erez-o/breath

A collection of portable C++ components.

Overview

GitHub's master at a glance:

Welcome to Breath, my personal toolkit of C++ components. The components range from cryptography (MD5, SHA-1, SHA-2) to string utilities, operating system identification and much more. You'll get a precise idea by exploring the breath/ subdirectory of the source tree or the full documentation (see below).

The library has been developed, in my spare time, over a period of about 13 years (as of June 2019) and I don't claim that all of it is of production quality.

Some components don't take full advantage of the latest standards and some are or will be superseded by standard components or features (e.g. those in the path/ subdirectory). But, generally, the library is up to date with C++14.

The test/ subdirectories can be a good place to look at if you need to see usage examples (but, please, let me know if you feel that the usage of a component should be documented better).

Building the library

Breath has been designed and implemented to be as portable as possible, without a single usage of #if, #ifdef or #ifndef (the only conditional compilation is for include guards), and the goal is that it can be compiled with any conforming C++14 compiler.

Building the library, however, requires a Unix toolkit, with GNU Make and, for the x86_64 builds only, the GNU Assembler. On Microsoft Windows, you'll need Cygwin. (If I had to redo it today, most things would probably use Python.)

Note that only Cygwin 64-bit is supported.

For the editor support, and for some tests, you need to define the environment variable BREATH_ROOT to the full path of the source tree. Use forward slashes, even on Windows; omit the trailing slash.

The bin/ subdirectory of the Cygwin installation must be in the PATH.

To build the library:

• if you are on Windows and you want to use Visual Studio, run a Visual Studio Command Prompt, issue the command cd /D "%BREATH_ROOT%/tool/use_cygwin/" (the /D option is for the case in which %BREATH_ROOT% is on a different drive) and launch use_cygwin.bat; then use the resulting Cygwin window

• cd to $BREATH_ROOT (add quotes if the value of $BREATH_ROOT contains spaces)

• issue a command like this:

  architecture=x86_64 system=windows compiler=gcc make
  

  Note: on some systems, you might need to use gmake instead of make.

The architecture part can be omitted for x86_64 (that's the default).

The clean target is also supported (you still need to provide system and compiler: when you clean, only the files generated for a given architecture/system/compiler triplet are removed).

At the moment, system must be set to one of the following:

• unix, windows

while compiler must be set to one of:

• clang, gcc, msvc

Finally, architecture can be anything, because it is currently only used to include or exclude a component (get_cpuid_info()) which is only implemented for x86_64.

Under Cygwin, with both Clang and GCC, you can build with system=windows or system=unix. In both cases, this will, by default, generate a library which depends on the Cygwin DLL. To avoid this dependency when system=windows, you can use the compilers provided by the mingw*gcc* or mingw*clang packages (available in the Cygwin installer) and select one of them via the compiler_command variable; e.g.:

system=windows compiler=gcc compiler_command=x86_64-w64-mingw32-g++ make

Warning: you might want to also add

cpp_extra_options="-static -static-libgcc -static-libstdc++"

to the command line, but note that the cpp_extra_options variable is experimental.

Note: to get a list of the available Make targets, with a brief description for each one, launch the command make help (or gmake help).

A note about the documentation

The documentation is contained in the source files, in the form of Doxygen comments. This keeps the code and the documentation together, and that's about the only advantage of it. For the rest, Doxygen is one of the most disappointing tools available, but I don't have time to migrate to something else.

Given the quality of the Doxygen output, I unwillingly recommend to mostly read the documentation directly from the source files. In any case, to generate separate documents, a documentation target is provided in the makefiles (please, remember to cd to BREATH_ROOT; the documentation will appear in BREATH_ROOT/doc).

Note on the note :-): I just registered the project with DocsForge; the resulting documentation seems much better than the one generated by Doxygen, although some interlinks are wrong. Unless you are without an Internet connection, it might be a good alternative for you to use: https://breath.docsforge.com.

Editor support

The source tree contains a .editorconfig (https://editorconfig.org). This support was added just recently. Before that, only Emacs and Vim were supported.

If you plan to contribute, please use tool/init_file/init_file.sh to initialize your source files. You should define the environment variable BREATH_CONTRIBUTOR to the name you wish to appear in your copyright notices. Also, you should build the include_guard tool (which is automatically built with the library: see Getting started), and copy it to BREATH_ROOT/bin/.

If you use Vim, just source breath.vim from your .vimrc and that will take care of running the initialization script on any file you create in BREATH_ROOT or in any subdirectory.

If you use Emacs, please contribute something analogous to breath.vim for that editor.

Git commit message template

To enable the Git commit message template provided with the library:

• cd to BREATH_ROOT

• run: git config --local commit.template ./.git_commit_message_template.txt

For better or for worse, the library uses the Git commit message guidelines outlined at https://chris.beams.io/posts/git-commit/, except that the subject line:

• can reach 72 characters, just like the body lines (50 is really too little)

• is worded in the imperative mood, but doesn't necessarily complete the sentence "this commit will...", e.g. it may begin with "Don't" (I believe that, in fact, this is the intent of the guidelines)

Please, have a look at the guidelines if you are not familiar with them.

Supported compilers

Note that, as of August 24, 2020, if you need to use the library with MSVC 2015, that's quite easy as long as you are willing to give up on constexpr for some components (BREATH_ASSERT(), count_bits(), gcd(), lcm()).

Compiler	Minimum supported version
Clang	5.0.1
GCC	6.1.0
MSVC	2017

Future directions

The facilities for command line options will be removed and replaced with something better. They came from another library, and seemed good at the time, but, on closer analysis, show their limitations.

License

Breath is made available subject to the terms of the 3-Clause BSD License, reproduced in the file 3_CLAUSE_BSD_LICENSE.txt, at the root of the source tree.

Reporting issues

I can't guarantee any kind of support, but if you have issues with the library, please send me a mail describing the problem ([e-mail]) and I will try to address it as soon as possible.

Acknowledgments

My most heartfelt thank you goes to James Kanze, without whom I wouldn't be the programmer I am.