[Project] Css: Add frozen library from https://github.com/serge-sans-paille/frozen/

5 years ago · e2799764c4
19 changed files with 2431 additions and 1 deletions
--- a/contrib/DEPENDENCY_INFO.md
+++ b/contrib/DEPENDENCY_INFO.md
@ -29,4 +29,5 @@
 | fpconv        | ?       | Boost               | YES     | many changes       |
 | fastutf8      | ?       | MIT                 | YES     | many changes       |
 | expected      | v1.0    | Public Domain / CC0 | NO      |                    |
-| robin-hood    | 3.9.1   | MIT                 | NO      |                    |
+| robin-hood    | 3.9.1   | MIT                 | NO      |                    |
+| frozen        | 1.0.1   | Apache 2            | NO      |                    |
--- a/contrib/frozen/AUTHORS
+++ b/contrib/frozen/AUTHORS
@ -0,0 +1,3 @@
+serge-sans-paille <sguelton@quarkslab.com>
+Jérôme Dumesnil <jerome.dumesnil@gmail.com>
+Chris Beck <chbeck@tesla.com>
--- a/contrib/frozen/CMakeLists.txt
+++ b/contrib/frozen/CMakeLists.txt
@ -0,0 +1,12 @@
+target_sources(frozen-headers INTERFACE
+  "${prefix}/frozen/algorithm.h"
+  "${prefix}/frozen/map.h"
+  "${prefix}/frozen/random.h"
+  "${prefix}/frozen/set.h"
+  "${prefix}/frozen/string.h"
+  "${prefix}/frozen/unordered_map.h"
+  "${prefix}/frozen/unordered_set.h"
+  "${prefix}/frozen/bits/algorithms.h"
+  "${prefix}/frozen/bits/basic_types.h"
+  "${prefix}/frozen/bits/elsa.h"
+  "${prefix}/frozen/bits/pmh.h")
--- a/contrib/frozen/LICENSE
+++ b/contrib/frozen/LICENSE
@ -0,0 +1,202 @@
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--- a/contrib/frozen/include/frozen/algorithm.h
+++ b/contrib/frozen/include/frozen/algorithm.h
@ -0,0 +1,197 @@
+/*
+ * Frozen
+ * Copyright 2016 QuarksLab
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+#ifndef FROZEN_LETITGO_ALGORITHM_H
+#define FROZEN_LETITGO_ALGORITHM_H
+
+#include "frozen/bits/basic_types.h"
+#include "frozen/bits/version.h"
+#include "frozen/string.h"
+
+namespace frozen {
+
+// 'search' implementation if C++17 is not available
+// https://en.cppreference.com/w/cpp/algorithm/search
+template<class ForwardIterator, class Searcher>
+ForwardIterator search(ForwardIterator first, ForwardIterator last, const Searcher & searcher)
+{
+  return searcher(first, last).first;
+}
+
+// text book implementation from
+// https://en.wikipedia.org/wiki/Knuth%E2%80%93Morris%E2%80%93Pratt_algorithm
+
+template <std::size_t size> class knuth_morris_pratt_searcher {
+  bits::carray<std::ptrdiff_t, size> step_;
+  bits::carray<char, size> needle_;
+
+  static constexpr bits::carray<std::ptrdiff_t, size>
+  build_kmp_cache(char const (&needle)[size + 1]) {
+    std::ptrdiff_t cnd = 0;
+    bits::carray<std::ptrdiff_t, size> cache;
+
+    cache.fill(-1);
+    for (std::size_t pos = 1; pos < size; ++pos) {
+      if (needle[pos] == needle[cnd]) {
+        cache[pos] = cache[cnd];
+        cnd += 1;
+      } else {
+        cache[pos] = cnd;
+        cnd = cache[cnd];
+        while (cnd >= 0 && needle[pos] != needle[cnd])
+          cnd = cache[cnd];
+        cnd += 1;
+      }
+    }
+    return cache;
+  }
+
+public:
+  constexpr knuth_morris_pratt_searcher(char const (&needle)[size + 1])
+    : step_{build_kmp_cache(needle)}, needle_(needle) {}
+
+  template <class ForwardIterator>
+  constexpr std::pair<ForwardIterator, ForwardIterator> operator()(ForwardIterator first, ForwardIterator last) const {
+    std::size_t i = 0;
+    ForwardIterator iter = first;
+    while (iter != last) {
+      if (needle_[i] == *iter) {
+        if (i == (size - 1))
+          return { iter - i, iter - i + size };
+        ++i;
+        ++iter;
+      } else {
+        if (step_[i] > -1) {
+          i = step_[i];
+        } else {
+          ++iter;
+          i = 0;
+        }
+      }
+    }
+    return { last, last };
+  }
+};
+
+template <std::size_t N>
+constexpr knuth_morris_pratt_searcher<N - 1> make_knuth_morris_pratt_searcher(char const (&needle)[N]) {
+  return {needle};
+}
+
+// text book implementation from
+// https://en.wikipedia.org/wiki/Boyer%E2%80%93Moore%E2%80%93Horspool_algorithm
+
+template <std::size_t size> class boyer_moore_searcher {
+  using skip_table_type = bits::carray<std::ptrdiff_t, sizeof(char) << 8>;
+  using suffix_table_type = bits::carray<std::ptrdiff_t, size>;
+
+  skip_table_type skip_table_;
+  suffix_table_type suffix_table_;
+  bits::carray<char, size> needle_;
+
+  constexpr auto build_skip_table(char const (&needle)[size + 1]) {
+    skip_table_type skip_table;
+
+    skip_table.fill(size);
+    for (std::size_t i = 0; i < size - 1; ++i)
+      skip_table[needle[i]] -= i + 1;
+    return skip_table;
+  }
+
+  constexpr bool is_prefix(char const (&needle)[size + 1], std::size_t pos) {
+    std::size_t suffixlen = size - pos;
+    
+    for (std::size_t i = 0; i < suffixlen; i++) {
+      if (needle[i] != needle[pos + i])
+        return false;
+    }
+    return true;
+  }
+
+  constexpr std::size_t suffix_length(char const (&needle)[size + 1],
+                                      std::size_t pos) {
+    // increment suffix length slen to the first mismatch or beginning
+    // of the word
+    for (std::size_t slen = 0; slen < pos ; slen++)
+      if (needle[pos - slen] != needle[size - 1 - slen])
+        return slen;
+
+    return pos;
+  }
+
+  constexpr auto build_suffix_table(char const (&needle)[size + 1]) {
+    suffix_table_type suffix;
+    std::ptrdiff_t last_prefix_index = size - 1;
+
+    // first loop
+    for (std::ptrdiff_t p = size - 1; p >= 0; p--) {
+      if (is_prefix(needle, p + 1))
+        last_prefix_index = p + 1;
+
+      suffix[p] = last_prefix_index + (size - 1 - p);
+    }
+
+    // second loop
+    for (std::size_t p = 0; p < size - 1; p++) {
+      auto slen = suffix_length(needle, p);
+      if (needle[p - slen] != needle[size - 1 - slen])
+        suffix[size - 1 - slen] = size - 1 - p + slen;
+
+    }
+    return suffix;
+  }
+
+public:
+  constexpr boyer_moore_searcher(char const (&needle)[size + 1])
+    : skip_table_{build_skip_table(needle)},
+      suffix_table_{build_suffix_table(needle)},
+      needle_(needle) {}
+
+  template <class ForwardIterator>
+  constexpr std::pair<ForwardIterator, ForwardIterator> operator()(ForwardIterator first, ForwardIterator last) const {
+    if (size == 0)
+      return { first, first + size };
+
+    ForwardIterator iter = first + size - 1;
+    while (iter < last) {
+      std::ptrdiff_t j = size - 1;
+      while (j > 0 && (*iter == needle_[j])) {
+        --iter;
+        --j;
+      }
+      if (*iter == needle_[0])
+        return { iter, iter + size};
+
+      iter += std::max(skip_table_[*iter], suffix_table_[j]);
+    }
+    return { last, last + size};
+  }
+};
+
+template <std::size_t N>
+constexpr boyer_moore_searcher<N - 1> make_boyer_moore_searcher(char const (&needle)[N]) {
+  return {needle};
+}
+
+} // namespace frozen
+
+#endif
--- a/contrib/frozen/include/frozen/bits/algorithms.h
+++ b/contrib/frozen/include/frozen/bits/algorithms.h
@ -0,0 +1,229 @@
+/*
+ * Frozen
+ * Copyright 2016 QuarksLab
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+#ifndef FROZEN_LETITGO_BITS_ALGORITHMS_H
+#define FROZEN_LETITGO_BITS_ALGORITHMS_H
+
+#include "frozen/bits/basic_types.h"
+
+#include <limits>
+#include <tuple>
+
+namespace frozen {
+
+namespace bits {
+
+auto constexpr next_highest_power_of_two(std::size_t v) {
+  // https://graphics.stanford.edu/~seander/bithacks.html#RoundUpPowerOf2
+  constexpr auto trip_count = std::numeric_limits<decltype(v)>::digits;
+  v--;
+  for(std::size_t i = 1; i < trip_count; i <<= 1)
+    v |= v >> i;
+  v++;
+  return v;
+}
+
+template<class T>
+auto constexpr log(T v) {
+  std::size_t n = 0;
+  while (v > 1) {
+    n += 1;
+    v >>= 1;
+  }
+  return n;
+}
+
+constexpr std::size_t bit_weight(std::size_t n) {
+  return (n <= 8*sizeof(unsigned int))
+    + (n <= 8*sizeof(unsigned long))
+    + (n <= 8*sizeof(unsigned long long))
+    + (n <= 128);
+}
+
+unsigned int select_uint_least(std::integral_constant<std::size_t, 4>);
+unsigned long select_uint_least(std::integral_constant<std::size_t, 3>);
+unsigned long long select_uint_least(std::integral_constant<std::size_t, 2>);
+template<std::size_t N>
+unsigned long long select_uint_least(std::integral_constant<std::size_t, N>) {
