Functions to inspect and change Nix language values, represented by nix_value. More...

Typedefs
typedef struct BindingsBuilder	BindingsBuilder
	Stores an under-construction set of bindings.
typedef struct ListBuilder	ListBuilder
	Stores an under-construction list.

Functions
BindingsBuilder *	nix_make_bindings_builder (nix_c_context context, EvalState state, size_t capacity)
	Create a bindings builder.
nix_err	nix_bindings_builder_insert (nix_c_context context, BindingsBuilder builder, const char name, nix_value value)
	Insert bindings into a builder.
void	nix_bindings_builder_free (BindingsBuilder *builder)
	Free a bindings builder.

Getters

ValueType	nix_get_type (nix_c_context context, const nix_value value)
	Get value type.
const char *	nix_get_typename (nix_c_context context, const nix_value value)
	Get type name of value as defined in the evaluator.
bool	nix_get_bool (nix_c_context context, const nix_value value)
	Get boolean value.
nix_err	nix_get_string (nix_c_context context, const nix_value value, nix_get_string_callback callback, void *user_data)
	Get the raw string.
const char *	nix_get_path_string (nix_c_context context, const nix_value value)
	Get path as string.
unsigned int	nix_get_list_size (nix_c_context context, const nix_value value)
	Get the length of a list.
unsigned int	nix_get_attrs_size (nix_c_context context, const nix_value value)
	Get the element count of an attrset.
double	nix_get_float (nix_c_context context, const nix_value value)
	Get float value in 64 bits.
int64_t	nix_get_int (nix_c_context context, const nix_value value)
	Get int value.
ExternalValue *	nix_get_external (nix_c_context context, nix_value value)
	Get external reference.
nix_value *	nix_get_list_byidx (nix_c_context context, const nix_value value, EvalState *state, unsigned int ix)
	Get the ix'th element of a list.
nix_value *	nix_get_attr_byname (nix_c_context context, const nix_value value, EvalState state, const char name)
	Get an attr by name.
bool	nix_has_attr_byname (nix_c_context context, const nix_value value, EvalState state, const char name)
	Check if an attribute name exists on a value.
nix_value *	nix_get_attr_byidx (nix_c_context context, const nix_value value, EvalState state, unsigned int i, const char *name)
	Get an attribute by index in the sorted bindings.
const char *	nix_get_attr_name_byidx (nix_c_context context, const nix_value value, EvalState *state, unsigned int i)
	Get an attribute name by index in the sorted bindings.

Initializers
Values are typically "returned" by initializing already allocated memory that serves as the return value. For this reason, the construction of values is not tied their allocation. Nix is a language with immutable values. Respect this property by only initializing Values once; and only initialize Values that are meant to be initialized by you. Failing to adhere to these rules may lead to undefined behavior.
nix_err	nix_init_bool (nix_c_context context, nix_value value, bool b)
	Set boolean value.
nix_err	nix_init_string (nix_c_context context, nix_value value, const char *str)
	Set a string.
nix_err	nix_init_path_string (nix_c_context context, EvalState s, nix_value value, const char str)
	Set a path.
nix_err	nix_init_float (nix_c_context context, nix_value value, double d)
	Set a float.
nix_err	nix_init_int (nix_c_context context, nix_value value, int64_t i)
	Set an int.
nix_err	nix_init_null (nix_c_context context, nix_value value)
	Set null.
nix_err	nix_init_apply (nix_c_context context, nix_value value, nix_value fn, nix_value arg)
	Set the value to a thunk that will perform a function application when needed.
nix_err	nix_init_external (nix_c_context context, nix_value value, ExternalValue *val)
	Set an external value.
nix_err	nix_make_list (nix_c_context context, ListBuilder list_builder, nix_value *value)
	Create a list from a list builder.
ListBuilder *	nix_make_list_builder (nix_c_context context, EvalState state, size_t capacity)
	Create a list builder.
nix_err	nix_list_builder_insert (nix_c_context context, ListBuilder list_builder, unsigned int index, nix_value *value)
	Insert bindings into a builder.
void	nix_list_builder_free (ListBuilder *list_builder)
	Free a list builder.
nix_err	nix_make_attrs (nix_c_context context, nix_value value, BindingsBuilder *b)
	Create an attribute set from a bindings builder.
nix_err	nix_init_primop (nix_c_context context, nix_value value, PrimOp *op)
	Set primop.
nix_err	nix_copy_value (nix_c_context context, nix_value value, const nix_value *source)
	Copy from another value.

Detailed Description

Functions to inspect and change Nix language values, represented by nix_value.

