items: ", .{});
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||||
for (self.items) |e, i| {
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if (i >= self.len) break;
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warn("{}, ", .{e});
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}
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||||
warn("array: ", .{});
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||||
for (self.items) |e, i| {
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warn("{}, ", .{e});
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}
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warn("len: {} ", .{self.len});
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warn("capacity: {}", .{self.capacity()});
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warn(" }}\n", .{});
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}
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fn parentIndex(index: usize) usize {
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return (index - 1) >> 1;
|
||||
}
|
||||
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fn grandparentIndex(index: usize) usize {
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return parentIndex(parentIndex(index));
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}
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fn firstChildIndex(index: usize) usize {
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return (index << 1) + 1;
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}
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||||
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fn firstGrandchildIndex(index: usize) usize {
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return firstChildIndex(firstChildIndex(index));
|
||||
}
|
||||
};
|
||||
}
|
||||
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fn lessThanComparison(a: u32, b: u32) Order {
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return std.math.order(a, b);
|
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}
|
||||
|
||||
const PDQ = PriorityDequeue(u32);
|
||||
|
||||
test "std.PriorityDequeue: add and remove min" {
|
||||
var queue = PDQ.init(testing.allocator, lessThanComparison);
|
||||
defer queue.deinit();
|
||||
|
||||
try queue.add(54);
|
||||
try queue.add(12);
|
||||
try queue.add(7);
|
||||
try queue.add(23);
|
||||
try queue.add(25);
|
||||
try queue.add(13);
|
||||
|
||||
expectEqual(@as(u32, 7), queue.removeMin());
|
||||
expectEqual(@as(u32, 12), queue.removeMin());
|
||||
expectEqual(@as(u32, 13), queue.removeMin());
|
||||
expectEqual(@as(u32, 23), queue.removeMin());
|
||||
expectEqual(@as(u32, 25), queue.removeMin());
|
||||
expectEqual(@as(u32, 54), queue.removeMin());
|
||||
}
|
||||
|
||||
test "std.PriorityDequeue: add and remove min structs" {
|
||||
const S = struct {
|
||||
size: u32,
|
||||
};
|
||||
var queue = PriorityDequeue(S).init(testing.allocator, struct {
|
||||
fn order(a: S, b: S) Order {
|
||||
return std.math.order(a.size, b.size);
|
||||
}
|
||||
}.order);
|
||||
defer queue.deinit();
|
||||
|
||||
try queue.add(.{ .size = 54 });
|
||||
try queue.add(.{ .size = 12 });
|
||||
try queue.add(.{ .size = 7 });
|
||||
try queue.add(.{ .size = 23 });
|
||||
try queue.add(.{ .size = 25 });
|
||||
try queue.add(.{ .size = 13 });
|
||||
|
||||
expectEqual(@as(u32, 7), queue.removeMin().size);
|
||||
expectEqual(@as(u32, 12), queue.removeMin().size);
|
||||
expectEqual(@as(u32, 13), queue.removeMin().size);
|
||||
expectEqual(@as(u32, 23), queue.removeMin().size);
