1/*
2 This file is part of the KDE libraries
3 SPDX-FileCopyrightText: 1999 Waldo Bastian <bastian@kde.org>
4
5 SPDX-License-Identifier: LGPL-2.0-only
6*/
7
8#ifndef KSYCOCADICT_H
9#define KSYCOCADICT_H
10
11#include "ksycocaentry.h"
12#include <kservice_export.h>
13
14#include <QList>
15
16#include <memory>
17
18class KSycocaDictPrivate;
19
20class QString;
21class QDataStream;
22
23/*!
24 * \internal
25 * Hash table implementation for the sycoca database file
26 *
27 * Only exported for the unit test
28 */
29class KSERVICE_EXPORT KSycocaDict // krazy:exclude=dpointer (not const because it gets deleted by clear())
30{
31public:
32 /*!
33 * Create an empty dict, for building the database
34 */
35 KSycocaDict();
36 /*!
37 * Create a dict from an existing database
38 */
39 KSycocaDict(QDataStream *str, int offset);
40
41 ~KSycocaDict();
42
43 /*!
44 * Adds a 'payload' to the dictionary with key 'key'.
45 *
46 * 'payload' should have a valid offset by the time
47 * the dictionary gets saved.
48 **/
49 void add(const QString &key, const KSycocaEntry::Ptr &payload);
50
51 /*!
52 * Removes the 'payload' from the dictionary with key 'key'.
53 *
54 * Not very fast, use with care O(N)
55 **/
56 void remove(const QString &key);
57
58 /*!
59 * Looks up an entry identified by 'key'.
60 *
61 * If 0 is returned, no matching entry exists.
62 * Otherwise, the offset of the entry is returned.
63 *
64 * NOTE: It is not guaranteed that this entry is
65 * indeed the one you were looking for.
66 * After loading the entry you should check that it
67 * indeed matches the search key. If it doesn't
68 * then no matching entry exists.
69 */
70 int find_string(const QString &key) const;
71
72 /*!
73 * Looks up all entries identified by 'key'.
74 * This is useful when the dict is used as a multi-hash.
75 *
76 * If an empty list is returned, no matching entry exists.
77 * Otherwise, the offset of the matching entries are returned.
78 *
79 * NOTE: It is not guaranteed that each entry is
80 * indeed among the ones you were looking for.
81 * After loading each entry you should check that it
82 * indeed matches the search key.
83 */
84 QList<int> findMultiString(const QString &key) const;
85
86 /*!
87 * The number of entries in the dictionary.
88 *
89 * Only valid when building the database.
90 */
91 uint count() const;
92
93 /*!
94 * Reset the dictionary.
95 *
96 * Only valid when building the database.
97 */
98 void clear();
99
100 /*!
101 * Save the dictionary to the stream
102 * A reasonable fast hash algorithm will be created.
103 *
104 * Typically this will find 90% of the entries directly.
105 * Average hash table size: nrOfItems * 20 bytes.
106 * Average duplicate list size: nrOfItms * avgKeyLength / 5.
107 *
108 * Unknown keys have an average 20% chance to give a false hit.
109 * (That's why your program should check the result)
110 *
111 * Example:
112 * Assume 1000 items with an average key length of 60 bytes.
113 *
114 * Approx. 900 items will hash directly to the right entry.
115 * Approx. 100 items require a lookup in the duplicate list.
116 *
117 * The hash table size will be approx. 20Kb.
118 * The duplicate list size will be approx. 12Kb.
119 **/
120 void save(QDataStream &str);
121
122private:
123 Q_DISABLE_COPY(KSycocaDict)
124 std::unique_ptr<KSycocaDictPrivate> d;
125};
126
127#endif
128

source code of kservice/src/sycoca/ksycocadict_p.h