mirror of
https://github.com/python/cpython.git
synced 2024-12-01 11:15:56 +01:00
1e6e9a2368
hash value. Interning strings (which requires hash caching) tries to ensure that only one string object with a given value exists, so equality tests are one pointer comparison. Together, these can speed the interpreter up by as much as 20%. Each costs the size of a long or pointer per string object. In addition, interned strings live until the end of times. If you are concerned about memory footprint, simply comment the #define out here (and rebuild everything!).
109 lines
4.1 KiB
C
109 lines
4.1 KiB
C
#ifndef Py_STRINGOBJECT_H
|
|
#define Py_STRINGOBJECT_H
|
|
#ifdef __cplusplus
|
|
extern "C" {
|
|
#endif
|
|
|
|
/***********************************************************
|
|
Copyright 1991-1995 by Stichting Mathematisch Centrum, Amsterdam,
|
|
The Netherlands.
|
|
|
|
All Rights Reserved
|
|
|
|
Permission to use, copy, modify, and distribute this software and its
|
|
documentation for any purpose and without fee is hereby granted,
|
|
provided that the above copyright notice appear in all copies and that
|
|
both that copyright notice and this permission notice appear in
|
|
supporting documentation, and that the names of Stichting Mathematisch
|
|
Centrum or CWI or Corporation for National Research Initiatives or
|
|
CNRI not be used in advertising or publicity pertaining to
|
|
distribution of the software without specific, written prior
|
|
permission.
|
|
|
|
While CWI is the initial source for this software, a modified version
|
|
is made available by the Corporation for National Research Initiatives
|
|
(CNRI) at the Internet address ftp://ftp.python.org.
|
|
|
|
STICHTING MATHEMATISCH CENTRUM AND CNRI DISCLAIM ALL WARRANTIES WITH
|
|
REGARD TO THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF
|
|
MERCHANTABILITY AND FITNESS, IN NO EVENT SHALL STICHTING MATHEMATISCH
|
|
CENTRUM OR CNRI BE LIABLE FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL
|
|
DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
|
|
PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
|
|
TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
|
|
PERFORMANCE OF THIS SOFTWARE.
|
|
|
|
******************************************************************/
|
|
|
|
/* String object interface */
|
|
|
|
/*
|
|
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.
|
|
*/
|
|
|
|
/* Two speedup hacks. Caching the hash saves recalculation of a
|
|
string's hash value. Interning strings (which requires hash
|
|
caching) tries to ensure that only one string object with a given
|
|
value exists, so equality tests are one pointer comparison.
|
|
Together, these can speed the interpreter up by as much as 20%.
|
|
Each costs the size of a long or pointer per string object. In
|
|
addition, interned strings live until the end of times. If you are
|
|
concerned about memory footprint, simply comment the #define out
|
|
here (and rebuild everything!). */
|
|
#define CACHE_HASH
|
|
#ifdef CACHE_HASH
|
|
#define INTERN_STRINGS
|
|
#endif
|
|
|
|
typedef struct {
|
|
PyObject_VAR_HEAD
|
|
#ifdef CACHE_HASH
|
|
long ob_shash;
|
|
#endif
|
|
#ifdef INTERN_STRINGS
|
|
PyObject *ob_sinterned;
|
|
#endif
|
|
char ob_sval[1];
|
|
} PyStringObject;
|
|
|
|
extern DL_IMPORT(PyTypeObject) PyString_Type;
|
|
|
|
#define PyString_Check(op) ((op)->ob_type == &PyString_Type)
|
|
|
|
extern PyObject *PyString_FromStringAndSize Py_PROTO((const char *, int));
|
|
extern PyObject *PyString_FromString Py_PROTO((const char *));
|
|
extern int PyString_Size Py_PROTO((PyObject *));
|
|
extern char *PyString_AsString Py_PROTO((PyObject *));
|
|
extern void PyString_Concat Py_PROTO((PyObject **, PyObject *));
|
|
extern void PyString_ConcatAndDel Py_PROTO((PyObject **, PyObject *));
|
|
extern int _PyString_Resize Py_PROTO((PyObject **, int));
|
|
extern PyObject *PyString_Format Py_PROTO((PyObject *, PyObject *));
|
|
|
|
#ifdef INTERN_STRINGS
|
|
extern void PyString_InternInPlace Py_PROTO((PyObject **));
|
|
extern PyObject *PyString_InternFromString Py_PROTO((const char *));
|
|
#else
|
|
#define PyString_InternInPlace(p)
|
|
#define PyString_InternFromString(cp) PyString_FromString(cp)
|
|
#endif
|
|
|
|
/* Macro, trading safety for speed */
|
|
#define PyString_AS_STRING(op) (((PyStringObject *)(op))->ob_sval)
|
|
#define PyString_GET_SIZE(op) (((PyStringObject *)(op))->ob_size)
|
|
|
|
#ifdef __cplusplus
|
|
}
|
|
#endif
|
|
#endif /* !Py_STRINGOBJECT_H */
|