|
||||
expectEqual(@as(u32, 25), queue.removeMin().size);
|
||||
expectEqual(@as(u32, 54), queue.removeMin().size);
|
||||
}
|
||||
|
||||
test "std.PriorityDequeue: add and remove max" {
|
||||
var queue = PDQ.init(testing.allocator, lessThanComparison);
|
||||
defer queue.deinit();
|
||||
|
||||
try queue.add(54);
|
||||
try queue.add(12);
|
||||
try queue.add(7);
|
||||
try queue.add(23);
|
||||
try queue.add(25);
|
||||
try queue.add(13);
|
||||
|
||||
expectEqual(@as(u32, 54), queue.removeMax());
|
||||
expectEqual(@as(u32, 25), queue.removeMax());
|
||||
expectEqual(@as(u32, 23), queue.removeMax());
|
||||
expectEqual(@as(u32, 13), queue.removeMax());
|
||||
expectEqual(@as(u32, 12), queue.removeMax());
|
||||
expectEqual(@as(u32, 7), queue.removeMax());
|
||||
}
|
||||
|
||||
test "std.PriorityDequeue: add and remove same min" {
|
||||
var queue = PDQ.init(testing.allocator, lessThanComparison);
|
||||
defer queue.deinit();
|
||||
|
||||
try queue.add(1);
|
||||
try queue.add(1);
|
||||
try queue.add(2);
|
||||
try queue.add(2);
|
||||
try queue.add(1);
|
||||
try queue.add(1);
|
||||
|
||||
expectEqual(@as(u32, 1), queue.removeMin());
|
||||
expectEqual(@as(u32, 1), queue.removeMin());
|
||||
expectEqual(@as(u32, 1), queue.removeMin());
|
||||
expectEqual(@as(u32, 1), queue.removeMin());
|
||||
expectEqual(@as(u32, 2), queue.removeMin());
|
||||
expectEqual(@as(u32, 2), queue.removeMin());
|
||||
}
|
||||
|
||||
test "std.PriorityDequeue: add and remove same max" {
|
||||
var queue = PDQ.init(testing.allocator, lessThanComparison);
|
||||
defer queue.deinit();
|
||||
|
||||
try queue.add(1);
|
||||
try queue.add(1);
|
||||
try queue.add(2);
|
||||
try queue.add(2);
|
||||
try queue.add(1);
|
||||
try queue.add(1);
|
||||
|
||||
expectEqual(@as(u32, 2), queue.removeMax());
|
||||
expectEqual(@as(u32, 2), queue.removeMax());
|
||||
expectEqual(@as(u32, 1), queue.removeMax());
|
||||
expectEqual(@as(u32, 1), queue.removeMax());
|
||||
expectEqual(@as(u32, 1), queue.removeMax());
|
||||
expectEqual(@as(u32, 1), queue.removeMax());
|
||||
}
|
||||
|
||||
test "std.PriorityDequeue: removeOrNull empty" {
|
||||
var queue = PDQ.init(testing.allocator, lessThanComparison);
|
||||
defer queue.deinit();
|
||||
|
||||
expect(queue.removeMinOrNull() == null);
|
||||
expect(queue.removeMaxOrNull() == null);
|
||||
}
|
||||
|
||||
test "std.PriorityDequeue: edge case 3 elements" {
|
||||
var queue = PDQ.init(testing.allocator, lessThanComparison);
|
||||
defer queue.deinit();
|
||||
|
||||
try queue.add(9);
|
||||
try queue.add(3);
|
||||
try queue.add(2);
|
||||
|
||||
expectEqual(@as(u32, 2), queue.removeMin());
|
||||
expectEqual(@as(u32, 3), queue.removeMin());
|
||||
expectEqual(@as(u32, 9), queue.removeMin());
|
||||
}
|
||||
|
||||
test "std.PriorityDequeue: edge case 3 elements max" {
|
||||
var queue = PDQ.init(testing.allocator, lessThanComparison);
|
||||
defer queue.deinit();
|
||||
|
||||
try queue.add(9);
|
||||
try queue.add(3);
|
||||
try queue.add(2);
|
||||
|
||||
expectEqual(@as(u32, 9), queue.removeMax());
|
||||
expectEqual(@as(u32, 3), queue.removeMax());
|
||||
expectEqual(@as(u32, 2), queue.removeMax());
|
||||
}
|
||||
|
||||
test "std.PriorityDequeue: peekMin" {
|
||||
var queue = PDQ.init(testing.allocator, lessThanComparison);
|
||||
defer queue.deinit();
|
||||
|
||||
expect(queue.peekMin() == null);
|
||||
|
||||
try queue.add(9);
|
||||
try queue.add(3);
|
||||
try queue.add(2);
|
||||
|
||||
expect(queue.peekMin().? == 2);
|
||||
expect(queue.peekMin().? == 2);
|
||||
}
|
||||
