/** * @file BPredicate.h * @author Ambroz Bizjak * * @section LICENSE * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. Neither the name of the author nor the * names of its contributors may be used to endorse or promote products * derived from this software without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE * DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. * * @section DESCRIPTION * * Object that parses and evaluates a logical expression. * Allows the user to define custom functions than can be * used in the expression. * * Syntax and semantics for logical expressions: * * - true * Logical true constant. Evaluates to 1. * * - false * Logical false constant. Evaluates to 0. * * - NOT expression * Logical negation. If the expression evaluates to error, the * negation evaluates to error. * * - expression OR expression * Logical disjunction. The second expression is only evaluated * if the first expression evaluates to false. If a sub-expression * evaluates to error, the disjunction evaluates to error. * * - expression AND expression * Logical conjunction. The second expression is only evaluated * if the first expression evaluates to true. If a sub-expression * evaluates to error, the conjunction evaluates to error. * * - function(arg, ..., arg) * Evaluation of a user-provided function (function is the name of the * function, [a-zA-Z0-9_]+). * If the function with the given name does not exist, it evaluates to * error. * Arguments are evaluated from left to right. Each argument can either * be a logical expression or a string (characters enclosed in double * quotes, without any double quote). * If an argument is encountered, but all needed arguments have already * been evaluated, the function evaluates to error. * If an argument is of wrong type, it is not evaluated and the function * evaluates to error. * If an argument evaluates to error, the function evaluates to error. * If after all arguments have been evaluated, the function needs more * arguments, it evaluates to error. * Then the handler function is called. If it returns anything other * than 1 and 0, the function evaluates to error. Otherwise it evaluates * to what the handler function returned. */ #ifndef BADVPN_PREDICATE_BPREDICATE_H #define BADVPN_PREDICATE_BPREDICATE_H #include #include #include #define PREDICATE_TYPE_BOOL 1 #define PREDICATE_TYPE_STRING 2 #define PREDICATE_MAX_NAME 16 #define PREDICATE_MAX_ARGS 16 /** * Handler function called when evaluating a custom function in the predicate. * * @param user value passed to {@link BPredicateFunction_Init} * @param args arguments to the function. Points to an array of pointers (as many as the * function has arguments), where each pointer points to either to an int or * a zero-terminated string (depending on the type of the argument). * @return 1 for true, 0 for false, -1 for error */ typedef int (*BPredicate_callback) (void *user, void **args); /** * Object that parses and evaluates a logical expression. * Allows the user to define custom functions than can be * used in the expression. */ typedef struct { DebugObject d_obj; void *root; BAVL functions_tree; #ifndef NDEBUG int in_function; #endif } BPredicate; /** * Object that represents a custom function in {@link BPredicate}. */ typedef struct { DebugObject d_obj; BPredicate *p; char name[PREDICATE_MAX_NAME + 1]; int args[PREDICATE_MAX_ARGS]; int num_args; BPredicate_callback callback; void *user; BAVLNode tree_node; } BPredicateFunction; /** * Initializes the object. * * @param p the object * @param str logical expression * @return 1 on success, 0 on failure */ int BPredicate_Init (BPredicate *p, char *str) WARN_UNUSED; /** * Frees the object. * Must have no custom functions. * Must not be called from function handlers. * * @param p the object */ void BPredicate_Free (BPredicate *p); /** * Evaluates the logical expression. * Must not be called from function handlers. * * @param p the object * @return 1 for true, 0 for false, -1 for error */ int BPredicate_Eval (BPredicate *p); /** * Registers a custom function for {@link BPredicate}. * Must not be called from function handlers. * * @param o the object * @param p predicate to register the function for * @param args array of argument types. Each type is either PREDICATE_TYPE_BOOL or PREDICATE_TYPE_STRING. * @param num_args number of arguments for the function. Must be >=0 and <=PREDICATE_MAX_ARGS. * @param callback handler to call to evaluate the function * @param user value to pass to handler */ void BPredicateFunction_Init (BPredicateFunction *o, BPredicate *p, char *name, int *args, int num_args, BPredicate_callback callback, void *user); /** * Removes a custom function for {@link BPredicate}. * Must not be called from function handlers. * * @param o the object */ void BPredicateFunction_Free (BPredicateFunction *o); #endif