FFmpeg 4.4.5
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eval.h
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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#include "avutil.h"
30
31typedef struct AVExpr AVExpr;
32
33/**
34 * Parse and evaluate an expression.
35 * Note, this is significantly slower than av_expr_eval().
36 *
37 * @param res a pointer to a double where is put the result value of
38 * the expression, or NAN in case of error
39 * @param s expression as a zero terminated string, for example "1+2^3+5*5+sin(2/3)"
40 * @param const_names NULL terminated array of zero terminated strings of constant identifiers, for example {"PI", "E", 0}
41 * @param const_values a zero terminated array of values for the identifiers from const_names
42 * @param func1_names NULL terminated array of zero terminated strings of funcs1 identifiers
43 * @param funcs1 NULL terminated array of function pointers for functions which take 1 argument
44 * @param func2_names NULL terminated array of zero terminated strings of funcs2 identifiers
45 * @param funcs2 NULL terminated array of function pointers for functions which take 2 arguments
46 * @param opaque a pointer which will be passed to all functions from funcs1 and funcs2
47 * @param log_ctx parent logging context
48 * @return >= 0 in case of success, a negative value corresponding to an
49 * AVERROR code otherwise
50 */
51int av_expr_parse_and_eval(double *res, const char *s,
52 const char * const *const_names, const double *const_values,
53 const char * const *func1_names, double (* const *funcs1)(void *, double),
54 const char * const *func2_names, double (* const *funcs2)(void *, double, double),
55 void *opaque, int log_offset, void *log_ctx);
56
57/**
58 * Parse an expression.
59 *
60 * @param expr a pointer where is put an AVExpr containing the parsed
61 * value in case of successful parsing, or NULL otherwise.
62 * The pointed to AVExpr must be freed with av_expr_free() by the user
63 * when it is not needed anymore.
64 * @param s expression as a zero terminated string, for example "1+2^3+5*5+sin(2/3)"
65 * @param const_names NULL terminated array of zero terminated strings of constant identifiers, for example {"PI", "E", 0}
66 * @param func1_names NULL terminated array of zero terminated strings of funcs1 identifiers
67 * @param funcs1 NULL terminated array of function pointers for functions which take 1 argument
68 * @param func2_names NULL terminated array of zero terminated strings of funcs2 identifiers
69 * @param funcs2 NULL terminated array of function pointers for functions which take 2 arguments
70 * @param log_ctx parent logging context
71 * @return >= 0 in case of success, a negative value corresponding to an
72 * AVERROR code otherwise
73 */
74int av_expr_parse(AVExpr **expr, const char *s,
75 const char * const *const_names,
76 const char * const *func1_names, double (* const *funcs1)(void *, double),
77 const char * const *func2_names, double (* const *funcs2)(void *, double, double),
78 int log_offset, void *log_ctx);
79
80/**
81 * Evaluate a previously parsed expression.
82 *
83 * @param const_values a zero terminated array of values for the identifiers from av_expr_parse() const_names
84 * @param opaque a pointer which will be passed to all functions from funcs1 and funcs2
85 * @return the value of the expression
86 */
87double av_expr_eval(AVExpr *e, const double *const_values, void *opaque);
88
89/**
90 * Track the presence of variables and their number of occurrences in a parsed expression
91 *
92 * @param counter a zero-initialized array where the count of each variable will be stored
93 * @param size size of array
94 * @return 0 on success, a negative value indicates that no expression or array was passed
95 * or size was zero
96 */
97int av_expr_count_vars(AVExpr *e, unsigned *counter, int size);
98
99/**
100 * Track the presence of user provided functions and their number of occurrences
101 * in a parsed expression.
102 *
103 * @param counter a zero-initialized array where the count of each function will be stored
104 * if you passed 5 functions with 2 arguments to av_expr_parse()
105 * then for arg=2 this will use upto 5 entries.
106 * @param size size of array
107 * @param arg number of arguments the counted functions have
108 * @return 0 on success, a negative value indicates that no expression or array was passed
109 * or size was zero
110 */
111int av_expr_count_func(AVExpr *e, unsigned *counter, int size, int arg);
112
113/**
114 * Free a parsed expression previously created with av_expr_parse().
115 */
117
118/**
119 * Parse the string in numstr and return its value as a double. If
120 * the string is empty, contains only whitespaces, or does not contain
121 * an initial substring that has the expected syntax for a
122 * floating-point number, no conversion is performed. In this case,
123 * returns a value of zero and the value returned in tail is the value
124 * of numstr.
125 *
126 * @param numstr a string representing a number, may contain one of
127 * the International System number postfixes, for example 'K', 'M',
128 * 'G'. If 'i' is appended after the postfix, powers of 2 are used
129 * instead of powers of 10. The 'B' postfix multiplies the value by
130 * 8, and can be appended after another postfix or used alone. This
131 * allows using for example 'KB', 'MiB', 'G' and 'B' as postfix.
132 * @param tail if non-NULL puts here the pointer to the char next
133 * after the last parsed character
134 */
135double av_strtod(const char *numstr, char **tail);
136
137#endif /* AVUTIL_EVAL_H */
Convenience header that includes libavutil's core.
void av_expr_free(AVExpr *e)
Free a parsed expression previously created with av_expr_parse().
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 and evaluate an expression.
int av_expr_count_vars(AVExpr *e, unsigned *counter, int size)
Track the presence of variables and their number of occurrences in a parsed expression.
double av_expr_eval(AVExpr *e, const double *const_values, void *opaque)
Evaluate a previously parsed expression.
double av_strtod(const char *numstr, char **tail)
Parse the string in numstr and return its value as a double.
struct AVExpr AVExpr
Definition eval.h:31
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)
Parse an expression.
int av_expr_count_func(AVExpr *e, unsigned *counter, int size, int arg)
Track the presence of user provided functions and their number of occurrences in a parsed expression.