|
||||
test "std.PriorityDequeue: peekMax" {
|
||||
var queue = PDQ.init(testing.allocator, lessThanComparison);
|
||||
defer queue.deinit();
|
||||
|
||||
expect(queue.peekMin() == null);
|
||||
|
||||
try queue.add(9);
|
||||
try queue.add(3);
|
||||
try queue.add(2);
|
||||
|
||||
expect(queue.peekMax().? == 9);
|
||||
expect(queue.peekMax().? == 9);
|
||||
}
|
||||
|
||||
test "std.PriorityDequeue: sift up with odd indices" {
|
||||
var queue = PDQ.init(testing.allocator, lessThanComparison);
|
||||
defer queue.deinit();
|
||||
const items = [_]u32{ 15, 7, 21, 14, 13, 22, 12, 6, 7, 25, 5, 24, 11, 16, 15, 24, 2, 1 };
|
||||
for (items) |e| {
|
||||
try queue.add(e);
|
||||
}
|
||||
|
||||
const sorted_items = [_]u32{ 1, 2, 5, 6, 7, 7, 11, 12, 13, 14, 15, 15, 16, 21, 22, 24, 24, 25 };
|
||||
for (sorted_items) |e| {
|
||||
expectEqual(e, queue.removeMin());
|
||||
}
|
||||
}
|
||||
|
||||
test "std.PriorityDequeue: sift up with odd indices" {
|
||||
var queue = PDQ.init(testing.allocator, lessThanComparison);
|
||||
defer queue.deinit();
|
||||
const items = [_]u32{ 15, 7, 21, 14, 13, 22, 12, 6, 7, 25, 5, 24, 11, 16, 15, 24, 2, 1 };
|
||||
for (items) |e| {
|
||||
try queue.add(e);
|
||||
}
|
||||
|
||||
const sorted_items = [_]u32{ 25, 24, 24, 22, 21, 16, 15, 15, 14, 13, 12, 11, 7, 7, 6, 5, 2, 1 };
|
||||
for (sorted_items) |e| {
|
||||
expectEqual(e, queue.removeMax());
|
||||
}
|
||||
}
|
||||
|
||||
test "std.PriorityDequeue: addSlice min" {
|
||||
var queue = PDQ.init(testing.allocator, lessThanComparison);
|
||||
defer queue.deinit();
|
||||
const items = [_]u32{ 15, 7, 21, 14, 13, 22, 12, 6, 7, 25, 5, 24, 11, 16, 15, 24, 2, 1 };
|
||||
try queue.addSlice(items[0..]);
|
||||
|
||||
const sorted_items = [_]u32{ 1, 2, 5, 6, 7, 7, 11, 12, 13, 14, 15, 15, 16, 21, 22, 24, 24, 25 };
|
||||
for (sorted_items) |e| {
|
||||
expectEqual(e, queue.removeMin());
|
||||
}
|
||||
}
|
||||
|
||||
test "std.PriorityDequeue: addSlice max" {
|
||||
var queue = PDQ.init(testing.allocator, lessThanComparison);
|
||||
defer queue.deinit();
|
||||
const items = [_]u32{ 15, 7, 21, 14, 13, 22, 12, 6, 7, 25, 5, 24, 11, 16, 15, 24, 2, 1 };
|
||||
try queue.addSlice(items[0..]);
|
||||
|
||||
const sorted_items = [_]u32{ 25, 24, 24, 22, 21, 16, 15, 15, 14, 13, 12, 11, 7, 7, 6, 5, 2, 1 };
|
||||
for (sorted_items) |e| {
|
||||
expectEqual(e, queue.removeMax());
|
||||
}
|
||||
}
|
||||
|
||||
test "std.PriorityDequeue: fromOwnedSlice trivial case 0" {
|
||||
const items = [0]u32{};
|
||||
const queue_items = try testing.allocator.dupe(u32, &items);
|
||||
var queue = PDQ.fromOwnedSlice(testing.allocator, lessThanComparison, queue_items[0..]);
|
||||
defer queue.deinit();
|
||||
expectEqual(@as(usize, 0), queue.len);
|
||||
expect(queue.removeMinOrNull() == null);
|
||||
}
|
||||
|
||||
test "std.PriorityDequeue: fromOwnedSlice trivial case 1" {
|
||||
const items = [1]u32{1};
|
||||
const queue_items = try testing.allocator.dupe(u32, &items);
|
||||
var queue = PDQ.fromOwnedSlice(testing.allocator, lessThanComparison, queue_items[0..]);
|
||||
defer queue.deinit();
|
||||
|
||||
expectEqual(@as(usize, 1), queue.len);
|
||||
expectEqual(items[0], queue.removeMin());
|
||||
expect(queue.removeMinOrNull() == null);
|
||||
}
|
||||
|
||||
test "std.PriorityDequeue: fromOwnedSlice" {
|
||||
const items = [_]u32{ 15, 7, 21, 14, 13, 22, 12, 6, 7, 25, 5, 24, 11, 16, 15, 24, 2, 1 };
|
||||
const queue_items = try testing.allocator.dupe(u32, items[0..]);
|
||||
var queue = PDQ.fromOwnedSlice(testing.allocator, lessThanComparison, queue_items[0..]);
