Data Structures
struct	sg_expr_extension

struct	sg_expr

struct	sg_expr_argument

Typedefs
typedef double(*	sg_expr_func) (void cls, struct sg_expr_argument args, const char *identifier)

Enumerations
enum	sg_expr_err_type { SG_EXPR_ERR_UNKNOWN , SG_EXPR_ERR_UNEXPECTED_NUMBER , SG_EXPR_ERR_UNEXPECTED_WORD , SG_EXPR_ERR_UNEXPECTED_PARENS , SG_EXPR_ERR_MISSING_OPERAND , SG_EXPR_ERR_UNKNOWN_OPERATOR , SG_EXPR_ERR_INVALID_FUNC_NAME , SG_EXPR_ERR_BAD_PARENS , SG_EXPR_ERR_TOO_FEW_FUNC_ARGS , SG_EXPR_ERR_FIRST_ARG_IS_NOT_VAR , SG_EXPR_ERR_BAD_VARIABLE_NAME , SG_EXPR_ERR_BAD_ASSIGNMENT }

Functions
struct sg_expr *	sg_expr_new (void) __attribute__((malloc))

void	sg_expr_free (struct sg_expr *expr)

int	sg_expr_compile (struct sg_expr expr, const char str, size_t len, struct sg_expr_extension *extensions)

int	sg_expr_clear (struct sg_expr *expr)

double	sg_expr_eval (struct sg_expr *expr)

double	sg_expr_var (struct sg_expr expr, const char name, size_t len)

int	sg_expr_set_var (struct sg_expr expr, const char name, size_t len, double val)

double	sg_expr_arg (struct sg_expr_argument *args, int index)

int	sg_expr_near (struct sg_expr *expr)

enum sg_expr_err_type	sg_expr_err (struct sg_expr *expr)

const char *	sg_expr_strerror (struct sg_expr *expr)

double	sg_expr_calc (const char *str, size_t len)

Detailed Description

Mathematical expression evaluator.

Typedef Documentation

◆ sg_expr_func

typedef double(* sg_expr_func) (void *cls, struct sg_expr_argument *args, const char *identifier)

Callback signature to specify a function at build time to be executed at run time in a mathematical expression.

Parameters

[out]	cls	User-defined closure.
[out]	args	Floating-point arguments passed to the function.
[out]	identifier	Null-terminated string to identify the function.

Returns: Floating-point value calculated at build time to be used at run time in a mathematical expression.

Enumeration Type Documentation

◆ sg_expr_err_type

enum sg_expr_err_type

Possible error types returned by the mathematical expression evaluator.

Enumerator
SG_EXPR_ERR_UNKNOWN	Error not related to evaluation, e.g. `EINVAL`.
SG_EXPR_ERR_UNEXPECTED_NUMBER	Unexpected number, e.g. `"(1+2)3"`.
SG_EXPR_ERR_UNEXPECTED_WORD	Unexpected word, e.g. `"(1+2)x"`.
SG_EXPR_ERR_UNEXPECTED_PARENS	Unexpected parenthesis, e.g. `"1(2+3)"`.
SG_EXPR_ERR_MISSING_OPERAND	Missing expected operand, e.g. `"0^+1"`.
SG_EXPR_ERR_UNKNOWN_OPERATOR	Unknown operator, e.g. `"(1+2)."`.
SG_EXPR_ERR_INVALID_FUNC_NAME	Invalid function name, e.g. `"unknownfunc()"`.
SG_EXPR_ERR_BAD_PARENS	Bad parenthesis, e.g. `"(1+2"`.
SG_EXPR_ERR_TOO_FEW_FUNC_ARGS	Too few arguments passed to a macro, e.g. `"$()"`.
SG_EXPR_ERR_FIRST_ARG_IS_NOT_VAR	First macro argument is not variable, e.g. `"$(1)"`.
SG_EXPR_ERR_BAD_VARIABLE_NAME	Bad variable name, e.g. `"2.3.4"`.
SG_EXPR_ERR_BAD_ASSIGNMENT	Bad assignment, e.g. `"2=3"`.

Function Documentation

◆ sg_expr_new()

struct sg_expr * sg_expr_new ( void )

Creates a new mathematical expression evaluator handle.

Returns: New mathematical expression evaluator handle.

Return values

NULL	If no memory space is available and set the `errno` to `ENOMEM`.

Examples: example_expr_full.c.

◆ sg_expr_free()

void sg_expr_free ( struct sg_expr * expr )

Frees the mathematical expression evaluator handle previously allocated by sg_expr_new().

Parameters

[in] expr Expression evaluator handle.

Examples: example_expr_full.c.