+  static_assert(N < 2, "unsupported type size");
+  return {};
+}
+
+
+template<std::size_t N>
+using select_uint_least_t = decltype(select_uint_least(std::integral_constant<std::size_t, bit_weight(N)>()));
+
+template <typename Iter, typename Compare>
+constexpr auto min_element(Iter begin, const Iter end,
+                           Compare const &compare) {
+  auto result = begin;
+  while (begin != end) {
+    if (compare(*begin, *result)) {
+      result = begin;
+    }
+    ++begin;
+  }
+  return result;
+}
+
+template <class T>
+constexpr void cswap(T &a, T &b) {
+  auto tmp = a;
+  a = b;
+  b = tmp;
+}
+
+template <class T, class U>
+constexpr void cswap(std::pair<T, U> & a, std::pair<T, U> & b) {
+  cswap(a.first, b.first);
+  cswap(a.second, b.second);
+}
+
+template <class... Tys, std::size_t... Is>
+constexpr void cswap(std::tuple<Tys...> &a, std::tuple<Tys...> &b, std::index_sequence<Is...>) {
+  using swallow = int[];
+  (void) swallow{(cswap(std::get<Is>(a), std::get<Is>(b)), 0)...};
+}
+
+template <class... Tys>
+constexpr void cswap(std::tuple<Tys...> &a, std::tuple<Tys...> &b) {
+  cswap(a, b, std::make_index_sequence<sizeof...(Tys)>());
+}
+
+template <typename Iterator, class Compare>
+constexpr Iterator partition(Iterator left, Iterator right, Compare const &compare) {
+  auto pivot = left + (right - left) / 2;
+  auto value = *pivot;
+  cswap(*right, *pivot);
+  for (auto it = left; 0 < right - it; ++it) {
+    if (compare(*it, value)) {
+      cswap(*it, *left);
+      left++;
+    }
+  }
+  cswap(*right, *left);
+  return left;
+}
+
+template <typename Iterator, class Compare>
+constexpr void quicksort(Iterator left, Iterator right, Compare const &compare) {
+  while (0 < right - left) {
+    auto new_pivot = bits::partition(left, right, compare);
+    quicksort(left, new_pivot, compare);
+    left = new_pivot + 1;
+  }
+}
+
+template <typename T, std::size_t N, class Compare>
+constexpr bits::carray<T, N> quicksort(bits::carray<T, N> const &array,
+                                     Compare const &compare) {
+  bits::carray<T, N> res = array;
+  quicksort(res.begin(), res.end() - 1, compare);
+  return res;
+}
+
+template <class T, class Compare> struct LowerBound {
+  T const &value_;
+  Compare const &compare_;
+  constexpr LowerBound(T const &value, Compare const &compare)
+      : value_(value), compare_(compare) {}
+
+  template <class ForwardIt>
+  inline constexpr ForwardIt doit_fast(ForwardIt first,
+                                  std::integral_constant<std::size_t, 0>) {
+    return first;
+  }
+
+  template <class ForwardIt, std::size_t N>
+  inline constexpr ForwardIt doit_fast(ForwardIt first,
+                                  std::integral_constant<std::size_t, N>) {
+    auto constexpr step = N / 2;
+    static_assert(N/2 == N - N / 2 - 1, "power of two minus 1");
+    auto it = first + step;
+    auto next_it = compare_(*it, value_) ? it + 1 : first;
+    return doit_fast(next_it, std::integral_constant<std::size_t, N / 2>{});
+  }
+
+  template <class ForwardIt, std::size_t N>
+  inline constexpr ForwardIt doitfirst(ForwardIt first, std::integral_constant<std::size_t, N>, std::integral_constant<bool, true>) {
+    return doit_fast(first, std::integral_constant<std::size_t, N>{});
+  }
+
+  template <class ForwardIt, std::size_t N>
+  inline constexpr ForwardIt doitfirst(ForwardIt first, std::integral_constant<std::size_t, N>, std::integral_constant<bool, false>) {
+    auto constexpr next_power = next_highest_power_of_two(N);
+    auto constexpr next_start = next_power / 2 - 1;
+    auto it = first + next_start;
+    if (compare_(*it, value_)) {
+      auto constexpr next = N - next_start - 1;
+      return doitfirst(it + 1, std::integral_constant<std::size_t, next>{}, std::integral_constant<bool, next_highest_power_of_two(next) - 1 == next>{});
+    }
+    else
+      return doit_fast(first, std::integral_constant<std::size_t, next_start>{});
+  }
+
+  template <class ForwardIt>
+  inline constexpr ForwardIt doitfirst(ForwardIt first, std::integral_constant<std::size_t, 1>, std::integral_constant<bool, false>) {
+    return doit_fast(first, std::integral_constant<std::size_t, 1>{});
+  }
+};
+
+template <std::size_t N, class ForwardIt, class T, class Compare>
+constexpr ForwardIt lower_bound(ForwardIt first, const T &value, Compare const &compare) {
+  return LowerBound<T, Compare>{value, compare}.doitfirst(first, std::integral_constant<std::size_t, N>{}, std::integral_constant<bool, next_highest_power_of_two(N) - 1 == N>{});
+}
+
+template <std::size_t N, class Compare, class ForwardIt, class T>
+constexpr bool binary_search(ForwardIt first, const T &value,
+                             Compare const &compare) {
+  ForwardIt where = lower_bound<N>(first, value, compare);
+  return (!(where == first + N) && !(compare(value, *where)));
+}
+
+
+template<class InputIt1, class InputIt2>
+constexpr bool equal(InputIt1 first1, InputIt1 last1, InputIt2 first2)
+{
+  for (; first1 != last1; ++first1, ++first2) {
+    if (!(*first1 == *first2)) {
+      return false;
+    }
+  }
+  return true;
+}
+
+template<class InputIt1, class InputIt2>
+constexpr bool lexicographical_compare(InputIt1 first1, InputIt1 last1, InputIt2 first2, InputIt2 last2)
+{
+  for (; (first1 != last1) && (first2 != last2); ++first1, ++first2) {
+    if (*first1 < *first2)
+      return true;
+    if (*first2 < *first1)
+      return false;
+  }
+  return (first1 == last1) && (first2 != last2);
+}
+
+} // namespace bits
+} // namespace frozen
+
+#endif
--- a/contrib/frozen/include/frozen/bits/basic_types.h
+++ b/contrib/frozen/include/frozen/bits/basic_types.h
@ -0,0 +1,200 @@
+/*
+ * Frozen
+ * Copyright 2016 QuarksLab
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+#ifndef FROZEN_LETITGO_BASIC_TYPES_H
+#define FROZEN_LETITGO_BASIC_TYPES_H
+
+#include "frozen/bits/exceptions.h"
+
+#include <utility>
+#include <iterator>
+#include <string>
+
+namespace frozen {
+
+namespace bits {
+
+// used as a fake argument for frozen::make_set and frozen::make_map in the case of N=0
+struct ignored_arg {};
+
+template <class T, std::size_t N>
+class cvector {
+  T data [N] = {}; // zero-initialization for scalar type T, default-initialized otherwise
+  std::size_t dsize = 0;
+
+public:
+  // Container typdefs
+  using value_type = T;
+  using reference = value_type &;
+  using const_reference = const value_type &;
+  using pointer = value_type *;
+  using const_pointer = const value_type *;
+  using iterator = pointer;
+  using const_iterator = const_pointer;
+  using size_type = std::size_t;
+  using difference_type = std::ptrdiff_t;
+
+  // Constructors
+  constexpr cvector(void) = default;
+  constexpr cvector(size_type count, const T& value) : dsize(count) {
+    for (std::size_t i = 0; i < N; ++i)
+      data[i] = value;
+  }
+
+  // Iterators
+  constexpr iterator begin() noexcept { return data; }
+  constexpr iterator end() noexcept { return data + dsize; }
+
+  // Capacity
+  constexpr size_type size() const { return dsize; }
+
+  // Element access
+  constexpr       reference operator[](std::size_t index) { return data[index]; }
+  constexpr const_reference operator[](std::size_t index) const { return data[index]; }
+
+  constexpr       reference back() { return data[dsize - 1]; }
+  constexpr const_reference back() const { return data[dsize - 1]; }
+
+  // Modifiers
+  constexpr void push_back(const T & a) { data[dsize++] = a; }
+  constexpr void push_back(T && a) { data[dsize++] = std::move(a); }
+  constexpr void pop_back() { --dsize; }
+
+  constexpr void clear() { dsize = 0; }
+};
+
+template <class T, std::size_t N>
+class carray {
+  T data_ [N] = {}; // zero-initialization for scalar type T, default-initialized otherwise
+
+  template <std::size_t M, std::size_t... I>
+  constexpr carray(T const (&init)[M], std::index_sequence<I...>)
+      : data_{init[I]...} {}
+  template <class Iter, std::size_t... I>
+  constexpr carray(Iter iter, std::index_sequence<I...>)
+      : data_{((void)I, *iter++)...} {}
+
+public:
+  // Container typdefs
+  using value_type = T;
+  using reference = value_type &;
+  using const_reference = const value_type &;
+  using pointer = value_type *;
+  using const_pointer = const value_type *;
+  using iterator = pointer;
