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sortCmp allows for a custom cmp function

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This commit is contained in:
Steve Perkins 2016-11-02 18:52:00 -04:00
parent c5b2bdae11
commit e761aa2d2f
1 changed files with 81 additions and 0 deletions
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81
std/sort.zig
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@ -1,5 +1,8 @@
const assert = @import("debug.zig").assert;
const str = @import("str.zig");
const math = @import("math.zig");
pub const Cmp = math.Cmp;
pub fn sort(inline T: type, array: []T) {
if (array.len > 0) {
@ -32,6 +35,43 @@ fn quicksort(inline T: type, array: []T, left: usize, right: usize) {
if (i < right) quicksort(T, array, i, right);
}
// ---------------------------------------
// sortCmp
pub fn sortCmp(inline T: type, array: []T, inline cmp: fn(a: T, b: T)->Cmp) {
if (array.len > 0) {
quicksortCmp(T, array, 0, array.len - 1, cmp);
}
}
fn quicksortCmp(inline T: type, array: []T, left: usize, right: usize, inline cmp: fn(a: T, b: T)->Cmp) {
var i = left;
var j = right;
var p = (i + j) / 2;
while (i <= j) {
while (cmp(array[i], array[p]) == Cmp.Less) {
i += 1;
}
while (cmp(array[j], array[p]) == Cmp.Greater) {
j -= 1;
}
if (i <= j) {
const tmp = array[i];
array[i] = array[j];
array[j] = tmp;
i += 1;
if (j > 0) j -= 1;
}
}
if (left < j) quicksortCmp(T, array, left, j, cmp);
if (i < right) quicksortCmp(T, array, i, right, cmp);
}
// ---------------------------------------
// tests
fn testSort() {
@setFnTest(this, true);
@ -63,3 +103,44 @@ fn testSort() {
assert(str.sliceEql(i32, case[0], case[1]));
}
}
fn testSortCmp() {
@setFnTest(this, true);
const i32cases = [][][]i32 {
[][]i32{[]i32{}, []i32{}},
[][]i32{[]i32{1}, []i32{1}},
[][]i32{[]i32{0, 1}, []i32{0, 1}},
[][]i32{[]i32{1, 0}, []i32{0, 1}},
[][]i32{[]i32{1, -1, 0}, []i32{-1, 0, 1}},
[][]i32{[]i32{2, 1, 3}, []i32{1, 2, 3}},
};
for (i32cases) |case| {
sortCmp(i32, case[0], normalCmp);
assert(str.sliceEql(i32, case[0], case[1]));
}
const revCases = [][][]i32 {
[][]i32{[]i32{}, []i32{}},
[][]i32{[]i32{1}, []i32{1}},
[][]i32{[]i32{0, 1}, []i32{1, 0}},
[][]i32{[]i32{1, 0}, []i32{1, 0}},
[][]i32{[]i32{1, -1, 0}, []i32{1, 0, -1}},
[][]i32{[]i32{2, 1, 3}, []i32{3, 2, 1}},
};
for (revCases) |case| {
sortCmp(i32, case[0], revCmp);
assert(str.sliceEql(i32, case[0], case[1]));
}
}
fn normalCmp(a: i32, b: i32) -> Cmp {
return if (a > b) Cmp.Greater else if (a < b) Cmp.Less else Cmp.Equal;
}
fn revCmp(a: i32, b: i32) -> Cmp {
return if (a < b) Cmp.Greater else if (a > b) Cmp.Less else Cmp.Equal;
}