GI.GLib.Structs.Bytes

A simple refcounted data type representing an immutable sequence of zero or more bytes from an unspecified origin.

The purpose of a Bytes is to keep the memory region that it holds alive for as long as anyone holds a reference to the bytes. When the last reference count is dropped, the memory is released. Multiple unrelated callers can use byte data in the Bytes without coordinating their activities, resting assured that the byte data will not change or move while they hold a reference.

A Bytes can come from many different origins that may have different procedures for freeing the memory region. Examples are memory from malloc, from memory slices, from a MappedFile or memory from other allocators.

Bytes work well as keys in HashTable. Use bytesEqual and bytesHash as parameters to g_hash_table_new() or g_hash_table_new_full(). Bytes can also be used as keys in a Tree by passing the bytesCompare function to g_tree_new().

The data pointed to by this bytes must not be modified. For a mutable array of bytes see ByteArray. Use bytesUnrefToArray to create a mutable array for a Bytes sequence. To create an immutable Bytes from a mutable ByteArray, use the byteArrayFreeToBytes function.

Since: 2.32

Exported types

newtype Bytes

Memory-managed wrapper type.

Constructors

Bytes (ManagedPtr Bytes)

Instances

Eq Bytes

Defined in GI.GLib.Structs.Bytes

Methods

(==) :: Bytes -> Bytes -> Bool

(/=) :: Bytes -> Bytes -> Bool

GBoxed Bytes

Defined in GI.GLib.Structs.Bytes

ManagedPtrNewtype Bytes

Defined in GI.GLib.Structs.Bytes

Methods

toManagedPtr :: Bytes -> ManagedPtr Bytes

TypedObject Bytes

Defined in GI.GLib.Structs.Bytes

Methods

glibType :: IO GType

HasParentTypes Bytes

Defined in GI.GLib.Structs.Bytes

IsGValue (Maybe Bytes)

Convert Bytes to and from GValue. See toGValue and fromGValue.

Defined in GI.GLib.Structs.Bytes

Methods

gvalueGType_ :: IO GType

gvalueSet_ :: Ptr GValue -> Maybe Bytes -> IO ()

gvalueGet_ :: Ptr GValue -> IO (Maybe Bytes)

type ParentTypes Bytes

Defined in GI.GLib.Structs.Bytes

type ParentTypes Bytes = '[] :: [Type]

Methods

Click to display all available methods, including inherited ones

Methods

compare, equal, hash, newFromBytes, ref, unref, unrefToArray, unrefToData.

Getters

getData, getRegion, getSize.

Setters

None.

compare

bytesCompare

Arguments

:: (HasCallStack, MonadIO m)

=> Bytes

bytes1: a pointer to a Bytes

-> Bytes

bytes2: a pointer to a Bytes to compare with bytes1

-> m Int32

Returns: a negative value if bytes1 is less than bytes2, a positive value if bytes1 is greater than bytes2, and zero if bytes1 is equal to bytes2

Compares the two Bytes values.

This function can be used to sort GBytes instances in lexicographical order.

If bytes1 and bytes2 have different length but the shorter one is a prefix of the longer one then the shorter one is considered to be less than the longer one. Otherwise the first byte where both differ is used for comparison. If bytes1 has a smaller value at that position it is considered less, otherwise greater than bytes2.

Since: 2.32

equal

bytesEqual

Arguments

:: (HasCallStack, MonadIO m)

=> Bytes

bytes1: a pointer to a Bytes

-> Bytes

bytes2: a pointer to a Bytes to compare with bytes1

-> m Bool

Returns: True if the two keys match.

Compares the two Bytes values being pointed to and returns True if they are equal.

This function can be passed to g_hash_table_new() as the keyEqualFunc parameter, when using non-Nothing Bytes pointers as keys in a HashTable.

Since: 2.32

getData

bytesGetData

Arguments

:: (HasCallStack, MonadIO m)

=> Bytes

bytes: a Bytes

-> m (Maybe ByteString)

Returns: a pointer to the byte data, or Nothing

Get the byte data in the Bytes. This data should not be modified.

This function will always return the same pointer for a given Bytes.

Nothing may be returned if size is 0. This is not guaranteed, as the Bytes may represent an empty string with data non-Nothing and size as 0. Nothing will not be returned if size is non-zero.

Since: 2.32

getRegion

bytesGetRegion

Arguments

:: (HasCallStack, MonadIO m)

=> Bytes

bytes: a Bytes

-> CSize

elementSize: a non-zero element size

-> CSize

offset: an offset to the start of the region within the bytes

-> CSize

nElements: the number of elements in the region

-> m (Ptr ())

Returns: the requested region, or Nothing in case of an error

Gets a pointer to a region in bytes.