+  using const_iterator = const_pointer;
+  using reverse_iterator = std::reverse_iterator<iterator>;
+  using const_reverse_iterator = std::reverse_iterator<const_iterator>;
+  using size_type = std::size_t;
+  using difference_type = std::ptrdiff_t;
+
+  // Constructors
+  constexpr carray(void) = default;
+  template <std::size_t M>
+  constexpr carray(T const (&init)[M])
+    : carray(init, std::make_index_sequence<N>())
+  {
+    static_assert(M >= N, "Cannot initialize a carray with an smaller array");
+  }
+  constexpr carray(std::initializer_list<T> init)
+    : carray(init.begin(), std::make_index_sequence<N>())
+  {
+    // clang & gcc doesn't recognize init.size() as a constexpr
+    // static_assert(init.size() >= N, "Cannot initialize a carray with an smaller initializer list");
+  }
+
+  // Iterators
+  constexpr iterator begin() noexcept { return data_; }
+  constexpr const_iterator begin() const noexcept { return data_; }
+  constexpr const_iterator cbegin() const noexcept { return data_; }
+  constexpr iterator end() noexcept { return data_ + N; }
+  constexpr const_iterator end() const noexcept { return data_ + N; }
+  constexpr const_iterator cend() const noexcept { return data_ + N; }
+
+  constexpr reverse_iterator rbegin() noexcept { return reverse_iterator(end()); }
+  constexpr const_reverse_iterator rbegin() const noexcept { return const_reverse_iterator(end()); }
+  constexpr const_reverse_iterator crbegin() const noexcept { return const_reverse_iterator(end()); }
+  constexpr reverse_iterator rend() noexcept { return reverse_iterator(begin()); }
+  constexpr const_reverse_iterator rend() const noexcept { return const_reverse_iterator(begin()); }
+  constexpr const_reverse_iterator crend() const noexcept { return const_reverse_iterator(begin()); }
+
+  // Capacity
+  constexpr size_type size() const { return N; }
+  constexpr size_type max_size() const { return N; }
+
+  // Element access
+  constexpr       reference operator[](std::size_t index) { return data_[index]; }
+  constexpr const_reference operator[](std::size_t index) const { return data_[index]; }
+
+  constexpr       reference at(std::size_t index) {
+    if (index > N)
+      FROZEN_THROW_OR_ABORT(std::out_of_range("Index (" + std::to_string(index) + ") out of bound (" + std::to_string(N) + ')'));
+    return data_[index];
+  }
+  constexpr const_reference at(std::size_t index) const {
+    if (index > N)
+      FROZEN_THROW_OR_ABORT(std::out_of_range("Index (" + std::to_string(index) + ") out of bound (" + std::to_string(N) + ')'));
+    return data_[index];
+  }
+
+  constexpr       reference front() { return data_[0]; }
+  constexpr const_reference front() const { return data_[0]; }
+
+  constexpr       reference back() { return data_[N - 1]; }
+  constexpr const_reference back() const { return data_[N - 1]; }
+
+  constexpr       value_type* data() noexcept { return data_; }
+  constexpr const value_type* data() const noexcept { return data_; }
+
+  // Modifiers
+  constexpr void fill(const value_type& val) {
+    for (std::size_t i = 0; i < N; ++i)
+      data_[i] = val;
+  }
+};
+template <class T>
+class carray<T, 0> {
+
+public:
+  // Container typdefs
+  using value_type = T;
+  using reference = value_type &;
+  using const_reference = const value_type &;
+  using pointer = value_type *;
+  using const_pointer = const value_type *;
+  using iterator = pointer;
+  using const_iterator = const_pointer;
+  using reverse_iterator = std::reverse_iterator<iterator>;
+  using const_reverse_iterator = std::reverse_iterator<const_iterator>;
+  using size_type = std::size_t;
+  using difference_type = std::ptrdiff_t;
+
+  // Constructors
+  constexpr carray(void) = default;
+
+};
+
+} // namespace bits
+
+} // namespace frozen
+
+#endif
--- a/contrib/frozen/include/frozen/bits/constexpr_assert.h
+++ b/contrib/frozen/include/frozen/bits/constexpr_assert.h
@ -0,0 +1,40 @@
+/*
+ * Frozen
+ * Copyright 2016 QuarksLab
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+#ifndef FROZEN_LETITGO_CONSTEXPR_ASSERT_H
+#define FROZEN_LETITGO_CONSTEXPR_ASSERT_H
+
+#include <cassert>
+
+#ifdef _MSC_VER
+
+// FIXME: find a way to implement that correctly for msvc
+#define constexpr_assert(cond, msg)
+
+#else
+
+#define constexpr_assert(cond, msg)\
+    assert(cond && msg);
+#endif
+
+#endif
+
--- a/contrib/frozen/include/frozen/bits/defines.h
+++ b/contrib/frozen/include/frozen/bits/defines.h
@ -0,0 +1,58 @@
+/*
+ * Frozen
+ * Copyright 2016 QuarksLab
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+#ifndef FROZEN_LETITGO_DEFINES_H
+#define FROZEN_LETITGO_DEFINES_H
+
+#if defined(_MSVC_LANG) && !(defined(__EDG__) && defined(__clang__)) // TRANSITION, VSO#273681
+  #define FROZEN_LETITGO_IS_MSVC
+#endif
+
+// Code taken from https://stackoverflow.com/questions/43639122/which-values-can-msvc-lang-have
+#if defined(FROZEN_LETITGO_IS_MSVC)
+  #if _MSVC_LANG > 201402
+    #define FROZEN_LETITGO_HAS_CXX17  1
+  #else /* _MSVC_LANG > 201402 */
+    #define FROZEN_LETITGO_HAS_CXX17  0
+  #endif /* _MSVC_LANG > 201402 */
+#else /* _MSVC_LANG etc. */
+  #if __cplusplus > 201402
+    #define FROZEN_LETITGO_HAS_CXX17  1
+  #else /* __cplusplus > 201402 */
+    #define FROZEN_LETITGO_HAS_CXX17  0
+  #endif /* __cplusplus > 201402 */
+#endif /* _MSVC_LANG etc. */
+// End if taken code
+
+#if FROZEN_LETITGO_HAS_CXX17 == 1 && defined(FROZEN_LETITGO_IS_MSVC)
+  #define FROZEN_LETITGO_HAS_STRING_VIEW // We assume Visual Studio always has string_view in C++17
+#else
+  #if FROZEN_LETITGO_HAS_CXX17 == 1 && __has_include(<string_view>)
+    #define FROZEN_LETITGO_HAS_STRING_VIEW
+  #endif
+#endif
+
+#ifdef __cpp_char8_t
+  #define FROZEN_LETITGO_HAS_CHAR8T
+#endif
+
+#endif // FROZEN_LETITGO_DEFINES_H
--- a/contrib/frozen/include/frozen/bits/elsa.h
+++ b/contrib/frozen/include/frozen/bits/elsa.h
@ -0,0 +1,50 @@
+/*
+ * Frozen
+ * Copyright 2016 QuarksLab
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+#ifndef FROZEN_LETITGO_ELSA_H
+#define FROZEN_LETITGO_ELSA_H
+
+#include <type_traits>
+
+namespace frozen {
+
+template <class T> struct elsa {
+  static_assert(std::is_integral<T>::value || std::is_enum<T>::value,
+                "only supports integral types, specialize for other types");
+
+  constexpr std::size_t operator()(T const &value, std::size_t seed) const {
+    std::size_t key = seed ^ static_cast<std::size_t>(value);
+    key = (~key) + (key << 21); // key = (key << 21) - key - 1;
+    key = key ^ (key >> 24);
+    key = (key + (key << 3)) + (key << 8); // key * 265
+    key = key ^ (key >> 14);
+    key = (key + (key << 2)) + (key << 4); // key * 21
+    key = key ^ (key >> 28);
+    key = key + (key << 31);
+    return key;
+  }
+};
+
+template <class T> using anna = elsa<T>;
+} // namespace frozen
+
+#endif
--- a/contrib/frozen/include/frozen/bits/exceptions.h
+++ b/contrib/frozen/include/frozen/bits/exceptions.h
@ -0,0 +1,39 @@
+/*
+ * Frozen
+ * Copyright 2016 QuarksLab
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+#ifndef FROZEN_LETITGO_EXCEPTIONS_H
+#define FROZEN_LETITGO_EXCEPTIONS_H
+
+#if defined(FROZEN_NO_EXCEPTIONS) || (defined(_MSC_VER) && !defined(_CPPUNWIND)) || (!defined(_MSC_VER) && !defined(__cpp_exceptions))
+
+#include <cstdlib>
+#define FROZEN_THROW_OR_ABORT(_) std::abort()
+
+#else
+
+#include <stdexcept>
+#define FROZEN_THROW_OR_ABORT(err) throw err
+
+
+#endif
+
+#endif
--- a/contrib/frozen/include/frozen/bits/pmh.h
+++ b/contrib/frozen/include/frozen/bits/pmh.h
@ -0,0 +1,240 @@
+/*
+ * Frozen
+ * Copyright 2016 QuarksLab
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+// inspired from http://stevehanov.ca/blog/index.php?id=119
+#ifndef FROZEN_LETITGO_PMH_H
+#define FROZEN_LETITGO_PMH_H
+
+#include "frozen/bits/algorithms.h"
+#include "frozen/bits/basic_types.h"
+
+#include <array>
+#include <limits>
+
+namespace frozen {
+
+namespace bits {
+
+// Function object for sorting buckets in decreasing order of size
+struct bucket_size_compare {
+  template <typename B>
+  bool constexpr operator()(B const &b0,
+                            B const &b1) const {
+    return b0.size() > b1.size();
+  }
+};
+
+// Step One in pmh routine is to take all items and hash them into buckets,
+// with some collisions. Then process those buckets further to build a perfect
+// hash function.
