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 /*  GRAPHITE2 LICENSING

     Copyright 2011, SIL International

     All rights reserved.

     This library is free software; you can redistribute it and/or modify

     it under the terms of the GNU Lesser General Public License as published

     by the Free Software Foundation; either version 2.1 of License, or

     (at your option) any later version.

     This program is distributed in the hope that it will be useful,

     but WITHOUT ANY WARRANTY; without even the implied warranty of

     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

     Lesser General Public License for more details.

     You should also have received a copy of the GNU Lesser General Public

     License along with this library in the file named "LICENSE".

     If not, write to the Free Software Foundation, 51 Franklin Street, 

     Suite 500, Boston, MA 02110-1335, USA or visit their web page on the 

     internet at http://www.fsf.org/licenses/lgpl.html.

 Alternatively, the contents of this file may be used under the terms of the

 Mozilla Public License (http://mozilla.org/MPL) or the GNU General Public

 License, as published by the Free Software Foundation, either version 2

 of the License or (at your option) any later version.

 */

 #pragma once

 #include "inc/Code.h"

 #include "inc/Slot.h"

 namespace graphite2 {

 struct Rule {

   const vm::Machine::Code * constraint, 

                  * action;

   unsigned short   sort;

   byte             preContext;

 #ifndef NDEBUG

   uint16           rule_idx;

 #endif

   Rule() : constraint(0), action(0), sort(0), preContext(0) {}

   ~Rule();

   CLASS_NEW_DELETE;

 private:

   Rule(const Rule &);

   Rule & operator = (const Rule &);

 };

 inline Rule::~Rule()

 {

   delete constraint;

   delete action;

 }

 struct RuleEntry

 {

   const Rule   * rule;

   inline

   bool operator < (const RuleEntry &r) const

   {

     const unsigned short lsort = rule->sort, rsort = r.rule->sort;

     return lsort > rsort || (lsort == rsort && rule < r.rule);

   }

   inline

   bool operator == (const RuleEntry &r) const

   {

     return rule == r.rule;

   }

 };

 struct State

 {

   const RuleEntry     * rules,

                       * rules_end;

   bool   empty() const;

 };

 inline

 bool State::empty() const

 {

     return rules_end == rules;

 }

 class SlotMap

 {

 public:

   enum {MAX_SLOTS=64};

   SlotMap(Segment & seg);

   Slot       * * begin();

   Slot       * * end();

   size_t         size() const;

   unsigned short context() const;

   void           reset(Slot &, unsigned short);

   Slot * const & operator[](int n) const;

   Slot       * & operator [] (int);

   void           pushSlot(Slot * const slot);

   void           collectGarbage();

   Slot         * highwater() { return m_highwater; }

   void           highwater(Slot *s) { m_highwater = s; m_highpassed = false; }

   bool           highpassed() const { return m_highpassed; }

   void           highpassed(bool v) { m_highpassed = v; }

   Segment &    segment;

 private:

   Slot         * m_slot_map[MAX_SLOTS+1];

   unsigned short m_size;

   unsigned short m_precontext;

   Slot         * m_highwater;

   bool           m_highpassed;

 };

 class FiniteStateMachine

 {

 public:

   enum {MAX_RULES=128};

 private:

   class Rules

   {

   public:

       Rules();

       void              clear();

       const RuleEntry * begin() const;

       const RuleEntry * end() const;

       size_t            size() const;

       void accumulate_rules(const State &state);

   private:

       RuleEntry * m_begin, 

                 * m_end,

                   m_rules[MAX_RULES*2];

   };

 public:

   FiniteStateMachine(SlotMap & map, json * logger);

   void      reset(Slot * & slot, const short unsigned int max_pre_ctxt);

   Rules     rules;

   SlotMap   & slots;

   json    * const dbgout;

 };

 inline

 FiniteStateMachine::FiniteStateMachine(SlotMap& map, json * logger)

 : slots(map),

   dbgout(logger)

 {

 }

 inline

 void FiniteStateMachine::reset(Slot * & slot, const short unsigned int max_pre_ctxt)

 {

   rules.clear();

   int ctxt = 0;

   for (; ctxt != max_pre_ctxt && slot->prev(); ++ctxt, slot = slot->prev());

   slots.reset(*slot, ctxt);

 }

 inline

 FiniteStateMachine::Rules::Rules()

   : m_begin(m_rules), m_end(m_rules)

 {

 }

 inline

 void FiniteStateMachine::Rules::clear()

 {

   m_end = m_begin;

 }

 inline

 const RuleEntry * FiniteStateMachine::Rules::begin() const

 {

   return m_begin;

 }

 inline

 const RuleEntry * FiniteStateMachine::Rules::end() const

 {

   return m_end;

 }

 inline

 size_t FiniteStateMachine::Rules::size() const

 {

   return m_end - m_begin;

 }

 inline

 void FiniteStateMachine::Rules::accumulate_rules(const State &state)

 {

   // Only bother if there are rules in the State object.

   if (state.empty()) return;

   // Merge the new sorted rules list into the current sorted result set.

   const RuleEntry * lre = begin(), * rre = state.rules;

   RuleEntry * out = m_rules + (m_begin == m_rules)*MAX_RULES;    

   const RuleEntry * const lrend = out + MAX_RULES,

                   * const rrend = state.rules_end;

   m_begin = out; 

   while (lre != end() && out != lrend)

   {

     if (*lre < *rre)      *out++ = *lre++;

     else if (*rre < *lre) { *out++ = *rre++; }

     else                { *out++ = *lre++; ++rre; }

     if (rre == rrend)

     { 

       while (lre != end() && out != lrend) { *out++ = *lre++; }

       m_end = out;

       return;

     }

   }

   while (rre != rrend && out != lrend) { *out++ = *rre++; }

   m_end = out;

 }

 inline

 SlotMap::SlotMap(Segment & seg)

 : segment(seg), m_size(0), m_precontext(0), m_highwater(0), m_highpassed(false)

 {

     m_slot_map[0] = 0;

 }

 inline

 Slot * * SlotMap::begin()

 {

   return &m_slot_map[1]; // allow map to go 1 before slot_map when inserting

                          // at start of segment.

 }

 inline

 Slot * * SlotMap::end()

 {

   return m_slot_map + m_size + 1;

 }

 inline

 size_t SlotMap::size() const

 {

   return m_size;

 }

 inline

 short unsigned int SlotMap::context() const

 {

   return m_precontext;

 }

 inline

 void SlotMap::reset(Slot & slot, short unsigned int ctxt)

 {

   m_size = 0;

   m_precontext = ctxt;

   *m_slot_map = slot.prev();

 }

 inline

 void SlotMap::pushSlot(Slot*const slot)

 {

   m_slot_map[++m_size] = slot;

 }

 inline

 Slot * const & SlotMap::operator[](int n) const

 {

   return m_slot_map[n + 1];

 }

 inline

 Slot * & SlotMap::operator[](int n)

 {

   return m_slot_map[n + 1];

 }

 } // namespace graphite2