[common] macros to get first/second/rest of variadic arguments (#5650)

This commit adds three macros in a new header `arg_macros.hpp` `OT_GET_FIRST()`, `OT_GET_RESET(...)`, and `OT_GET_SECOND()`. These macros help with parsing variadic arguments passed to a function/macro and can handle the case where variadic macro arguments is empty without requiring toolchain specific behavior/support. This commit also adds a unit test `test_macros` for the newly added macros.
2026-08-18 16:39:52 +00:00 · 2020-10-16 06:10:06 -07:00
parent 5c7850ebe5
commit 05b71b9dc2
6 changed files with 255 additions and 0 deletions
@@ -0,0 +1,124 @@
+/*
+ *  Copyright (c) 2020, The OpenThread Authors.
+ *  All rights reserved.
+ *
+ *  Redistribution and use in source and binary forms, with or without
+ *  modification, are permitted provided that the following conditions are met:
+ *  1. Redistributions of source code must retain the above copyright
+ *     notice, this list of conditions and the following disclaimer.
+ *  2. Redistributions in binary form must reproduce the above copyright
+ *     notice, this list of conditions and the following disclaimer in the
+ *     documentation and/or other materials provided with the distribution.
+ *  3. Neither the name of the copyright holder nor the
+ *     names of its contributors may be used to endorse or promote products
+ *     derived from this software without specific prior written permission.
+ *
+ *  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ *  AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ *  IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ *  ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
+ *  LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ *  CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ *  SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ *  INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ *  CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ *  ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ *  POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include "test_platform.h"
+
+#include "common/arg_macros.hpp"
+
+static constexpr uint8_t NumberOfArgs(void)
+{
+    return 0;
+}
+
+static constexpr uint8_t NumberOfArgs(uint8_t)
+{
+    return 1;
+}
+
+static constexpr uint8_t NumberOfArgs(uint8_t, uint8_t)
+{
+    return 2;
+}
+
+static constexpr uint8_t NumberOfArgs(uint8_t, uint8_t, uint8_t)
+{
+    return 3;
+}
+
+static constexpr uint8_t NumberOfArgs(uint8_t, uint8_t, uint8_t, uint8_t)
+{
+    return 4;
+}
+
+static constexpr uint8_t NumberOfArgs(uint8_t, uint8_t, uint8_t, uint8_t, uint8_t)
+{
+    return 5;
+}
+
+static constexpr uint8_t NumberOfArgs(uint8_t, uint8_t, uint8_t, uint8_t, uint8_t, uint8_t)
+{
+    return 6;
+}
+
+static constexpr uint8_t NumberOfArgs(uint8_t, uint8_t, uint8_t, uint8_t, uint8_t, uint8_t, uint8_t)
+{
+    return 7;
+}
+
+int Sum(int aFirst)
+{
+    return aFirst;
+}
+
+template <typename... Args> int Sum(int aFirst, Args... aArgs)
+{
+    return aFirst + Sum(aArgs...);
+}
+
+void TestMacros(void)
+{
+    // Verify `OT_FIRST_ARG()` macro.
+
+    VerifyOrQuit(OT_FIRST_ARG(1) == 1, "OT_FIRST_ARG() failed");
+    VerifyOrQuit(OT_FIRST_ARG(1, 2, 3) == 1, "OT_FIRST_ARG() failed");
+    VerifyOrQuit(OT_FIRST_ARG(1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12) == 1, "OT_FIRST_ARG() failed");
+
+    // Verify `OT_REST_ARGS()` macro.
+
+    VerifyOrQuit(NumberOfArgs(OT_REST_ARGS(1)) == 0, "OT_REST_ARGS() failed for empty");
+
+    VerifyOrQuit(NumberOfArgs(0 OT_REST_ARGS(1)) == 1, "OT_REST_ARGS() failed");
+    VerifyOrQuit(NumberOfArgs(0 OT_REST_ARGS(1, 2)) == 2, "OT_REST_ARGS() failed");
+    VerifyOrQuit(NumberOfArgs(0 OT_REST_ARGS(1, 2, 3)) == 3, "OT_REST_ARGS() failed");
+    VerifyOrQuit(NumberOfArgs(0 OT_REST_ARGS(1, 2, 3, 4)) == 4, "OT_REST_ARGS() failed");
+    VerifyOrQuit(NumberOfArgs(0 OT_REST_ARGS(1, 2, 3, 4, 5)) == 5, "OT_REST_ARGS() failed");
+    VerifyOrQuit(NumberOfArgs(0 OT_REST_ARGS(1, 2, 3, 4, 5, 6)) == 6, "OT_REST_ARGS() failed");
+    VerifyOrQuit(NumberOfArgs(0 OT_REST_ARGS(1, 2, 3, 4, 5, 6, 7)) == 7, "OT_REST_ARGS() failed");
+
+    VerifyOrQuit(Sum(100 OT_REST_ARGS(1)) == 100, "OT_REST_ARGS() failed");
+    VerifyOrQuit(Sum(100 OT_REST_ARGS(1, 2)) == 102, "OT_REST_ARGS() failed");
+    VerifyOrQuit(Sum(100 OT_REST_ARGS(1, 2, 3)) == 105, "OT_REST_ARGS() failed");
+    VerifyOrQuit(Sum(100 OT_REST_ARGS(1, 2, 3, 4)) == 109, "OT_REST_ARGS() failed");
+    VerifyOrQuit(Sum(100 OT_REST_ARGS(1, 2, 3, 4, 5)) == 114, "OT_REST_ARGS() failed");
+    VerifyOrQuit(Sum(100 OT_REST_ARGS(1, 2, 3, 4, 5, 6)) == 120, "OT_REST_ARGS() failed");
+    VerifyOrQuit(Sum(100 OT_REST_ARGS(1, 2, 3, 4, 5, 6, 7)) == 127, "OT_REST_ARGS() failed");
+
+    // Verify `OT_SECOND_ARG()` macro.
+
+    VerifyOrQuit(NumberOfArgs(OT_SECOND_ARG(1)) == 0, "OT_SECOND_ARG() failed");
+    VerifyOrQuit(NumberOfArgs(OT_SECOND_ARG(1, 2)) == 1, "OT_SECOND_ARG() failed");
+
+    VerifyOrQuit(OT_SECOND_ARG(1, 2) == 2, "OT_SECOND_ARG() failed");
+}
+
+int main(void)
+{
+    TestMacros();
+    printf("All tests passed\n");
+    return 0;
+}