# Objetos bytes

Estas funciones lanzan `TypeError` cuando se espera un parámetro de bytes y se llama con un parámetro que no es bytes.

type PyBytesObject

  Este subtipo de `PyObject` representa un objeto bytes de Python.

PyTypeObject PyBytes_Type
  Part of the Stable ABI.

  Esta instancia de `PyTypeObject` representa el tipo bytes de Python; es el mismo objeto que `bytes` en la capa de Python.

int PyBytes_Check(PyObject *o)

  Retorna verdadero si el objeto o es un objeto bytes o una instancia de un subtipo del tipo bytes. Esta función siempre finaliza con éxito.

int PyBytes_CheckExact(PyObject *o)

  Retorna verdadero si el objeto o es un objeto bytes, pero no una instancia de un subtipo del tipo bytes. Esta función siempre finaliza con éxito.

PyObject *PyBytes_FromString(const char *v)
  Return value: New reference. Part of the Stable ABI.

  Retorna un nuevo objeto bytes con una copia de la cadena de caracteres v como valor en caso de éxito y `NULL` en caso de error. El parámetro v no debe ser `NULL`; no se comprobará.

PyObject *PyBytes_FromStringAndSize(const char *v, Py_ssize_t len)
  Return value: New reference. Part of the Stable ABI.

  Retorna un nuevo objeto bytes con una copia de la cadena de caracteres v como valor y longitud len en caso de éxito y `NULL` en caso de error. Si v es `NULL`, el contenido del objeto bytes no se inicializa.

  Obsoleto desde la versión 3.15: `PyBytes_FromStringAndSize(NULL, len)` is soft deprecated, use the `PyBytesWriter` API instead.

PyObject *PyBytes_FromFormat(const char *format, ...)
  Return value: New reference. Part of the Stable ABI.

  Toma una cadena de caracteres format del estilo C `printf()` y un número variable de argumentos, calcula el tamaño del objeto bytes Python resultante y retorna un objeto bytes con los valores formateados. Los argumentos variables deben ser tipos C y deben corresponder exactamente a los caracteres de formato en la cadena de caracteres format. Se permiten los siguientes caracteres de formato:

  Caracteres de formato | Tipo | Comentario
  --- | --- | ---
  `%%` | n/a | El carácter literal %.
  `%c` | int | Un solo byte, representado como un C int.
  `%d` | int | Equivalente a `printf("%d")`. [1]
  `%u` | unsigned int | Equivalente a `printf("%u")`. [1]
  `%ld` | long | Equivalente a `printf("%ld")`. [1]
  `%lu` | unsigned long | Equivalente a `printf("%lu")`. [1]
  `%zd` | `Py_ssize_t` | Equivalente a `printf("%zd")`. [1]
  `%zu` | size_t | Equivalente a `printf("%zu")`. [1]
  `%i` | int | Equivalente a `printf("%i")`. [1]
  `%x` | int | Equivalente a `printf("%x")`. [1]
  `%s` | const char* | Un arreglo de caracteres C terminados en nulo.
  `%p` | const void* | La representación hexadecimal de un puntero en C. Principalmente equivalente a `printf("%p")` excepto que se garantiza que comience con el literal `0x`, independientemente de lo que produzca el `printf` de la plataforma.

  Un carácter de formato no reconocido hace que todo el resto de la cadena de caracteres de formato se copie como está en el objeto de resultado y se descartan los argumentos adicionales.

  [1] (1,2,3,4,5,6,7,8)

  Para especificadores de enteros (d, u, ld, lu, zd, zu, i, x): el indicador de conversión 0 tiene efecto incluso cuando se proporciona una precisión.

PyObject *PyBytes_FromFormatV(const char *format, va_list vargs)
  Return value: New reference. Part of the Stable ABI.

  Idéntica a `PyBytes_FromFormat()` excepto que toma exactamente dos argumentos.

PyObject *PyBytes_FromObject(PyObject *o)
  Return value: New reference. Part of the Stable ABI.

  Retorna la representación en bytes del objeto o que implementa el protocolo de búfer.

Py_ssize_t PyBytes_Size(PyObject *o)
  Part of the Stable ABI.

