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/* key-gen.c --- manufacturing sequential keys for some db tables
*
* ====================================================================
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing,
* software distributed under the License is distributed on an
* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
* KIND, either express or implied. See the License for the
* specific language governing permissions and limitations
* under the License.
* ====================================================================
*/
#ifndef SVN_LIBSVN_FS_KEY_GEN_H
#define SVN_LIBSVN_FS_KEY_GEN_H
#include <apr.h>
#include "svn_types.h"
#ifdef __cplusplus
extern "C" {
#endif /* __cplusplus */
/* The alphanumeric keys passed in and out of svn_fs_fs__next_key
are guaranteed never to be longer than this many bytes,
*including* the trailing null byte. It is therefore safe
to declare a key as "char key[MAX_KEY_SIZE]".
Note that this limit will be a problem if the number of
keys in a table ever exceeds
18217977168218728251394687124089371267338971528174
76066745969754933395997209053270030282678007662838
67331479599455916367452421574456059646801054954062
15017704234999886990788594743994796171248406730973
80736524850563115569208508785942830080999927310762
50733948404739350551934565743979678824151197232629
947748581376,
but that's a risk we'll live with for now. */
#define MAX_KEY_SIZE 200
/* Generate the next key after a given alphanumeric key.
*
* The first *LEN bytes of THIS are an ascii representation of a
* number in base 36: digits 0-9 have their usual values, and a-z have
* values 10-35.
*
* The new key is stored in NEXT, null-terminated. NEXT must be at
* least *LEN + 2 bytes long -- one extra byte to hold a possible
* overflow column, and one for null termination. On return, *LEN
* will be set to the length of the new key, not counting the null
* terminator. In other words, the outgoing *LEN will be either equal
* to the incoming, or to the incoming + 1.
*
* If THIS contains anything other than digits and lower-case
* alphabetic characters, or if it starts with `0' but is not the
* string "0", then *LEN is set to zero and the effect on NEXT
* is undefined.
*/
void svn_fs_fs__next_key(const char *this, apr_size_t *len, char *next);
/* Compare two strings A and B as base-36 alphanumeric keys.
*
* Return -1, 0, or 1 if A is less than, equal to, or greater than B,
* respectively.
*/
int svn_fs_fs__key_compare(const char *a, const char *b);
/* Add two base-36 alphanumeric keys to get a third, the result. */
void svn_fs_fs__add_keys(const char *key1, const char *key2, char *result);
#ifdef __cplusplus
}
#endif /* __cplusplus */
#endif /* SVN_LIBSVN_FS_KEY_GEN_H */
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