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