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https://fuchsia.googlesource.com/third_party/pigweed.googlesource.com/pigweed/pigweed
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c10c81201d
This change adds two Pigweed modules: pw_preprocessor and pw_unit_test. The preprocessor module contains header files providing helpful macros for the C preprocessor. The unit test module contains a starter implementation of a unit testing framework for Pigweed. Change-Id: I46e1a4cae1fd8ce36d7840a2e92f8013fb489cde
64 lines
2.0 KiB
ReStructuredText
64 lines
2.0 KiB
ReStructuredText
.. _chapter-preprocessor:
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.. default-domain:: cpp
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.. highlight:: sh
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------------
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Preprocessor
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------------
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The preprocessor module provides various helpful preprocessor macros.
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Compatibility
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=============
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C and C++
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Dependencies
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============
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This module has no dependencies.
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Headers
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=======
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The preprocessor module provides several headers.
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pw_preprocessor/boolean.h
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-------------------------
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Defines macros for boolean logic on literal 1s and 0s. This is useful for
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situations when a literal is needed to build the name of a function or macro.
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pw_preprocessor/compiler.h
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--------------------------
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Macros for compiler-specific features, such as attributes or builtins.
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pw_preprocessor/concat.h
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------------------------
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Defines the ``PW_CONCAT(...)`` macro, which expands its arguments if they are
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macros and token pastes the results. This can be used for building names of
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classes, variables, macros, etc.
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pw_preprocessor/macro_arg_count.h
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---------------------------------
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Defines the ``PW_ARG_COUNT(...)`` macro, which counts the number of arguments it
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was passed. It can be invoked directly or with ``__VA_ARGS__`` in another macro.
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``PW_ARG_COUNT(...)`` evaluates to a literal of the number of arguments which
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can be used directly or concatenated to build other names. Unlike many common
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implementations, this macro correctly evaluates to ``0`` when it is invoked
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without arguments.
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This header also defines ``PW_HAS_ARGS(...)`` and ``PW_HAS_NO_ARGS(...)``,
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which evaluate to ``1`` or ``0`` depending on whether they are invoked with
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arguments.
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pw_preprocessor/util.h
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----------------------
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General purpose, useful macros.
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* ``PW_ARRAY_SIZE(array)`` -- calculates the size of a C array
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* ``PW_UNUSED(value)`` -- silences "unused variable" compiler warnings
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* ``PW_STRINGIFY(...)`` -- expands its arguments as macros and converts them to
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a string literal
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* ``PW_EXTERN_C`` -- declares a name to be ``extern "C"`` in C++; expands to
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nothing in C
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* ``PW_EXTERN_C_START`` / ``PW_EXTERN_C_END`` -- declares an ``extern "C" { }``
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block in C++; expands to nothing in C
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