Typedef Documentation

◆ BindingsBuilder

typedef struct BindingsBuilder BindingsBuilder

Stores an under-construction set of bindings.

Do not reuse.

See also: nix_make_bindings_builder, nix_bindings_builder_free, nix_make_attrs; nix_bindings_builder_insert

◆ ListBuilder

typedef struct ListBuilder ListBuilder

Stores an under-construction list.

Do not reuse.

See also: nix_make_list_builder, nix_list_builder_free, nix_make_list; nix_list_builder_insert

Function Documentation

◆ nix_bindings_builder_free()

void nix_bindings_builder_free ( BindingsBuilder * builder )

Free a bindings builder.

Does not fail.

Parameters

[in] builder the builder to free

◆ nix_bindings_builder_insert()

nix_err nix_bindings_builder_insert	(	nix_c_context *	context,
		BindingsBuilder *	builder,
		const char *	name,
		nix_value *	value )

Insert bindings into a builder.

Parameters

[out]	context	Optional, stores error information
[in]	builder	BindingsBuilder to insert into
[in]	name	attribute name, only used for the duration of the call.
[in]	value	value to give the binding

Returns: error code, NIX_OK on success.

◆ nix_copy_value()

nix_err nix_copy_value	(	nix_c_context *	context,
		nix_value *	value,
		const nix_value *	source )

Copy from another value.

Parameters

[out]	context	Optional, stores error information
[out]	value	Nix value to modify
[in]	source	value to copy from

Returns: error code, NIX_OK on success.

◆ nix_get_attr_byidx()

nix_value * nix_get_attr_byidx	(	nix_c_context *	context,
		const nix_value *	value,
		EvalState *	state,
		unsigned int	i,
		const char **	name )

Get an attribute by index in the sorted bindings.

Also gives you the name.

Owned by the GC. Use nix_gc_decref when you're done with the pointer

Parameters

[out]	context	Optional, stores error information
[in]	value	Nix value to inspect
[in]	state	nix evaluator state
[in]	i	attribute index
[out]	name	will store a pointer to the attribute name

Returns: value, NULL in case of errors

◆ nix_get_attr_byname()

nix_value * nix_get_attr_byname	(	nix_c_context *	context,
		const nix_value *	value,
		EvalState *	state,
		const char *	name )

Get an attr by name.

Owned by the GC. Use nix_gc_decref when you're done with the pointer

Parameters

[out]	context	Optional, stores error information
[in]	value	Nix value to inspect
[in]	state	nix evaluator state
[in]	name	attribute name

Returns: value, NULL in case of errors

◆ nix_get_attr_name_byidx()

const char * nix_get_attr_name_byidx	(	nix_c_context *	context,
		const nix_value *	value,
		EvalState *	state,
		unsigned int	i )

Get an attribute name by index in the sorted bindings.

Useful when you want the name but want to avoid evaluation.

Owned by the nix EvalState

Parameters

[out]	context	Optional, stores error information
[in]	value	Nix value to inspect
[in]	state	nix evaluator state
[in]	i	attribute index

Returns: name, NULL in case of errors

◆ nix_get_attrs_size()

unsigned int nix_get_attrs_size	(	nix_c_context *	context,
		const nix_value *	value )

Get the element count of an attrset.

Parameters

[out]	context	Optional, stores error information
[in]	value	Nix value to inspect

Returns: attrset element count, error info via context

◆ nix_get_bool()

bool nix_get_bool	(	nix_c_context *	context,
		const nix_value *	value )

Get boolean value.

Parameters

[out]	context	Optional, stores error information
[in]	value	Nix value to inspect

Returns: true or false, error info via context

◆ nix_get_external()

ExternalValue * nix_get_external	(	nix_c_context *	context,
		nix_value *	value )

Get external reference.

Parameters

[out]	context	Optional, stores error information
[in]	value	Nix value to inspect

Returns: reference to external, NULL in case of error

◆ nix_get_float()

double nix_get_float	(	nix_c_context *	context,
		const nix_value *	value )

Get float value in 64 bits.

Parameters

[out]	context	Optional, stores error information
[in]	value	Nix value to inspect

Returns: float contents, error info via context

◆ nix_get_int()

int64_t nix_get_int	(	nix_c_context *	context,
		const nix_value *	value )

Get int value.

Parameters

[out]	context	Optional, stores error information
[in]	value	Nix value to inspect

Returns: int contents, error info via context

◆ nix_get_list_byidx()

nix_value * nix_get_list_byidx	(	nix_c_context *	context,
		const nix_value *	value,
		EvalState *	state,
		unsigned int	ix )

Get the ix'th element of a list.