◆ sg_expr_compile()

int sg_expr_compile	(	struct sg_expr *	expr,
		const char *	str,
		size_t	len,
		struct sg_expr_extension *	extensions
	)

Compiles a mathematical expression allowing to declare variables, macros and extensions.

Parameters

[in]	expr	Mathematical expression instance.
[in]	str	Null-terminated string with the mathematical expression to be compiled.
[in]	len	Length of the mathematical expression to be compiled.
[in]	extensions	Array of extensions to extend the evaluator.

Note: The extension array must be terminated by a zeroed item.

Return values

0	Success.
EINVAL	Invalid argument.
ENOENT	Missing a needed extenssion.
EALREADY	Mathematical expression already compiled.
ENOMEM	Out of memory.

Examples: example_expr_full.c.

◆ sg_expr_clear()

int sg_expr_clear ( struct sg_expr * expr )

Clears a mathematical expression instance.

Parameters

[in] expr Mathematical expression instance.

Return values

0	Success.
EINVAL	Invalid argument.

◆ sg_expr_eval()

double sg_expr_eval ( struct sg_expr * expr )

Evaluates a compiled mathematical expression.

Parameters

[in] expr Compiled mathematical expression.

Returns: Floating-point value of the evaluated mathematical expression.

Return values

NAN	If the `expr` is null and set the `errno` to `EINVAL`.

Examples: example_expr_full.c.

◆ sg_expr_var()

double sg_expr_var	(	struct sg_expr *	expr,
		const char *	name,
		size_t	len
	)

Gets the value of a declared variable.

Parameters

[in]	expr	Mathematical expression instance.
[in]	name	Name of the declared variable.
[in]	len	Length of the variable name.

Return values

NAN	If `expr` or `name` is null, or `len` is less than one, and set the `errno` to `EINVAL`. If no memory space is available and set the `errno` to `ENOMEM`.

◆ sg_expr_set_var()

int sg_expr_set_var	(	struct sg_expr *	expr,
		const char *	name,
		size_t	len,
		double	val
	)

Sets a variable to the mathematical expression.

Parameters

[in]	expr	Mathematical expression instance.
[in]	name	Name for the variable.
[in]	len	Length of the variable name.
[in]	val	Value for the variable.

Return values

0	Success.
EINVAL	Invalid argument.
ENOMEM	Out of memory.

◆ sg_expr_arg()

double sg_expr_arg	(	struct sg_expr_argument *	args,
		int	index
	)

Gets a function argument by its index.

Parameters

[in]	args	Arguments list.
[in]	index	Argument index.

Return values

NAN	If the `args` is null or `index` is less than zero and set the `errno` to `EINVAL`.

Examples: example_expr_full.c.

◆ sg_expr_near()

int sg_expr_near ( struct sg_expr * expr )

Returns the nearby position of an error in the mathematical expression.

Parameters

[in] expr Compiled mathematical expression.

Return values

0	Success.
EINVAL	Invalid argument.

Examples: example_expr_full.c.

◆ sg_expr_err()

enum sg_expr_err_type sg_expr_err ( struct sg_expr * expr )

Returns the type of an error in the mathematical expression.

Parameters

[in] expr Compiled mathematical expression.

Returns: Enumerator representing the error type.

Return values

SG_EXPR_ERR_UNKNOWN If the expr is null or an unknown error occurred and set the errno to EINVAL.

◆ sg_expr_strerror()

const char * sg_expr_strerror ( struct sg_expr * expr )

Returns the description of an error in the mathematical expression.

Parameters

[in] expr Compiled mathematical expression.

Returns: Description of the error as a null-terminated string.

Return values

NULL	If the `expr` is null and set the `errno` to `EINVAL`.

Examples: example_expr_full.c.

◆ sg_expr_calc()

double sg_expr_calc	(	const char *	str,
		size_t	len
	)

Returns the evaluated value of a mathematical expression.

Parameters

[in]	str	Null-terminated string with the mathematical expression to be evaluated.
[in]	len	Length of the mathematical expression to be evaluated.

Return values

NAN	If `str` is null, or `len` is less than one, and set the `errno` to `EINVAL`.

Examples: example_expr_basic.c.

Data Structures

Typedefs

Enumerations

Functions

Detailed Description

Typedef Documentation

◆ sg_expr_func

Enumeration Type Documentation

◆ sg_expr_err_type

Function Documentation

◆ sg_expr_new()

◆ sg_expr_free()

◆ sg_expr_compile()

◆ sg_expr_clear()

◆ sg_expr_eval()

◆ sg_expr_var()

◆ sg_expr_set_var()

◆ sg_expr_arg()

◆ sg_expr_near()

◆ sg_expr_err()

◆ sg_expr_strerror()

◆ sg_expr_calc()