1 /* 2 * Copyright (c) 2002 Michael Niedermayer <michaelni@gmx.at> 3 * 4 * This file is part of FFmpeg. 5 * 6 * FFmpeg is free software; you can redistribute it and/or 7 * modify it under the terms of the GNU Lesser General Public 8 * License as published by the Free Software Foundation; either 9 * version 2.1 of the License, or (at your option) any later version. 10 * 11 * FFmpeg is distributed in the hope that it will be useful, 12 * but WITHOUT ANY WARRANTY; without even the implied warranty of 13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 14 * Lesser General Public License for more details. 15 * 16 * You should have received a copy of the GNU Lesser General Public 17 * License along with FFmpeg; if not, write to the Free Software 18 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA 19 */ 20 21 /** 22 * @file 23 * simple arithmetic expression evaluator 24 */ 25 26 #ifndef AVUTIL_EVAL_H 27 #define AVUTIL_EVAL_H 28 29 typedef struct AVExpr AVExpr; 30 31 /** 32 * Parse and evaluate an expression. 33 * Note, this is significantly slower than av_expr_eval(). 34 * 35 * @param res a pointer to a double where is put the result value of 36 * the expression, or NAN in case of error 37 * @param s expression as a zero terminated string, for example "1+2^3+5*5+sin(2/3)" 38 * @param const_names NULL terminated array of zero terminated strings of constant identifiers, for example {"PI", "E", 0} 39 * @param const_values a zero terminated array of values for the identifiers from const_names 40 * @param func1_names NULL terminated array of zero terminated strings of funcs1 identifiers 41 * @param funcs1 NULL terminated array of function pointers for functions which take 1 argument 42 * @param func2_names NULL terminated array of zero terminated strings of funcs2 identifiers 43 * @param funcs2 NULL terminated array of function pointers for functions which take 2 arguments 44 * @param opaque a pointer which will be passed to all functions from funcs1 and funcs2 45 * @param log_ctx parent logging context 46 * @return >= 0 in case of success, a negative value corresponding to an 47 * AVERROR code otherwise 48 */ 49 int av_expr_parse_and_eval(double *res, const char *s, 50 const char * const *const_names, const double *const_values, 51 const char * const *func1_names, double (* const *funcs1)(void *, double), 52 const char * const *func2_names, double (* const *funcs2)(void *, double, double), 53 void *opaque, int log_offset, void *log_ctx); 54 55 /** 56 * Parse an expression. 57 * 58 * @param expr a pointer where is put an AVExpr containing the parsed 59 * value in case of successful parsing, or NULL otherwise. 60 * The pointed to AVExpr must be freed with av_expr_free() by the user 61 * when it is not needed anymore. 62 * @param s expression as a zero terminated string, for example "1+2^3+5*5+sin(2/3)" 63 * @param const_names NULL terminated array of zero terminated strings of constant identifiers, for example {"PI", "E", 0} 64 * @param func1_names NULL terminated array of zero terminated strings of funcs1 identifiers 65 * @param funcs1 NULL terminated array of function pointers for functions which take 1 argument 66 * @param func2_names NULL terminated array of zero terminated strings of funcs2 identifiers 67 * @param funcs2 NULL terminated array of function pointers for functions which take 2 arguments 68 * @param log_ctx parent logging context 69 * @return >= 0 in case of success, a negative value corresponding to an 70 * AVERROR code otherwise 71 */ 72 int av_expr_parse(AVExpr **expr, const char *s, 73 const char * const *const_names, 74 const char * const *func1_names, double (* const *funcs1)(void *, double), 75 const char * const *func2_names, double (* const *funcs2)(void *, double, double), 76 int log_offset, void *log_ctx); 77 78 /** 79 * Evaluate a previously parsed expression. 80 * 81 * @param const_values a zero terminated array of values for the identifiers from av_expr_parse() const_names 82 * @param opaque a pointer which will be passed to all functions from funcs1 and funcs2 83 * @return the value of the expression 84 */ 85 double av_expr_eval(AVExpr *e, const double *const_values, void *opaque); 86 87 /** 88 * Track the presence of variables and their number of occurrences in a parsed expression 89 * 90 * @param counter a zero-initialized array where the count of each variable will be stored 91 * @param size size of array 92 * @return 0 on success, a negative value indicates that no expression or array was passed 93 * or size was zero 94 */ 95 int av_expr_count_vars(AVExpr *e, unsigned *counter, int size); 96 97 /** 98 * Track the presence of user provided functions and their number of occurrences 99 * in a parsed expression. 100 * 101 * @param counter a zero-initialized array where the count of each function will be stored 102 * if you passed 5 functions with 2 arguments to av_expr_parse() 103 * then for arg=2 this will use upto 5 entries. 104 * @param size size of array 105 * @param arg number of arguments the counted functions have 106 * @return 0 on success, a negative value indicates that no expression or array was passed 107 * or size was zero 108 */ 109 int av_expr_count_func(AVExpr *e, unsigned *counter, int size, int arg); 110 111 /** 112 * Free a parsed expression previously created with av_expr_parse(). 113 */ 114 void av_expr_free(AVExpr *e); 115 116 /** 117 * Parse the string in numstr and return its value as a double. If 118 * the string is empty, contains only whitespaces, or does not contain 119 * an initial substring that has the expected syntax for a 120 * floating-point number, no conversion is performed. In this case, 121 * returns a value of zero and the value returned in tail is the value 122 * of numstr. 123 * 124 * @param numstr a string representing a number, may contain one of 125 * the International System number postfixes, for example 'K', 'M', 126 * 'G'. If 'i' is appended after the postfix, powers of 2 are used 127 * instead of powers of 10. The 'B' postfix multiplies the value by 128 * 8, and can be appended after another postfix or used alone. This 129 * allows using for example 'KB', 'MiB', 'G' and 'B' as postfix. 130 * @param tail if non-NULL puts here the pointer to the char next 131 * after the last parsed character 132 */ 133 double av_strtod(const char *numstr, char **tail); 134 135 #endif /* AVUTIL_EVAL_H */ 136