2 * simple arithmetic expression evaluator
4 * Copyright (c) 2002 Michael Niedermayer <michaelni@gmx.at>
6 * This file is part of FFmpeg.
8 * FFmpeg is free software; you can redistribute it and/or
9 * modify it under the terms of the GNU Lesser General Public
10 * License as published by the Free Software Foundation; either
11 * version 2.1 of the License, or (at your option) any later version.
13 * FFmpeg is distributed in the hope that it will be useful,
14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
16 * Lesser General Public License for more details.
18 * You should have received a copy of the GNU Lesser General Public
19 * License along with FFmpeg; if not, write to the Free Software
20 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
24 * @file libavcodec/eval.h
28 #ifndef AVCODEC_EVAL_H
29 #define AVCODEC_EVAL_H
32 * Parses and evaluates an expression.
33 * Note, this is significantly slower than ff_parse_eval()
34 * @param s expression as a zero terminated string for example "1+2^3+5*5+sin(2/3)"
35 * @param func1 NULL terminated array of function pointers for functions which take 1 argument
36 * @param func2 NULL terminated array of function pointers for functions which take 2 arguments
37 * @param const_name NULL terminated array of zero terminated strings of constant identifers for example {"PI", "E", 0}
38 * @param func1_name NULL terminated array of zero terminated strings of func1 identifers
39 * @param func2_name NULL terminated array of zero terminated strings of func2 identifers
40 * @param error pointer to a char* which is set to an error message if something goes wrong
41 * @param const_value a zero terminated array of values for the identifers from const_name
42 * @param opaque a pointer which will be passed to all functions from func1 and func2
43 * @return the value of the expression
45 double ff_eval2(const char *s
, const double *const_value
, const char * const *const_name
,
46 double (**func1
)(void *, double), const char **func1_name
,
47 double (**func2
)(void *, double, double), const char **func2_name
,
48 void *opaque
, const char **error
);
50 typedef struct ff_expr_s AVEvalExpr
;
53 * Parses a expression.
54 * @param s expression as a zero terminated string for example "1+2^3+5*5+sin(2/3)"
55 * @param func1 NULL terminated array of function pointers for functions which take 1 argument
56 * @param func2 NULL terminated array of function pointers for functions which take 2 arguments
57 * @param const_name NULL terminated array of zero terminated strings of constant identifers for example {"PI", "E", 0}
58 * @param func1_name NULL terminated array of zero terminated strings of func1 identifers
59 * @param func2_name NULL terminated array of zero terminated strings of func2 identifers
60 * @param error pointer to a char* which is set to an error message if something goes wrong
61 * @return AVEvalExpr which must be freed with ff_eval_free by the user when it is not needed anymore
62 * NULL if anything went wrong
64 AVEvalExpr
* ff_parse(const char *s
, const char * const *const_name
,
65 double (**func1
)(void *, double), const char **func1_name
,
66 double (**func2
)(void *, double, double), const char **func2_name
,
69 * Evaluates a previously parsed expression.
70 * @param const_value a zero terminated array of values for the identifers from ff_parse const_name
71 * @param opaque a pointer which will be passed to all functions from func1 and func2
72 * @return the value of the expression
74 double ff_parse_eval(AVEvalExpr
* e
, const double *const_value
, void *opaque
);
75 void ff_eval_free(AVEvalExpr
* e
);
78 * Parses the string in numstr and returns its value as a double. If
79 * the string is empty, contains only whitespaces, or does not contain
80 * an initial substring that has the expected syntax for a
81 * floating-point number, no conversion is performed. In this case,
82 * returns a value of zero and the value returned in tail is the value
85 * @param numstr a string representing a number, may contain one of
86 * the International System number postfixes, for example 'K', 'M',
87 * 'G'. If 'i' is appended after the postfix, powers of 2 are used
88 * instead of powers of 10. The 'B' postfix multiplies the value for
89 * 8, and can be appended after another postfix or used alone. This
90 * allows using for example 'KB', 'MiB', 'G' and 'B' as postfix.
91 * @param tail if non-NULL puts here the pointer to the char next
92 * after the last parsed character
94 double av_strtod(const char *numstr
, char **tail
);
96 #endif /* AVCODEC_EVAL_H */