common_cxx: A header-only micro-library for C++11

What is it?

This a tiny set of C++11 utility headers that bring minimal implementations of useful concepts useful for general C++ development, developed as needed at Starship. Some of these have analogues in later C++ standards, but most are modelled on the more functional Rust equivalents, like common::result and common::optional.

These are designed to be low to zero dependency, and minimal in implementation size, while enabling sane error handling sans exceptions.

Dependencies

Requires a C++11 conformant compiler and STL implementation. Currently uses some posix APIs directly, and is primarily tested on linux.

Tests (in the tests/ directory) require Google Test.

Trivial example

result<size_t, unix_err> extract_key_values(const char* filename, std::function<void (string_view key, string_view value)>&& dispatch_key_value)
{
    file_handle file;
    std::string content;
    return file
        .open(filename)
        .and_then([&] (ok) {
            return file.read_all(content);
        })
        .map([&] (ok) {
            size_t count{0};
            string_view{content}.split_fn('\n', [&] (string_view line)
            {
                string_view key, value;
                line.split_args('=', key, value);
                dispatch_key_value(key, value);
                count += 1;
            });
            return count;
        });
}

Current content

• optional<T>: a T or none, include reference support and map/and_then
• result<T, Error>: a T or Error including map/and_then
• array_view<T>: a non-owning view to a contiguous block of 0..N T
• string_view<T>: a non-owning view with string helper methods for splitting and in-place formatting
• unix_err: a trivial wrapper around errno
• file_handle: a very-trivial RAII wrapper around FILE* with a few convenience functions
• timestamp: a {seconds, nanoseconds} timestamp