1 /* Copyright 2001-2005 The Apache Software Foundation or its licensors, as
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 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,
64 /** @internal deprecated function, see apr_dynamic_fn_register */
65 APU_DECLARE_NONSTD(void) apr_register_optional_fn(const char *szName,
69 * Register an optional function. This can be later retrieved, type-safely, by
70 * name. Like all global functions, the name must be unique. Note that,
71 * confusingly but correctly, the function itself can be static!
72 * @param name The name of the function
74 #define APR_REGISTER_OPTIONAL_FN(name) do { \
75 APR_OPTIONAL_FN_TYPE(name) *apu__opt = name; \
76 apr_dynamic_fn_register(#name,(apr_opt_fn_t *)apu__opt); \
80 * Private function! DO NOT USE!
82 APU_DECLARE(apr_opt_fn_t *) apr_dynamic_fn_retrieve(const char *szName);
84 /** @internal deprecated function, see apr_dynamic_fn_retrieve */
85 APU_DECLARE(apr_opt_fn_t *) apr_retrieve_optional_fn(const char *szName);
88 * Retrieve an optional function. Returns NULL if the function is not present.
89 * @param name The name of the function
91 #define APR_RETRIEVE_OPTIONAL_FN(name) \
92 (APR_OPTIONAL_FN_TYPE(name) *)apr_dynamic_fn_retrieve(#name)
99 #endif /* APR_OPTIONAL_H */