cpython/Include/stringobject.h

/* String object interface */

#ifndef Py_STRINGOBJECT_H
#define Py_STRINGOBJECT_H
#ifdef __cplusplus
extern "C" {
#endif

#include <stdarg.h>

/*
Type PyStringObject represents a character string.  An extra zero byte is
reserved at the end to ensure it is zero-terminated, but a size is
present so strings with null bytes in them can be represented.  This
is an immutable object type.

There are functions to create new string objects, to test
an object for string-ness, and to get the
string value.  The latter function returns a null pointer
if the object is not of the proper type.
There is a variant that takes an explicit size as well as a
variant that assumes a zero-terminated string.  Note that none of the
functions should be applied to nil objects.
*/

/* Caching the hash (ob_shash) saves recalculation of a string's hash value.
   This significantly speeds up dict lookups. */

typedef struct {
    PyObject_VAR_HEAD
    long ob_shash;
    char ob_sval[1];

    /* Invariants:
     *     ob_sval contains space for 'ob_size+1' elements.
     *     ob_sval[ob_size] == 0.
     *     ob_shash is the hash of the string or -1 if not computed yet.
     */
} PyStringObject;

PyAPI_DATA(PyTypeObject) PyString_Type;
PyAPI_DATA(PyTypeObject) PyStringIter_Type;

#define PyString_Check(op) \
                 PyType_FastSubclass(Py_TYPE(op), Py_TPFLAGS_STRING_SUBCLASS)
#define PyString_CheckExact(op) (Py_TYPE(op) == &PyString_Type)

PyAPI_FUNC(PyObject *) PyString_FromStringAndSize(const char *, Py_ssize_t);
PyAPI_FUNC(PyObject *) PyString_FromString(const char *);
PyAPI_FUNC(PyObject *) PyString_FromFormatV(const char*, va_list)
				Py_GCC_ATTRIBUTE((format(printf, 1, 0)));
PyAPI_FUNC(PyObject *) PyString_FromFormat(const char*, ...)
				Py_GCC_ATTRIBUTE((format(printf, 1, 2)));
PyAPI_FUNC(Py_ssize_t) PyString_Size(PyObject *);
PyAPI_FUNC(char *) PyString_AsString(PyObject *);
PyAPI_FUNC(PyObject *) PyString_Repr(PyObject *, int);
PyAPI_FUNC(void) PyString_Concat(PyObject **, PyObject *);
PyAPI_FUNC(void) PyString_ConcatAndDel(PyObject **, PyObject *);
PyAPI_FUNC(int) _PyString_Resize(PyObject **, Py_ssize_t);
PyAPI_FUNC(PyObject *) PyString_Format(PyObject *, PyObject *);
PyAPI_FUNC(PyObject *) _PyString_FormatLong(PyObject*, int, int,
						  int, char**, int*);
PyAPI_FUNC(PyObject *) PyString_DecodeEscape(const char *, Py_ssize_t,
						   const char *, Py_ssize_t,
						   const char *);

/* Macro, trading safety for speed */
#define PyString_AS_STRING(op) (assert(PyString_Check(op)), \
                                (((PyStringObject *)(op))->ob_sval))
#define PyString_GET_SIZE(op)  (assert(PyString_Check(op)),Py_SIZE(op))

/* _PyString_Join(sep, x) is like sep.join(x).  sep must be PyStringObject*,
   x must be an iterable object. */
PyAPI_FUNC(PyObject *) _PyString_Join(PyObject *sep, PyObject *x);

/* Provides access to the internal data buffer and size of a string
   object or the default encoded version of an Unicode object. Passing
   NULL as *len parameter will force the string buffer to be
   0-terminated (passing a string with embedded NULL characters will
   cause an exception).  */
PyAPI_FUNC(int) PyString_AsStringAndSize(
    register PyObject *obj,	/* string or Unicode object */
    register char **s,		/* pointer to buffer variable */
    register Py_ssize_t *len	/* pointer to length variable or NULL
				   (only possible for 0-terminated
				   strings) */
    );

/* Using the current locale, insert the thousands grouping
   into the string pointed to by buffer.  For the argument descriptions,
   see Objects/stringlib/localeutil.h */

PyAPI_FUNC(int) _PyString_InsertThousandsGrouping(char *buffer,
						  Py_ssize_t len,
						  char *plast,
						  Py_ssize_t buf_size,
						  Py_ssize_t *count,
						  int append_zero_char);

/* Flags used by string formatting */
#define F_LJUST (1<<0)
#define F_SIGN	(1<<1)
#define F_BLANK (1<<2)
#define F_ALT	(1<<3)
#define F_ZERO	(1<<4)

#ifdef __cplusplus
}
#endif
#endif /* !Py_STRINGOBJECT_H */