1# Abseil - C++ Common Libraries 2 3The repository contains the Abseil C++ library code. Abseil is an open-source 4collection of C++ code (compliant to C++14) designed to augment the C++ 5standard library. 6 7## Table of Contents 8 9- [About Abseil](#about) 10- [Quickstart](#quickstart) 11- [Building Abseil](#build) 12- [Support](#support) 13- [Codemap](#codemap) 14- [Releases](#releases) 15- [License](#license) 16- [Links](#links) 17 18<a name="about"></a> 19## About Abseil 20 21Abseil is an open-source collection of C++ library code designed to augment 22the C++ standard library. The Abseil library code is collected from Google's 23own C++ code base, has been extensively tested and used in production, and 24is the same code we depend on in our daily coding lives. 25 26In some cases, Abseil provides pieces missing from the C++ standard; in 27others, Abseil provides alternatives to the standard for special needs 28we've found through usage in the Google code base. We denote those cases 29clearly within the library code we provide you. 30 31Abseil is not meant to be a competitor to the standard library; we've 32just found that many of these utilities serve a purpose within our code 33base, and we now want to provide those resources to the C++ community as 34a whole. 35 36<a name="quickstart"></a> 37## Quickstart 38 39If you want to just get started, make sure you at least run through the 40[Abseil Quickstart](https://abseil.io/docs/cpp/quickstart). The Quickstart 41contains information about setting up your development environment, downloading 42the Abseil code, running tests, and getting a simple binary working. 43 44<a name="build"></a> 45## Building Abseil 46 47[Bazel](https://bazel.build) and [CMake](https://cmake.org/) are the official 48build systems for Abseil. 49See the [quickstart](https://abseil.io/docs/cpp/quickstart) for more information 50on building Abseil using the Bazel build system. 51If you require CMake support, please check the [CMake build 52instructions](CMake/README.md) and [CMake 53Quickstart](https://abseil.io/docs/cpp/quickstart-cmake). 54 55<a name="support"></a> 56## Support 57 58Abseil follows Google's [Foundational C++ Support 59Policy](https://opensource.google/documentation/policies/cplusplus-support). See 60[this 61table](https://github.com/google/oss-policies-info/blob/main/foundational-cxx-support-matrix.md) 62for a list of currently supported versions compilers, platforms, and build 63tools. 64 65<a name="codemap"></a> 66## Codemap 67 68Abseil contains the following C++ library components: 69 70* [`base`](absl/base/) 71 <br /> The `base` library contains initialization code and other code which 72 all other Abseil code depends on. Code within `base` may not depend on any 73 other code (other than the C++ standard library). 74* [`algorithm`](absl/algorithm/) 75 <br /> The `algorithm` library contains additions to the C++ `<algorithm>` 76 library and container-based versions of such algorithms. 77* [`cleanup`](absl/cleanup/) 78 <br /> The `cleanup` library contains the control-flow-construct-like type 79 `absl::Cleanup` which is used for executing a callback on scope exit. 80* [`container`](absl/container/) 81 <br /> The `container` library contains additional STL-style containers, 82 including Abseil's unordered "Swiss table" containers. 83* [`crc`](absl/crc/) The `crc` library contains code for 84 computing error-detecting cyclic redundancy checks on data. 85* [`debugging`](absl/debugging/) 86 <br /> The `debugging` library contains code useful for enabling leak 87 checks, and stacktrace and symbolization utilities. 88* [`flags`](absl/flags/) 89 <br /> The `flags` library contains code for handling command line flags for 90 libraries and binaries built with Abseil. 91* [`hash`](absl/hash/) 92 <br /> The `hash` library contains the hashing framework and default hash 93 functor implementations for hashable types in Abseil. 94* [`iterator`](absl/iterator/) 95 <br /> The `iterator` library contains utilities for augmenting ranges in 96 range-based for loops. 97* [`log`](absl/log/) 98 <br /> The `log` library contains `LOG` and `CHECK` macros and facilities 99 for writing logged messages out to disk, `stderr`, or user-extensible 100 destinations. 101* [`memory`](absl/memory/) 102 <br /> The `memory` library contains memory management facilities that augment 103 C++'s `<memory>` library. 104* [`meta`](absl/meta/) 105 <br /> The `meta` library contains compatible versions of type checks 106 available within C++14 and C++17 versions of the C++ `<type_traits>` library. 107* [`numeric`](absl/numeric/) 108 <br /> The `numeric` library contains 128-bit integer types as well as 109 implementations of C++20's bitwise math functions. 110* [`profiling`](absl/profiling/) 111 <br /> The `profiling` library contains utility code for profiling C++ 112 entities. It is currently a private dependency of other Abseil libraries. 113* [`random`](absl/random/) 114 <br /> The `random` library contains functions for generating psuedorandom 115 values. 116* [`status`](absl/status/) 117 <br /> The `status` library contains abstractions for error handling, 118 specifically `absl::Status` and `absl::StatusOr<T>`. 119* [`strings`](absl/strings/) 120 <br /> The `strings` library contains a variety of strings routines and 121 utilities, including a C++14-compatible version of the C++17 122 `std::string_view` type. 123* [`synchronization`](absl/synchronization/) 124 <br /> The `synchronization` library contains concurrency primitives (Abseil's 125 `absl::Mutex` class, an alternative to `std::mutex`) and a variety of 126 synchronization abstractions. 127* [`time`](absl/time/) 128 <br /> The `time` library contains abstractions for computing with absolute 129 points in time, durations of time, and formatting and parsing time within 130 time zones. 131* [`types`](absl/types/) 132 <br /> The `types` library contains non-container utility types, like a 133 C++14-compatible version of the C++17 `std::optional` type. 134* [`utility`](absl/utility/) 135 <br /> The `utility` library contains utility and helper code. 136 137<a name="releases"></a> 138## Releases 139 140Abseil recommends users "live-at-head" (update to the latest commit from the 141master branch as often as possible). However, we realize this philosophy doesn't 142work for every project, so we also provide [Long Term Support 143Releases](https://github.com/abseil/abseil-cpp/releases) to which we backport 144fixes for severe bugs. See our [release 145management](https://abseil.io/about/releases) document for more details. 146 147<a name="license"></a> 148## License 149 150The Abseil C++ library is licensed under the terms of the Apache 151license. See [LICENSE](LICENSE) for more information. 152 153<a name="links"></a> 154## Links 155 156For more information about Abseil: 157 158* Consult our [Abseil Introduction](https://abseil.io/about/intro) 159* Read [Why Adopt Abseil](https://abseil.io/about/philosophy) to understand our 160 design philosophy. 161* Peruse our 162 [Abseil Compatibility Guarantees](https://abseil.io/about/compatibility) to 163 understand both what we promise to you, and what we expect of you in return. 164