+// pmh_buckets represents the initial placement into buckets.
+
+template <size_t M>
+struct pmh_buckets {
+  // Step 0: Bucket max is 2 * sqrt M
+  // TODO: Come up with justification for this, should it not be O(log M)?
+  static constexpr auto bucket_max = 2 * (1u << (log(M) / 2));
+
+  using bucket_t = cvector<std::size_t, bucket_max>;
+  carray<bucket_t, M> buckets;
+  uint64_t seed;
+
+  // Represents a reference to a bucket. This is used because the buckets
+  // have to be sorted, but buckets are big, making it slower than sorting refs
+  struct bucket_ref {
+    unsigned hash;
+    const bucket_t * ptr;
+
+    // Forward some interface of bucket
+    using value_type = typename bucket_t::value_type;
+    using const_iterator = typename bucket_t::const_iterator;
+
+    constexpr auto size() const { return ptr->size(); }
+    constexpr const auto & operator[](std::size_t idx) const { return (*ptr)[idx]; }
+    constexpr auto begin() const { return ptr->begin(); }
+    constexpr auto end() const { return ptr->end(); }
+  };
+
+  // Make a bucket_ref for each bucket
+  template <std::size_t... Is>
+  carray<bucket_ref, M> constexpr make_bucket_refs(std::index_sequence<Is...>) const {
+    return {{ bucket_ref{Is, &buckets[Is]}... }};
+  }
+
+  // Makes a bucket_ref for each bucket and sorts them by size
+  carray<bucket_ref, M> constexpr get_sorted_buckets() const {
+    carray<bucket_ref, M> result{this->make_bucket_refs(std::make_index_sequence<M>())};
+    bits::quicksort(result.begin(), result.end() - 1, bucket_size_compare{});
+    return result;
+  }
+};
+
+template <size_t M, class Item, size_t N, class Hash, class Key, class PRG>
+pmh_buckets<M> constexpr make_pmh_buckets(const carray<Item, N> & items,
+                                Hash const & hash,
+                                Key const & key,
+                                PRG & prg) {
+  using result_t = pmh_buckets<M>;
+  result_t result{};
+  bool rejected = false;
+  // Continue until all items are placed without exceeding bucket_max
+  while (1) {
+    for (auto & b : result.buckets) {
+      b.clear();
+    }
+    result.seed = prg();
+    rejected = false;
+    for (std::size_t i = 0; i < N; ++i) {
+      auto & bucket = result.buckets[hash(key(items[i]), static_cast<size_t>(result.seed)) % M];
+      if (bucket.size() >= result_t::bucket_max) {
+        rejected = true;
+        break;
+      }
+      bucket.push_back(i);
+    }
+    if (!rejected) { return result; }
+  }
+}
+
+// Check if an item appears in a cvector
+template<class T, size_t N>
+constexpr bool all_different_from(cvector<T, N> & data, T & a) {
+  for (std::size_t i = 0; i < data.size(); ++i)
+    if (data[i] == a)
+      return false;
+
+  return true;
+}
+
+// Represents either an index to a data item array, or a seed to be used with
+// a hasher. Seed must have high bit of 1, value has high bit of zero.
+struct seed_or_index {
+  using value_type = uint64_t;
+
+private:
+  static constexpr value_type MINUS_ONE = std::numeric_limits<value_type>::max();
+  static constexpr value_type HIGH_BIT = ~(MINUS_ONE >> 1);
+
+  value_type value_ = 0;
+
+public:
+  constexpr value_type value() const { return value_; }
+  constexpr bool is_seed() const { return value_ & HIGH_BIT; }
+
+  constexpr seed_or_index(bool is_seed, value_type value)
+    : value_(is_seed ? (value | HIGH_BIT) : (value & ~HIGH_BIT)) {}
+
+  constexpr seed_or_index() = default;
+  constexpr seed_or_index(const seed_or_index &) = default;
+  constexpr seed_or_index & operator =(const seed_or_index &) = default;
+};
+
+// Represents the perfect hash function created by pmh algorithm
+template <std::size_t M, class Hasher>
+struct pmh_tables {
+  uint64_t first_seed_;
+  carray<seed_or_index, M> first_table_;
+  carray<std::size_t, M> second_table_;
+  Hasher hash_;
+
+  // Looks up a given key, to find its expected index in carray<Item, N>
+  // Always returns a valid index, must use KeyEqual test after to confirm.
+  template <typename KeyType>
+  constexpr std::size_t lookup(const KeyType & key) const {
+    auto const d = first_table_[hash_(key, static_cast<size_t>(first_seed_)) % M];
+    if (!d.is_seed()) { return static_cast<std::size_t>(d.value()); } // this is narrowing uint64 -> size_t but should be fine
+    else { return second_table_[hash_(key, static_cast<std::size_t>(d.value())) % M]; }
+  }
+};
+
+// Make pmh tables for given items, hash function, prg, etc.
+template <std::size_t M, class Item, std::size_t N, class Hash, class Key, class PRG>
+pmh_tables<M, Hash> constexpr make_pmh_tables(const carray<Item, N> &
+                                                               items,
+                                                           Hash const &hash,
+                                                           Key const &key,
+                                                           PRG prg) {
+  // Step 1: Place all of the keys into buckets
+  auto step_one = make_pmh_buckets<M>(items, hash, key, prg);
+
+  // Step 2: Sort the buckets to process the ones with the most items first.
+  auto buckets = step_one.get_sorted_buckets();
+
+  // G becomes the first hash table in the resulting pmh function
+  carray<seed_or_index, M> G; // Default constructed to "index 0"
+
+  // H becomes the second hash table in the resulting pmh function
+  constexpr std::size_t UNUSED = std::numeric_limits<std::size_t>::max();
+  carray<std::size_t, M> H;
+  H.fill(UNUSED);
+
+  // Step 3: Map the items in buckets into hash tables.
+  for (const auto & bucket : buckets) {
+    auto const bsize = bucket.size();
+
+    if (bsize == 1) {
+      // Store index to the (single) item in G
+      // assert(bucket.hash == hash(key(items[bucket[0]]), step_one.seed) % M);
+      G[bucket.hash] = {false, static_cast<uint64_t>(bucket[0])};
+    } else if (bsize > 1) {
+
+      // Repeatedly try different H of d until we find a hash function
+      // that places all items in the bucket into free slots
+      seed_or_index d{true, prg()};
+      cvector<std::size_t, decltype(step_one)::bucket_max> bucket_slots;
+
+      while (bucket_slots.size() < bsize) {
+        auto slot = hash(key(items[bucket[bucket_slots.size()]]), static_cast<size_t>(d.value())) % M;
+
+        if (H[slot] != UNUSED || !all_different_from(bucket_slots, slot)) {
+          bucket_slots.clear();
+          d = {true, prg()};
+          continue;
+        }
+
+        bucket_slots.push_back(slot);
+      }
+
+      // Put successful seed in G, and put indices to items in their slots
+      // assert(bucket.hash == hash(key(items[bucket[0]]), step_one.seed) % M);
+      G[bucket.hash] = d;
+      for (std::size_t i = 0; i < bsize; ++i)
+        H[bucket_slots[i]] = bucket[i];
+    }
+  }
+
+  // Any unused entries in the H table have to get changed to zero.
+  // This is because hashing should not fail or return an out-of-bounds entry.
+  // A lookup fails after we apply user-supplied KeyEqual to the query and the
+  // key found by hashing. Sending such queries to zero cannot hurt.
