diff options
Diffstat (limited to 'library/cpp')
| -rw-r--r-- | library/cpp/yt/misc/preprocessor.h | 8 | ||||
| -rw-r--r-- | library/cpp/yt/misc/unittests/preprocessor_ut.cpp | 13 |
2 files changed, 21 insertions, 0 deletions
diff --git a/library/cpp/yt/misc/preprocessor.h b/library/cpp/yt/misc/preprocessor.h index 5b929a03b59..818c3be3546 100644 --- a/library/cpp/yt/misc/preprocessor.h +++ b/library/cpp/yt/misc/preprocessor.h @@ -50,6 +50,7 @@ #define PP_RIGHT_PARENTHESIS ) #define PP_COMMA() , #define PP_EMPTY() +#define PP_EMPTINESS //! \endcond //! Removes the enclosing parens, if any. @@ -123,6 +124,13 @@ #define PP_ONE_OR_NONE(a, ...) PP_THIRD(a, ## __VA_ARGS__, a) #define PP_THIRD(a, b, ...) __VA_ARGS__ +//! Checks whether emptiness was passed. +#define PP_IS_EMPTY(...) PP_IS_EMPTY_A(__VA_ARGS__) +//! \cond Implementation +#define PP_IS_EMPTY_A(...) PP_FIRST(__VA_OPT__(PP_FALSE,) PP_TRUE) +#define PP_FIRST(a, ...) a +//! \endcond + //! \cond Implementation #define PREPROCESSOR_GEN_H_ #include "preprocessor-gen.h" diff --git a/library/cpp/yt/misc/unittests/preprocessor_ut.cpp b/library/cpp/yt/misc/unittests/preprocessor_ut.cpp index b712d8a48f5..e4c88a7fe8e 100644 --- a/library/cpp/yt/misc/unittests/preprocessor_ut.cpp +++ b/library/cpp/yt/misc/unittests/preprocessor_ut.cpp @@ -104,6 +104,19 @@ TEST(TPreprocessorTest, Deparen) EXPECT_STREQ("( a, b)", PP_STRINGIZE((PP_DEPAREN((a, b))))); } +TEST(TPreprocessorTest, IsEmpty) +{ + EXPECT_EQ(1, PP_IF(PP_IS_EMPTY(), 1, 2)); + EXPECT_EQ(1, PP_IF(PP_IS_EMPTY(PP_EMPTINESS), 1, 2)); + EXPECT_EQ(1, PP_IF(PP_IS_EMPTY(PP_EMPTY()), 1, 2)); + EXPECT_EQ(1, PP_IF(PP_IS_EMPTY(PP_EMPTY PP_LEFT_PARENTHESIS PP_RIGHT_PARENTHESIS), 1, 2)); + + EXPECT_EQ(2, PP_IF(PP_IS_EMPTY(()), 1, 2)); + EXPECT_EQ(2, PP_IF(PP_IS_EMPTY(PP_EMPTY), 1, 2)); + EXPECT_EQ(2, PP_IF(PP_IS_EMPTY(0), 1, 2)); + EXPECT_EQ(2, PP_IF(PP_IS_EMPTY(hello), 1, 2)); +} + //////////////////////////////////////////////////////////////////////////////// } // namespace |