|
||||
defer queue.deinit();
|
||||
|
||||
const sorted_items = [_]u32{ 1, 2, 5, 6, 7, 7, 11, 12, 13, 14, 15, 15, 16, 21, 22, 24, 24, 25 };
|
||||
for (sorted_items) |e| {
|
||||
expectEqual(e, queue.removeMin());
|
||||
}
|
||||
}
|
||||
|
||||
test "std.PriorityDequeue: update min queue" {
|
||||
var queue = PDQ.init(testing.allocator, lessThanComparison);
|
||||
defer queue.deinit();
|
||||
|
||||
try queue.add(55);
|
||||
try queue.add(44);
|
||||
try queue.add(11);
|
||||
try queue.update(55, 5);
|
||||
try queue.update(44, 4);
|
||||
try queue.update(11, 1);
|
||||
expectEqual(@as(u32, 1), queue.removeMin());
|
||||
expectEqual(@as(u32, 4), queue.removeMin());
|
||||
expectEqual(@as(u32, 5), queue.removeMin());
|
||||
}
|
||||
|
||||
test "std.PriorityDequeue: update same min queue" {
|
||||
var queue = PDQ.init(testing.allocator, lessThanComparison);
|
||||
defer queue.deinit();
|
||||
|
||||
try queue.add(1);
|
||||
try queue.add(1);
|
||||
try queue.add(2);
|
||||
try queue.add(2);
|
||||
try queue.update(1, 5);
|
||||
try queue.update(2, 4);
|
||||
expectEqual(@as(u32, 1), queue.removeMin());
|
||||
expectEqual(@as(u32, 2), queue.removeMin());
|
||||
expectEqual(@as(u32, 4), queue.removeMin());
|
||||
expectEqual(@as(u32, 5), queue.removeMin());
|
||||
}
|
||||
|
||||
test "std.PriorityDequeue: update max queue" {
|
||||
var queue = PDQ.init(testing.allocator, lessThanComparison);
|
||||
defer queue.deinit();
|
||||
|
||||
try queue.add(55);
|
||||
try queue.add(44);
|
||||
try queue.add(11);
|
||||
try queue.update(55, 5);
|
||||
try queue.update(44, 1);
|
||||
try queue.update(11, 4);
|
||||
|
||||
expectEqual(@as(u32, 5), queue.removeMax());
|
||||
expectEqual(@as(u32, 4), queue.removeMax());
|
||||
expectEqual(@as(u32, 1), queue.removeMax());
|
||||
}
|
||||
|
||||
test "std.PriorityDequeue: update same max queue" {
|
||||
var queue = PDQ.init(testing.allocator, lessThanComparison);
|
||||
defer queue.deinit();
|
||||
|
||||
try queue.add(1);
|
||||
try queue.add(1);
|
||||
try queue.add(2);
|
||||
try queue.add(2);
|
||||
try queue.update(1, 5);
|
||||
try queue.update(2, 4);
|
||||
expectEqual(@as(u32, 5), queue.removeMax());
|
||||
expectEqual(@as(u32, 4), queue.removeMax());
|
||||
expectEqual(@as(u32, 2), queue.removeMax());
|
||||
expectEqual(@as(u32, 1), queue.removeMax());
|
||||
}
|
||||
|
||||
test "std.PriorityDequeue: iterator" {
|
||||
var queue = PDQ.init(testing.allocator, lessThanComparison);
|
||||
var map = std.AutoHashMap(u32, void).init(testing.allocator);
|
||||
defer {
|
||||
queue.deinit();
|
||||
map.deinit();
|
||||
}
|
||||
|
||||
const items = [_]u32{ 54, 12, 7, 23, 25, 13 };
|
||||
for (items) |e| {
|
||||
_ = try queue.add(e);
|
||||
_ = try map.put(e, {});
|
||||
}
|
||||
|
||||
var it = queue.iterator();
|
||||
while (it.next()) |e| {
|
||||
_ = map.remove(e);
|
||||
}
|
||||
|
||||
expectEqual(@as(usize, 0), map.count());
|
||||
}
|
||||
|
||||
test "std.PriorityDequeue: remove at index" {
|
||||
var queue = PDQ.init(testing.allocator, lessThanComparison);
|
||||
defer queue.deinit();
|
||||
|
||||
try queue.add(3);
|
||||
try queue.add(2);
|
||||
try queue.add(1);
|
||||
|
||||
var it = queue.iterator();
|
||||
var elem = it.next();
|
||||
var idx: usize = 0;
|
||||
const two_idx = while (elem != null) : (elem = it.next()) {
|
||||
if (elem.? == 2)
|
||||
break idx;
|
||||
idx += 1;
|
||||
} else unreachable;
|
||||
|
||||
expectEqual(queue.removeIndex(two_idx), 2);
|
||||
expectEqual(queue.removeMin(), 1);
|
||||
expectEqual(queue.removeMin(), 3);
|
||||