+  for (std::size_t i = 0; i < M; ++i)
+    if (H[i] == UNUSED)
+      H[i] = 0;
+
+  return {step_one.seed, G, H, hash};
+}
+
+} // namespace bits
+
+} // namespace frozen
+
+#endif
--- a/contrib/frozen/include/frozen/bits/version.h
+++ b/contrib/frozen/include/frozen/bits/version.h
@ -0,0 +1,30 @@
+/*
+ * Frozen
+ * Copyright 2016 QuarksLab
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+#ifndef FROZEN_LETITGO_VERSION_H
+#define FROZEN_LETITGO_VERSION_H
+
+#define FROZEN_MAJOR_VERSION 1
+#define FROZEN_MINOR_VERSION 0
+#define FROZEN_PATCH_VERSION 1
+
+#endif
--- a/contrib/frozen/include/frozen/map.h
+++ b/contrib/frozen/include/frozen/map.h
@ -0,0 +1,323 @@
+/*
+ * Frozen
+ * Copyright 2016 QuarksLab
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+#ifndef FROZEN_LETITGO_MAP_H
+#define FROZEN_LETITGO_MAP_H
+
+#include "frozen/bits/algorithms.h"
+#include "frozen/bits/basic_types.h"
+#include "frozen/bits/constexpr_assert.h"
+#include "frozen/bits/exceptions.h"
+#include "frozen/bits/version.h"
+
+#include <utility>
+
+namespace frozen {
+
+namespace impl {
+
+template <class Comparator> class CompareKey {
+
+  Comparator const comparator_;
+
+public:
+  constexpr CompareKey(Comparator const &comparator)
+      : comparator_(comparator) {}
+
+  template <class Key, class Value>
+  constexpr int operator()(std::pair<Key, Value> const &self,
+                           std::pair<Key, Value> const &other) const {
+    return comparator_(std::get<0>(self), std::get<0>(other));
+  }
+
+  template <class Key, class Value>
+  constexpr int operator()(Key const &self_key,
+                           std::pair<Key, Value> const &other) const {
+    return comparator_(self_key, std::get<0>(other));
+  }
+
+  template <class Key, class Value>
+  constexpr int operator()(std::pair<Key, Value> const &self,
+                           Key const &other_key) const {
+    return comparator_(std::get<0>(self), other_key);
+  }
+
+  template <class Key>
+  constexpr int operator()(Key const &self_key, Key const &other_key) const {
+    return comparator_(self_key, other_key);
+  }
+};
+
+} // namespace impl
+
+template <class Key, class Value, std::size_t N, class Compare = std::less<Key>>
+class map {
+  using container_type = bits::carray<std::pair<Key, Value>, N>;
+  impl::CompareKey<Compare> less_than_;
+  container_type items_;
+
+public:
+  using key_type = Key;
+  using mapped_type = Value;
+  using value_type = typename container_type::value_type;
+  using size_type = typename container_type::size_type;
+  using difference_type = typename container_type::difference_type;
+  using key_compare = decltype(less_than_);
+  using reference = typename container_type::reference;
+  using const_reference = typename container_type::const_reference;
+  using pointer = typename container_type::pointer;
+  using const_pointer = typename container_type::const_pointer;
+  using iterator = typename container_type::iterator;
+  using const_iterator = typename container_type::const_iterator;
+  using reverse_iterator = typename container_type::reverse_iterator;
+  using const_reverse_iterator =
+      typename container_type::const_reverse_iterator;
+
+public:
+  /* constructors */
+  constexpr map(container_type items, Compare const &compare)
+      : less_than_{compare}
+      , items_{bits::quicksort(items, less_than_)} {}
+
+  explicit constexpr map(container_type items)
+      : map{items, Compare{}} {}
+
+  constexpr map(std::initializer_list<value_type> items, Compare const &compare)
+      : map{container_type {items}, compare} {
+        constexpr_assert(items.size() == N, "Inconsistent initializer_list size and type size argument");
+      }
+
+  constexpr map(std::initializer_list<value_type> items)
+      : map{items, Compare{}} {}
+
+  /* element access */
+  constexpr Value const& at(Key const &key) const {
+    return at_impl(*this, key);
+  }
+  constexpr Value& at(Key const &key) {
+    return at_impl(*this, key);
+  }
+
+  /* iterators */
+  constexpr iterator begin() { return items_.begin(); }
+  constexpr const_iterator begin() const { return items_.begin(); }
+  constexpr const_iterator cbegin() const { return items_.cbegin(); }
+  constexpr iterator end() { return items_.end(); }
+  constexpr const_iterator end() const { return items_.end(); }
+  constexpr const_iterator cend() const { return items_.cend(); }
+
+  constexpr reverse_iterator rbegin() { return items_.rbegin(); }
+  constexpr const_reverse_iterator rbegin() const { return items_.rbegin(); }
+  constexpr const_reverse_iterator crbegin() const { return items_.crbegin(); }
+  constexpr reverse_iterator rend() { return items_.rend(); }
+  constexpr const_reverse_iterator rend() const { return items_.rend(); }
+  constexpr const_reverse_iterator crend() const { return items_.crend(); }
+
+  /* capacity */
+  constexpr bool empty() const { return !N; }
+  constexpr size_type size() const { return N; }
+  constexpr size_type max_size() const { return N; }
+
+  /* lookup */
+
+  constexpr std::size_t count(Key const &key) const {
+    return bits::binary_search<N>(items_.begin(), key, less_than_);
+  }
+
+  constexpr const_iterator find(Key const &key) const {
+    return find_impl(*this, key);
+  }
+  constexpr iterator find(Key const &key) {
+    return find_impl(*this, key);
+  }
+
+  constexpr std::pair<const_iterator, const_iterator>
+  equal_range(Key const &key) const {
+    return equal_range_impl(*this, key);
+  }
+  constexpr std::pair<iterator, iterator> equal_range(Key const &key) {
+    return equal_range_impl(*this, key);
+  }
+
+  constexpr const_iterator lower_bound(Key const &key) const {
+    return lower_bound_impl(*this, key);
+  }
+  constexpr iterator lower_bound(Key const &key) {
+    return lower_bound_impl(*this, key);
+  }
+
+  constexpr const_iterator upper_bound(Key const &key) const {
+    return upper_bound_impl(*this, key);
+  }
+  constexpr iterator upper_bound(Key const &key) {
+    return upper_bound_impl(*this, key);
+  }
+
+  /* observers */
+  constexpr key_compare key_comp() const { return less_than_; }
+  constexpr key_compare value_comp() const { return less_than_; }
+
+ private:
+  template <class This>
+  static inline constexpr auto& at_impl(This&& self, Key const &key) {
+    auto where = self.lower_bound(key);
+    if (where != self.end())
+      return where->second;
+    else
+      FROZEN_THROW_OR_ABORT(std::out_of_range("unknown key"));
+  }
+
+  template <class This>
+  static inline constexpr auto find_impl(This&& self, Key const &key) {
+    auto where = self.lower_bound(key);
+    if ((where != self.end()) && !self.less_than_(key, *where))
+      return where;
+    else
+      return self.end();
+  }
+
+  template <class This>
+  static inline constexpr auto equal_range_impl(This&& self, Key const &key) {
+    auto lower = self.lower_bound(key);
+    using lower_t = decltype(lower);
+    if (lower == self.end())
+      return std::pair<lower_t, lower_t>{lower, lower};
+    else
+      return std::pair<lower_t, lower_t>{lower, lower + 1};
+  }
+
+  template <class This>
+  static inline constexpr auto lower_bound_impl(This&& self, Key const &key) -> decltype(self.end()) {
+    auto where = bits::lower_bound<N>(self.items_.begin(), key, self.less_than_);
+    if ((where != self.end()) && !self.less_than_(key, *where))
+      return where;
+    else
+      return self.end();
+  }
+
+  template <class This>
+  static inline constexpr auto upper_bound_impl(This&& self, Key const &key) -> decltype(self.end()) {
+    auto where = bits::lower_bound<N>(self.items_.begin(), key, self.less_than_);
+    if ((where != self.end()) && !self.less_than_(key, *where))
+      return where + 1;
+    else
+      return self.end();
+  }
+};
+
+template <class Key, class Value, class Compare>
+class map<Key, Value, 0, Compare> {
+  using container_type = bits::carray<std::pair<Key, Value>, 0>;
+  impl::CompareKey<Compare> less_than_;
+
+public:
+  using key_type = Key;
+  using mapped_type = Value;
+  using value_type = typename container_type::value_type;
+  using size_type = typename container_type::size_type;
+  using difference_type = typename container_type::difference_type;
+  using key_compare = decltype(less_than_);
+  using reference = typename container_type::reference;
+  using const_reference = typename container_type::const_reference;
+  using pointer = typename container_type::pointer;
+  using const_pointer = typename container_type::const_pointer;
+  using iterator = pointer;
+  using const_iterator = const_pointer;
+  using reverse_iterator = pointer;
+  using const_reverse_iterator = const_pointer;
+
+public:
+  /* constructors */
+  constexpr map(const map &other) = default;
+  constexpr map(std::initializer_list<value_type>, Compare const &compare)
