1 /* Licensed to the Apache Software Foundation (ASF) under one or more
2 * contributor license agreements. See the NOTICE file distributed with
3 * this work for additional information regarding copyright ownership.
4 * The ASF licenses this file to You under the Apache License, Version 2.0
5 * (the "License"); you may not use this file except in compliance with
6 * the License. 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 APR_OPTIONAL_H
18 #define APR_OPTIONAL_H
22 * @file apr_optional.h
23 * @brief APR-UTIL registration of functions exported by modules
30 * @defgroup APR_Util_Opt Optional Functions
33 * Typesafe registration and retrieval of functions that may not be present
34 * (i.e. functions exported by optional modules)
39 * The type of an optional function.
40 * @param name The name of the function
42 #define APR_OPTIONAL_FN_TYPE(name) apr_OFN_##name##_t
45 * Declare an optional function.
46 * @param ret The return type of the function
47 * @param name The name of the function
48 * @param args The function arguments (including brackets)
50 #define APR_DECLARE_OPTIONAL_FN(ret,name,args) \
51 typedef ret (APR_OPTIONAL_FN_TYPE(name)) args
54 * XXX: This doesn't belong here, then!
55 * Private function! DO NOT USE!
59 typedef void (apr_opt_fn_t)(void);
61 APU_DECLARE_NONSTD(void) apr_dynamic_fn_register(const char *szName,
65 * Register an optional function. This can be later retrieved, type-safely, by
66 * name. Like all global functions, the name must be unique. Note that,
67 * confusingly but correctly, the function itself can be static!
68 * @param name The name of the function
70 #define APR_REGISTER_OPTIONAL_FN(name) do { \
71 APR_OPTIONAL_FN_TYPE(name) *apu__opt = name; \
72 apr_dynamic_fn_register(#name,(apr_opt_fn_t *)apu__opt); \
76 * Private function! DO NOT USE!
78 APU_DECLARE(apr_opt_fn_t *) apr_dynamic_fn_retrieve(const char *szName);
81 * Retrieve an optional function. Returns NULL if the function is not present.
82 * @param name The name of the function
84 #define APR_RETRIEVE_OPTIONAL_FN(name) \
85 (APR_OPTIONAL_FN_TYPE(name) *)apr_dynamic_fn_retrieve(#name)
92 #endif /* APR_OPTIONAL_H */