Export of internal Abseil changes

--
2130ba98c8359b08d97fb16d84dfd05687005dcf by Abseil Team <absl-team@google.com>:

Tweaking the documentation of c_all_of to state the effect more directly.

PiperOrigin-RevId: 410557900

--
4732289bf4b56123fed113e36be4710b55c6a6c7 by Greg Falcon <gfalcon@google.com>:

Improve the quality of absl::Hash<std::vector<bool>>.

This previously dispatched to std::hash<vector<bool>>, which suffers from trivial collisions on many platforms.  (They often hash the internal words but no size info, so that, e.g., {1, 1} and {1, 1, 0} collide.)

Also extended the unit test to exercise this.

PiperOrigin-RevId: 410329943

--
1c5f3934230a7669f74c96b305251786a265e235 by Greg Falcon <gfalcon@google.com>:

Add broader testing of absl hash contracts in the hash unit test.

In particular, test that the hash erasure mechanism works.

PiperOrigin-RevId: 410312738

--
5e1923f527ed3d02f6752a5b38d5e1c17a4a146f by Derek Mauro <dmauro@google.com>:

Internal change

PiperOrigin-RevId: 410290663

--
8c74bc962b3b98a5908017c345efc592393048ea by Martijn Vels <mvels@google.com>:

Add Cord::CreateFlat() function

PiperOrigin-RevId: 410260776

--
bd0de4e94c85620d3b8dd60fae367b730fc4cb34 by Evan Brown <ezb@google.com>:

Rename node_hash_policy to node_slot_policy.

Motivation: we can potentially reuse this code for node_btree_*.
PiperOrigin-RevId: 410082271
GitOrigin-RevId: 2130ba98c8359b08d97fb16d84dfd05687005dcf
Change-Id: Ie052084cf992dee250d8b2f388d39c4de0dcff40

1 files changed, 92 insertions, 0 deletions

diff --git a/absl/container/internal/node_slot_policy.h b/absl/container/internal/node_slot_policy.h
new file mode 100644
index 00000000..baba5743
--- /dev/null
+++ b/absl/container/internal/node_slot_policy.h
@@ -0,0 +1,92 @@
+// Copyright 2018 The Abseil Authors.
+//
+// Licensed 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
+//
+//      https://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.
+//
+// Adapts a policy for nodes.
+//
+// The node policy should model:
+//
+// struct Policy {
+//   // Returns a new node allocated and constructed using the allocator, using
+//   // the specified arguments.
+//   template <class Alloc, class... Args>
+//   value_type* new_element(Alloc* alloc, Args&&... args) const;
+//
+//   // Destroys and deallocates node using the allocator.
+//   template <class Alloc>
+//   void delete_element(Alloc* alloc, value_type* node) const;
+// };
+//
+// It may also optionally define `value()` and `apply()`. For documentation on
+// these, see hash_policy_traits.h.
+
+#ifndef ABSL_CONTAINER_INTERNAL_NODE_SLOT_POLICY_H_
+#define ABSL_CONTAINER_INTERNAL_NODE_SLOT_POLICY_H_
+
+#include <cassert>
+#include <cstddef>
+#include <memory>
+#include <type_traits>
+#include <utility>
+
+#include "absl/base/config.h"
+
+namespace absl {
+ABSL_NAMESPACE_BEGIN
+namespace container_internal {
+
+template <class Reference, class Policy>
+struct node_slot_policy {
+  static_assert(std::is_lvalue_reference<Reference>::value, "");
+
+  using slot_type = typename std::remove_cv<
+      typename std::remove_reference<Reference>::type>::type*;
+
+  template <class Alloc, class... Args>
+  static void construct(Alloc* alloc, slot_type* slot, Args&&... args) {
+    *slot = Policy::new_element(alloc, std::forward<Args>(args)...);
+  }
+
+  template <class Alloc>
+  static void destroy(Alloc* alloc, slot_type* slot) {
+    Policy::delete_element(alloc, *slot);
+  }
+
+  template <class Alloc>
+  static void transfer(Alloc*, slot_type* new_slot, slot_type* old_slot) {
+    *new_slot = *old_slot;
+  }
+
+  static size_t space_used(const slot_type* slot) {
+    if (slot == nullptr) return Policy::element_space_used(nullptr);
+    return Policy::element_space_used(*slot);
+  }
+
+  static Reference element(slot_type* slot) { return **slot; }
+
+  template <class T, class P = Policy>
+  static auto value(T* elem) -> decltype(P::value(elem)) {
+    return P::value(elem);
+  }
+
+  template <class... Ts, class P = Policy>
+  static auto apply(Ts&&... ts) -> decltype(P::apply(std::forward<Ts>(ts)...)) {
+    return P::apply(std::forward<Ts>(ts)...);
+  }
+};
+
+}  // namespace container_internal
+ABSL_NAMESPACE_END
+}  // namespace absl
+
+#endif  // ABSL_CONTAINER_INTERNAL_NODE_SLOT_POLICY_H_