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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 
31 typedef 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  */
51 int 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  */
74 int 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  */
87 double av_expr_eval(AVExpr *e, const double *const_values, void *opaque);
88 
89 /**
90  * Free a parsed expression previously created with av_expr_parse().
91  */
92 void av_expr_free(AVExpr *e);
93 
94 /**
95  * Parse the string in numstr and return its value as a double. If
96  * the string is empty, contains only whitespaces, or does not contain
97  * an initial substring that has the expected syntax for a
98  * floating-point number, no conversion is performed. In this case,
99  * returns a value of zero and the value returned in tail is the value
100  * of numstr.
101  *
102  * @param numstr a string representing a number, may contain one of
103  * the International System number postfixes, for example 'K', 'M',
104  * 'G'. If 'i' is appended after the postfix, powers of 2 are used
105  * instead of powers of 10. The 'B' postfix multiplies the value for
106  * 8, and can be appended after another postfix or used alone. This
107  * allows using for example 'KB', 'MiB', 'G' and 'B' as postfix.
108  * @param tail if non-NULL puts here the pointer to the char next
109  * after the last parsed character
110  */
111 double av_strtod(const char *numstr, char **tail);
112 
113 #endif /* AVUTIL_EVAL_H */
const char * s
Definition: avisynth_c.h:631
static const char *const func1_names[]
Definition: vf_rotate.c:184
external API header
void av_expr_free(AVExpr *e)
Free a parsed expression previously created with av_expr_parse().
Definition: eval.c:312
static double(*const funcs1[])(void *, double)
Definition: vf_lut.c:188
Definition: eval.c:143
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.
Definition: eval.c:652
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.
Definition: eval.c:717
double av_expr_eval(AVExpr *e, const double *const_values, void *opaque)
Evaluate a previously parsed expression.
Definition: eval.c:707
double av_strtod(const char *numstr, char **tail)
Parse the string in numstr and return its value as a double.
Definition: eval.c:92