/* * Copyright (c) 2002 Michael Niedermayer <michaelni@gmx.at> * * This file is part of FFmpeg. * * FFmpeg is free software; you can redistribute it and/or * modify it under the terms of the GNU Lesser General Public * License as published by the Free Software Foundation; either * version 2.1 of the License, or (at your option) any later version. * * FFmpeg is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU * Lesser General Public License for more details. * * You should have received a copy of the GNU Lesser General Public * License along with FFmpeg; if not, write to the Free Software * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA */ /** * @file * simple arithmetic expression evaluator */ #ifndef AVUTIL_EVAL_H #define AVUTIL_EVAL_H typedef struct AVExpr AVExpr; /** * Parse and evaluate an expression. * Note, this is significantly slower than av_expr_eval(). * * @param res a pointer to a double where is put the result value of * the expression, or NAN in case of error * @param s expression as a zero terminated string, for example "1+2^3+5*5+sin(2/3)" * @param const_names NULL terminated array of zero terminated strings of constant identifiers, for example {"PI", "E", 0} * @param const_values a zero terminated array of values for the identifiers from const_names * @param func1_names NULL terminated array of zero terminated strings of funcs1 identifiers * @param funcs1 NULL terminated array of function pointers for functions which take 1 argument * @param func2_names NULL terminated array of zero terminated strings of funcs2 identifiers * @param funcs2 NULL terminated array of function pointers for functions which take 2 arguments * @param opaque a pointer which will be passed to all functions from funcs1 and funcs2 * @param log_offset log level offset, can be used to silence error messages * @param log_ctx parent logging context * @return >= 0 in case of success, a negative value corresponding to an * AVERROR code otherwise */ int av_expr_parse_and_eval(double *res, const char *s, const char * const *const_names, const double *const_values, const char * const *func1_names, double (* const *funcs1)(void *, double), const char * const *func2_names, double (* const *funcs2)(void *, double, double), void *opaque, int log_offset, void *log_ctx); /** * Parse an expression. * * @param expr a pointer where is put an AVExpr containing the parsed * value in case of successful parsing, or NULL otherwise. * The pointed to AVExpr must be freed with av_expr_free() by the user * when it is not needed anymore. * @param s expression as a zero terminated string, for example "1+2^3+5*5+sin(2/3)" * @param const_names NULL terminated array of zero terminated strings of constant identifiers, for example {"PI", "E", 0} * @param func1_names NULL terminated array of zero terminated strings of funcs1 identifiers * @param funcs1 NULL terminated array of function pointers for functions which take 1 argument * @param func2_names NULL terminated array of zero terminated strings of funcs2 identifiers * @param funcs2 NULL terminated array of function pointers for functions which take 2 arguments * @param log_offset log level offset, can be used to silence error messages * @param log_ctx parent logging context * @return >= 0 in case of success, a negative value corresponding to an * AVERROR code otherwise */ int av_expr_parse(AVExpr **expr, const char *s, const char * const *const_names, const char * const *func1_names, double (* const *funcs1)(void *, double), const char * const *func2_names, double (* const *funcs2)(void *, double, double), int log_offset, void *log_ctx); /** * Evaluate a previously parsed expression. * * @param e the AVExpr to evaluate * @param const_values a zero terminated array of values for the identifiers from av_expr_parse() const_names * @param opaque a pointer which will be passed to all functions from funcs1 and funcs2 * @return the value of the expression */ double av_expr_eval(AVExpr *e, const double *const_values, void *opaque); /** * Track the presence of variables and their number of occurrences in a parsed expression * * @param e the AVExpr to track variables in * @param counter a zero-initialized array where the count of each variable will be stored * @param size size of array * @return 0 on success, a negative value indicates that no expression or array was passed * or size was zero */ int av_expr_count_vars(AVExpr *e, unsigned *counter, int size); /** * Track the presence of user provided functions and their number of occurrences * in a parsed expression. * * @param e the AVExpr to track user provided functions in * @param counter a zero-initialized array where the count of each function will be stored * if you passed 5 functions with 2 arguments to av_expr_parse() * then for arg=2 this will use up to 5 entries. * @param size size of array * @param arg number of arguments the counted functions have * @return 0 on success, a negative value indicates that no expression or array was passed * or size was zero */ int av_expr_count_func(AVExpr *e, unsigned *counter, int size, int arg); /** * Free a parsed expression previously created with av_expr_parse(). */ void av_expr_free(AVExpr *e); /** * Parse the string in numstr and return its value as a double. If * the string is empty, contains only whitespaces, or does not contain * an initial substring that has the expected syntax for a * floating-point number, no conversion is performed. In this case, * returns a value of zero and the value returned in tail is the value * of numstr. * * @param numstr a string representing a number, may contain one of * the International System number postfixes, for example 'K', 'M', * 'G'. If 'i' is appended after the postfix, powers of 2 are used * instead of powers of 10. The 'B' postfix multiplies the value by * 8, and can be appended after another postfix or used alone. This * allows using for example 'KB', 'MiB', 'G' and 'B' as postfix. * @param tail if non-NULL puts here the pointer to the char next * after the last parsed character */ double av_strtod(const char *numstr, char **tail); #endif /* AVUTIL_EVAL_H */