~bzr-pqm/bzr/bzr.dev

/* Copyright (C) 2009 Canonical Ltd

 * 

 * This program is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License as published by

 * the Free Software Foundation; either version 2 of the License, or

 * (at your option) any later version.

 *

 * This program is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

 * GNU General Public License for more details.

 *

 * You should have received a copy of the GNU General Public License

 * along with this program; if not, write to the Free Software

 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA

 */

#ifndef _STATIC_TUPLE_H_

#define _STATIC_TUPLE_H_

#include <Python.h>

#include <string.h>

#define STATIC_TUPLE_HAS_HASH 0

/* Caching the hash adds memory, but allows us to save a little time during

 * lookups. TIMEIT hash(key) shows it as

 *  0.108usec w/ hash

 *  0.160usec w/o hash

 * Note that the entries themselves are strings, which already cache their

 * hashes. So while there is a 1.5:1 difference in the time for hash(), it is

 * already a function which is quite fast. Probably the only reason we might

 * want to do so, is if we customized SimpleSet to the point that the item

 * pointers were exactly certain types, and then accessed table[i]->hash

 * directly. So far StaticTuple_hash() is fast enough to not warrant the memory

 * difference.

 */

/* This defines a single variable-width key.

 * It is basically the same as a tuple, but

 * 1) Lighter weight in memory

 * 2) Only supports strings or other static types (that don't reference other

 *    objects.)

 */

#define STATIC_TUPLE_INTERNED_FLAG 0x01

typedef struct {

    PyObject_HEAD

    // We could go with unsigned short here, and support 64k width tuples

    // without any memory impact, might be worthwhile

    unsigned char size;

    unsigned char flags;

    unsigned char _unused0;

    unsigned char _unused1;

    // Note that on 64-bit, we actually have 4-more unused bytes

    // because items will always be aligned to a 64-bit boundary

#if STATIC_TUPLE_HAS_HASH

    long hash;

#endif

    PyObject *items[0];

} StaticTuple;

extern PyTypeObject StaticTuple_Type;

typedef struct {

    PyObject_VAR_HEAD

    PyObject *table[0];

} KeyIntern;

#define StaticTuple_SET_ITEM(key, offset, val) \

    ((((StaticTuple*)(key))->items[(offset)]) = ((PyObject *)(val)))

#define StaticTuple_GET_ITEM(key, offset) (((StaticTuple*)key)->items[offset])

#ifdef STATIC_TUPLE_MODULE

/* Used when compiling _static_tuple_c.c */

static StaticTuple * StaticTuple_New(Py_ssize_t);

static StaticTuple * StaticTuple_Intern(StaticTuple *self);

static StaticTuple * StaticTuple_FromSequence(PyObject *);

#define StaticTuple_CheckExact(op) (Py_TYPE(op) == &StaticTuple_Type)

#else

/* Used as the foreign api */

#include "_import_c_api.h"

static StaticTuple *(*StaticTuple_New)(Py_ssize_t);

static StaticTuple *(*StaticTuple_Intern)(StaticTuple *);

static StaticTuple *(*StaticTuple_FromSequence)(PyObject *);

static PyTypeObject *_p_StaticTuple_Type;

#define StaticTuple_CheckExact(op) (Py_TYPE(op) == _p_StaticTuple_Type)

static int (*_StaticTuple_CheckExact)(PyObject *);

/* Return -1 and set exception on error, 0 on success */

static int

import_static_tuple_c(void)

{

    struct function_description functions[] = {

        {"StaticTuple_New", (void **)&StaticTuple_New,

            "StaticTuple *(Py_ssize_t)"},

        {"StaticTuple_Intern", (void **)&StaticTuple_Intern,

            "StaticTuple *(StaticTuple *)"},

        {"StaticTuple_FromSequence", (void **)&StaticTuple_FromSequence,

            "StaticTuple *(PyObject *)"},

        {"_StaticTuple_CheckExact", (void **)&_StaticTuple_CheckExact,

            "int(PyObject *)"},

        {NULL}};

    struct type_description types[] = {

        {"StaticTuple", &_p_StaticTuple_Type},

        {NULL}};

    return _import_extension_module("bzrlib._static_tuple_c",

        functions, types);

}

#endif // !STATIC_TUPLE_MODULE

#endif // !_STATIC_TUPLE_H_