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svn_hash.h

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00001 /**
00002  * @copyright
00003  * ====================================================================
00004  * Copyright (c) 2000-2004 CollabNet.  All rights reserved.
00005  *
00006  * This software is licensed as described in the file COPYING, which
00007  * you should have received as part of this distribution.  The terms
00008  * are also available at http://subversion.tigris.org/license-1.html.
00009  * If newer versions of this license are posted there, you may use a
00010  * newer version instead, at your option.
00011  *
00012  * This software consists of voluntary contributions made by many
00013  * individuals.  For exact contribution history, see the revision
00014  * history and logs, available at http://subversion.tigris.org/.
00015  * ====================================================================
00016  * @endcopyright
00017  *
00018  * @file svn_hash.h
00019  * @brief Dumping and reading hash tables to/from files.
00020  */
00021 
00022 
00023 #ifndef SVN_HASH_H
00024 #define SVN_HASH_H
00025 
00026 #include <apr_pools.h>
00027 #include <apr_hash.h>
00028 #include <apr_file_io.h>
00029 
00030 #include "svn_types.h"
00031 #include "svn_error.h"
00032 
00033 
00034 #ifdef __cplusplus
00035 extern "C" {
00036 #endif /* __cplusplus */
00037 
00038 
00039 /** The longest the "K <number>" line can be in one of our hashdump files. */
00040 #define SVN_KEYLINE_MAXLEN 100
00041 
00042 
00043 /*----------------------------------------------------*/
00044 
00045 /** Reading/writing hashtables to disk
00046  *
00047  * @defgroup svn_hash_read_write reading and writing hashtables to disk
00048  * @{
00049  */
00050 
00051 /** Read a hash table from @a srcfile, storing the resultants names and
00052  * values in @a hash.  Use a @a pool for all allocations.  @a hash will 
00053  * have <tt>const char *</tt> keys and <tt>svn_string_t *</tt> values.  
00054  */
00055 svn_error_t *svn_hash_read (apr_hash_t *hash, 
00056                             apr_file_t *srcfile,
00057                             apr_pool_t *pool);
00058 
00059 /** Dump @a hash to @a destfile.  Use @a pool for all allocations.  @a hash 
00060  * has <tt>const char *</tt> keys and <tt>svn_string_t *</tt> values.  
00061  */
00062 svn_error_t *svn_hash_write (apr_hash_t *hash, 
00063                 apr_file_t *destfile,
00064                 apr_pool_t *pool);
00065 
00066 /** @} */
00067 
00068 
00069 /** Taking the "diff" of two hash tables.
00070  *
00071  * @defgroup svn_hash_diff taking the diff of two hash tables.
00072  * @{
00073  */
00074 
00075 /** Hash key status indicator for svn_hash_diff_func_t.  */
00076 enum svn_hash_diff_key_status
00077   {
00078     /* Key is present in both hashes. */
00079     svn_hash_diff_key_both,
00080 
00081     /* Key is present in first hash only. */
00082     svn_hash_diff_key_a,
00083 
00084     /* Key is present in second hash only. */
00085     svn_hash_diff_key_b
00086   };
00087 
00088 
00089 /** Function type for expressing a key's status between two hash tables. */
00090 typedef svn_error_t *(*svn_hash_diff_func_t)
00091        (const void *key, apr_ssize_t klen,
00092         enum svn_hash_diff_key_status status,
00093         void *baton);
00094 
00095 
00096 /** Take the diff of two hashtables.
00097  *
00098  * For each key in the union of @a hash_a's and @a hash_b's keys, invoke
00099  * @a diff_func exactly once, passing the key, the key's length, an enum
00100  * @c svn_hash_diff_key_status indicating which table(s) the key appears
00101  * in, and @a diff_func_baton.
00102  *
00103  * Process all keys of @a hash_a first, then all remaining keys of @a hash_b. 
00104  *
00105  * If @a diff_func returns error, return that error immediately, without
00106  * applying @a diff_func to anything else.
00107  *
00108  * @a hash_a or @a hash_b or both may be null; treat a null table as though
00109  * empty.
00110  *
00111  * Use @a pool for temporary allocation.
00112  */
00113 svn_error_t *svn_hash_diff (apr_hash_t *hash_a,
00114                             apr_hash_t *hash_b,
00115                             svn_hash_diff_func_t diff_func,
00116                             void *diff_func_baton,
00117                             apr_pool_t *pool);
00118 
00119 /** @} */
00120 
00121 #ifdef __cplusplus
00122 }
00123 #endif /* __cplusplus */
00124 
00125 #endif /* SVN_HASH_H */

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