The region starts at offset many bytes from the start of the data and contains nElements many elements of elementSize size.

nElements may be zero, but elementSize must always be non-zero. Ideally, elementSize is a static constant (eg: sizeof a struct).

This function does careful bounds checking (including checking for arithmetic overflows) and returns a non-Nothing pointer if the specified region lies entirely within the bytes. If the region is in some way out of range, or if an overflow has occurred, then Nothing is returned.

Note: it is possible to have a valid zero-size region. In this case, the returned pointer will be equal to the base pointer of the data of bytes, plus offset. This will be non-Nothing except for the case where bytes itself was a zero-sized region. Since it is unlikely that you will be using this function to check for a zero-sized region in a zero-sized bytes, Nothing effectively always means "error".

Since: 2.70

getSize

bytesGetSize

Arguments

:: (HasCallStack, MonadIO m)

=> Bytes

bytes: a Bytes

-> m CSize

Returns: the size

Get the size of the byte data in the Bytes.

This function will always return the same value for a given Bytes.

Since: 2.32

hash

bytesHash

Arguments

:: (HasCallStack, MonadIO m)

=> Bytes

bytes: a pointer to a Bytes key

-> m Word32

Returns: a hash value corresponding to the key.

Creates an integer hash code for the byte data in the Bytes.

This function can be passed to g_hash_table_new() as the keyHashFunc parameter, when using non-Nothing Bytes pointers as keys in a HashTable.

Since: 2.32

new

bytesNew

Arguments

:: (HasCallStack, MonadIO m)

=> Maybe ByteString

data: the data to be used for the bytes

-> m Bytes

Returns: a new Bytes

Creates a new Bytes from data.

data is copied. If size is 0, data may be Nothing.

Since: 2.32

newFromBytes

bytesNewFromBytes

Arguments

:: (HasCallStack, MonadIO m)

=> Bytes

bytes: a Bytes

-> CSize

offset: offset which subsection starts at

-> CSize

length: length of subsection

-> m Bytes

Returns: a new Bytes

Creates a Bytes which is a subsection of another Bytes. The offset + length may not be longer than the size of bytes.

A reference to bytes will be held by the newly created Bytes until the byte data is no longer needed.

Since 2.56, if offset is 0 and length matches the size of bytes, then bytes will be returned with the reference count incremented by 1. If bytes is a slice of another Bytes, then the resulting Bytes will reference the same Bytes instead of bytes. This allows consumers to simplify the usage of Bytes when asynchronously writing to streams.

Since: 2.32

newTake

bytesNewTake

Arguments

:: (HasCallStack, MonadIO m)

=> Maybe ByteString

data: the data to be used for the bytes

-> m Bytes

Returns: a new Bytes

Creates a new Bytes from data.

After this call, data belongs to the Bytes and may no longer be modified by the caller. The memory of data has to be dynamically allocated and will eventually be freed with free.

For creating Bytes with memory from other allocators, see g_bytes_new_with_free_func().

data may be Nothing if size is 0.

Since: 2.32

ref

bytesRef

Arguments

:: (HasCallStack, MonadIO m)

=> Bytes

bytes: a Bytes

-> m Bytes

Returns: the Bytes

Increase the reference count on bytes.

Since: 2.32

unref

bytesUnref

Arguments

:: (HasCallStack, MonadIO m)

=> Maybe Bytes

bytes: a Bytes

-> m ()

Releases a reference on bytes. This may result in the bytes being freed. If bytes is Nothing, it will return immediately.

Since: 2.32

unrefToArray

bytesUnrefToArray

Arguments

:: (HasCallStack, MonadIO m)

=> Bytes

bytes: a Bytes

-> m ByteString

Returns: a new mutable ByteArray containing the same byte data

Unreferences the bytes, and returns a new mutable ByteArray containing the same byte data.

As an optimization, the byte data is transferred to the array without copying if this was the last reference to bytes and bytes was created with bytesNew, bytesNewTake or byteArrayFreeToBytes. In all other cases the data is copied.

Do not use it if bytes contains more than G_MAXUINT bytes. ByteArray stores the length of its data in guint, which may be shorter than gsize, that bytes is using.

Since: 2.32

unrefToData

bytesUnrefToData

Arguments

:: (HasCallStack, MonadIO m)

=> Bytes

bytes: a Bytes

-> m ByteString

Returns: a pointer to the same byte data, which should be freed with free

Unreferences the bytes, and returns a pointer the same byte data contents.

As an optimization, the byte data is returned without copying if this was the last reference to bytes and bytes was created with bytesNew, bytesNewTake or byteArrayFreeToBytes. In all other cases the data is copied.

Since: 2.32