add permutation (sort) to std_utils

framework/std_utils/src/mm/permutation.hpp

@@ -0,0 +1,37 @@
+#pragma once
+
+#include <vector>
+#include <numeric>
+#include <algorithm>
+
+namespace MM::std_utils {
+
+// TODO: move to some lib in engine
+// TODO: determain the ideal sort
+// uses std::sort rn
+template<typename F>
+std::vector<size_t> generate_sort_permutation(size_t size, F&& sort_fn) {
+	std::vector<size_t> index_mapping;
+
+	index_mapping.resize(size);
+	std::iota(index_mapping.begin(), index_mapping.end(), 0);
+
+	std::sort(index_mapping.begin(), index_mapping.end(), sort_fn);
+
+	return index_mapping;
+}
+
+// TODO: reimplement, this naive solution is kind of costly
+template<typename ContainerType>
+void apply_permutation(ContainerType& vec, const std::vector<size_t>& perm) {
+	ContainerType new_vec(vec.size());
+
+	for (size_t i = 0; i < vec.size(); i++) {
+		new_vec[i] = vec[perm[i]]; // thx ec and random guy
+	}
+
+	vec = std::move(new_vec);
+}
+
+} // MM::std_utils
+