michael@0: /*  GRAPHITE2 LICENSING
michael@0: 
michael@0:     Copyright 2010, SIL International
michael@0:     All rights reserved.
michael@0: 
michael@0:     This library is free software; you can redistribute it and/or modify
michael@0:     it under the terms of the GNU Lesser General Public License as published
michael@0:     by the Free Software Foundation; either version 2.1 of License, or
michael@0:     (at your option) any later version.
michael@0: 
michael@0:     This program is distributed in the hope that it will be useful,
michael@0:     but WITHOUT ANY WARRANTY; without even the implied warranty of
michael@0:     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
michael@0:     Lesser General Public License for more details.
michael@0: 
michael@0:     You should also have received a copy of the GNU Lesser General Public
michael@0:     License along with this library in the file named "LICENSE".
michael@0:     If not, write to the Free Software Foundation, 51 Franklin Street,
michael@0:     Suite 500, Boston, MA 02110-1335, USA or visit their web page on the
michael@0:     internet at http://www.fsf.org/licenses/lgpl.html.
michael@0: 
michael@0: Alternatively, the contents of this file may be used under the terms of the
michael@0: Mozilla Public License (http://mozilla.org/MPL) or the GNU General Public
michael@0: License, as published by the Free Software Foundation, either version 2
michael@0: of the License or (at your option) any later version.
michael@0: */
michael@0: #pragma once
michael@0: 
michael@0: #ifndef GRAPHITE2_NSEGCACHE
michael@0: 
michael@0: #include "inc/Main.h"
michael@0: #include "inc/Slot.h"
michael@0: 
michael@0: namespace graphite2 {
michael@0: 
michael@0: class Segment;
michael@0: class Slot;
michael@0: class SegCacheEntry;
michael@0: class SegCachePrefixEntry;
michael@0: 
michael@0: enum SegCacheParameters {
michael@0:     /** number of characters used in initial prefix tree */
michael@0:     ePrefixLength = 2,
michael@0:     /** Segments more recent than maxSegmentCount() / eAgeFactor are kept */
michael@0:     eAgeFactor = 4,
michael@0:     /** Segments are purged according to the formular:
michael@0:      * accessCount < (totalAccesses)/(ePurgeFactor * maxSegments) */
michael@0:     ePurgeFactor = 5,
michael@0:     /** Maximum number of Segments to store which have the same
michael@0:      * prefix. Needed to prevent unique identifiers flooding the cache */
michael@0:     eMaxSuffixCount = 15
michael@0: 
michael@0: };
michael@0: 
michael@0: class SegCacheCharInfo
michael@0: {
michael@0: public:
michael@0:     uint16 m_unicode;
michael@0:     uint16 m_before;
michael@0:     uint16 m_after;
michael@0: };
michael@0: 
michael@0: /**
michael@0:  * SegCacheEntry stores the result of running the engine for specific unicode
michael@0:  * code points in the typical mid-line situation.
michael@0:  */
michael@0: class SegCacheEntry
michael@0: {
michael@0:     // Prevent any implict copying;
michael@0:     SegCacheEntry(const SegCacheEntry &);
michael@0:     SegCacheEntry & operator = (const SegCacheEntry &);
michael@0: 
michael@0:     friend class SegCachePrefixEntry;
michael@0: public:
michael@0:     SegCacheEntry() :
michael@0:         m_glyphLength(0), m_unicode(NULL), m_glyph(NULL), m_attr(NULL), m_justs(0),
michael@0:         m_accessCount(0), m_lastAccess(0)
michael@0:     {}
michael@0:     SegCacheEntry(const uint16 * cmapGlyphs, size_t length, Segment * seg, size_t charOffset, long long cacheTime);
michael@0:     ~SegCacheEntry() { clear(); };
michael@0:     void clear();
michael@0:     size_t glyphLength() const { return m_glyphLength; }
michael@0:     const Slot * first() const { return m_glyph; }
michael@0:     const Slot * last() const { return m_glyph + (m_glyphLength - 1); }
michael@0: 
michael@0:     /** Total number of times this entry has been accessed since creation */
michael@0:     unsigned long long accessCount() const { return m_accessCount; }
michael@0:     /** "time" of last access where "time" is measured in accesses to the cache owning this entry */
michael@0:     void accessed(unsigned long long cacheTime) const
michael@0:     {
michael@0:         m_lastAccess = cacheTime; ++m_accessCount;
michael@0:     };
michael@0: 
michael@0:     int compareRank(const SegCacheEntry & entry) const
michael@0:     {
michael@0:         if (m_accessCount > entry.m_accessCount) return 1;
michael@0:         else if (m_accessCount < entry.m_accessCount) return 1;
michael@0:         else if (m_lastAccess > entry.m_lastAccess) return 1;
michael@0:         else if (m_lastAccess < entry.m_lastAccess) return -1;
michael@0:         return 0;
michael@0:     }
michael@0:     unsigned long long lastAccess() const { return m_lastAccess; };
michael@0: 
michael@0:     CLASS_NEW_DELETE;
michael@0: private:
michael@0: 
michael@0:     size_t   m_glyphLength;
michael@0:     /** glyph ids resulting from cmap mapping from unicode to glyph before substitution
michael@0:      * the length of this array is determined by the position in the SegCachePrefixEntry */
michael@0:     uint16 * m_unicode;
michael@0:     /** slots after shapping and positioning */
michael@0:     Slot   * m_glyph;
michael@0:     int16  * m_attr;
michael@0:     byte   * m_justs;
michael@0:     mutable unsigned long long m_accessCount;
michael@0:     mutable unsigned long long m_lastAccess;
michael@0: };
michael@0: 
michael@0: } // namespace graphite2
michael@0: 
michael@0: #endif