expectEqual(queue.removeMinOrNull(), null);
|
||||
}
|
||||
|
||||
test "std.PriorityDequeue: iterator while empty" {
|
||||
var queue = PDQ.init(testing.allocator, lessThanComparison);
|
||||
defer queue.deinit();
|
||||
|
||||
var it = queue.iterator();
|
||||
|
||||
expectEqual(it.next(), null);
|
||||
}
|
||||
|
||||
test "std.PriorityDequeue: shrinkRetainingCapacity and shrinkAndFree" {
|
||||
var queue = PDQ.init(testing.allocator, lessThanComparison);
|
||||
defer queue.deinit();
|
||||
|
||||
try queue.ensureCapacity(4);
|
||||
expect(queue.capacity() >= 4);
|
||||
|
||||
try queue.add(1);
|
||||
try queue.add(2);
|
||||
try queue.add(3);
|
||||
expect(queue.capacity() >= 4);
|
||||
expectEqual(@as(usize, 3), queue.len);
|
||||
|
||||
queue.shrinkRetainingCapacity(3);
|
||||
expect(queue.capacity() >= 4);
|
||||
expectEqual(@as(usize, 3), queue.len);
|
||||
|
||||
queue.shrinkAndFree(3);
|
||||
expectEqual(@as(usize, 3), queue.capacity());
|
||||
expectEqual(@as(usize, 3), queue.len);
|
||||
|
||||
expectEqual(@as(u32, 3), queue.removeMax());
|
||||
expectEqual(@as(u32, 2), queue.removeMax());
|
||||
expectEqual(@as(u32, 1), queue.removeMax());
|
||||
expect(queue.removeMaxOrNull() == null);
|
||||
}
|
||||
|
||||
test "std.PriorityDequeue: fuzz testing min" {
|
||||
var prng = std.rand.DefaultPrng.init(0x12345678);
|
||||
|
||||
const test_case_count = 100;
|
||||
const queue_size = 1_000;
|
||||
|
||||
var i: usize = 0;
|
||||
while (i < test_case_count) : (i += 1) {
|
||||
try fuzzTestMin(&prng.random, queue_size);
|
||||
}
|
||||
}
|
||||
|
||||
fn fuzzTestMin(rng: *std.rand.Random, comptime queue_size: usize) !void {
|
||||
const allocator = testing.allocator;
|
||||
const items = try generateRandomSlice(allocator, rng, queue_size);
|
||||
|
||||
var queue = PDQ.fromOwnedSlice(allocator, lessThanComparison, items);
|
||||
defer queue.deinit();
|
||||
|
||||
var last_removed: ?u32 = null;
|
||||
while (queue.removeMinOrNull()) |next| {
|
||||
if (last_removed) |last| {
|
||||
expect(last <= next);
|
||||
}
|
||||
last_removed = next;
|
||||
}
|
||||
}
|
||||
|
||||
test "std.PriorityDequeue: fuzz testing max" {
|
||||
var prng = std.rand.DefaultPrng.init(0x87654321);
|
||||
|
||||
const test_case_count = 100;
|
||||
const queue_size = 1_000;
|
||||
|
||||
var i: usize = 0;
|
||||
while (i < test_case_count) : (i += 1) {
|
||||
try fuzzTestMax(&prng.random, queue_size);
|
||||
}
|
||||
}
|
||||
|
||||
fn fuzzTestMax(rng: *std.rand.Random, queue_size: usize) !void {
|
||||
const allocator = testing.allocator;
|
||||
const items = try generateRandomSlice(allocator, rng, queue_size);
|
||||
|
||||
var queue = PDQ.fromOwnedSlice(testing.allocator, lessThanComparison, items);
|
||||
defer queue.deinit();
|
||||
|
||||
var last_removed: ?u32 = null;
|
||||
while (queue.removeMaxOrNull()) |next| {
|
||||
if (last_removed) |last| {
|
||||
expect(last >= next);
|
||||
}
|
||||
last_removed = next;
|
||||
}
|
||||
}
|
||||
|
||||
test "std.PriorityDequeue: fuzz testing min and max" {
|
||||
var prng = std.rand.DefaultPrng.init(0x87654321);
|
||||
|
||||
const test_case_count = 100;
|
||||
const queue_size = 1_000;
|
||||
|
||||
var i: usize = 0;
|
||||
while (i < test_case_count) : (i += 1) {
|
||||
try fuzzTestMinMax(&prng.random, queue_size);
|
||||
}
|
||||
}
|
||||
|
||||
fn fuzzTestMinMax(rng: *std.rand.Random, queue_size: usize) !void {
|
||||
const allocator = testing.allocator;
|
||||
const items = try generateRandomSlice(allocator, rng, queue_size);
|
||||
|
||||
var queue = PDQ.fromOwnedSlice(allocator, lessThanComparison, items);
