Moar sorting

third_party/libcxx/utils.h

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+// -*- c++ -*-
+// clang-format off
+#ifndef COSMOPOLITAN_THIRD_PARTY_LEARNED_SORT_UTILS_H_
+#define COSMOPOLITAN_THIRD_PARTY_LEARNED_SORT_UTILS_H_
+#include "third_party/libcxx/iterator"
+
+namespace learned_sort {
+namespace utils {
+
+// Helper functions for working with unsigned types
+template <typename T>
+inline T _get_key(T a) {
+  return a;
+}
+
+template <class RandomIt>
+void insertion_sort(RandomIt begin, RandomIt end) {
+  // Determine the data type
+  typedef typename std::iterator_traits<RandomIt>::value_type T;
+
+  // Determine the input size
+  const size_t input_sz = std::distance(begin, end);
+
+  if (input_sz <= 0) return;
+
+  RandomIt cmp_idx;
+  T key;
+  for (auto i = begin + 1; i != end; ++i) {
+    key = i[0];
+    cmp_idx = i - 1;
+    while (cmp_idx >= begin && cmp_idx[0] > key) {
+      cmp_idx[1] = cmp_idx[0];
+      --cmp_idx;
+    }
+    cmp_idx[1] = key;
+  }
+}
+
+}  // namespace utils
+}  // namespace learned_sort
+
+#endif /* COSMOPOLITAN_THIRD_PARTY_LEARNED_SORT_UTILS_H_ */