+      : less_than_{compare} {}
+  constexpr map(std::initializer_list<value_type> items)
+      : map{items, Compare{}} {}
+
+  /* element access */
+  constexpr mapped_type at(Key const &) const {
+    FROZEN_THROW_OR_ABORT(std::out_of_range("invalid key"));
+  }
+  constexpr mapped_type at(Key const &) {
+    FROZEN_THROW_OR_ABORT(std::out_of_range("invalid key"));
+  }
+
+  /* iterators */
+  constexpr iterator begin() { return nullptr; }
+  constexpr const_iterator begin() const { return nullptr; }
+  constexpr const_iterator cbegin() const { return nullptr; }
+  constexpr iterator end() { return nullptr; }
+  constexpr const_iterator end() const { return nullptr; }
+  constexpr const_iterator cend() const { return nullptr; }
+
+  constexpr reverse_iterator rbegin() { return nullptr; }
+  constexpr const_reverse_iterator rbegin() const { return nullptr; }
+  constexpr const_reverse_iterator crbegin() const { return nullptr; }
+  constexpr reverse_iterator rend() { return nullptr; }
+  constexpr const_reverse_iterator rend() const { return nullptr; }
+  constexpr const_reverse_iterator crend() const { return nullptr; }
+
+  /* capacity */
+  constexpr bool empty() const { return true; }
+  constexpr size_type size() const { return 0; }
+  constexpr size_type max_size() const { return 0; }
+
+  /* lookup */
+
+  constexpr std::size_t count(Key const &) const { return 0; }
+
+  constexpr const_iterator find(Key const &) const { return end(); }
+  constexpr iterator find(Key const &) { return end(); }
+
+  constexpr std::pair<const_iterator, const_iterator>
+  equal_range(Key const &) const {
+    return {end(), end()};
+  }
+  constexpr std::pair<iterator, iterator>
+  equal_range(Key const &) {
+    return {end(), end()};
+  }
+
+  constexpr const_iterator lower_bound(Key const &) const { return end(); }
+  constexpr iterator lower_bound(Key const &) { return end(); }
+
+  constexpr const_iterator upper_bound(Key const &) const { return end(); }
+  constexpr iterator upper_bound(Key const &) { return end(); }
+
+  /* observers */
+  constexpr key_compare key_comp() const { return less_than_; }
+  constexpr key_compare value_comp() const { return less_than_; }
+};
+
+template <typename T, typename U>
+constexpr auto make_map(bits::ignored_arg = {}/* for consistency with the initializer below for N = 0*/) {
+  return map<T, U, 0>{};
+}
+
+template <typename T, typename U, std::size_t N>
+constexpr auto make_map(std::pair<T, U> const (&items)[N]) {
+  return map<T, U, N>{items};
+}
+
+} // namespace frozen
+
+#endif
--- a/contrib/frozen/include/frozen/random.h
+++ b/contrib/frozen/include/frozen/random.h
@ -0,0 +1,90 @@
+/*
+ * Frozen
+ * Copyright 2016 QuarksLab
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+#ifndef FROZEN_LETITGO_RANDOM_H
+#define FROZEN_LETITGO_RANDOM_H
+
+#include "frozen/bits/algorithms.h"
+#include "frozen/bits/version.h"
+
+#include <cstdint>
+#include <type_traits>
+
+namespace frozen {
+template <class UIntType, UIntType a, UIntType c, UIntType m>
+class linear_congruential_engine {
+
+  static_assert(std::is_unsigned<UIntType>::value,
+                "UIntType must be an unsigned integral type");
+
+public:
+  using result_type = UIntType;
+  static constexpr result_type multiplier = a;
+  static constexpr result_type increment = c;
+  static constexpr result_type modulus = m;
+  static constexpr result_type default_seed = 1u;
+
+  linear_congruential_engine() = default;
+  constexpr linear_congruential_engine(result_type s) { seed(s); }
+
+  void seed(result_type s = default_seed) { state_ = s; }
+  constexpr result_type operator()() {
+	  using uint_least_t = bits::select_uint_least_t<bits::log(a) + bits::log(m) + 4>;
+    uint_least_t tmp = static_cast<uint_least_t>(multiplier) * state_ + increment;
+
+    // the static cast below may end up doing a truncation
+    if(modulus != 0)
+      state_ = static_cast<result_type>(tmp % modulus);
+    else
+      state_ = static_cast<result_type>(tmp);
+    return state_;
+  }
+  constexpr void discard(unsigned long long n) {
+    while (n--)
+      operator()();
+  }
+  static constexpr result_type min() { return increment == 0u ? 1u : 0u; };
+  static constexpr result_type max() { return modulus - 1u; };
+  friend constexpr bool operator==(linear_congruential_engine const &self,
+                                   linear_congruential_engine const &other) {
+    return self.state_ == other.state_;
+  }
+  friend constexpr bool operator!=(linear_congruential_engine const &self,
+                                   linear_congruential_engine const &other) {
+    return !(self == other);
+  }
+
+private:
+  result_type state_ = default_seed;
+};
+
+using minstd_rand0 =
+    linear_congruential_engine<std::uint_fast32_t, 16807, 0, 2147483647>;
+using minstd_rand =
+    linear_congruential_engine<std::uint_fast32_t, 48271, 0, 2147483647>;
+
+// This generator is used by default in unordered frozen containers
+using default_prg_t = minstd_rand;
+
+} // namespace frozen
+
+#endif
--- a/contrib/frozen/include/frozen/set.h
+++ b/contrib/frozen/include/frozen/set.h
@ -0,0 +1,220 @@
+/*
+ * Frozen
+ * Copyright 2016 QuarksLab
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+#ifndef FROZEN_SET_H
+#define FROZEN_SET_H
+
+#include "frozen/bits/algorithms.h"
+#include "frozen/bits/basic_types.h"
+#include "frozen/bits/constexpr_assert.h"
+#include "frozen/bits/version.h"
+
+#include <utility>
+
+namespace frozen {
+
+template <class Key, std::size_t N, class Compare = std::less<Key>> class set {
+  using container_type = bits::carray<Key, N>;
+  Compare less_than_;
+  container_type keys_;
+
+public:
+  /* container typedefs*/
+  using key_type = Key;
+  using value_type = Key;
+  using size_type = typename container_type::size_type;
+  using difference_type = typename container_type::size_type;
+  using key_compare = Compare;
+  using value_compare = Compare;
+  using reference = typename container_type::const_reference;
+  using const_reference = reference;
+  using pointer = typename container_type::const_pointer;
+  using const_pointer = pointer;
+  using iterator = typename container_type::const_iterator;
+  using reverse_iterator = typename container_type::const_reverse_iterator;
+  using const_iterator = iterator;
+  using const_reverse_iterator = reverse_iterator;
+
+public:
+  /* constructors */
+  constexpr set(const set &other) = default;
+
+  constexpr set(container_type keys, Compare const & comp)
+      : less_than_{comp}
+      , keys_(bits::quicksort(keys, less_than_)) {
+      }
+
+  explicit constexpr set(container_type keys)
+      : set{keys, Compare{}} {}
+
+  constexpr set(std::initializer_list<Key> keys, Compare const & comp)
+      : set{container_type{keys}, comp} {
+        constexpr_assert(keys.size() == N, "Inconsistent initializer_list size and type size argument");
+      }
+
+  constexpr set(std::initializer_list<Key> keys)
+      : set{keys, Compare{}} {}
+
+  /* capacity */
+  constexpr bool empty() const { return !N; }
+  constexpr size_type size() const { return N; }
+  constexpr size_type max_size() const { return N; }
+
+  /* lookup */
+  constexpr std::size_t count(Key const &key) const {
+    return bits::binary_search<N>(keys_.begin(), key, less_than_);
+  }
+
+  constexpr const_iterator find(Key const &key) const {
+    const_iterator where = lower_bound(key);
+    if ((where != end()) && !less_than_(key, *where))
+      return where;
+    else
+      return end();
+  }
+
+  constexpr std::pair<const_iterator, const_iterator> equal_range(Key const &key) const {
+    auto const lower = lower_bound(key);
+    if (lower == end())
+      return {lower, lower};
+    else
+      return {lower, lower + 1};
+  }
+
+  constexpr const_iterator lower_bound(Key const &key) const {
+    auto const where = bits::lower_bound<N>(keys_.begin(), key, less_than_);
+    if ((where != end()) && !less_than_(key, *where))
+      return where;
+    else
+      return end();
+  }
+
+  constexpr const_iterator upper_bound(Key const &key) const {
+    auto const where = bits::lower_bound<N>(keys_.begin(), key, less_than_);
+    if ((where != end()) && !less_than_(key, *where))
+      return where + 1;
+    else
+      return end();
+  }
+
+  /* observers */
+  constexpr key_compare key_comp() const { return less_than_; }
+  constexpr key_compare value_comp() const { return less_than_; }
+
+  /* iterators */
+  constexpr const_iterator begin() const { return keys_.begin(); }
+  constexpr const_iterator cbegin() const { return keys_.cbegin(); }
+  constexpr const_iterator end() const { return keys_.end(); }
+  constexpr const_iterator cend() const { return keys_.cend(); }
+
+  constexpr const_reverse_iterator rbegin() const { return keys_.rbegin(); }
+  constexpr const_reverse_iterator crbegin() const { return keys_.crbegin(); }
