kdecore/sycoca/ksycocadict.h

   1 /*  This file is part of the KDE libraries
   2  *  Copyright (C) 1999 Waldo Bastian <bastian@kde.org>
   3  *
   4  *  This library is free software; you can redistribute it and/or
   5  *  modify it under the terms of the GNU Library General Public
   6  *  License version 2 as published by the Free Software Foundation;
   7  *
   8  *  This library is distributed in the hope that it will be useful,
   9  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  10  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  11  *  Library General Public License for more details.
  12  *
  13  *  You should have received a copy of the GNU Library General Public License
  14  *  along with this library; see the file COPYING.LIB.  If not, write to
  15  *  the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
  16  *  Boston, MA 02110-1301, USA.
  17  **/
  18
  19 #ifndef KSYCOCADICT_H
  20 #define KSYCOCADICT_H
  21
  22 #include <kdecore_export.h>
  23 #include "ksycocaentry.h"
  24
  25 #include <QList>
  26
  27 class QString;
  28 class QDataStream;
  29
  30 /**
  31  * @internal
  32  * Hash table implementation for the sycoca database file
  33  */
  34 class KDECORE_EXPORT KSycocaDict //krazy:exclude=dpointer (not const because it gets deleted by clear())
  35 {
  36 public:
  37    /**
  38     * Create an empty dict, for building the database
  39     */
  40    KSycocaDict();
  41    /**
  42     * Create a dict from an existing database
  43     */
  44    KSycocaDict(QDataStream *str, int offset);
  45
  46    ~KSycocaDict();
  47
  48    /**
  49     * Adds a 'payload' to the dictionary with key 'key'.
  50     *
  51     * 'payload' should have a valid offset by the time
  52     * the dictionary gets saved.
  53     **/
  54    void add(const QString &key, const KSycocaEntry::Ptr& payload);
  55
  56    /**
  57     * Removes the 'payload' from the dictionary with key 'key'.
  58     *
  59     * Not very fast, use with care O(N)
  60     **/
  61    void remove(const QString &key);
  62
  63    /**
  64     * Looks up an entry identified by 'key'.
  65     *
  66     * If 0 is returned, no matching entry exists.
  67     * Otherwise, the offset of the entry is returned.
  68     *
  69     * NOTE: It is not guaranteed that this entry is
  70     * indeed the one you were looking for.
  71     * After loading the entry you should check that it
  72     * indeed matches the search key. If it doesn't
  73     * then no matching entry exists.
  74     */
  75    int find_string(const QString &key ) const;
  76
  77    /**
  78     * Looks up all entries identified by 'key'.
  79     * This is useful when the dict is used as a multi-hash.
  80     *
  81     * If an empty list is returned, no matching entry exists.
  82     * Otherwise, the offset of the matching entries are returned.
  83     *
  84     * NOTE: It is not guaranteed that each entry is
  85     * indeed among the ones you were looking for.
  86     * After loading each entry you should check that it
  87     * indeed matches the search key.
  88     */
  89    QList<int> findMultiString(const QString &key ) const;
  90
  91     /**
  92     * The number of entries in the dictionary.
  93     *
  94     * Only valid when building the database.
  95     */
  96    uint count();
  97
  98    /**
  99     * Reset the dictionary.
 100     *
 101     * Only valid when building the database.
 102     */
 103    void clear();
 104
 105    /**
 106     * Save the dictionary to the stream
 107     * A reasonable fast hash algorithm will be created.
 108     *
 109     * Typically this will find 90% of the entries directly.
 110     * Average hash table size: nrOfItems * 20 bytes.
 111     * Average duplicate list size: nrOfItms * avgKeyLength / 5.
 112     *
 113     * Unknown keys have an average 20% chance to give a false hit.
 114     * (That's why your program should check the result)
 115     *
 116     * Example:
 117     *   Assume 1000 items with an average key length of 60 bytes.
 118     *
 119     *   Approx. 900 items will hash directly to the right entry.
 120     *   Approx. 100 items require a lookup in the duplicate list.
 121     *
 122     *   The hash table size will be approx. 20Kb.
 123     *   The duplicate list size will be approx. 12Kb.
 124     **/
 125    void save(QDataStream &str);
 126
 127 private:
 128     Q_DISABLE_COPY(KSycocaDict)
 129     class Private;
 130     Private* d;
 131 };
 132
 133 #endif