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Add generic comparator generator functions for sorting

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- Copy-by-value instead of pointer where appropriate
 - Clean up old zig fmt issues
This commit is contained in:
Marc Tiehuis
2018-07-11 18:16:58 +12:00
parent c6c49389eb
commit 9b054e73f6
2 changed files with 87 additions and 240 deletions
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2
std/macho.zig
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@@ -42,7 +42,7 @@ pub const Symbol = struct {
name: []const u8,
address: u64,
fn addressLessThan(lhs: *const Symbol, rhs: *const Symbol) bool {
fn addressLessThan(lhs: Symbol, rhs: Symbol) bool {
return lhs.address < rhs.address;
}
};

325
std/sort.zig
View File

@@ -5,7 +5,7 @@ const math = std.math;
const builtin = @import("builtin");
/// Stable in-place sort. O(n) best case, O(pow(n, 2)) worst case. O(1) memory (no allocator required).
pub fn insertionSort(comptime T: type, items: []T, lessThan: fn (lhs: *const T, rhs: *const T) bool) void {
pub fn insertionSort(comptime T: type, items: []T, lessThan: fn (lhs: T, rhs: T) bool) void {
{
var i: usize = 1;
while (i < items.len) : (i += 1) {
@@ -30,7 +30,7 @@ const Range = struct {
};
}
fn length(self: *const Range) usize {
fn length(self: Range) usize {
return self.end - self.start;
}
};
@@ -108,7 +108,7 @@ const Pull = struct {
/// Stable in-place sort. O(n) best case, O(n*log(n)) worst case and average case. O(1) memory (no allocator required).
/// Currently implemented as block sort.
pub fn sort(comptime T: type, items: []T, lessThan: fn (lhs: *const T, rhs: *const T) bool) void {
pub fn sort(comptime T: type, items: []T, lessThan: fn (lhs: T, rhs: T) bool) void {
// Implementation ported from https://github.com/BonzaiThePenguin/WikiSort/blob/master/WikiSort.c
var cache: [512]T = undefined;
@@ -131,16 +131,7 @@ pub fn sort(comptime T: type, items: []T, lessThan: fn (lhs: *const T, rhs: *con
// http://pages.ripco.net/~jgamble/nw.html
var iterator = Iterator.init(items.len, 4);
while (!iterator.finished()) {
var order = []u8{
0,
1,
2,
3,
4,
5,
6,
7,
};
var order = []u8{ 0, 1, 2, 3, 4, 5, 6, 7 };
const range = iterator.nextRange();
const sliced_items = items[range.start..];
@@ -741,7 +732,7 @@ pub fn sort(comptime T: type, items: []T, lessThan: fn (lhs: *const T, rhs: *con
}
// merge operation without a buffer
fn mergeInPlace(comptime T: type, items: []T, A_arg: *const Range, B_arg: *const Range, lessThan: fn (*const T, *const T) bool) void {
fn mergeInPlace(comptime T: type, items: []T, A_arg: Range, B_arg: Range, lessThan: fn (T, T) bool) void {
if (A_arg.length() == 0 or B_arg.length() == 0) return;
// this just repeatedly binary searches into B and rotates A into position.
@@ -762,8 +753,8 @@ fn mergeInPlace(comptime T: type, items: []T, A_arg: *const Range, B_arg: *const
// again, this is NOT a general-purpose solution – it only works well in this case!
