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117 lines
4.3 KiB
C
117 lines
4.3 KiB
C
/********************************************************************\
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* qof-string-cache.h -- QOF string cache functions *
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* *
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* This program is free software; you can redistribute it and/or *
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* modify it under the terms of the GNU General Public License as *
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* published by the Free Software Foundation; either version 2 of *
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* the License, or (at your option) any later version. *
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* *
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* This program is distributed in the hope that it will be useful, *
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* but WITHOUT ANY WARRANTY; without even the implied warranty of *
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the *
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* GNU General Public License for more details. *
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* *
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* You should have received a copy of the GNU General Public License*
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* along with this program; if not, contact: *
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* *
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* Free Software Foundation Voice: +1-617-542-5942 *
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* 51 Franklin Street, Fifth Floor Fax: +1-617-542-2652 *
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* Boston, MA 02110-1301, USA gnu@gnu.org *
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\********************************************************************/
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/** @addtogroup Utilities
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@{ */
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/** @file qof-string-cache.h
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@brief QOF String cache functions
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@author Copyright (C) 1997 Robin D. Clark <rclark@cs.hmc.edu>
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@author Copyright (C) 2000 Bill Gribble <grib@billgribble.com>
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@author Copyright (C) 1997-2002,2004 Linas Vepstas <linas@linas.org>
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@author Copyright 2006 Neil Williams <linux@codehelp.co.uk>
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@author Copyright 2012 Phil Longstaff <phil.longstaff@yahoo.ca>
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*/
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#ifndef QOF_STRING_UTIL_H
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#define QOF_STRING_UTIL_H
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#ifdef __cplusplus
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extern "C"
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{
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#endif
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#define QOF_MOD_UTIL "qof.utilities"
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/** The QOF String Cache:
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*
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* Many strings used throughout QOF and QOF applications are likely to
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* be duplicated.
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*
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* QOF provides a reference counted cache system for the strings, which
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* shares strings whenever possible.
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*
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* Use qof_string_cache_insert to insert a string into the cache (it
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* will return a pointer to the cached string). Basically you should
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* use this instead of g_strdup.
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*
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* Use qof_string_cache_remove (giving it a pointer to a cached
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* string) if the string is unused. If this is the last reference to
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* the string it will be removed from the cache, otherwise it will
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* just decrement the reference count. Basically you should use this
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* instead of g_free.
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*
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* Just in case it's not clear: The remove function must NOT be called
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* for the string you passed INTO the insert function. It must be
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* called for the _cached_ string that is _returned_ by the insert
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* function.
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*
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* Note that all the work is done when inserting or removing. Once
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* cached the strings are just plain C strings.
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*
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* The string cache is demand-created on first use.
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*
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**/
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/** Initialize the string cache */
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void qof_string_cache_init(void);
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/** Destroy the qof_string_cache */
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void qof_string_cache_destroy(void);
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/** You can use this function as a destroy notifier for a GHashTable
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that uses common strings as keys (or values, for that matter.)
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*/
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void qof_string_cache_remove(const char * key);
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/** You can use this function with g_hash_table_insert(), for the key
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(or value), as long as you use the destroy notifier above.
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*/
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char * qof_string_cache_insert(const char * key);
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/** Same as CACHE_REPLACE below, but safe to call from C++.
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*/
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char * qof_string_cache_replace(const char * dst, const char * src);
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#define CACHE_INSERT(str) qof_string_cache_insert((str))
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#define CACHE_REMOVE(str) qof_string_cache_remove((str))
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/* Replace cached string currently in 'dst' with string in 'src'.
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* Typical usage:
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* void foo_set_name(Foo *f, const char *str) {
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* CACHE_REPLACE(f->name, str);
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* }
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* It avoids unnecessary ejection by doing INSERT before REMOVE.
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*/
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#define CACHE_REPLACE(dst, src) do { \
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gpointer tmp = CACHE_INSERT((src)); \
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CACHE_REMOVE((dst)); \
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(dst) = tmp; \
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} while (0)
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#define QOF_CACHE_NEW(void) qof_string_cache_insert("")
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#ifdef __cplusplus
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}
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#endif
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#endif /* QOF_STRING_CACHE_H */
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/** @} */
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