| // Copyright 2021 The Dawn Authors |
| // |
| // Licensed under the Apache License, Version 2.0 (the "License"); |
| // you may not use this file except in compliance with the License. |
| // You may obtain a copy of the License at |
| // |
| // http://www.apache.org/licenses/LICENSE-2.0 |
| // |
| // Unless required by applicable law or agreed to in writing, software |
| // distributed under the License is distributed on an "AS IS" BASIS, |
| // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| // See the License for the specific language governing permissions and |
| // limitations under the License. |
| |
| #ifndef SRC_DAWN_COMMON_PREPROCESSOR_H_ |
| #define SRC_DAWN_COMMON_PREPROCESSOR_H_ |
| |
| // DAWN_PP_GET_HEAD: get the first element of a __VA_ARGS__ without triggering empty |
| // __VA_ARGS__ warnings. |
| #define DAWN_INTERNAL_PP_GET_HEAD(firstParam, ...) firstParam |
| #define DAWN_PP_GET_HEAD(...) DAWN_INTERNAL_PP_GET_HEAD(__VA_ARGS__, placeholderArg) |
| |
| // DAWN_PP_CONCATENATE: Concatenate tokens, first expanding the arguments passed in. |
| #define DAWN_PP_CONCATENATE(arg1, arg2) DAWN_PP_CONCATENATE_1(arg1, arg2) |
| #define DAWN_PP_CONCATENATE_1(arg1, arg2) DAWN_PP_CONCATENATE_2(arg1, arg2) |
| #define DAWN_PP_CONCATENATE_2(arg1, arg2) arg1##arg2 |
| |
| // DAWN_PP_EXPAND: Needed to help expand __VA_ARGS__ out on MSVC |
| #define DAWN_PP_EXPAND(...) __VA_ARGS__ |
| |
| // Implementation of DAWN_PP_FOR_EACH, called by concatenating DAWN_PP_FOR_EACH_ with a number. |
| #define DAWN_PP_FOR_EACH_1(func, x) func(x) |
| #define DAWN_PP_FOR_EACH_2(func, x, ...) \ |
| func(x) DAWN_PP_EXPAND(DAWN_PP_EXPAND(DAWN_PP_FOR_EACH_1)(func, __VA_ARGS__)) |
| #define DAWN_PP_FOR_EACH_3(func, x, ...) \ |
| func(x) DAWN_PP_EXPAND(DAWN_PP_EXPAND(DAWN_PP_FOR_EACH_2)(func, __VA_ARGS__)) |
| #define DAWN_PP_FOR_EACH_4(func, x, ...) \ |
| func(x) DAWN_PP_EXPAND(DAWN_PP_EXPAND(DAWN_PP_FOR_EACH_3)(func, __VA_ARGS__)) |
| #define DAWN_PP_FOR_EACH_5(func, x, ...) \ |
| func(x) DAWN_PP_EXPAND(DAWN_PP_EXPAND(DAWN_PP_FOR_EACH_4)(func, __VA_ARGS__)) |
| #define DAWN_PP_FOR_EACH_6(func, x, ...) \ |
| func(x) DAWN_PP_EXPAND(DAWN_PP_EXPAND(DAWN_PP_FOR_EACH_5)(func, __VA_ARGS__)) |
| #define DAWN_PP_FOR_EACH_7(func, x, ...) \ |
| func(x) DAWN_PP_EXPAND(DAWN_PP_EXPAND(DAWN_PP_FOR_EACH_6)(func, __VA_ARGS__)) |
| #define DAWN_PP_FOR_EACH_8(func, x, ...) \ |
| func(x) DAWN_PP_EXPAND(DAWN_PP_EXPAND(DAWN_PP_FOR_EACH_7)(func, __VA_ARGS__)) |
| |
| // Implementation for DAWN_PP_FOR_EACH. Get the number of args in __VA_ARGS__ so we can concat |
| // DAWN_PP_FOR_EACH_ and N. |
| // ex.) DAWN_PP_FOR_EACH_NARG(a, b, c) -> |
| // DAWN_PP_FOR_EACH_NARG(a, b, c, DAWN_PP_FOR_EACH_RSEQ()) -> |
| // DAWN_PP_FOR_EACH_NARG_(a, b, c, 8, 7, 6, 5, 4, 3, 2, 1, 0) -> |
| // DAWN_PP_FOR_EACH_ARG_N(a, b, c, 8, 7, 6, 5, 4, 3, 2, 1, 0) -> |
| // DAWN_PP_FOR_EACH_ARG_N( , , , , , , , , N) -> |
| // 3 |
| #define DAWN_PP_FOR_EACH_NARG(...) DAWN_PP_FOR_EACH_NARG_(__VA_ARGS__, DAWN_PP_FOR_EACH_RSEQ()) |
| #define DAWN_PP_FOR_EACH_NARG_(...) \ |
| DAWN_PP_EXPAND(DAWN_PP_EXPAND(DAWN_PP_FOR_EACH_ARG_N)(__VA_ARGS__)) |
| #define DAWN_PP_FOR_EACH_ARG_N(_1, _2, _3, _4, _5, _6, _7, _8, N, ...) N |
| #define DAWN_PP_FOR_EACH_RSEQ() 8, 7, 6, 5, 4, 3, 2, 1, 0 |
| |
| // Implementation for DAWN_PP_FOR_EACH. |
| // Creates a call to DAWN_PP_FOR_EACH_X where X is 1, 2, ..., etc. |
| #define DAWN_PP_FOR_EACH_(N, func, ...) DAWN_PP_CONCATENATE(DAWN_PP_FOR_EACH_, N)(func, __VA_ARGS__) |
| |
| // DAWN_PP_FOR_EACH: Apply |func| to each argument in |x| and __VA_ARGS__ |
| #define DAWN_PP_FOR_EACH(func, ...) \ |
| DAWN_PP_FOR_EACH_(DAWN_PP_FOR_EACH_NARG(__VA_ARGS__), func, __VA_ARGS__) |
| |
| #endif // SRC_DAWN_COMMON_PREPROCESSOR_H_ |