+  constexpr const_reverse_iterator rend() const { return keys_.rend(); }
+  constexpr const_reverse_iterator crend() const { return keys_.crend(); }
+
+  /* comparison */
+  constexpr bool operator==(set const& rhs) const { return bits::equal(begin(), end(), rhs.begin()); }
+  constexpr bool operator!=(set const& rhs) const { return !(*this == rhs); }
+  constexpr bool operator<(set const& rhs) const { return bits::lexicographical_compare(begin(), end(), rhs.begin(), rhs.end()); }
+  constexpr bool operator<=(set const& rhs) const { return (*this < rhs) || (*this == rhs); }
+  constexpr bool operator>(set const& rhs) const { return bits::lexicographical_compare(rhs.begin(), rhs.end(), begin(), end()); }
+  constexpr bool operator>=(set const& rhs) const { return (*this > rhs) || (*this == rhs); }
+};
+
+template <class Key, class Compare> class set<Key, 0, Compare> {
+  using container_type = bits::carray<Key, 0>; // just for the type definitions
+  Compare less_than_;
+
+public:
+  /* container typedefs*/
+  using key_type = Key;
+  using value_type = Key;
+  using size_type = typename container_type::size_type;
+  using difference_type = typename container_type::size_type;
+  using key_compare = Compare;
+  using value_compare = Compare;
+  using reference = typename container_type::const_reference;
+  using const_reference = reference;
+  using pointer = typename container_type::const_pointer;
+  using const_pointer = pointer;
+  using iterator = pointer;
+  using reverse_iterator = pointer;
+  using const_iterator = const_pointer;
+  using const_reverse_iterator = const_pointer;
+
+public:
+  /* constructors */
+  constexpr set(const set &other) = default;
+  constexpr set(bits::carray<Key, 0>, Compare const &) {}
+  explicit constexpr set(bits::carray<Key, 0>) {}
+
+  constexpr set(std::initializer_list<Key>, Compare const &comp)
+      : less_than_{comp} {}
+  constexpr set(std::initializer_list<Key> keys) : set{keys, Compare{}} {}
+
+  /* capacity */
+  constexpr bool empty() const { return true; }
+  constexpr size_type size() const { return 0; }
+  constexpr size_type max_size() const { return 0; }
+
+  /* lookup */
+  constexpr std::size_t count(Key const &) const { return 0; }
+
+  constexpr const_iterator find(Key const &) const { return end(); }
+
+  constexpr std::pair<const_iterator, const_iterator>
+  equal_range(Key const &) const { return {end(), end()}; }
+
+  constexpr const_iterator lower_bound(Key const &) const { return end(); }
+
+  constexpr const_iterator upper_bound(Key const &) const { return end(); }
+
+  /* observers */
+  constexpr key_compare key_comp() const { return less_than_; }
+  constexpr key_compare value_comp() const { return less_than_; }
+
+  /* iterators */
+  constexpr const_iterator begin() const { return nullptr; }
+  constexpr const_iterator cbegin() const { return nullptr; }
+  constexpr const_iterator end() const { return nullptr; }
+  constexpr const_iterator cend() const { return nullptr; }
+
+  constexpr const_reverse_iterator rbegin() const { return nullptr; }
+  constexpr const_reverse_iterator crbegin() const { return nullptr; }
+  constexpr const_reverse_iterator rend() const { return nullptr; }
+  constexpr const_reverse_iterator crend() const { return nullptr; }
+};
+
+template <typename T>
+constexpr auto make_set(bits::ignored_arg = {}/* for consistency with the initializer below for N = 0*/) {
+  return set<T, 0>{};
+}
+
+template <typename T, std::size_t N>
+constexpr auto make_set(const T (&args)[N]) {
+  return set<T, N>(args);
+}
+
+
+} // namespace frozen
+
+#endif
--- a/contrib/frozen/include/frozen/string.h
+++ b/contrib/frozen/include/frozen/string.h
@ -0,0 +1,152 @@
+/*
+ * Frozen
+ * Copyright 2016 QuarksLab
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+#ifndef FROZEN_LETITGO_STRING_H
+#define FROZEN_LETITGO_STRING_H
+
+#include "frozen/bits/elsa.h"
+#include "frozen/bits/version.h"
+#include "frozen/bits/defines.h"
+
+#include <functional>
+
+#ifdef FROZEN_LETITGO_HAS_STRING_VIEW
+#include <string_view>
+#endif
+
+namespace frozen {
+
+template <typename _CharT>
+class basic_string {
+  using chr_t = _CharT;
+
+  chr_t const *data_;
+  std::size_t size_;
+
+public:
+  template <std::size_t N>
+  constexpr basic_string(chr_t const (&data)[N])
+      : data_(data), size_(N - 1) {}
+  constexpr basic_string(chr_t const *data, std::size_t size)
+      : data_(data), size_(size) {}
+
+#ifdef FROZEN_LETITGO_HAS_STRING_VIEW
+  constexpr basic_string(std::basic_string_view<chr_t> data)
+      : data_(data.data()), size_(data.size()) {}
+#endif
+
+  constexpr basic_string(const basic_string &) noexcept = default;
+  constexpr basic_string &operator=(const basic_string &) noexcept = default;
+
+  constexpr std::size_t size() const { return size_; }
+
+  constexpr chr_t operator[](std::size_t i) const { return data_[i]; }
+
+  constexpr bool operator==(basic_string other) const {
+    if (size_ != other.size_)
+      return false;
+    for (std::size_t i = 0; i < size_; ++i)
+      if (data_[i] != other.data_[i])
+        return false;
+    return true;
+  }
+
+  constexpr bool operator<(const basic_string &other) const {
+    unsigned i = 0;
+    while (i < size() && i < other.size()) {
+      if ((*this)[i] < other[i]) {
+        return true;
+      }
+      if ((*this)[i] > other[i]) {
+        return false;
+      }
+      ++i;
+    }
+    return size() < other.size();
+  }
+
+  constexpr const chr_t *data() const { return data_; }
+};
+
+template <typename _CharT> struct elsa<basic_string<_CharT>> {
+  constexpr std::size_t operator()(basic_string<_CharT> value) const {
+    std::size_t d = 5381;
+    for (std::size_t i = 0; i < value.size(); ++i)
+      d = d * 33 + value[i];
+    return d;
+  }
+  // https://en.wikipedia.org/wiki/Fowler%E2%80%93Noll%E2%80%93Vo_hash_function
+  // With the lowest bits removed, based on experimental setup.
+  constexpr std::size_t operator()(basic_string<_CharT> value, std::size_t seed) const {
+    std::size_t d =  (0x811c9dc5 ^ seed) * 0x01000193;
+    for (std::size_t i = 0; i < value.size(); ++i)
+      d = (d ^ value[i]) * 0x01000193;
+    return d >> 8 ;
+  }
+};
+
+using string = basic_string<char>;
+using wstring = basic_string<wchar_t>;
+using u16string = basic_string<char16_t>;
+using u32string = basic_string<char32_t>;
+
+#ifdef FROZEN_LETITGO_HAS_CHAR8T
+using u8string = basic_string<char8_t>;
+#endif
+
+namespace string_literals {
+
+constexpr string operator"" _s(const char *data, std::size_t size) {
+  return {data, size};
+}
+
+constexpr wstring operator"" _s(const wchar_t *data, std::size_t size) {
+  return {data, size};
+}
+
+constexpr u16string operator"" _s(const char16_t *data, std::size_t size) {
+  return {data, size};
+}
+
+constexpr u32string operator"" _s(const char32_t *data, std::size_t size) {
+  return {data, size};
+}
+
+#ifdef FROZEN_LETITGO_HAS_CHAR8T
+constexpr u8string operator"" _s(const char8_t *data, std::size_t size) {
+  return {data, size};
+}
+#endif
+
+} // namespace string_literals
+
+} // namespace frozen
+
+namespace std {
+template <typename _CharT> struct hash<frozen::basic_string<_CharT>> {
+  size_t operator()(frozen::basic_string<_CharT> s) const {
+    return frozen::elsa<frozen::basic_string<_CharT>>{}(s);
+  }
+};
+} // namespace std
+
+#endif
--- a/contrib/frozen/include/frozen/unordered_map.h
+++ b/contrib/frozen/include/frozen/unordered_map.h
@ -0,0 +1,197 @@
+/*
+ * Frozen
+ * Copyright 2016 QuarksLab
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+#ifndef FROZEN_LETITGO_UNORDERED_MAP_H
+#define FROZEN_LETITGO_UNORDERED_MAP_H
+
+#include "frozen/bits/basic_types.h"
+#include "frozen/bits/constexpr_assert.h"
+#include "frozen/bits/elsa.h"
+#include "frozen/bits/exceptions.h"
+#include "frozen/bits/pmh.h"
+#include "frozen/bits/version.h"
+#include "frozen/random.h"
+
+#include <tuple>
+#include <functional>
+
+namespace frozen {
+
+namespace bits {
+
+struct GetKey {
+  template <class KV> constexpr auto const &operator()(KV const &kv) const {
+    return kv.first;
+  }
+};
+
+} // namespace bits
+
+template <class Key, class Value, std::size_t N, typename Hash = anna<Key>,
+          class KeyEqual = std::equal_to<Key>>
+class unordered_map {
+  static constexpr std::size_t storage_size =
+      bits::next_highest_power_of_two(N) * (N < 32 ? 2 : 1); // size adjustment to prevent high collision rate for small sets
+  using container_type = bits::carray<std::pair<Key, Value>, N>;
+  using tables_type = bits::pmh_tables<storage_size, Hash>;
+
+  KeyEqual const equal_;
+  container_type items_;
+  tables_type tables_;
+
+public:
+  /* typedefs */
+  using Self = unordered_map<Key, Value, N, Hash, KeyEqual>;
+  using key_type = Key;
+  using mapped_type = Value;