|
||||
defer queue.deinit();
|
||||
|
||||
var last_min: ?u32 = null;
|
||||
var last_max: ?u32 = null;
|
||||
var i: usize = 0;
|
||||
while (i < queue_size) : (i += 1) {
|
||||
if (i % 2 == 0) {
|
||||
const next = queue.removeMin();
|
||||
if (last_min) |last| {
|
||||
expect(last <= next);
|
||||
}
|
||||
last_min = next;
|
||||
} else {
|
||||
const next = queue.removeMax();
|
||||
if (last_max) |last| {
|
||||
expect(last >= next);
|
||||
}
|
||||
last_max = next;
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
fn generateRandomSlice(allocator: *std.mem.Allocator, rng: *std.rand.Random, size: usize) ![]u32 {
|
||||
var array = std.ArrayList(u32).init(allocator);
|
||||
try array.ensureCapacity(size);
|
||||
|
||||
var i: usize = 0;
|
||||
while (i < size) : (i += 1) {
|
||||
const elem = rng.int(u32);
|
||||
try array.append(elem);
|
||||
}
|
||||
|
||||
return array.toOwnedSlice();
|
||||
}
|
||||
@ -6,6 +6,8 @@
|
||||
const std = @import("std.zig");
|
||||
const Allocator = std.mem.Allocator;
|
||||
const assert = std.debug.assert;
|
||||
const warn = std.debug.warn;
|
||||
const Order = std.math.Order;
|
||||
const testing = std.testing;
|
||||
const expect = testing.expect;
|
||||
const expectEqual = testing.expectEqual;
|
||||
@ -19,15 +21,17 @@ pub fn PriorityQueue(comptime T: type) type {
|
||||
items: []T,
|
||||
len: usize,
|
||||
allocator: *Allocator,
|
||||
compareFn: fn (a: T, b: T) bool,
|
||||
compareFn: fn (a: T, b: T) Order,
|
||||
|
||||
/// Initialize and return a priority queue. Provide
|
||||
/// `compareFn` that returns `true` when its first argument
|
||||
/// should get popped before its second argument. For example,
|
||||
/// to make `pop` return the minimum value, provide
|
||||
/// Initialize and return a priority queue. Provide `compareFn`
|
||||
/// that returns `Order.lt` when its first argument should
|
||||
/// get popped before its second argument, `Order.eq` if the
|
||||
/// arguments are of equal priority, or `Order.gt` if the second
|
||||
/// argument should be popped first. For example, to make `pop`
|
||||
/// return the smallest number, provide
|
||||
///
|
||||
/// `fn lessThan(a: T, b: T) bool { return a < b; }`
|
||||
pub fn init(allocator: *Allocator, compareFn: fn (a: T, b: T) bool) Self {
|
||||
/// `fn lessThan(a: T, b: T) Order { return std.math.order(a, b); }`
|
||||
pub fn init(allocator: *Allocator, compareFn: fn (a: T, b: T) Order) Self {
|
||||
return Self{
|
||||
.items = &[_]T{},
|
||||
.len = 0,
|
||||
@ -60,7 +64,7 @@ pub fn PriorityQueue(comptime T: type) type {
|
||||
const child = self.items[child_index];
|
||||
const parent = self.items[parent_index];
|
||||
|
||||
if (!self.compareFn(child, parent)) break;
|
||||
if (self.compareFn(child, parent) != .lt) break;
|
||||
|
||||
self.items[parent_index] = child;
|
||||
self.items[child_index] = parent;
|
||||
@ -132,14 +136,14 @@ pub fn PriorityQueue(comptime T: type) type {
|
||||
var smallest = self.items[index];
|
||||
|
||||
if (left) |e| {
|
||||
if (self.compareFn(e, smallest)) {
|
||||
if (self.compareFn(e, smallest) == .lt) {
|
||||
smallest_index = left_index;
|
||||
smallest = e;
|
||||
}
|
||||
}
|
||||
|
||||
if (right) |e| {
|
||||
if (self.compareFn(e, smallest)) {
|
||||
if (self.compareFn(e, smallest) == .lt) {
|
||||
smallest_index = right_index;
|
||||
smallest = e;
|
||||
}
|
||||
@ -158,13 +162,16 @@ pub fn PriorityQueue(comptime T: type) type {
|
||||
/// PriorityQueue takes ownership of the passed in slice. The slice must have been
|
||||
/// allocated with `allocator`.
