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sort requires compare function.

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Provide some handy functions for builtin comparable types.
This commit is contained in:
Steve Perkins 2016-11-03 04:10:33 +00:00
parent e761aa2d2f
commit cf00245bf9
1 changed files with 29 additions and 64 deletions
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93
std/sort.zig
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@ -4,47 +4,13 @@ const math = @import("math.zig");
pub const Cmp = math.Cmp;
pub fn sort(inline T: type, array: []T) {
pub fn sort(inline T: type, array: []T, inline cmp: fn(a: T, b: T)->Cmp) {
if (array.len > 0) {
quicksort(T, array, 0, array.len - 1);
quicksort(T, array, 0, array.len - 1, cmp);
}
}
fn quicksort(inline T: type, array: []T, left: usize, right: usize) {
var i = left;
var j = right;
var p = (i + j) / 2;
while (i <= j) {
while (array[i] < array[p]) {
i += 1;
}
while (array[j] > array[p]) {
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) quicksort(T, array, left, j);
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) {
fn quicksort(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;
@ -65,8 +31,28 @@ fn quicksortCmp(inline T: type, array: []T, left: usize, right: usize, inline cm
}
}
if (left < j) quicksortCmp(T, array, left, j, cmp);
if (i < right) quicksortCmp(T, array, i, right, cmp);
if (left < j) quicksort(T, array, left, j, cmp);
if (i < right) quicksort(T, array, i, right, cmp);
}
pub fn i32asc(a: i32, b: i32) -> Cmp {
return if (a > b) Cmp.Greater else if (a < b) Cmp.Less else Cmp.Equal;
}
pub fn i32desc(a: i32, b: i32) -> Cmp {
return reverse(i32asc(a, b));
}
pub fn u8asc(a: u8, b: u8) -> Cmp {
return if (a > b) Cmp.Greater else if (a < b) Cmp.Less else Cmp.Equal;
}
pub fn u8desc(a: u8, b: u8) -> Cmp {
return reverse(u8asc(a, b));
}
fn reverse(was: Cmp) -> Cmp {
return if (was == Cmp.Greater) Cmp.Less else if (was == Cmp.Less) Cmp.Greater else Cmp.Equal;
}
// ---------------------------------------
@ -85,7 +71,7 @@ fn testSort() {
};
for (u8cases) |case| {
sort(u8, case[0]);
sort(u8, case[0], u8asc);
assert(str.eql(case[0], case[1]));
}
@ -99,28 +85,14 @@ fn testSort() {
};
for (i32cases) |case| {
sort(i32, case[0]);
sort(i32, case[0], i32asc);
assert(str.sliceEql(i32, case[0], case[1]));
}
}
fn testSortCmp() {
fn testSortDesc() {
@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}},
@ -131,16 +103,9 @@ fn testSortCmp() {
};
for (revCases) |case| {
sortCmp(i32, case[0], revCmp);
sort(i32, case[0], i32desc);
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;
}