quicksort

CMakeLists.txt

@@ -222,6 +222,7 @@ install(FILES "${CMAKE_SOURCE_DIR}/std/net.zig" DESTINATION "${ZIG_STD_DEST}")
 install(FILES "${CMAKE_SOURCE_DIR}/std/os.zig" DESTINATION "${ZIG_STD_DEST}")
 install(FILES "${CMAKE_SOURCE_DIR}/std/rand.zig" DESTINATION "${ZIG_STD_DEST}")
 install(FILES "${CMAKE_SOURCE_DIR}/std/rand_test.zig" DESTINATION "${ZIG_STD_DEST}")
+install(FILES "${CMAKE_SOURCE_DIR}/std/sort.zig" DESTINATION "${ZIG_STD_DEST}")
 install(FILES "${CMAKE_SOURCE_DIR}/std/str.zig" DESTINATION "${ZIG_STD_DEST}")
 install(FILES "${CMAKE_SOURCE_DIR}/std/test_runner.zig" DESTINATION "${ZIG_STD_DEST}")
 install(FILES "${CMAKE_SOURCE_DIR}/std/test_runner_libc.zig" DESTINATION "${ZIG_STD_DEST}")

std/index.zig

@@ -4,6 +4,7 @@ pub const os = @import("os.zig");
 pub const math = @import("math.zig");
 pub const str = @import("str.zig");
 pub const cstr = @import("cstr.zig");
+pub const sort = @import("sort.zig");
 pub const net = @import("net.zig");
 pub const list = @import("list.zig");
 pub const hash_map = @import("hash_map.zig");

std/sort.zig

@@ -0,0 +1,111 @@
+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, inline cmp: fn(a: T, b: T)->Cmp) {
+    if (array.len > 0) {
+        quicksort(T, array, 0, array.len - 1, 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;
+
+    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) 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;
+}
+
+// ---------------------------------------
+// tests
+
+fn testSort() {
+    @setFnTest(this, true);
+
+    const u8cases = [][][]u8 {
+        [][]u8{"", ""},
+        [][]u8{"a", "a"},
+        [][]u8{"az", "az"},
+        [][]u8{"za", "az"},
+        [][]u8{"asdf", "adfs"},
+        [][]u8{"one", "eno"},
+    };
+
+    for (u8cases) |case| {
+        sort(u8, case[0], u8asc);
+        assert(str.eql(case[0], case[1]));
+    }
+
+    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| {
+        sort(i32, case[0], i32asc);
+        assert(str.sliceEql(i32, case[0], case[1]));
+    }
+}
+
+fn testSortDesc() {
+    @setFnTest(this, true);
+
+    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| {
+        sort(i32, case[0], i32desc);
+        assert(str.sliceEql(i32, case[0], case[1]));
+    }
+
+}
+