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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!).
108 lines
4.1 KiB
C
108 lines
4.1 KiB
C
#ifndef Py_STRINGOBJECT_H
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#define Py_STRINGOBJECT_H
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#ifdef __cplusplus
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extern "C" {
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#endif
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/***********************************************************
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Copyright 1991-1995 by Stichting Mathematisch Centrum, Amsterdam,
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The Netherlands.
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All Rights Reserved
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Permission to use, copy, modify, and distribute this software and its
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documentation for any purpose and without fee is hereby granted,
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provided that the above copyright notice appear in all copies and that
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both that copyright notice and this permission notice appear in
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supporting documentation, and that the names of Stichting Mathematisch
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Centrum or CWI or Corporation for National Research Initiatives or
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CNRI not be used in advertising or publicity pertaining to
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distribution of the software without specific, written prior
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permission.
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While CWI is the initial source for this software, a modified version
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is made available by the Corporation for National Research Initiatives
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(CNRI) at the Internet address ftp://ftp.python.org.
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STICHTING MATHEMATISCH CENTRUM AND CNRI DISCLAIM ALL WARRANTIES WITH
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REGARD TO THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF
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MERCHANTABILITY AND FITNESS, IN NO EVENT SHALL STICHTING MATHEMATISCH
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CENTRUM OR CNRI BE LIABLE FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL
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DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
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PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
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TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
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PERFORMANCE OF THIS SOFTWARE.
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******************************************************************/
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/* String object interface */
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/*
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Type PyStringObject represents a character string. An extra zero byte is
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reserved at the end to ensure it is zero-terminated, but a size is
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present so strings with null bytes in them can be represented. This
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is an immutable object type.
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There are functions to create new string objects, to test
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an object for string-ness, and to get the
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string value. The latter function returns a null pointer
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if the object is not of the proper type.
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There is a variant that takes an explicit size as well as a
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variant that assumes a zero-terminated string. Note that none of the
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functions should be applied to nil objects.
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*/
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/* Two speedup hacks. Caching the hash saves recalculation of a
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string's hash value. Interning strings (which requires hash
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caching) tries to ensure that only one string object with a given
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value exists, so equality tests are one pointer comparison.
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Together, these can speed the interpreter up by as much as 20%.
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Each costs the size of a long or pointer per string object. In
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addition, interned strings live until the end of times. If you are
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concerned about memory footprint, simply comment the #define out
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here (and rebuild everything!). */
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#define CACHE_HASH
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#ifdef CACHE_HASH
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#define INTERN_STRINGS
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#endif
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typedef struct {
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PyObject_VAR_HEAD
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#ifdef CACHE_HASH
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long ob_shash;
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#endif
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#ifdef INTERN_STRINGS
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PyObject *ob_sinterned;
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#endif
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char ob_sval[1];
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} PyStringObject;
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extern DL_IMPORT(PyTypeObject) PyString_Type;
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#define PyString_Check(op) ((op)->ob_type == &PyString_Type)
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extern PyObject *PyString_FromStringAndSize Py_PROTO((const char *, int));
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extern PyObject *PyString_FromString Py_PROTO((const char *));
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extern int PyString_Size Py_PROTO((PyObject *));
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extern char *PyString_AsString Py_PROTO((PyObject *));
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extern void PyString_Concat Py_PROTO((PyObject **, PyObject *));
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extern void PyString_ConcatAndDel Py_PROTO((PyObject **, PyObject *));
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extern int _PyString_Resize Py_PROTO((PyObject **, int));
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extern PyObject *PyString_Format Py_PROTO((PyObject *, PyObject *));
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#ifdef INTERN_STRINGS
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extern void PyString_InternInPlace Py_PROTO((PyObject **));
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extern PyObject *PyString_InternFromString Py_PROTO((const char *));
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#else
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#define PyString_InternInPlace(p)
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#define PyString_InternFromString(cp) PyString_FromString(cp)
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#endif
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/* Macro, trading safety for speed */
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#define PyString_AS_STRING(op) (((PyStringObject *)(op))->ob_sval)
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#define PyString_GET_SIZE(op) (((PyStringObject *)(op))->ob_size)
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#ifdef __cplusplus
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}
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#endif
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#endif /* !Py_STRINGOBJECT_H */
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