// kind of like how the O(n^2) insertion sort is used in some places
var A = A_arg.*;
var B = B_arg.*;
var A = A_arg;
var B = B_arg;
while (true) {
// find the first place in B where the first item in A needs to be inserted
@@ -783,7 +774,7 @@ fn mergeInPlace(comptime T: type, items: []T, A_arg: *const Range, B_arg: *const
}
// merge operation using an internal buffer
fn mergeInternal(comptime T: type, items: []T, A: *const Range, B: *const Range, lessThan: fn (*const T, *const T) bool, buffer: *const Range) void {
fn mergeInternal(comptime T: type, items: []T, A: Range, B: Range, lessThan: fn (T, T) bool, buffer: Range) void {
// whenever we find a value to add to the final array, swap it with the value that's already in that spot
// when this algorithm is finished, 'buffer' will contain its original contents, but in a different order
var A_count: usize = 0;
@@ -819,7 +810,7 @@ fn blockSwap(comptime T: type, items: []T, start1: usize, start2: usize, block_s
// combine a linear search with a binary search to reduce the number of comparisons in situations
// where have some idea as to how many unique values there are and where the next value might be
fn findFirstForward(comptime T: type, items: []T, value: *const T, range: *const Range, lessThan: fn (*const T, *const T) bool, unique: usize) usize {
fn findFirstForward(comptime T: type, items: []T, value: T, range: Range, lessThan: fn (T, T) bool, unique: usize) usize {
if (range.length() == 0) return range.start;
const skip = math.max(range.length() / unique, usize(1));
@@ -833,7 +824,7 @@ fn findFirstForward(comptime T: type, items: []T, value: *const T, range: *const
return binaryFirst(T, items, value, Range.init(index - skip, index), lessThan);
}
fn findFirstBackward(comptime T: type, items: []T, value: *const T, range: *const Range, lessThan: fn (*const T, *const T) bool, unique: usize) usize {
fn findFirstBackward(comptime T: type, items: []T, value: T, range: Range, lessThan: fn (T, T) bool, unique: usize) usize {
if (range.length() == 0) return range.start;
const skip = math.max(range.length() / unique, usize(1));
@@ -847,7 +838,7 @@ fn findFirstBackward(comptime T: type, items: []T, value: *const T, range: *cons
return binaryFirst(T, items, value, Range.init(index, index + skip), lessThan);
}
fn findLastForward(comptime T: type, items: []T, value: *const T, range: *const Range, lessThan: fn (*const T, *const T) bool, unique: usize) usize {
fn findLastForward(comptime T: type, items: []T, value: T, range: Range, lessThan: fn (T, T) bool, unique: usize) usize {
if (range.length() == 0) return range.start;
const skip = math.max(range.length() / unique, usize(1));
@@ -861,7 +852,7 @@ fn findLastForward(comptime T: type, items: []T, value: *const T, range: *const
return binaryLast(T, items, value, Range.init(index - skip, index), lessThan);
}
fn findLastBackward(comptime T: type, items: []T, value: *const T, range: *const Range, lessThan: fn (*const T, *const T) bool, unique: usize) usize {
fn findLastBackward(comptime T: type, items: []T, value: T, range: Range, lessThan: fn (T, T) bool, unique: usize) usize {
if (range.length() == 0) return range.start;
const skip = math.max(range.length() / unique, usize(1));
@@ -875,7 +866,7 @@ fn findLastBackward(comptime T: type, items: []T, value: *const T, range: *const
return binaryLast(T, items, value, Range.init(index, index + skip), lessThan);
}
fn binaryFirst(comptime T: type, items: []T, value: *const T, range: *const Range, lessThan: fn (*const T, *const T) bool) usize {
fn binaryFirst(comptime T: type, items: []T, value: T, range: Range, lessThan: fn (T, T) bool) usize {
var start = range.start;
var end = range.end - 1;
if (range.start >= range.end) return range.end;
@@ -893,7 +884,7 @@ fn binaryFirst(comptime T: type, items: []T, value: *const T, range: *const Rang
return start;
}
fn binaryLast(comptime T: type, items: []T, value: *const T, range: *const Range, lessThan: fn (*const T, *const T) bool) usize {
fn binaryLast(comptime T: type, items: []T, value: T, range: Range, lessThan: fn (T, T) bool) usize {
var start = range.start;
var end = range.end - 1;
if (range.start >= range.end) return range.end;
@@ -911,7 +902,7 @@ fn binaryLast(comptime T: type, items: []T, value: *const T, range: *const Range
return start;
}
fn mergeInto(comptime T: type, from: []T, A: *const Range, B: *const Range, lessThan: fn (*const T, *const T) bool, into: []T) void {
fn mergeInto(comptime T: type, from: []T, A: Range, B: Range, lessThan: fn (T, T) bool, into: []T) void {
var A_index: usize = A.start;
var B_index: usize = B.start;
const A_last = A.end;
@@ -941,7 +932,7 @@ fn mergeInto(comptime T: type, from: []T, A: *const Range, B: *const Range, less
}
}
fn mergeExternal(comptime T: type, items: []T, A: *const Range, B: *const Range, lessThan: fn (*const T, *const T) bool, cache: []T) void {
fn mergeExternal(comptime T: type, items: []T, A: Range, B: Range, lessThan: fn (T, T) bool, cache: []T) void {
// A fits into the cache, so use that instead of the internal buffer
var A_index: usize = 0;
var B_index: usize = B.start;
@@ -969,27 +960,32 @@ fn mergeExternal(comptime T: type, items: []T, A: *const Range, B: *const Range,
mem.copy(T, items[insert_index..], cache[A_index..A_last]);
}
fn swap(comptime T: type, items: []T, lessThan: fn (lhs: *const T, rhs: *const T) bool, order: *[8]u8, x: usize, y: usize) void {
fn swap(comptime T: type, items: []T, lessThan: fn (lhs: T, rhs: T) bool, order: *[8]u8, x: usize, y: usize) void {
if (lessThan(items[y], items[x]) or ((order.*)[x] > (order.*)[y] and !lessThan(items[x], items[y]))) {
mem.swap(T, &items[x], &items[y]);
mem.swap(u8, &(order.*)[x], &(order.*)[y]);
}
}
fn i32asc(lhs: *const i32, rhs: *const i32) bool {
return lhs.* < rhs.*;
// Use these to generate a comparator function for a given type. e.g. `sort(u8, slice, asc(u8))`.