Owned by the GC. Use nix_gc_decref when you're done with the pointer

Parameters

[out]	context	Optional, stores error information
[in]	value	Nix value to inspect
[in]	state	nix evaluator state
[in]	ix	list element to get

Returns: value, NULL in case of errors

◆ nix_get_list_size()

unsigned int nix_get_list_size	(	nix_c_context *	context,
		const nix_value *	value )

Get the length of a list.

Parameters

[out]	context	Optional, stores error information
[in]	value	Nix value to inspect

Returns: length of list, error info via context

◆ nix_get_path_string()

const char * nix_get_path_string	(	nix_c_context *	context,
		const nix_value *	value )

Get path as string.

Parameters

[out]	context	Optional, stores error information
[in]	value	Nix value to inspect

Returns: string, if the type is NIX_TYPE_PATH; NULL in case of error.

◆ nix_get_string()

nix_err nix_get_string	(	nix_c_context *	context,
		const nix_value *	value,
		nix_get_string_callback	callback,
		void *	user_data )

Get the raw string.

This may contain placeholders.

Parameters

[out]	context	Optional, stores error information
[in]	value	Nix value to inspect
[in]	callback	Called with the string value.
[in]	user_data	optional, arbitrary data, passed to the callback when it's called.

Returns: string; error code, NIX_OK on success.

◆ nix_get_type()

ValueType nix_get_type	(	nix_c_context *	context,
		const nix_value *	value )

Get value type.

Parameters

[out]	context	Optional, stores error information
[in]	value	Nix value to inspect

Returns: type of nix value

◆ nix_get_typename()

const char * nix_get_typename	(	nix_c_context *	context,
		const nix_value *	value )

Get type name of value as defined in the evaluator.

Parameters

[out]	context	Optional, stores error information
[in]	value	Nix value to inspect

Returns: type name, owned string

Todo: way to free the result

◆ nix_has_attr_byname()

bool nix_has_attr_byname	(	nix_c_context *	context,
		const nix_value *	value,
		EvalState *	state,
		const char *	name )

Check if an attribute name exists on a value.

Parameters

[out]	context	Optional, stores error information
[in]	value	Nix value to inspect
[in]	state	nix evaluator state
[in]	name	attribute name

Returns: value, error info via context

◆ nix_init_apply()

nix_err nix_init_apply	(	nix_c_context *	context,
		nix_value *	value,
		nix_value *	fn,
		nix_value *	arg )

Set the value to a thunk that will perform a function application when needed.

Thunks may be put into attribute sets and lists to perform some computation lazily; on demand. However, note that in some places, a thunk must not be returned, such as in the return value of a PrimOp. In such cases, you may use nix_value_call() instead (but note the different argument order).

Parameters

[out]	context	Optional, stores error information
[out]	value	Nix value to modify
[in]	fn	function to call
[in]	arg	argument to pass

Returns: error code, NIX_OK on successful initialization.

See also: nix_value_call() for a similar function that performs the call immediately and only stores the return value. Note the different argument order.

◆ nix_init_bool()

nix_err nix_init_bool	(	nix_c_context *	context,
		nix_value *	value,
		bool	b )

Set boolean value.

Parameters

[out]	context	Optional, stores error information
[out]	value	Nix value to modify
[in]	b	the boolean value

Returns: error code, NIX_OK on success.

◆ nix_init_external()

nix_err nix_init_external	(	nix_c_context *	context,
		nix_value *	value,
		ExternalValue *	val )

Set an external value.

Parameters

[out]	context	Optional, stores error information
[out]	value	Nix value to modify
[in]	val	the external value to set. Will be GC-referenced by the value.

Returns: error code, NIX_OK on success.

◆ nix_init_float()

nix_err nix_init_float	(	nix_c_context *	context,
		nix_value *	value,
		double	d )

Set a float.

Parameters

[out]	context	Optional, stores error information
[out]	value	Nix value to modify
[in]	d	the float, 64-bits

Returns: error code, NIX_OK on success.

◆ nix_init_int()

nix_err nix_init_int	(	nix_c_context *	context,
		nix_value *	value,
		int64_t	i )

Set an int.

Parameters

[out]	context	Optional, stores error information
[out]	value	Nix value to modify
[in]	i	the int

Returns: error code, NIX_OK on success.

◆ nix_init_null()

nix_err nix_init_null	(	nix_c_context *	context,
		nix_value *	value )

Set null.

