Export of internal Abseil changes

--
b1fc72630aaa81c8395c3b22ba267d938fe29a2e by Derek Mauro <dmauro@google.com>:

Fix -Wdeprecated-copy warnings from Clang 13.

Example:
error: definition of implicit copy assignment operator for 'UDT' is deprecated because it has a user-declared copy constructor [-Werror,-Wdeprecated-copy]
PiperOrigin-RevId: 380058303

--
0422744812b1a2010d9eea5b17fbe89f3441b66b by Evan Brown <ezb@google.com>:

Change the "full table!" asserts in raw_hash_set to use `<= capacity` instead of `< capacity`.

If we add support for non-power-of-two-minus-one capacities, this is the correct thing to assert. For example, consider: Group::kWidth = 8, capacity_ = 8, ctrl_ = {kEmpty, 1, 2, 3, 4, 5, 6, 7, kSentinel, kEmpty, 1, 2, 3, 4, 5, 6}. In this case, if we do an unsuccessful lookup with H2 mapping to slot 1, then the first Group will contain {1, 2, 3, 4, 5, 6, 7, kSentinel} so we need to continue to the second Group (at which point seq.index() == 8 == capacity_) to find a kEmpty.

Note: this is a no-op change for now since we never have `capacity % Group::kWidth == 0`.
PiperOrigin-RevId: 380033480

--
40628c34d540356de65fabb16c1439c0ec7a0764 by Abseil Team <absl-team@google.com>:

Drop out-of-date documentation about `absl::FixedArray`'s allocator support

PiperOrigin-RevId: 379811653

--
e7ad047863ae55c9b7aec0753cfc527a4ea614bc by Evan Brown <ezb@google.com>:

Fix a bug in ConvertDeletedToEmptyAndFullToDeleted in which we were copying 1 more cloned control byte than actually exists.

When alignof(slot_type)>1, this wouldn't cause a problem because the extra byte is padding.

Also change loop bounds to not rely on the fact that capacity_+1 is a multiple of Group::kWidth.

PiperOrigin-RevId: 379311830

--
1a3ba500fb2c33205854eb9258cd6e0fb1061bca by Martijn Vels <mvels@google.com>:

Change Ring, EXTERNAL and FLAT tag values to be consecutive values

The purpose of this change is to have FLAT = EXTERNAL + 1. Especially in the ring and btree alternative code, there is a common check if a node is a 'plain' edge (EXTERNAL or FLAT), or 'something else'. This change can make that check a single branch, i.e., instead of 'tag == EXTERNAL || tag >= FLAT', we can simply check for 'tag >= EXTERNAL'. Likewise we have some cases where we check for RING, EXTERNAL or FLAT, so we align RING + 1 with EXTERNAL.

PiperOrigin-RevId: 379291576

--
0c78e65ca4d85244b106c3f8e24cf268e09e72a3 by Benjamin Barenblat <bbaren@google.com>:

Round a double multiplication before casting it to integer

The code

    static_cast<int>(x * y)

(for double x and y) performs a double multiplication into a temporary
that, by standard, may have excess precision. The subsequent cast to int
discards the excess precision. However, the cast may examine the excess
precision during conversion, producing surprising results like

    static_cast<int>(1.7 * 10) == 16

on certain systems. Correct this case by explicitly rounding 1.7 * 10
before casting it.

PiperOrigin-RevId: 378922064
GitOrigin-RevId: b1fc72630aaa81c8395c3b22ba267d938fe29a2e
Change-Id: Ica708a006921118673e78d5fd2d61fe0fb0894d1
9 files changed
tree: 1543724ab9dd4be7d67f4c5a827211a58a050941
  1. .github/
  2. absl/
  3. ci/
  4. CMake/
  5. .clang-format
  6. .gitignore
  7. ABSEIL_ISSUE_TEMPLATE.md
  8. AUTHORS
  9. BUILD.bazel
  10. CMakeLists.txt
  11. conanfile.py
  12. CONTRIBUTING.md
  13. create_lts.py
  14. FAQ.md
  15. LICENSE
  16. README.md
  17. UPGRADES.md
  18. WORKSPACE
README.md

Abseil - C++ Common Libraries

The repository contains the Abseil C++ library code. Abseil is an open-source collection of C++ code (compliant to C++11) designed to augment the C++ standard library.

Table of Contents

About Abseil

Abseil is an open-source collection of C++ library code designed to augment the C++ standard library. The Abseil library code is collected from Google's own C++ code base, has been extensively tested and used in production, and is the same code we depend on in our daily coding lives.

In some cases, Abseil provides pieces missing from the C++ standard; in others, Abseil provides alternatives to the standard for special needs we've found through usage in the Google code base. We denote those cases clearly within the library code we provide you.

Abseil is not meant to be a competitor to the standard library; we've just found that many of these utilities serve a purpose within our code base, and we now want to provide those resources to the C++ community as a whole.

Quickstart

If you want to just get started, make sure you at least run through the Abseil Quickstart. The Quickstart contains information about setting up your development environment, downloading the Abseil code, running tests, and getting a simple binary working.

Building Abseil

Bazel and CMake are the official build systems for Abseil.

See the quickstart for more information on building Abseil using the Bazel build system.

If you require CMake support, please check the CMake build instructions and CMake Quickstart.

Support

Abseil is officially supported on many platforms. See the Abseil platform support guide for details on supported operating systems, compilers, CPUs, etc.

Codemap

Abseil contains the following C++ library components:

  • base Abseil Fundamentals
    The base library contains initialization code and other code which all other Abseil code depends on. Code within base may not depend on any other code (other than the C++ standard library).
  • algorithm
    The algorithm library contains additions to the C++ <algorithm> library and container-based versions of such algorithms.
  • cleanup
    The cleanup library contains the control-flow-construct-like type absl::Cleanup which is used for executing a callback on scope exit.
  • container
    The container library contains additional STL-style containers, including Abseil's unordered “Swiss table” containers.
  • debugging
    The debugging library contains code useful for enabling leak checks, and stacktrace and symbolization utilities.
  • hash
    The hash library contains the hashing framework and default hash functor implementations for hashable types in Abseil.
  • memory
    The memory library contains C++11-compatible versions of std::make_unique() and related memory management facilities.
  • meta
    The meta library contains C++11-compatible versions of type checks available within C++14 and C++17 versions of the C++ <type_traits> library.
  • numeric
    The numeric library contains C++11-compatible 128-bit integers.
  • status
    The status contains abstractions for error handling, specifically absl::Status and absl::StatusOr<T>.
  • strings
    The strings library contains a variety of strings routines and utilities, including a C++11-compatible version of the C++17 std::string_view type.
  • synchronization
    The synchronization library contains concurrency primitives (Abseil's absl::Mutex class, an alternative to std::mutex) and a variety of synchronization abstractions.
  • time
    The time library contains abstractions for computing with absolute points in time, durations of time, and formatting and parsing time within time zones.
  • types
    The types library contains non-container utility types, like a C++11-compatible version of the C++17 std::optional type.
  • utility
    The utility library contains utility and helper code.

Releases

Abseil recommends users “live-at-head” (update to the latest commit from the master branch as often as possible). However, we realize this philosophy doesn't work for every project, so we also provide Long Term Support Releases to which we backport fixes for severe bugs. See our release management document for more details.

License

The Abseil C++ library is licensed under the terms of the Apache license. See LICENSE for more information.

Links

For more information about Abseil: