Edit File: apr_optional.h
/* Licensed to the Apache Software Foundation (ASF) under one or more * contributor license agreements. See the NOTICE file distributed with * this work for additional information regarding copyright ownership. * The ASF licenses this file to You 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 APR_OPTIONAL_H #define APR_OPTIONAL_H #include "apu.h" /** * @file apr_optional.h * @brief APR-UTIL registration of functions exported by modules */ #ifdef __cplusplus extern "C" { #endif /** * @defgroup APR_Util_Opt Optional Functions * @ingroup APR_Util * * Typesafe registration and retrieval of functions that may not be present * (i.e. functions exported by optional modules) * @{ */ /** * The type of an optional function. * @param name The name of the function */ #define APR_OPTIONAL_FN_TYPE(name) apr_OFN_##name##_t /** * Declare an optional function. * @param ret The return type of the function * @param name The name of the function * @param args The function arguments (including brackets) */ #define APR_DECLARE_OPTIONAL_FN(ret,name,args) \ typedef ret (APR_OPTIONAL_FN_TYPE(name)) args /** * XXX: This doesn't belong here, then! * Private function! DO NOT USE! * @internal */ typedef void (apr_opt_fn_t)(void); /** @internal */ APU_DECLARE_NONSTD(void) apr_dynamic_fn_register(const char *szName, apr_opt_fn_t *pfn); /** * Register an optional function. This can be later retrieved, type-safely, by * name. Like all global functions, the name must be unique. Note that, * confusingly but correctly, the function itself can be static! * @param name The name of the function */ #define APR_REGISTER_OPTIONAL_FN(name) do { \ APR_OPTIONAL_FN_TYPE(name) *apu__opt = name; \ apr_dynamic_fn_register(#name,(apr_opt_fn_t *)apu__opt); \ } while (0) /** @internal * Private function! DO NOT USE! */ APU_DECLARE(apr_opt_fn_t *) apr_dynamic_fn_retrieve(const char *szName); /** * Retrieve an optional function. Returns NULL if the function is not present. * @param name The name of the function */ #define APR_RETRIEVE_OPTIONAL_FN(name) \ (APR_OPTIONAL_FN_TYPE(name) *)apr_dynamic_fn_retrieve(#name) /** @} */ #ifdef __cplusplus } #endif #endif /* APR_OPTIONAL_H */
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