+  using value_type = typename container_type::value_type;
+  using size_type = typename container_type::size_type;
+  using difference_type = typename container_type::difference_type;
+  using hasher = Hash;
+  using key_equal = KeyEqual;
+  using reference = typename container_type::reference;
+  using const_reference = typename container_type::const_reference;
+  using pointer = typename container_type::pointer;
+  using const_pointer = typename container_type::const_pointer;
+  using iterator = typename container_type::iterator;
+  using const_iterator = typename container_type::const_iterator;
+
+public:
+  /* constructors */
+  unordered_map(unordered_map const &) = default;
+  constexpr unordered_map(container_type items,
+                          Hash const &hash, KeyEqual const &equal)
+      : equal_{equal}
+      , items_{items}
+      , tables_{
+            bits::make_pmh_tables<storage_size>(
+                items_, hash, bits::GetKey{}, default_prg_t{})} {}
+  explicit constexpr unordered_map(container_type items)
+      : unordered_map{items, Hash{}, KeyEqual{}} {}
+
+  constexpr unordered_map(std::initializer_list<value_type> items,
+                          Hash const & hash, KeyEqual const & equal)
+      : unordered_map{container_type{items}, hash, equal} {
+        constexpr_assert(items.size() == N, "Inconsistent initializer_list size and type size argument");
+      }
+
+  constexpr unordered_map(std::initializer_list<value_type> items)
+      : unordered_map{items, Hash{}, KeyEqual{}} {}
+
+  /* iterators */
+  constexpr iterator begin() { return items_.begin(); }
+  constexpr iterator end() { return items_.end(); }
+  constexpr const_iterator begin() const { return items_.begin(); }
+  constexpr const_iterator end() const { return items_.end(); }
+  constexpr const_iterator cbegin() const { return items_.cbegin(); }
+  constexpr const_iterator cend() const { return items_.cend(); }
+
+  /* capacity */
+  constexpr bool empty() const { return !N; }
+  constexpr size_type size() const { return N; }
+  constexpr size_type max_size() const { return N; }
+
+  /* lookup */
+  constexpr std::size_t count(Key const &key) const {
+    auto const &kv = lookup(key);
+    return equal_(kv.first, key);
+  }
+
+  constexpr Value const &at(Key const &key) const {
+    return at_impl(*this, key);
+  }
+  constexpr Value &at(Key const &key) {
+    return at_impl(*this, key);
+  }
+
+  constexpr const_iterator find(Key const &key) const {
+    return find_impl(*this, key);
+  }
+  constexpr iterator find(Key const &key) {
+    return find_impl(*this, key);
+  }
+
+  constexpr std::pair<const_iterator, const_iterator> equal_range(Key const &key) const {
+    return equal_range_impl(*this, key);
+  }
+  constexpr std::pair<iterator, iterator> equal_range(Key const &key) {
+    return equal_range_impl(*this, key);
+  }
+
+  /* bucket interface */
+  constexpr std::size_t bucket_count() const { return storage_size; }
+  constexpr std::size_t max_bucket_count() const { return storage_size; }
+
+  /* observers*/
+  constexpr hasher hash_function() const { return tables_.hash_; }
+  constexpr key_equal key_eq() const { return equal_; }
+
+private:
+  template <class This>
+  static inline constexpr auto& at_impl(This&& self, Key const &key) {
+    auto& kv = self.lookup(key);
+    if (self.equal_(kv.first, key))
+      return kv.second;
+    else
+      FROZEN_THROW_OR_ABORT(std::out_of_range("unknown key"));
+  }
+
+  template <class This>
+  static inline constexpr auto find_impl(This&& self, Key const &key) {
+    auto& kv = self.lookup(key);
+    if (self.equal_(kv.first, key))
+      return &kv;
+    else
+      return self.items_.end();
+  }
+
+  template <class This>
+  static inline constexpr auto equal_range_impl(This&& self, Key const &key) {
+    auto& kv = self.lookup(key);
+    using kv_ptr = decltype(&kv);
+    if (self.equal_(kv.first, key))
+      return std::pair<kv_ptr, kv_ptr>{&kv, &kv + 1};
+    else
+      return std::pair<kv_ptr, kv_ptr>{self.items_.end(), self.items_.end()};
+  }
+
+  template <class This>
+  static inline constexpr auto& lookup_impl(This&& self, Key const &key) {
+    return self.items_[self.tables_.lookup(key)];
+  }
+
+  constexpr auto const& lookup(Key const &key) const {
+    return lookup_impl(*this, key);
+  }
+  constexpr auto& lookup(Key const &key) {
+    return lookup_impl(*this, key);
+  }
+};
+
+template <typename T, typename U, std::size_t N>
+constexpr auto make_unordered_map(std::pair<T, U> const (&items)[N]) {
+  return unordered_map<T, U, N>{items};
+}
+
+} // namespace frozen
+
+#endif
--- a/contrib/frozen/include/frozen/unordered_set.h
+++ b/contrib/frozen/include/frozen/unordered_set.h
@ -0,0 +1,147 @@
+/*
+ * Frozen
+ * Copyright 2016 QuarksLab
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+#ifndef FROZEN_LETITGO_UNORDERED_SET_H
+#define FROZEN_LETITGO_UNORDERED_SET_H
+
+#include "frozen/bits/basic_types.h"
+#include "frozen/bits/constexpr_assert.h"
+#include "frozen/bits/elsa.h"
+#include "frozen/bits/pmh.h"
+#include "frozen/bits/version.h"
+#include "frozen/random.h"
+
+#include <utility>
+
+namespace frozen {
+
+namespace bits {
+
+struct Get {
+  template <class T> constexpr T const &operator()(T const &key) const {
+    return key;
+  }
+};
+
+} // namespace bits
+
+template <class Key, std::size_t N, typename Hash = elsa<Key>,
+          class KeyEqual = std::equal_to<Key>>
+class unordered_set {
+  static constexpr std::size_t storage_size =
+      bits::next_highest_power_of_two(N) * (N < 32 ? 2 : 1); // size adjustment to prevent high collision rate for small sets
+  using container_type = bits::carray<Key, N>;
+  using tables_type = bits::pmh_tables<storage_size, Hash>;
+
+  KeyEqual const equal_;
+  container_type keys_;
+  tables_type tables_;
+
+public:
+  /* typedefs */
+  using key_type = Key;
+  using value_type = Key;
+  using size_type = typename container_type::size_type;
+  using difference_type = typename container_type::difference_type;
+  using hasher = Hash;
+  using key_equal = KeyEqual;
+  using const_reference = typename container_type::const_reference;
+  using reference = const_reference;
+  using const_pointer = typename container_type::const_pointer;
+  using pointer = const_pointer;
+  using const_iterator = const_pointer;
+  using iterator = const_iterator;
+
+public:
+  /* constructors */
+  unordered_set(unordered_set const &) = default;
+  constexpr unordered_set(container_type keys, Hash const &hash,
+                          KeyEqual const &equal)
+      : equal_{equal}
+      , keys_{keys}
+      , tables_{bits::make_pmh_tables<storage_size>(
+            keys_, hash, bits::Get{}, default_prg_t{})} {}
+  explicit constexpr unordered_set(container_type keys)
+      : unordered_set{keys, Hash{}, KeyEqual{}} {}
+
+  constexpr unordered_set(std::initializer_list<Key> keys)
+      : unordered_set{keys, Hash{}, KeyEqual{}} {}
+
+  constexpr unordered_set(std::initializer_list<Key> keys, Hash const & hash, KeyEqual const & equal)
+      : unordered_set{container_type{keys}, hash, equal} {
+        constexpr_assert(keys.size() == N, "Inconsistent initializer_list size and type size argument");
+      }
+
+  /* iterators */
+  constexpr const_iterator begin() const { return keys_.begin(); }
+  constexpr const_iterator end() const { return keys_.end(); }
+  constexpr const_iterator cbegin() const { return keys_.cbegin(); }
+  constexpr const_iterator cend() const { return keys_.cend(); }
+
+  /* capacity */
+  constexpr bool empty() const { return !N; }
+  constexpr size_type size() const { return N; }
+  constexpr size_type max_size() const { return N; }
+
+  /* lookup */
+  constexpr std::size_t count(Key const &key) const {
+    auto const k = lookup(key);
+    return equal_(k, key);
+  }
+  constexpr const_iterator find(Key const &key) const {
+    auto const &k = lookup(key);
+    if (equal_(k, key))
+      return &k;
+    else
+      return keys_.end();
+  }
+
+  constexpr std::pair<const_iterator, const_iterator> equal_range(Key const &key) const {
+    auto const &k = lookup(key);
+    if (equal_(k, key))
+      return {&k, &k + 1};
+    else
+      return {keys_.end(), keys_.end()};
+  }
+
+  /* bucket interface */
+  constexpr std::size_t bucket_count() const { return storage_size; }
+  constexpr std::size_t max_bucket_count() const { return storage_size; }
+
+  /* observers*/
+  constexpr hasher hash_function() const { return tables_.hash_; }
+  constexpr key_equal key_eq() const { return equal_; }
+
+private:
+  constexpr auto const &lookup(Key const &key) const {
+    return keys_[tables_.lookup(key)];
+  }
+};
+
+template <typename T, std::size_t N>
+constexpr auto make_unordered_set(T const (&keys)[N]) {
+  return unordered_set<T, N>{keys};
+}
+
+} // namespace frozen
+
+#endif