pub fn asc(comptime T: type) fn (T, T) bool {
const impl = struct {
fn inner(a: T, b: T) bool {
return a < b;
}
};
return impl.inner;
}
fn i32desc(lhs: *const i32, rhs: *const i32) bool {
return rhs.* < lhs.*;
}
pub fn desc(comptime T: type) fn (T, T) bool {
const impl = struct {
fn inner(a: T, b: T) bool {
return a > b;
}
};
fn u8asc(lhs: *const u8, rhs: *const u8) bool {
return lhs.* < rhs.*;
}
fn u8desc(lhs: *const u8, rhs: *const u8) bool {
return rhs.* < lhs.*;
return impl.inner;
}
test "stable sort" {
@@ -998,119 +994,38 @@ test "stable sort" {
}
fn testStableSort() void {
var expected = []IdAndValue{
IdAndValue{
.id = 0,
.value = 0,
},
IdAndValue{
.id = 1,
.value = 0,
},
IdAndValue{
.id = 2,
.value = 0,
},
IdAndValue{
.id = 0,
.value = 1,
},
IdAndValue{
.id = 1,
.value = 1,
},
IdAndValue{
.id = 2,
.value = 1,
},
IdAndValue{
.id = 0,
.value = 2,
},
IdAndValue{
.id = 1,
.value = 2,
},
IdAndValue{
.id = 2,
.value = 2,
},
IdAndValue{ .id = 0, .value = 0 },
IdAndValue{ .id = 1, .value = 0 },
IdAndValue{ .id = 2, .value = 0 },
IdAndValue{ .id = 0, .value = 1 },
IdAndValue{ .id = 1, .value = 1 },
IdAndValue{ .id = 2, .value = 1 },
IdAndValue{ .id = 0, .value = 2 },
IdAndValue{ .id = 1, .value = 2 },
IdAndValue{ .id = 2, .value = 2 },
};
var cases = [][9]IdAndValue{
[]IdAndValue{
IdAndValue{
.id = 0,
.value = 0,
},
IdAndValue{
.id = 0,
.value = 1,
},
IdAndValue{
.id = 0,
.value = 2,
},
IdAndValue{
.id = 1,
.value = 0,
},
IdAndValue{
.id = 1,
.value = 1,
},
IdAndValue{
.id = 1,
.value = 2,
},
IdAndValue{
.id = 2,
.value = 0,
},
IdAndValue{
.id = 2,
.value = 1,
},
IdAndValue{
.id = 2,
.value = 2,
},
IdAndValue{ .id = 0, .value = 0 },
IdAndValue{ .id = 0, .value = 1 },
IdAndValue{ .id = 0, .value = 2 },
IdAndValue{ .id = 1, .value = 0 },
IdAndValue{ .id = 1, .value = 1 },
IdAndValue{ .id = 1, .value = 2 },
IdAndValue{ .id = 2, .value = 0 },
IdAndValue{ .id = 2, .value = 1 },
IdAndValue{ .id = 2, .value = 2 },
},
[]IdAndValue{
IdAndValue{
.id = 0,
.value = 2,
},
IdAndValue{
.id = 0,
.value = 1,
},
IdAndValue{
.id = 0,
.value = 0,
},
IdAndValue{
.id = 1,
.value = 2,
},
IdAndValue{
.id = 1,
.value = 1,
},
IdAndValue{
.id = 1,
.value = 0,
},
IdAndValue{
.id = 2,
.value = 2,
},
IdAndValue{
.id = 2,
.value = 1,
},
IdAndValue{
.id = 2,
.value = 0,
},
IdAndValue{ .id = 0, .value = 2 },
IdAndValue{ .id = 0, .value = 1 },
IdAndValue{ .id = 0, .value = 0 },
IdAndValue{ .id = 1, .value = 2 },
IdAndValue{ .id = 1, .value = 1 },
IdAndValue{ .id = 1, .value = 0 },
IdAndValue{ .id = 2, .value = 2 },
IdAndValue{ .id = 2, .value = 1 },
IdAndValue{ .id = 2, .value = 0 },
},
};
for (cases) |*case| {
@@ -1125,8 +1040,8 @@ const IdAndValue = struct {
id: usize,
value: i32,
