string_table.h revision 362181 
1/* string_table.h : interface to string tables, private to libsvn_fs_x
2 *
3 * ====================================================================
4 *    Licensed to the Apache Software Foundation (ASF) under one
5 *    or more contributor license agreements.  See the NOTICE file
6 *    distributed with this work for additional information
7 *    regarding copyright ownership.  The ASF licenses this file
8 *    to you under the Apache License, Version 2.0 (the
9 *    "License"); you may not use this file except in compliance
10 *    with the License.  You may obtain a copy of the License at
11 *
12 *      http://www.apache.org/licenses/LICENSE-2.0
13 *
14 *    Unless required by applicable law or agreed to in writing,
15 *    software distributed under the License is distributed on an
16 *    "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
17 *    KIND, either express or implied.  See the License for the
18 *    specific language governing permissions and limitations
19 *    under the License.
20 * ====================================================================
21 */
22
23#ifndef SVN_LIBSVN_FS_X_STRING_TABLE_H
24#define SVN_LIBSVN_FS_X_STRING_TABLE_H
25
26#include "svn_io.h"
27#include "private/svn_temp_serializer.h"
28
29#ifdef __cplusplus
30extern "C" {
31#endif /* __cplusplus */
32
33/* A string table is a very space efficient, read-only representation for
34 * a set of strings with high degreed of prefix and postfix overhead.
35 *
36 * Creating a string table is a two-stage process:  Use a builder class,
37 * stuff all the strings in there and let it then do the heavy lifting of
38 * classification and compression to create the actual string table object.
39 *
40 * We will use this for the various path values in FSX change lists and
41 * node revision items.
42 */
43
44/* the string table builder */
45typedef struct string_table_builder_t string_table_builder_t;
46
47/* the string table */
48typedef struct string_table_t string_table_t;
49
50/* Returns a new string table builder object, allocated in RESULT_POOL.
51 */
52string_table_builder_t *
53svn_fs_x__string_table_builder_create(apr_pool_t *result_pool);
54
55/* Add an arbitrary NUL-terminated C-string STRING of the given length LEN
56 * to BUILDER.  Return the index of that string in the future string table.
57 * If LEN is 0, determine the length of the C-string internally.
58 */
59apr_size_t
60svn_fs_x__string_table_builder_add(string_table_builder_t *builder,
61                                   const char *string,
62                                   apr_size_t len);
63
64/* Return an estimate for the on-disk size of the resulting string table.
65 * The estimate may err in both directions but tends to overestimate the
66 * space requirements for larger tables.
67 */
68apr_size_t
69svn_fs_x__string_table_builder_estimate_size(string_table_builder_t *builder);
70
71/* From the given BUILDER object, create a string table object allocated
72 * in RESULT_POOL that contains all strings previously added to BUILDER.
73 */
74string_table_t *
75svn_fs_x__string_table_create(const string_table_builder_t *builder,
76                              apr_pool_t *result_pool);
77
78/* Extract string number INDEX from TABLE and return a copy of it allocated
79 * in RESULT_POOL.  If LENGTH is not NULL, set *LENGTH to strlen() of the
80 * result string.  Returns an empty string for invalid indexes.
81 */
82const char*
83svn_fs_x__string_table_get(const string_table_t *table,
84                           apr_size_t index,
85                           apr_size_t *length,
86                           apr_pool_t *result_pool);
87
88/* Write a serialized representation of the string table TABLE to STREAM.
89 * Use SCRATCH_POOL for temporary allocations.
90 */
91svn_error_t *
92svn_fs_x__write_string_table(svn_stream_t *stream,
93                             const string_table_t *table,
94                             apr_pool_t *scratch_pool);
95
96/* Read the serialized string table representation from STREAM and return
97 * the resulting runtime representation in *TABLE_P.  Allocate it in
98 * RESULT_POOL and use SCRATCH_POOL for temporary allocations.
99 */
100svn_error_t *
101svn_fs_x__read_string_table(string_table_t **table_p,
102                            svn_stream_t *stream,
103                            apr_pool_t *result_pool,
104                            apr_pool_t *scratch_pool);
105
106/* Serialize string table *ST within the serialization CONTEXT.
107 */
108void
109svn_fs_x__serialize_string_table(svn_temp_serializer__context_t *context,
110                                 string_table_t **st);
111
112/* Deserialize string table *TABLE within the BUFFER.
113 */
114void
115svn_fs_x__deserialize_string_table(void *buffer,
116                                   string_table_t **table);
117
118/* Extract string number INDEX from the cache serialized representation at
119 * TABLE and return a copy of it allocated in RESULT_POOL.  If LENGTH is not
120 * NULL, set *LENGTH to strlen() of the result string.  Returns an empty
121 * string for invalid indexes.
122 */
123const char*
124svn_fs_x__string_table_get_func(const string_table_t *table,
125                                apr_size_t idx,
126                                apr_size_t *length,
127                                apr_pool_t *result_pool);
128
129#ifdef __cplusplus
130}
131#endif /* __cplusplus */
132
133#endif /* SVN_LIBSVN_FS_X_STRING_TABLE_H */
134