Parameters

[out]	context	Optional, stores error information
[out]	value	Nix value to modify

Returns: error code, NIX_OK on success.

◆ nix_init_path_string()

nix_err nix_init_path_string	(	nix_c_context *	context,
		EvalState *	s,
		nix_value *	value,
		const char *	str )

Set a path.

Parameters

[out]	context	Optional, stores error information
[out]	value	Nix value to modify
[in]	str	the path string, copied

Returns: error code, NIX_OK on success.

◆ nix_init_primop()

nix_err nix_init_primop	(	nix_c_context *	context,
		nix_value *	value,
		PrimOp *	op )

Set primop.

Parameters

[out]	context	Optional, stores error information
[out]	value	Nix value to modify
[in]	op	primop, will be gc-referenced by the value

See also: nix_alloc_primop

Returns: error code, NIX_OK on success.

◆ nix_init_string()

nix_err nix_init_string	(	nix_c_context *	context,
		nix_value *	value,
		const char *	str )

Set a string.

Parameters

[out]	context	Optional, stores error information
[out]	value	Nix value to modify
[in]	str	the string, copied

Returns: error code, NIX_OK on success.

◆ nix_list_builder_free()

void nix_list_builder_free ( ListBuilder * list_builder )

Free a list builder.

Does not fail.

Parameters

[in] list_builder The builder to free.

◆ nix_list_builder_insert()

nix_err nix_list_builder_insert	(	nix_c_context *	context,
		ListBuilder *	list_builder,
		unsigned int	index,
		nix_value *	value )

Insert bindings into a builder.

Parameters

[out]	context	Optional, stores error information
[in]	list_builder	ListBuilder to insert into
[in]	index	index to manipulate
[in]	value	value to insert

Returns: error code, NIX_OK on success.

◆ nix_make_attrs()

nix_err nix_make_attrs	(	nix_c_context *	context,
		nix_value *	value,
		BindingsBuilder *	b )

Create an attribute set from a bindings builder.

Parameters

[out]	context	Optional, stores error information
[out]	value	Nix value to modify
[in]	b	bindings builder to use. Make sure to unref this afterwards.

Returns: error code, NIX_OK on success.

◆ nix_make_bindings_builder()

BindingsBuilder * nix_make_bindings_builder	(	nix_c_context *	context,
		EvalState *	state,
		size_t	capacity )

Create a bindings builder.

Parameters

[out]	context	Optional, stores error information
[in]	state	nix evaluator state
[in]	capacity	how many bindings you'll add. Don't exceed.

Returns: owned reference to a bindings builder. Make sure to unref when you're done.

◆ nix_make_list()

nix_err nix_make_list	(	nix_c_context *	context,
		ListBuilder *	list_builder,
		nix_value *	value )

Create a list from a list builder.

Parameters

[out]	context	Optional, stores error information
[in]	list_builder	list builder to use. Make sure to unref this afterwards.
[out]	value	Nix value to modify

Returns: error code, NIX_OK on success.

◆ nix_make_list_builder()

ListBuilder * nix_make_list_builder	(	nix_c_context *	context,
		EvalState *	state,
		size_t	capacity )

Create a list builder.

Parameters

[out]	context	Optional, stores error information
[in]	state	nix evaluator state
[in]	capacity	how many bindings you'll add. Don't exceed.

Returns: owned reference to a list builder. Make sure to unref when you're done.

Typedefs

Functions

Getters

Initializers

Detailed Description

Typedef Documentation

◆ BindingsBuilder

◆ ListBuilder

Function Documentation

◆ nix_bindings_builder_free()

◆ nix_bindings_builder_insert()

◆ nix_copy_value()

◆ nix_get_attr_byidx()

◆ nix_get_attr_byname()

◆ nix_get_attr_name_byidx()

◆ nix_get_attrs_size()

◆ nix_get_bool()

◆ nix_get_external()

◆ nix_get_float()

◆ nix_get_int()

◆ nix_get_list_byidx()

◆ nix_get_list_size()

◆ nix_get_path_string()

◆ nix_get_string()

◆ nix_get_type()

◆ nix_get_typename()

◆ nix_has_attr_byname()

◆ nix_init_apply()

◆ nix_init_bool()

◆ nix_init_external()

◆ nix_init_float()

◆ nix_init_int()

◆ nix_init_null()

◆ nix_init_path_string()

◆ nix_init_primop()

◆ nix_init_string()

◆ nix_list_builder_free()

◆ nix_list_builder_insert()

◆ nix_make_attrs()

◆ nix_make_bindings_builder()

◆ nix_make_list()

◆ nix_make_list_builder()