};
fn cmpByValue(a: *const IdAndValue, b: *const IdAndValue) bool {
return i32asc(a.value, b.value);
fn cmpByValue(a: IdAndValue, b: IdAndValue) bool {
return asc(i32)(a.value, b.value);
}
test "std.sort" {
@@ -1161,7 +1076,7 @@ test "std.sort" {
var buf: [8]u8 = undefined;
const slice = buf[0..case[0].len];
mem.copy(u8, slice, case[0]);
sort(u8, slice, u8asc);
sort(u8, slice, asc(u8));
assert(mem.eql(u8, slice, case[1]));
}
@@ -1175,48 +1090,20 @@ test "std.sort" {
[]i32{1},
},
[][]const i32{
[]i32{
0,
1,
},
[]i32{
0,
1,
},
[]i32{ 0, 1 },
[]i32{ 0, 1 },
},
[][]const i32{
[]i32{
1,
0,
},
[]i32{
0,
1,
},
[]i32{ 1, 0 },
[]i32{ 0, 1 },
},
[][]const i32{
[]i32{
1,
-1,
0,
},
[]i32{
-1,
0,
1,
},
[]i32{ 1, -1, 0 },
[]i32{ -1, 0, 1 },
},
[][]const i32{
[]i32{
2,
1,
3,
},
[]i32{
1,
2,
3,
},
[]i32{ 2, 1, 3 },
[]i32{ 1, 2, 3 },
},
};
@@ -1224,7 +1111,7 @@ test "std.sort" {
var buf: [8]i32 = undefined;
const slice = buf[0..case[0].len];
mem.copy(i32, slice, case[0]);
sort(i32, slice, i32asc);
sort(i32, slice, asc(i32));
assert(mem.eql(i32, slice, case[1]));
}
}
@@ -1240,48 +1127,20 @@ test "std.sort descending" {
[]i32{1},
},
[][]const i32{
[]i32{
0,
1,
},
[]i32{
1,
0,
},
[]i32{ 0, 1 },
[]i32{ 1, 0 },
},
[][]const i32{
[]i32{
1,
0,
},
[]i32{
1,
0,
},
[]i32{ 1, 0 },
[]i32{ 1, 0 },
},
[][]const i32{
[]i32{
1,
-1,
0,
},
[]i32{
1,
0,
-1,
},
[]i32{ 1, -1, 0 },
[]i32{ 1, 0, -1 },
},
[][]const i32{
[]i32{
2,
1,
3,
},
[]i32{
3,
2,
1,
},
[]i32{ 2, 1, 3 },
[]i32{ 3, 2, 1 },
},
};
@@ -1289,28 +1148,16 @@ test "std.sort descending" {
var buf: [8]i32 = undefined;
const slice = buf[0..case[0].len];
mem.copy(i32, slice, case[0]);
sort(i32, slice, i32desc);
sort(i32, slice, desc(i32));
assert(mem.eql(i32, slice, case[1]));
}
}
test "another sort case" {
var arr = []i32{
5,
3,
1,
2,
4,
};
sort(i32, arr[0..], i32asc);
var arr = []i32{ 5, 3, 1, 2, 4 };
sort(i32, arr[0..], asc(i32));
assert(mem.eql(i32, arr, []i32{
1,
2,
3,
4,
5,
}));
assert(mem.eql(i32, arr, []i32{ 1, 2, 3, 4, 5 }));
}
test "sort fuzz testing" {
@@ -1345,7 +1192,7 @@ fn fuzzTest(rng: *std.rand.Random) void {
}
}
pub fn min(comptime T: type, items: []T, lessThan: fn (lhs: *const T, rhs: *const T) bool) T {
pub fn min(comptime T: type, items: []T, lessThan: fn (lhs: T, rhs: T) bool) T {
var i: usize = 0;
var smallest = items[0];
for (items[1..]) |item| {
@@ -1356,7 +1203,7 @@ pub fn min(comptime T: type, items: []T, lessThan: fn (lhs: *const T, rhs: *cons
return smallest;
}
pub fn max(comptime T: type, items: []T, lessThan: fn (lhs: *const T, rhs: *const T) bool) T {
pub fn max(comptime T: type, items: []T, lessThan: fn (lhs: T, rhs: T) bool) T {
var i: usize = 0;
var biggest = items[0];
for (items[1..]) |item| {