2019-12-05 18:52:31 +00:00
|
|
|
.. _chapter-pw-preprocessor:
|
2019-11-01 23:31:19 +00:00
|
|
|
|
|
|
|
.. default-domain:: cpp
|
|
|
|
|
|
|
|
.. highlight:: sh
|
|
|
|
|
2019-11-25 21:56:31 +00:00
|
|
|
---------------
|
|
|
|
pw_preprocessor
|
|
|
|
---------------
|
2019-11-01 23:31:19 +00:00
|
|
|
The preprocessor module provides various helpful preprocessor macros.
|
|
|
|
|
|
|
|
Compatibility
|
|
|
|
=============
|
|
|
|
C and C++
|
|
|
|
|
|
|
|
Headers
|
|
|
|
=======
|
|
|
|
The preprocessor module provides several headers.
|
|
|
|
|
|
|
|
pw_preprocessor/boolean.h
|
|
|
|
-------------------------
|
|
|
|
Defines macros for boolean logic on literal 1s and 0s. This is useful for
|
|
|
|
situations when a literal is needed to build the name of a function or macro.
|
|
|
|
|
|
|
|
pw_preprocessor/compiler.h
|
|
|
|
--------------------------
|
|
|
|
Macros for compiler-specific features, such as attributes or builtins.
|
|
|
|
|
|
|
|
pw_preprocessor/concat.h
|
|
|
|
------------------------
|
|
|
|
Defines the ``PW_CONCAT(...)`` macro, which expands its arguments if they are
|
|
|
|
macros and token pastes the results. This can be used for building names of
|
|
|
|
classes, variables, macros, etc.
|
|
|
|
|
|
|
|
pw_preprocessor/macro_arg_count.h
|
|
|
|
---------------------------------
|
|
|
|
Defines the ``PW_ARG_COUNT(...)`` macro, which counts the number of arguments it
|
|
|
|
was passed. It can be invoked directly or with ``__VA_ARGS__`` in another macro.
|
|
|
|
``PW_ARG_COUNT(...)`` evaluates to a literal of the number of arguments which
|
|
|
|
can be used directly or concatenated to build other names. Unlike many common
|
|
|
|
implementations, this macro correctly evaluates to ``0`` when it is invoked
|
|
|
|
without arguments.
|
|
|
|
|
|
|
|
This header also defines ``PW_HAS_ARGS(...)`` and ``PW_HAS_NO_ARGS(...)``,
|
|
|
|
which evaluate to ``1`` or ``0`` depending on whether they are invoked with
|
|
|
|
arguments.
|
|
|
|
|
|
|
|
pw_preprocessor/util.h
|
|
|
|
----------------------
|
|
|
|
General purpose, useful macros.
|
|
|
|
|
|
|
|
* ``PW_ARRAY_SIZE(array)`` -- calculates the size of a C array
|
|
|
|
* ``PW_UNUSED(value)`` -- silences "unused variable" compiler warnings
|
|
|
|
* ``PW_STRINGIFY(...)`` -- expands its arguments as macros and converts them to
|
|
|
|
a string literal
|
|
|
|
* ``PW_EXTERN_C`` -- declares a name to be ``extern "C"`` in C++; expands to
|
|
|
|
nothing in C
|
|
|
|
* ``PW_EXTERN_C_START`` / ``PW_EXTERN_C_END`` -- declares an ``extern "C" { }``
|
|
|
|
block in C++; expands to nothing in C
|