|
||||
/// Deinitialize with `deinit`.
|
||||
pub fn fromOwnedSlice(allocator: *Allocator, compareFn: fn (a: T, b: T) bool, items: []T) Self {
|
||||
pub fn fromOwnedSlice(allocator: *Allocator, compareFn: fn (a: T, b: T) Order, items: []T) Self {
|
||||
var queue = Self{
|
||||
.items = items,
|
||||
.len = items.len,
|
||||
.allocator = allocator,
|
||||
.compareFn = compareFn,
|
||||
};
|
||||
|
||||
if (queue.len <= 1) return queue;
|
||||
|
||||
const half = (queue.len >> 1) - 1;
|
||||
var i: usize = 0;
|
||||
while (i <= half) : (i += 1) {
|
||||
@ -183,25 +190,40 @@ pub fn PriorityQueue(comptime T: type) type {
|
||||
self.items = try self.allocator.realloc(self.items, better_capacity);
|
||||
}
|
||||
|
||||
pub fn resize(self: *Self, new_len: usize) !void {
|
||||
try self.ensureCapacity(new_len);
|
||||
/// Reduce allocated capacity to `new_len`.
|
||||
pub fn shrinkAndFree(self: *Self, new_len: usize) void {
|
||||
assert(new_len <= self.items.len);
|
||||
|
||||
// Cannot shrink to smaller than the current queue size without invalidating the heap property
|
||||
assert(new_len >= self.len);
|
||||
|
||||
self.items = self.allocator.realloc(self.items[0..], new_len) catch |e| switch (e) {
|
||||
error.OutOfMemory => { // no problem, capacity is still correct then.
|
||||
self.items.len = new_len;
|
||||
return;
|
||||
},
|
||||
};
|
||||
self.len = new_len;
|
||||
}
|
||||
|
||||
pub fn shrink(self: *Self, new_len: usize) void {
|
||||
// TODO take advantage of the new realloc semantics
|
||||
assert(new_len <= self.len);
|
||||
/// Reduce length to `new_len`.
|
||||
pub fn shrinkRetainingCapacity(self: *Self, new_len: usize) void {
|
||||
assert(new_len <= self.items.len);
|
||||
|
||||
// Cannot shrink to smaller than the current queue size without invalidating the heap property
|
||||
assert(new_len >= self.len);
|
||||
|
||||
self.len = new_len;
|
||||
}
|
||||
|
||||
pub fn update(self: *Self, elem: T, new_elem: T) !void {
|
||||
var update_index: usize = std.mem.indexOfScalar(T, self.items, elem) orelse return error.ElementNotFound;
|
||||
var update_index: usize = std.mem.indexOfScalar(T, self.items[0..self.len], elem) orelse return error.ElementNotFound;
|
||||
const old_elem: T = self.items[update_index];
|
||||
self.items[update_index] = new_elem;
|
||||
if (self.compareFn(new_elem, old_elem)) {
|
||||
siftUp(self, update_index);
|
||||
} else {
|
||||
siftDown(self, update_index);
|
||||
switch (self.compareFn(new_elem, old_elem)) {
|
||||
.lt => siftUp(self, update_index),
|
||||
.gt => siftDown(self, update_index),
|
||||
.eq => {}, // Nothing to do as the items have equal priority
|
||||
}
|
||||
}
|
||||
|
||||
@ -248,12 +270,12 @@ pub fn PriorityQueue(comptime T: type) type {
|
||||
};
|
||||
}
|
||||
|
||||
fn lessThan(a: u32, b: u32) bool {
|
||||
return a < b;
|
||||
fn lessThan(a: u32, b: u32) Order {
|
||||
return std.math.order(a, b);
|
||||
}
|
||||
|
||||
fn greaterThan(a: u32, b: u32) bool {
|
||||
return a > b;
|
||||
fn greaterThan(a: u32, b: u32) Order {
|
||||
