libgpiod v2: C++ bindings

This series contains the implementation of the C++ bindings for libgpiod v2. In general the C++ library follows the data structure model as defined by the C library with one notable exception: objects that represent immutable snapshots of kernel data (line_info and edge & info events) are copyable (or rather shared behind the scenes using ::std::shared_ptr). The rest of the classes delete their copy constructors and assignment operators and are only move constructible and move assignable.

All classes follow the pimpl idiom - using either shared_ptr or unique_ptr - and all implementations are hidden from the user for easier maintenance and less ABI breakage in the future.

The edge_event class is a bit of a special case. While it looks the same as other copyable objects to the user, the implementation uses a tiny bit of polymorphism (although it never crosses the ABI boundary). This is done to make it possible to use the edge_event_buffer without any memory allocations like what the C API enables. The edge_event objects stored in the buffer only contain a raw pointer to the C object stored in the underlying C edge_event_buffer. The event is copied into a fully managed object once the copy assignment operator is called.

I'm Cc'ing people who showed interest and helped me with C++ bindings before for review.

v1 -> v2:
Kent: I addressed most points from your review. Some are unaddressed due to personal preference (for instance: I still allow creating of empty line-request objects as they may be reused in subsequent requests). I also kept the 'watch' argument in get_line_info() as well as the boolean operators for chip and request - although with (hopefully) better documentation.

v2 -> v3:
- use scoped class enums instead of regular integer ones
- rename getters to get_<property>() in order to avoid name conflicts with the new enum types

v3 -> v4:
The bindings have been significantly rebuilt and the list of changes is mostly likely too long put all here but in short:
- renamed and reworked the accessors
- added custom stream insertion operators and exceptions
- used scoped C++ enum and unifying their definitions across classes
- deconstified all mutators for logical consistency
- modified the implementation to work with the reworked C API
- many more small tweaks all over the place

Bartosz Golaszewski (2):
line-config: rework the interface some more
bindings: cxx: implement C++ bindings for libgpiod v2.0

 Doxyfile.in                                 |   4 +-
 bindings/cxx/Makefile.am                    |  18 +-
 bindings/cxx/chip.cpp                       | 214 +++--
 bindings/cxx/edge-event-buffer.cpp          | 118 +++
 bindings/cxx/edge-event.cpp                 | 135 +++
 bindings/cxx/examples/Makefile.am           |  12 +-
 bindings/cxx/examples/gpiodetectcxx.cpp     |   9 +-
 bindings/cxx/examples/gpiogetcxx.cpp        |  12 +-
 bindings/cxx/examples/gpioinfocxx.cpp       |  62 +-
 bindings/cxx/examples/gpiomoncxx.cpp        |  39 +-
 bindings/cxx/examples/gpiosetcxx.cpp        |  19 +-
 bindings/cxx/exception.cpp                  | 107 +++
 bindings/cxx/gpiod.hpp                      | 946 +-------------------
 bindings/cxx/gpiodcxx/Makefile.am           |  16 +
 bindings/cxx/gpiodcxx/chip.hpp              | 197 ++++
 bindings/cxx/gpiodcxx/edge-event-buffer.hpp | 122 +++
 bindings/cxx/gpiodcxx/edge-event.hpp        | 135 +++
 bindings/cxx/gpiodcxx/exception.hpp         | 149 +++
 bindings/cxx/gpiodcxx/info-event.hpp        | 115 +++
 bindings/cxx/gpiodcxx/line-config.hpp       | 445 +++++++++
 bindings/cxx/gpiodcxx/line-info.hpp         | 169 ++++
 bindings/cxx/gpiodcxx/line-request.hpp      | 214 +++++
 bindings/cxx/gpiodcxx/line.hpp              | 123 +++
 bindings/cxx/gpiodcxx/misc.hpp              |  44 +
 bindings/cxx/gpiodcxx/request-config.hpp    | 128 +++
 bindings/cxx/info-event.cpp                 | 102 +++
 bindings/cxx/internal.cpp                   |  91 ++
 bindings/cxx/internal.hpp                   | 188 +++-
 bindings/cxx/iter.cpp                       |  60 --
 bindings/cxx/line-config.cpp                | 589 ++++++++++++
 bindings/cxx/line-info.cpp                  | 199 ++++
 bindings/cxx/line-request.cpp               | 200 +++++
 bindings/cxx/line.cpp                       | 321 -------
 bindings/cxx/line_bulk.cpp                  | 366 --------
 bindings/cxx/misc.cpp                       |  20 +
 bindings/cxx/request-config.cpp             | 117 +++
 configure.ac                                |   1 +
 include/gpiod.h                             | 255 ++++--
 lib/line-config.c                           | 295 ++++--
 tools/gpioget.c                             |   6 +-
 tools/gpiomon.c                             |   6 +-
 tools/gpioset.c                             |   9 +-
 42 files changed, 4380 insertions(+), 1997 deletions(-)
 create mode 100644 bindings/cxx/edge-event-buffer.cpp
 create mode 100644 bindings/cxx/edge-event.cpp
 create mode 100644 bindings/cxx/exception.cpp
 create mode 100644 bindings/cxx/gpiodcxx/Makefile.am
 create mode 100644 bindings/cxx/gpiodcxx/chip.hpp
 create mode 100644 bindings/cxx/gpiodcxx/edge-event-buffer.hpp
 create mode 100644 bindings/cxx/gpiodcxx/edge-event.hpp
 create mode 100644 bindings/cxx/gpiodcxx/exception.hpp
 create mode 100644 bindings/cxx/gpiodcxx/info-event.hpp
 create mode 100644 bindings/cxx/gpiodcxx/line-config.hpp
 create mode 100644 bindings/cxx/gpiodcxx/line-info.hpp
 create mode 100644 bindings/cxx/gpiodcxx/line-request.hpp
 create mode 100644 bindings/cxx/gpiodcxx/line.hpp
 create mode 100644 bindings/cxx/gpiodcxx/misc.hpp
 create mode 100644 bindings/cxx/gpiodcxx/request-config.hpp
 create mode 100644 bindings/cxx/info-event.cpp
 create mode 100644 bindings/cxx/internal.cpp
 delete mode 100644 bindings/cxx/iter.cpp
 create mode 100644 bindings/cxx/line-config.cpp
 create mode 100644 bindings/cxx/line-info.cpp
 create mode 100644 bindings/cxx/line-request.cpp
 delete mode 100644 bindings/cxx/line.cpp
 delete mode 100644 bindings/cxx/line_bulk.cpp
 create mode 100644 bindings/cxx/misc.cpp
 create mode 100644 bindings/cxx/request-config.cpp

2.30.1