libavcodec/eval.c File Reference

simple arithmetic expression evaluator. More...

#include "libavutil/avutil.h"
#include "eval.h"

Go to the source code of this file.

Data Structures

struct Parser

struct AVExpr

Defines

#define VARS 10

Functions

double av_strtod (const char *numstr, char **tail)

Parses the string in numstr and returns its value as a double.

static int strmatch (const char *s, const char *prefix)

static double eval_expr (Parser *p, AVExpr *e)

static AVExpr * parse_expr (Parser *p)

void ff_free_expr (AVExpr *e)

Frees a parsed expression previously created with ff_parse().

static AVExpr * parse_primary (Parser *p)

static AVExpr * new_eval_expr (int type, int value, AVExpr *p0, AVExpr *p1)

static AVExpr * parse_pow (Parser *p, int *sign)

static AVExpr * parse_factor (Parser *p)

static AVExpr * parse_term (Parser *p)

static AVExpr * parse_subexpr (Parser *p)

static int verify_expr (AVExpr *e)

AVExpr * ff_parse_expr (const char *s, const char *const *const_name, double(*const *func1)(void *, double), const char *const *func1_name, double(*const *func2)(void *, double, double), const char *const *func2_name, const char **error)

Parses an expression.

double ff_eval_expr (AVExpr *e, const double *const_value, void *opaque)

Evaluates a previously parsed expression.

double ff_parse_and_eval_expr (const char *s, const double *const_value, const char *const *const_name, double(*const *func1)(void *, double), const char *const *func1_name, double(*const *func2)(void *, double, double), const char *const *func2_name, void *opaque, const char **error)

Parses and evaluates an expression.

Variables

static const int8_t si_prefixes ['z'- 'E'+1]

Detailed Description

simple arithmetic expression evaluator.

see http://joe.hotchkiss.com/programming/eval/eval.html

Definition in file eval.c.

Define Documentation

#define VARS 10

Definition at line 43 of file eval.c.

Referenced by eval_expr().

Function Documentation

double av_strtod	(	const char *	numstr,
		char **	tail
	)

Parses the string in numstr and returns its value as a double.

If the string is empty, contains only whitespaces, or does not contain an initial substring that has the expected syntax for a floating-point number, no conversion is performed. In this case, returns a value of zero and the value returned in tail is the value of numstr.

Parameters:

	numstr	a string representing a number, may contain one of the International System number postfixes, for example 'K', 'M', 'G'. If 'i' is appended after the postfix, powers of 2 are used instead of powers of 10. The 'B' postfix multiplies the value for 8, and can be appended after another postfix or used alone. This allows using for example 'KB', 'MiB', 'G' and 'B' as postfix.
	tail	if non-NULL puts here the pointer to the char next after the last parsed character

Definition at line 70 of file eval.c.

Referenced by parse_primary().

static double eval_expr	(	Parser *	p,
		AVExpr *	e
	)			`[static]`

Definition at line 128 of file eval.c.

Referenced by ff_eval_expr().

double ff_eval_expr	(	AVExpr *	e,
		const double *	const_value,
		void *	opaque
	)

Evaluates a previously parsed expression.

Parameters:

	const_value	a zero terminated array of values for the identifers from ff_parse const_name
	opaque	a pointer which will be passed to all functions from func1 and func2

Returns:: the value of the expression

Definition at line 407 of file eval.c.

Referenced by ff_parse_and_eval_expr(), and get_qscale().

void ff_free_expr ( AVExpr * e )

Frees a parsed expression previously created with ff_parse().

Definition at line 168 of file eval.c.

Referenced by ff_free_expr(), ff_parse_and_eval_expr(), ff_parse_expr(), ff_rate_control_uninit(), and parse_primary().

double ff_parse_and_eval_expr	(	const char *	s,
		const double *	const_value,
		const char const	const_name,
		double(*)(void , double)	func1,
		const char const	func1_name,
		double(*)(void , double, double)	func2,
		const char const	func2_name,
		void *	opaque,
		const char **	error
	)

Parses and evaluates an expression.

Note, this is significantly slower than ff_eval_expr().

Parameters:

	s	expression as a zero terminated string for example "1+2^3+5*5+sin(2/3)"
	func1	NULL terminated array of function pointers for functions which take 1 argument
	func2	NULL terminated array of function pointers for functions which take 2 arguments
	const_name	NULL terminated array of zero terminated strings of constant identifers for example {"PI", "E", 0}
	func1_name	NULL terminated array of zero terminated strings of func1 identifers
	func2_name	NULL terminated array of zero terminated strings of func2 identifers
	error	pointer to a char* which is set to an error message if something goes wrong
	const_value	a zero terminated array of values for the identifers from const_name
	opaque	a pointer which will be passed to all functions from func1 and func2

Returns:: the value of the expression

Definition at line 415 of file eval.c.

Referenced by av_set_string3().

