1# GSL: Guideline Support Library [![Build Status](https://travis-ci.org/Microsoft/GSL.svg?branch=master)](https://travis-ci.org/Microsoft/GSL) [![Build status](https://ci.appveyor.com/api/projects/status/github/Microsoft/GSL?svg=true)](https://ci.appveyor.com/project/neilmacintosh/GSL)
2
3The Guideline Support Library (GSL) contains functions and types that are suggested for use by the
4[C++ Core Guidelines](https://github.com/isocpp/CppCoreGuidelines) maintained by the [Standard C++ Foundation](https://isocpp.org).
5This repo contains Microsoft's implementation of GSL.
6
7The library includes types like `span<T>`, `string_span`, `owner<>` and others.
8
9The entire implementation is provided inline in the headers under the [gsl](./include/gsl) directory. The implementation generally assumes a platform that implements C++14 support. There are specific workarounds to support MSVC 2015.
10
11While some types have been broken out into their own headers (e.g. [gsl/span](./include/gsl/span)),
12it is simplest to just include [gsl/gsl](./include/gsl/gsl) and gain access to the entire library.
13
14> NOTE: We encourage contributions that improve or refine any of the types in this library as well as ports to
15other platforms. Please see [CONTRIBUTING.md](./CONTRIBUTING.md) for more information about contributing.
16
17# Project Code of Conduct
18This project has adopted the [Microsoft Open Source Code of Conduct](https://opensource.microsoft.com/codeofconduct/). For more information see the [Code of Conduct FAQ](https://opensource.microsoft.com/codeofconduct/faq/) or contact [opencode@microsoft.com](mailto:opencode@microsoft.com) with any additional questions or comments.
19
20# Usage of Third Party Libraries
21This project makes use of the [Catch](https://github.com/philsquared/catch) testing library. Please see the [ThirdPartyNotices.txt](./ThirdPartyNotices.txt) file for details regarding the licensing of Catch.
22
23# Quick Start
24## Supported Platforms
25The test suite that exercises GSL has been built and passes successfully on the following platforms:<sup>1)</sup>
26
27* Windows using Visual Studio 2015
28* Windows using Visual Studio 2017
29* Windows using Clang/LLVM 3.6
30* Windows using GCC 5.1
31* GNU/Linux using Clang/LLVM 3.6
32* GNU/Linux using GCC 5.1
33* OS X Yosemite using Xcode with Apple Clang 7.0.0.7000072
34* OS X Yosemite using GCC-5.2.0
35* OS X Sierra 10.12.4 using Apple LLVM version 8.1.0 (Clang-802.0.42)
36* FreeBSD 10.x with Clang/LLVM 3.6
37
38> If you successfully port GSL to another platform, we would love to hear from you. Please submit an issue to let us know. Also please consider
39contributing any changes that were necessary back to this project to benefit the wider community.
40
41<sup>1)</sup> For `gsl::byte` to work correctly with Clang and GCC you might have to use the ` -fno-strict-aliasing` compiler option.
42
43## Building the tests
44To build the tests, you will require the following:
45
46* [CMake](http://cmake.org), version 3.1.3 or later to be installed and in your PATH.
47
48These steps assume the source code of this repository has been cloned into a directory named `c:\GSL`.
49
501. Create a directory to contain the build outputs for a particular architecture (we name it c:\GSL\build-x86 in this example).
51
52        cd GSL
53        md build-x86
54        cd build-x86
55
562. Configure CMake to use the compiler of your choice (you can see a list by running `cmake --help`).
57
58        cmake -G "Visual Studio 14 2015" c:\GSL
59
603. Build the test suite (in this case, in the Debug configuration, Release is another good choice).
61
62        cmake --build . --config Debug
63
644. Run the test suite.
65
66        ctest -C Debug
67
68All tests should pass - indicating your platform is fully supported and you are ready to use the GSL types!
69
70## Using the libraries
71As the types are entirely implemented inline in headers, there are no linking requirements.
72
73You can copy the [gsl](./include/gsl) directory into your source tree so it is available
74to your compiler, then include the appropriate headers in your program.
75
76Alternatively set your compiler's *include path* flag to point to the GSL development folder (`c:\GSL\include` in the example above) or installation folder (after running the install). Eg.
77
78MSVC++
79
80    /I c:\GSL\include
81
82GCC/clang
83
84    -I$HOME/dev/GSL/include
85
86Include the library using:
87
88    #include <gsl/gsl>
89
90## Debugging visualization support
91For Visual Studio users, the file [GSL.natvis](./GSL.natvis) in the root directory of the repository can be added to your project if you would like more helpful visualization of GSL types in the Visual Studio debugger than would be offered by default.
92