  Retorna la longitud de los bytes en el objeto bytes o.

Py_ssize_t PyBytes_GET_SIZE(PyObject *o)

  Forma macro de `PyBytes_Size()` pero sin verificación de errores.

char *PyBytes_AsString(PyObject *o)
  Part of the Stable ABI.

  Retorna un puntero al contenido de o. El puntero se refiere al búfer interno de o, que consiste en `len(o) + 1` bytes. El último byte en el búfer siempre es nulo, independientemente de si hay otros bytes nulos. Los datos no deben modificarse de ninguna manera, a menos que el objeto se haya creado usando `PyBytes_FromStringAndSize(NULL, size)`. No debe ser desasignado. Si o no es un objeto de bytes en absoluto, `PyBytes_AsString()` retorna `NULL` y lanza un `TypeError`.

char *PyBytes_AS_STRING(PyObject *string)

  Forma macro de `PyBytes_AsString()` pero sin verificación de errores.

int PyBytes_AsStringAndSize(PyObject *obj, char **buffer, Py_ssize_t *length)
  Part of the Stable ABI.

  Return the null-terminated contents of the object obj through the output variables buffer and length. Returns `0` on success.

  Si length es `NULL`, el objeto bytes no puede contener bytes nulos incrustados; en caso contrario, la función retorna `-1` y se lanza un `ValueError`.

  El búfer se refiere a un búfer interno de obj, que incluye un byte nulo adicional al final (no está considerado en length). Los datos no deben modificarse de ninguna manera, a menos que el objeto se haya creado usando `PyBytes_FromStringAndSize(NULL, size)`. No debe ser desasignado. Si obj no es un objeto bytes en absoluto, `PyBytes_AsStringAndSize()` retorna `-1` y lanza `TypeError`.

  Distinto en la versión 3.5: Anteriormente, `TypeError` se lanzaba cuando se encontraban bytes nulos incrustados en el objeto bytes.

void PyBytes_Concat(PyObject **bytes, PyObject *newpart)
  Part of the Stable ABI.

  Crea un nuevo objeto de bytes en *bytes que contiene el contenido de newpart agregado a bytes; la persona que llama poseerá la nueva referencia. La referencia al valor anterior de bytes será robada. Si no se puede crear el nuevo objeto, la referencia anterior a bytes se seguirá descartando y el valor de *bytes se establecerá en `NULL`; se establecerá la excepción apropiada.

void PyBytes_ConcatAndDel(PyObject **bytes, PyObject *newpart)
  Part of the Stable ABI.

  Create a new bytes object in *bytes containing the contents of newpart appended to bytes. This version releases the strong reference to newpart (i.e. decrements its reference count).

PyObject *PyBytes_Join(PyObject *sep, PyObject *iterable)

  Similar to `sep.join(iterable)` in Python.

  sep must be Python `bytes` object. (Note that `PyUnicode_Join()` accepts `NULL` separator and treats it as a space, whereas `PyBytes_Join()` doesn’t accept `NULL` separator.)

  iterable must be an iterable object yielding objects that implement the buffer protocol.

  On success, return a new `bytes` object. On error, set an exception and return `NULL`.

  Added in version 3.14.

int _PyBytes_Resize(PyObject **bytes, Py_ssize_t newsize)

  Resize a bytes object. newsize will be the new length of the bytes object. You can think of it as creating a new bytes object and destroying the old one, only more efficiently. Pass the address of an existing bytes object as an lvalue (it may be written into), and the new size desired. On success, *bytes holds the resized bytes object and `0` is returned; the address in *bytes may differ from its input value. If the reallocation fails, the original bytes object at *bytes is deallocated, *bytes is set to `NULL`, `MemoryError` is set, and `-1` is returned.

  Obsoleto desde la versión 3.15: The function is soft deprecated, use the `PyBytesWriter` API instead.

# PyBytesWriter

The `PyBytesWriter` API can be used to create a Python `bytes` object.

Added in version 3.15.0a0 (unreleased).

type PyBytesWriter

  A bytes writer instance.

  The API is not thread safe: a writer should only be used by a single thread at the same time.

