Merge pull request #8661

f50b9e3 revisions (koe) e5aa058 vtnerd review comments (koe)
c60b11f add compare_func() method so user-defined comparison functions are easier to use (koe)
7329873 adjust is_sorted_and_unique() (koe)
3d60475 comment updates (koe) acfaaed add container helpers (koe)

src/common/container_helpers.h

@@ -0,0 +1,170 @@
+// Copyright (c) 2022, The Monero Project
+//
+// All rights reserved.
+//
+// Redistribution and use in source and binary forms, with or without modification, are
+// permitted provided that the following conditions are met:
+//
+// 1. Redistributions of source code must retain the above copyright notice, this list of
+//    conditions and the following disclaimer.
+//
+// 2. Redistributions in binary form must reproduce the above copyright notice, this list
+//    of conditions and the following disclaimer in the documentation and/or other
+//    materials provided with the distribution.
+//
+// 3. Neither the name of the copyright holder nor the names of its contributors may be
+//    used to endorse or promote products derived from this software without specific
+//    prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY
+// EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
+// MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
+// THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+// PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+// STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
+// THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+// Miscellaneous container helpers.
+
+#pragma once
+
+//local headers
+
+//third party headers
+
+//standard headers
+#include <algorithm>
+#include <unordered_map>
+#include <utility>
+
+//forward declarations
+
+
+namespace tools
+{
+
+/// convert an arbitrary function to functor
+template <typename F>
+inline auto as_functor(F f)
+{
+    return [f = std::move(f)](auto&&... args) { return f(std::forward<decltype(args)>(args)...); };
+}
+/// convert a binary comparison function to a functor
+/// note: for most use-cases 'const T&' will work because only non-trivial types need a user-defined comparison operation
+template <typename T, typename ComparisonOpT = bool(const T&, const T&)>
+inline auto compare_func(ComparisonOpT comparison_op_func)
+{
+    static_assert(
+            std::is_same<
+                    bool,
+                    decltype(
+                        comparison_op_func(
+                            std::declval<std::remove_cv_t<T>>(),
+                            std::declval<std::remove_cv_t<T>>()
+                        )
+                    )
+                >::value,
+            "invalid callable - expected callable in form bool(T, T)"
+        );
+
+    return as_functor(std::move(comparison_op_func));
+}
+/// test if a container is sorted and unique according to a comparison criteria (defaults to operator<)
+/// NOTE: ComparisonOpT must establish 'strict weak ordering' https://en.cppreference.com/w/cpp/named_req/Compare
+template <typename T, typename ComparisonOpT = std::less<typename T::value_type>>
+bool is_sorted_and_unique(const T &container, ComparisonOpT comparison_op = ComparisonOpT{})
+{
+    using ValueT = typename T::value_type;
+    static_assert(
+            std::is_same<
+                    bool,
+                    decltype(
+                        comparison_op(
+                            std::declval<std::remove_cv_t<ValueT>>(),
+                            std::declval<std::remove_cv_t<ValueT>>()
+                        )
+                    )
+                >::value,
+            "invalid callable - expected callable in form bool(ValueT, ValueT)"
+        );
+
+    if (!std::is_sorted(container.begin(), container.end(), comparison_op))
+        return false;
+
+    if (std::adjacent_find(container.begin(),
+                container.end(),
+                [comparison_op = std::move(comparison_op)](const ValueT &a, const ValueT &b) -> bool
+                {
+                    return !comparison_op(a, b) && !comparison_op(b, a);
+                })
+            != container.end())
+        return false;
+
+    return true;
+}
+/// specialization for raw function pointers
+template <typename T>
+bool is_sorted_and_unique(const T &container,
+    bool (*const comparison_op_func)(const typename T::value_type&, const typename T::value_type&))
+{
+    return is_sorted_and_unique(container, compare_func<typename T::value_type>(comparison_op_func));
+}
+/// convenience wrapper for checking if the key to a mapped object is correct for that object
+/// example: std::unorderd_map<rct::key, std::pair<rct::key, rct::xmr_amount>> where the map key is supposed to
+///   reproduce the pair's rct::key; use the predicate to check that relationship
+template <typename KeyT, typename ValueT, typename PredT>
+bool keys_match_internal_values(const std::unordered_map<KeyT, ValueT> &map, PredT check_key_func)
+{
+    static_assert(
+            std::is_same<
+                    bool,
+                    decltype(
+                        check_key_func(
+                            std::declval<std::remove_cv_t<KeyT>>(),
+                            std::declval<std::remove_cv_t<ValueT>>()
+                        )
+                    )
+                >::value,
+            "invalid callable - expected callable in form bool(KeyT, ValueT)"
+        );
+
+    for (const auto &map_element : map)
+    {
+        if (!check_key_func(map_element.first, map_element.second))
+            return false;
+    }
+
+    return true;
+}
+/// convenience wrapper for getting the last element after emplacing back
+template <typename ContainerT>
+typename ContainerT::value_type& add_element(ContainerT &container)
+{
+    container.emplace_back();
+    return container.back();
+}
+/// convenience erasor for unordered maps: std::erase_if(std::unordered_map) is C++20
+template <typename KeyT, typename ValueT, typename PredT>
+void for_all_in_map_erase_if(std::unordered_map<KeyT, ValueT> &map_inout, PredT predicate)
+{
+    using MapValueT = typename std::unordered_map<KeyT, ValueT>::value_type;
+    static_assert(
+            std::is_same<
+                    bool,
+                    decltype(predicate(std::declval<std::remove_cv_t<MapValueT>>()))
+                >::value,
+            "invalid callable - expected callable in form bool(Value)"
+        );
+
+    for (auto map_it = map_inout.begin(); map_it != map_inout.end();)
+    {
+        if (predicate(*map_it))
+            map_it = map_inout.erase(map_it);
+        else
+            ++map_it;
+    }
+}
+
+} //namespace tools