2 * Copyright 2016 Facebook, Inc.
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
8 * http://www.apache.org/licenses/LICENSE-2.0
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
17 #ifndef FOLLY_CONSTEXPR_H_
18 #define FOLLY_CONSTEXPR_H_
26 constexpr T constexpr_max(T a, T b) {
31 constexpr T constexpr_min(T a, T b) {
36 constexpr size_t constexpr_strlen_internal(const char* s, size_t len) {
37 return *s == '\0' ? len : constexpr_strlen_internal(s + 1, len + 1);
39 static_assert(constexpr_strlen_internal("123456789", 0) == 9,
40 "Someone appears to have broken constexpr_strlen...");
43 constexpr size_t constexpr_strlen(const char* s) {
44 #if defined(__clang__)
45 return __builtin_strlen(s);
46 #elif defined(_MSC_VER)
47 return s == nullptr ? 0 : constexpr_strlen_internal(s, 0);
49 return std::strlen(s);