return lessThan(a, b).invert();
|
||||
}
|
||||
|
||||
const PQ = PriorityQueue(u32);
|
||||
@ -351,6 +373,26 @@ test "std.PriorityQueue: addSlice" {
|
||||
}
|
||||
}
|
||||
|
||||
test "std.PriorityQueue: fromOwnedSlice trivial case 0" {
|
||||
const items = [0]u32{};
|
||||
const queue_items = try testing.allocator.dupe(u32, &items);
|
||||
var queue = PQ.fromOwnedSlice(testing.allocator, lessThan, queue_items[0..]);
|
||||
defer queue.deinit();
|
||||
expectEqual(@as(usize, 0), queue.len);
|
||||
expect(queue.removeOrNull() == null);
|
||||
}
|
||||
|
||||
test "std.PriorityQueue: fromOwnedSlice trivial case 1" {
|
||||
const items = [1]u32{1};
|
||||
const queue_items = try testing.allocator.dupe(u32, &items);
|
||||
var queue = PQ.fromOwnedSlice(testing.allocator, lessThan, queue_items[0..]);
|
||||
defer queue.deinit();
|
||||
|
||||
expectEqual(@as(usize, 1), queue.len);
|
||||
expectEqual(items[0], queue.remove());
|
||||
expect(queue.removeOrNull() == null);
|
||||
}
|
||||
|
||||
test "std.PriorityQueue: fromOwnedSlice" {
|
||||
const items = [_]u32{ 15, 7, 21, 14, 13, 22, 12, 6, 7, 25, 5, 24, 11, 16, 15, 24, 2, 1 };
|
||||
const heap_items = try testing.allocator.dupe(u32, items[0..]);
|
||||
@ -453,6 +495,33 @@ test "std.PriorityQueue: iterator while empty" {
|
||||
expectEqual(it.next(), null);
|
||||
}
|
||||
|
||||
test "std.PriorityQueue: shrinkRetainingCapacity and shrinkAndFree" {
|
||||
var queue = PQ.init(testing.allocator, lessThan);
|
||||
defer queue.deinit();
|
||||
|
||||
try queue.ensureCapacity(4);
|
||||
expect(queue.capacity() >= 4);
|
||||
|
||||
try queue.add(1);
|
||||
try queue.add(2);
|
||||
try queue.add(3);
|
||||
expect(queue.capacity() >= 4);
|
||||
expectEqual(@as(usize, 3), queue.len);
|
||||
|
||||
queue.shrinkRetainingCapacity(3);
|
||||
expect(queue.capacity() >= 4);
|
||||
expectEqual(@as(usize, 3), queue.len);
|
||||
|
||||
queue.shrinkAndFree(3);
|
||||
expectEqual(@as(usize, 3), queue.capacity());
|
||||
expectEqual(@as(usize, 3), queue.len);
|
||||
|
||||
expectEqual(@as(u32, 1), queue.remove());
|
||||
expectEqual(@as(u32, 2), queue.remove());
|
||||
expectEqual(@as(u32, 3), queue.remove());
|
||||
expect(queue.removeOrNull() == null);
|
||||
}
|
||||
|
||||
test "std.PriorityQueue: update min heap" {
|
||||
var queue = PQ.init(testing.allocator, lessThan);
|
||||
defer queue.deinit();
|
||||
|
||||
@ -31,6 +31,7 @@ pub const PackedIntArrayEndian = @import("packed_int_array.zig").PackedIntArrayE
|
||||
pub const PackedIntSlice = @import("packed_int_array.zig").PackedIntSlice;
|
||||
pub const PackedIntSliceEndian = @import("packed_int_array.zig").PackedIntSliceEndian;
|
||||
pub const PriorityQueue = @import("priority_queue.zig").PriorityQueue;
|
||||
pub const PriorityDequeue = @import("priority_dequeue.zig").PriorityDequeue;
|
||||
pub const Progress = @import("Progress.zig");
|
||||
pub const SemanticVersion = @import("SemanticVersion.zig");
|
||||
pub const SinglyLinkedList = @import("linked_list.zig").SinglyLinkedList;
|
||||
|
||||
Loading…
x
Reference in New Issue
Block a user