2 * Copyright (c) 2002 Michael Niedermayer <michaelni@gmx.at>
4 * This file is part of FFmpeg.
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.
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.
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
23 * simple arithmetic expression evaluator
29 typedef struct AVExpr AVExpr
;
32 * Parse and evaluate an expression.
33 * Note, this is significantly slower than av_expr_eval().
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_offset log level offset, can be used to silence error messages
46 * @param log_ctx parent logging context
47 * @return >= 0 in case of success, a negative value corresponding to an
48 * AVERROR code otherwise
50 int av_expr_parse_and_eval(double *res
, const char *s
,
51 const char * const *const_names
, const double *const_values
,
52 const char * const *func1_names
, double (* const *funcs1
)(void *, double),
53 const char * const *func2_names
, double (* const *funcs2
)(void *, double, double),
54 void *opaque
, int log_offset
, void *log_ctx
);
57 * Parse an expression.
59 * @param expr a pointer where is put an AVExpr containing the parsed
60 * value in case of successful parsing, or NULL otherwise.
61 * The pointed to AVExpr must be freed with av_expr_free() by the user
62 * when it is not needed anymore.
63 * @param s expression as a zero terminated string, for example "1+2^3+5*5+sin(2/3)"
64 * @param const_names NULL terminated array of zero terminated strings of constant identifiers, for example {"PI", "E", 0}
65 * @param func1_names NULL terminated array of zero terminated strings of funcs1 identifiers
66 * @param funcs1 NULL terminated array of function pointers for functions which take 1 argument
67 * @param func2_names NULL terminated array of zero terminated strings of funcs2 identifiers
68 * @param funcs2 NULL terminated array of function pointers for functions which take 2 arguments
69 * @param log_offset log level offset, can be used to silence error messages
70 * @param log_ctx parent logging context
71 * @return >= 0 in case of success, a negative value corresponding to an
72 * AVERROR code otherwise
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
);
81 * Evaluate a previously parsed expression.
83 * @param e the AVExpr to evaluate
84 * @param const_values a zero terminated array of values for the identifiers from av_expr_parse() const_names
85 * @param opaque a pointer which will be passed to all functions from funcs1 and funcs2
86 * @return the value of the expression
88 double av_expr_eval(AVExpr
*e
, const double *const_values
, void *opaque
);
91 * Track the presence of variables and their number of occurrences in a parsed expression
93 * @param e the AVExpr to track variables in
94 * @param counter a zero-initialized array where the count of each variable will be stored
95 * @param size size of array
96 * @return 0 on success, a negative value indicates that no expression or array was passed
99 int av_expr_count_vars(AVExpr
*e
, unsigned *counter
, int size
);
102 * Track the presence of user provided functions and their number of occurrences
103 * in a parsed expression.
105 * @param e the AVExpr to track user provided functions in
106 * @param counter a zero-initialized array where the count of each function will be stored
107 * if you passed 5 functions with 2 arguments to av_expr_parse()
108 * then for arg=2 this will use up to 5 entries.
109 * @param size size of array
110 * @param arg number of arguments the counted functions have
111 * @return 0 on success, a negative value indicates that no expression or array was passed
114 int av_expr_count_func(AVExpr
*e
, unsigned *counter
, int size
, int arg
);
117 * Free a parsed expression previously created with av_expr_parse().
119 void av_expr_free(AVExpr
*e
);
122 * Parse the string in numstr and return its value as a double. If
123 * the string is empty, contains only whitespaces, or does not contain
124 * an initial substring that has the expected syntax for a
125 * floating-point number, no conversion is performed. In this case,
126 * returns a value of zero and the value returned in tail is the value
129 * @param numstr a string representing a number, may contain one of
130 * the International System number postfixes, for example 'K', 'M',
131 * 'G'. If 'i' is appended after the postfix, powers of 2 are used
132 * instead of powers of 10. The 'B' postfix multiplies the value by
133 * 8, and can be appended after another postfix or used alone. This
134 * allows using for example 'KB', 'MiB', 'G' and 'B' as postfix.
135 * @param tail if non-NULL puts here the pointer to the char next
136 * after the last parsed character
138 double av_strtod(const char *numstr
, char **tail
);
140 #endif /* AVUTIL_EVAL_H */