pw_trace: Add facade
This change adds the start of the pw_trace facade, include the API and
some basic tests. Currently this only has the gn build file, and still
needs docs.
Change-Id: I76eee7bcdb68e688d2f1c47978916d775ea1e84f
diff --git a/pw_preprocessor/macro_arg_count_test.cc b/pw_preprocessor/macro_arg_count_test.cc
index fe985c2..0ce8831 100644
--- a/pw_preprocessor/macro_arg_count_test.cc
+++ b/pw_preprocessor/macro_arg_count_test.cc
@@ -251,5 +251,17 @@
// clang-format on
}
+TEST(DelegateByArgCount, WithoutAndWithoutArguments) {
+#define TEST_SUM0() (0)
+#define TEST_SUM1(a) (a)
+#define TEST_SUM2(a, b) ((a) + (b))
+#define TEST_SUM3(a, b, c) ((a) + (b) + (c))
+
+ static_assert(PW_DELEGATE_BY_ARG_COUNT(TEST_SUM) == 0);
+ static_assert(PW_DELEGATE_BY_ARG_COUNT(TEST_SUM, 5) == 5);
+ static_assert(PW_DELEGATE_BY_ARG_COUNT(TEST_SUM, 1, 2) == 3);
+ static_assert(PW_DELEGATE_BY_ARG_COUNT(TEST_SUM, 1, 2, 3) == 6);
+}
+
} // namespace
} // namespace pw
diff --git a/pw_preprocessor/public/pw_preprocessor/macro_arg_count.h b/pw_preprocessor/public/pw_preprocessor/macro_arg_count.h
index cca6238..163eb47 100644
--- a/pw_preprocessor/public/pw_preprocessor/macro_arg_count.h
+++ b/pw_preprocessor/public/pw_preprocessor/macro_arg_count.h
@@ -136,3 +136,22 @@
#define _PW_COMMA_ARGS_X(has_args, ...) _PW_COMMA_ARGS_##has_args(__VA_ARGS__)
#define _PW_COMMA_ARGS_0(...) // no args, no comma
#define _PW_COMMA_ARGS_1(...) , __VA_ARGS__ // comma, followed by args
+
+// Allows calling a different function-like macro based on the number of
+// arguments. For example:
+//
+// #define ARG_PRINT(...) PW_DELEGATE_BY_ARG_COUNT(_ARG_PRINT, __VA_ARGS__)
+// #define _ARG_PRINT1(a) LOG_INFO("1 arg: %s", a)
+// #define _ARG_PRINT2(a, b) LOG_INFO("2 args: %s, %s", a, b)
+// #define _ARG_PRINT3(a, b, c) LOG_INFO("3 args: %s, %s, %s", a, b, c)
+//
+// This can the be called in code:
+// ARG_PRINT("a"); // Outputs: 1 arg: a
+// ARG_PRINT("a", "b"); // Outputs: 2 arg: a, b
+// ARG_PRINT("a", "b", "c"); // Outputs: 3 arg: a, b, c
+//
+#define PW_DELEGATE_BY_ARG_COUNT(func, ...) \
+ _PW_DELEGATE_BY_ARG_COUNT(func, PW_ARG_COUNT(__VA_ARGS__))(__VA_ARGS__)
+#define _PW_DELEGATE_BY_ARG_COUNT_EXPANDED(name, n) name##n
+#define _PW_DELEGATE_BY_ARG_COUNT(name, n) \
+ _PW_DELEGATE_BY_ARG_COUNT_EXPANDED(name, n)
