From 13b8607cc392bfa925c9dc65589ea93b67f2df83 Mon Sep 17 00:00:00 2001
From: gingerBill <gingerBill@users.noreply.github.com>
Date: Tue, 7 Oct 2025 14:15:40 +0100
Subject: [PATCH] Add `_internal_sort_from_indices_permuation`

---
 core/slice/ptr.odin  | 10 +++++-----
 core/slice/sort.odin | 29 ++++++++++++++++++++++++++++-
 2 files changed, 33 insertions(+), 6 deletions(-)

diff --git a/core/slice/ptr.odin b/core/slice/ptr.odin
index 99d4157c3..b52853375 100644
--- a/core/slice/ptr.odin
+++ b/core/slice/ptr.odin
@@ -3,14 +3,14 @@ package slice
 import "base:builtin"
 import "base:runtime"
 
-ptr_add :: proc(p: $P/^$T, x: int) -> ^T {
+ptr_add :: proc "contextless" (p: $P/^$T, x: int) -> ^T {
 	return ([^]T)(p)[x:]
 }
-ptr_sub :: proc(p: $P/^$T, x: int) -> ^T {
+ptr_sub :: proc "contextless" (p: $P/^$T, x: int) -> ^T {
 	return ([^]T)(p)[-x:]
 }
 
-ptr_swap_non_overlapping :: proc(x, y: rawptr, len: int) {
+ptr_swap_non_overlapping :: proc "contextless" (x, y: rawptr, len: int) {
 	if len <= 0 {
 		return
 	}
@@ -44,7 +44,7 @@ ptr_swap_non_overlapping :: proc(x, y: rawptr, len: int) {
 	}
 }
 
-ptr_swap_overlapping :: proc(x, y: rawptr, len: int) {
+ptr_swap_overlapping :: proc "contextless" (x, y: rawptr, len: int) {
 	if len <= 0 {
 		return
 	}
@@ -68,7 +68,7 @@ ptr_swap_overlapping :: proc(x, y: rawptr, len: int) {
 }
 
 
-ptr_rotate :: proc(left: int, mid: ^$T, right: int) {
+ptr_rotate :: proc "contextless" (left: int, mid: ^$T, right: int) {
 	when size_of(T) != 0 {
 		left, mid, right := left, mid, right
 
diff --git a/core/slice/sort.odin b/core/slice/sort.odin
index 7e2415249..dde5592e8 100644
--- a/core/slice/sort.odin
+++ b/core/slice/sort.odin
@@ -81,6 +81,25 @@ sort_by_indices_overwrite :: proc(data: $T/[]$E, indices: []int) {
 	swap_with_slice(data, temp)
 }
 
+@(private)
+_internal_sort_from_indices_permuation :: proc(data: $T/[]$E, indices: []int) {
+	assert(len(data) == len(indices))
+	if len(indices) <= 1 {
+		return
+	}
+
+	// TODO(bill): This is not O(N)
+	for i in 0..<len(indices) {
+		index_to_swap := indices[i]
+
+		for index_to_swap < i {
+			index_to_swap = indices[index_to_swap]
+		}
+
+		ptr_swap_non_overlapping(&data[i], &data[index_to_swap], size_of(E))
+	}
+}
+
 // sort sorts a slice and returns a slice of the original indices
 // This sort is not guaranteed to be stable
 sort_with_indices :: proc(data: $T/[]$E, allocator := context.allocator) -> (indices: []int) where ORD(E) {
@@ -90,11 +109,13 @@ sort_with_indices :: proc(data: $T/[]$E, allocator := context.allocator) -> (ind
 			for _, idx in indices {
 				indices[idx] = idx
 			}
+
 			raw := ([^]byte)(raw_data(indices))
 			_smoothsort(raw, uint(len(indices)), size_of(int), proc(lhs, rhs: rawptr, user_data: rawptr) -> Ordering {
 				data := ([^]E)(user_data)
+
 				xi, yi := (^int)(lhs)^, (^int)(rhs)^
-				x, y := data[xi], data[yi]
+				#no_bounds_check x, y := data[xi], data[yi]
 				if x < y {
 					return .Less
 				} else if x > y {
@@ -102,6 +123,8 @@ sort_with_indices :: proc(data: $T/[]$E, allocator := context.allocator) -> (ind
 				}
 				return .Equal
 			}, raw_data(data))
+
+			_internal_sort_from_indices_permuation(data, indices)
 		}
 		return indices
 	}
@@ -177,6 +200,8 @@ sort_by_with_indices :: proc(data: $T/[]$E, less: proc(i, j: E) -> bool, allocat
 				}
 				return .Equal
 			}, ctx)
+
+			_internal_sort_from_indices_permuation(data, indices)
 		}
 	}
 	return indices
@@ -208,6 +233,8 @@ sort_by_with_indices_with_data :: proc(data: $T/[]$E, less: proc(i, j: E, user_d
 				}
 				return .Equal
 			}, ctx)
+
+			_internal_sort_from_indices_permuation(data, indices)
 		}
 	}
 	return indices