AVExpr* ff_parse_expr	(	const char *	s,
		const char const	const_name,
		double(*)(void , double)	func1,
		const char const	func1_name,
		double(*)(void , double, double)	func2,
		const char const	func2_name,
		const char **	error
	)

Parses an expression.

Parameters:

	s	expression as a zero terminated string for example "1+2^3+5*5+sin(2/3)"
	func1	NULL terminated array of function pointers for functions which take 1 argument
	func2	NULL terminated array of function pointers for functions which take 2 arguments
	const_name	NULL terminated array of zero terminated strings of constant identifers for example {"PI", "E", 0}
	func1_name	NULL terminated array of zero terminated strings of func1 identifers
	func2_name	NULL terminated array of zero terminated strings of func2 identifers
	error	pointer to a char* which is set to an error message if something goes wrong

Returns:: AVExpr which must be freed with ff_free_expr() by the user when it is not needed anymore NULL if anything went wrong

Definition at line 372 of file eval.c.

Referenced by ff_parse_and_eval_expr(), and ff_rate_control_init().

static AVExpr* new_eval_expr	(	int	type,
		int	value,
		AVExpr *	p0,
		AVExpr *	p1
	)			`[static]`

Definition at line 284 of file eval.c.

Referenced by parse_expr(), parse_factor(), parse_subexpr(), and parse_term().

static AVExpr * parse_expr ( Parser * p ) [static]

Definition at line 337 of file eval.c.

Referenced by ff_parse_expr(), and parse_primary().

static AVExpr* parse_factor ( Parser * p ) [static]

Definition at line 301 of file eval.c.

Referenced by parse_term().

static AVExpr* parse_pow	(	Parser *	p,
		int *	sign
	)			`[static]`

Definition at line 295 of file eval.c.

Referenced by parse_factor().

static AVExpr* parse_primary ( Parser * p ) [static]

Definition at line 175 of file eval.c.

Referenced by parse_pow().

static AVExpr* parse_subexpr ( Parser * p ) [static]

Definition at line 326 of file eval.c.

Referenced by parse_expr().

static AVExpr* parse_term ( Parser * p ) [static]

Definition at line 315 of file eval.c.

Referenced by parse_subexpr().

static int strmatch	(	const char *	s,
		const char *	prefix
	)			`[static]`

Definition at line 102 of file eval.c.

Referenced by parse_primary().

static int verify_expr ( AVExpr * e ) [static]

Definition at line 358 of file eval.c.

Referenced by ff_parse_expr().

Variable Documentation

const int8_t si_prefixes['z'- 'E'+1] [static]

Initial value:

{
    ['y'-'E']= -24,
    ['z'-'E']= -21,
    ['a'-'E']= -18,
    ['f'-'E']= -15,
    ['p'-'E']= -12,
    ['n'-'E']= - 9,
    ['u'-'E']= - 6,
    ['m'-'E']= - 3,
    ['c'-'E']= - 2,
    ['d'-'E']= - 1,
    ['h'-'E']=   2,
    ['k'-'E']=   3,
    ['K'-'E']=   3,
    ['M'-'E']=   6,
    ['G'-'E']=   9,
    ['T'-'E']=  12,
    ['P'-'E']=  15,
    ['E'-'E']=  18,
    ['Z'-'E']=  21,
    ['Y'-'E']=  24,
}

Definition at line 47 of file eval.c.

Referenced by av_strtod().


Data Structures
struct	Parser
struct	AVExpr
Defines
#define	VARS 10
Functions
double	av_strtod (const char numstr, char *tail)
	Parses the string in numstr and returns its value as a double.
static int	strmatch (const char s, const char prefix)
static double	eval_expr (Parser p, AVExpr e)
static AVExpr *	parse_expr (Parser *p)
void	ff_free_expr (AVExpr *e)
	Frees a parsed expression previously created with ff_parse().
static AVExpr *	parse_primary (Parser *p)
static AVExpr *	new_eval_expr (int type, int value, AVExpr p0, AVExpr p1)
static AVExpr *	parse_pow (Parser p, int sign)
static AVExpr *	parse_factor (Parser *p)
static AVExpr *	parse_term (Parser *p)
static AVExpr *	parse_subexpr (Parser *p)
static int	verify_expr (AVExpr *e)
AVExpr *	ff_parse_expr (const char s, const char const const_name, double(const func1)(void , double), const char const func1_name, double(const func2)(void , double, double), const char const func2_name, const char *error)
	Parses an expression.
double	ff_eval_expr (AVExpr e, const double const_value, void *opaque)
	Evaluates a previously parsed expression.
double	ff_parse_and_eval_expr (const char s, const double const_value, const char const const_name, double(const func1)(void , double), const char const func1_name, double(const func2)(void , double, double), const char const func2_name, void opaque, const char *error)
	Parses and evaluates an expression.
Variables
static const int8_t	si_prefixes ['z'- 'E'+1]