  The instance must be destroyed by `PyBytesWriter_Finish()` on success, or `PyBytesWriter_Discard()` on error.

## Create, Finish, Discard

PyBytesWriter *PyBytesWriter_Create(Py_ssize_t size)

  Create a `PyBytesWriter` to write size bytes.

  If size is greater than zero, allocate size bytes, and set the writer size to size. The caller is responsible to write size bytes using `PyBytesWriter_GetData()`.

  On error, set an exception and return NULL.

  size must be positive or zero.

PyObject *PyBytesWriter_Finish(PyBytesWriter *writer)

  Finish a `PyBytesWriter` created by `PyBytesWriter_Create()`.

  On success, return a Python `bytes` object. On error, set an exception and return `NULL`.

  The writer instance is invalid after the call in any case. No API can be called on the writer after `PyBytesWriter_Finish()`.

PyObject *PyBytesWriter_FinishWithSize(PyBytesWriter *writer, Py_ssize_t size)

  Similar to `PyBytesWriter_Finish()`, but resize the writer to size bytes before creating the `bytes` object.

PyObject *PyBytesWriter_FinishWithPointer(PyBytesWriter *writer, void *buf)

  Similar to `PyBytesWriter_Finish()`, but resize the writer using buf pointer before creating the `bytes` object.

  Set an exception and return `NULL` if buf pointer is outside the internal buffer bounds.

  Function pseudo-code:

      Py_ssize_t size = (char*)buf - (char*)PyBytesWriter_GetData(writer);
      return PyBytesWriter_FinishWithSize(writer, size);

void PyBytesWriter_Discard(PyBytesWriter *writer)

  Discard a `PyBytesWriter` created by `PyBytesWriter_Create()`.

  Do nothing if writer is `NULL`.

  The writer instance is invalid after the call. No API can be called on the writer after `PyBytesWriter_Discard()`.

## High-level API

int PyBytesWriter_WriteBytes(PyBytesWriter *writer, const void *bytes, Py_ssize_t size)

  Grow the writer internal buffer by size bytes, write size bytes of bytes at the writer end, and add size to the writer size.

  If size is equal to `-1`, call `strlen(bytes)` to get the string length.

  On success, return `0`. On error, set an exception and return `-1`.

int PyBytesWriter_Format(PyBytesWriter *writer, const char *format, ...)

  Similar to `PyBytes_FromFormat()`, but write the output directly at the writer end. Grow the writer internal buffer on demand. Then add the written size to the writer size.

  On success, return `0`. On error, set an exception and return `-1`.

## Getters

Py_ssize_t PyBytesWriter_GetSize(PyBytesWriter *writer)

  Get the writer size.

void *PyBytesWriter_GetData(PyBytesWriter *writer)

  Get the writer data: start of the internal buffer.

  The pointer is valid until `PyBytesWriter_Finish()` or `PyBytesWriter_Discard()` is called on writer.

## Low-level API

int PyBytesWriter_Resize(PyBytesWriter *writer, Py_ssize_t size)

  Resize the writer to size bytes. It can be used to enlarge or to shrink the writer.

  Newly allocated bytes are left uninitialized.

  On success, return `0`. On error, set an exception and return `-1`.

  size must be positive or zero.

int PyBytesWriter_Grow(PyBytesWriter *writer, Py_ssize_t grow)

  Resize the writer by adding grow bytes to the current writer size.

  Newly allocated bytes are left uninitialized.

  On success, return `0`. On error, set an exception and return `-1`.

  size can be negative to shrink the writer.

void *PyBytesWriter_GrowAndUpdatePointer(PyBytesWriter *writer, Py_ssize_t size, void *buf)

  Similar to `PyBytesWriter_Grow()`, but update also the buf pointer.

  The buf pointer is moved if the internal buffer is moved in memory. The buf relative position within the internal buffer is left unchanged.

  On error, set an exception and return `NULL`.

  buf must not be `NULL`.

  Function pseudo-code:

      Py_ssize_t pos = (char*)buf - (char*)PyBytesWriter_GetData(writer);
      if (PyBytesWriter_Grow(writer, size) < 0) {
          return NULL;
      }
      return (char*)PyBytesWriter_GetData(writer) + pos;