src/ConverterCache.h

   1 // -*- C++ -*-
   2 /**
   3  * \file ConverterCache.h
   4  * This file is part of LyX, the document processor.
   5  * Licence details can be found in the file COPYING.
   6  *
   7  * \author Baruch Even
   8  * \author Angus Leeming
   9  * \author Georg Baum
  10  *
  11  * Full author contact details are available in file CREDITS.
  12  *
  13  * ConverterCache is the manager of the file cache.
  14  * It is responsible for creating the ConverterCacheItem's
  15  * and maintaining them.
  16  *
  17  * ConverterCache is a singleton class. It is possible to have
  18  * only one instance of it at any moment.
  19  */
  20
  21 #ifndef CONVERTERCACHE_H
  22 #define CONVERTERCACHE_H
  23
  24 #include "support/strfwd.h"
  25
  26
  27 namespace lyx {
  28
  29 namespace support { class FileName; }
  30
  31 /**
  32  * Cache for converted files. The cache works as follows:
  33  *
  34  * The key for a cache item consists of the absolute name of the original
  35  * file and the format name of the target format.  The original file in the
  36  * user directory is named \c orig_from in the code, the format name is named
  37  * \c to_format. Example:
  38  * \c orig_from = "/home/me/myfigure.fig"
  39  * \c to_format = "eps"
  40  * A cache item is considered up to date (inCache() returns \c true) if
  41  * - The cache contains an item with key (\c orig_to, \c to_format)
  42  * - The stored timestamp of the item is identical with the actual timestamp
  43  *   of \c orig_from, or, if that is not the case, the stored checksum is
  44  *   identical with the actual checksum of \c orig_from.
  45  * Otherwise the item is not considered up to date, and add() will refresh it.
  46  *
  47  * There is no cache maintenance yet (max size, max age etc.)
  48  */
  49 class ConverterCache {
  50 public:
  51
  52         /// This is a singleton class. Get the instance.
  53         static ConverterCache & get();
  54
  55         /// Init the cache. This must be done after package initialization.
  56         static void init();
  57
  58         /// Writes the index list. This must be called on exit.
  59         void writeIndex() const;
  60
  61         /**
  62          * Add \c converted_file (\c orig_from converted to \c to_format) to
  63          * the cache if it is not already in or not up to date.
  64          */
  65         void add(support::FileName const & orig_from, std::string const & to_format,
  66                  support::FileName const & converted_file) const;
  67
  68         /// Remove a file from the cache.
  69         void remove(support::FileName const & orig_from,
  70                     std::string const & to_format) const;
  71
  72         /// Remove all cached \p from_format -> \p to_format conversions
  73         void remove_all(std::string const & from_format,
  74                         std::string const & to_format) const;
  75
  76         /**
  77          * Returns \c true if \c orig_from converted to \c to_format is in
  78          * the cache and up to date.
  79          */
  80         bool inCache(support::FileName const & orig_from,
  81                      std::string const & to_format) const;
  82
  83         /// Get the name of the cached file
  84         support::FileName const & cacheName(support::FileName const & orig_from,
  85                                             std::string const & to_format) const;
  86
  87         /// Copy the file from the cache to \p dest
  88         bool copy(support::FileName const & orig_from, std::string const & to_format,
  89                   support::FileName const & dest) const;
  90
  91 private:
  92         /// noncopyable
  93         ConverterCache(ConverterCache const &);
  94         void operator=(ConverterCache const &);
  95
  96         /** Make the c-tor, d-tor private so we can control how many objects
  97          *  are instantiated.
  98          */
  99         ConverterCache();
 100         ///
 101         ~ConverterCache();
 102
 103         /// Use the Pimpl idiom to hide the internals.
 104         class Impl;
 105         /// The pointer never changes although *pimpl_'s contents may.
 106         Impl * const pimpl_;
 107 };
 108
 109 } // namespace lyx
 110
 111 #endif