Searchable.cpp

 
 
// MIT License
//
// Copyright (c) 2023 Ian Parberry
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to
// deal in the Software without restriction, including without limitation the
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// sell copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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// IN THE SOFTWARE.
 
#include "Searchable.h"
 
 
CSearchable::CSearchable(): C1NF(){
  m_nNumMatchings = 1;
  for(size_t i = oddfloor(m_nWidth); i>1; i-=2)
    m_nNumMatchings *= i;
} //constructor
 
 
void CSearchable::Save(){
  std::string filename = 
    "w" + std::to_string(m_nWidth) + 
    "d" + std::to_string(m_nDepth) +
    "n" + std::to_string(m_nCount) + ".txt"; 
 
  CComparatorNetwork::Save(filename); //save to file with that name
} //Save
 
 
void CSearchable::SetToS(){
  m_nToS = (int)m_nDepth - 1;
} //SetToS
 
 
void CSearchable::Process(){
  if(Sorts()){ //if it sorts
    Save(); //save it
    m_nCount++; //add 1 to the total
  } //if
} //Process
 
 
void CSearchable::Search(){
  bool unfinished = true; //assume we're not finished
 
  while(unfinished){ //until we're finished
    Process(); //process the current comparator network, that is, see if it sorts
    unfinished = NextComparatorNetwork(); //get the next comparator network, we're finished if this function says so  
  } //while
} //Search
 
 
void CSearchable::Backtrack(){
  m_nCount = 0; //we've found none so far
  FirstComparatorNetwork(1); //assuming first normal form here
  Search(); //perform the search
} //Backtrack
 
 
void CSearchable::FirstComparatorNetwork(size_t toplevel){
  m_nTop = (int)toplevel; //save value of toplevel for later use
 
  for(size_t i=toplevel; i<m_nDepth; i++) //for each level in range
    InitMatchingRepresentations(i); //initialize both matching representations
} //FirstComparatorNetwork
 
 
void CSearchable::SynchMatchingRepresentations(size_t level){
  for(size_t j=0; j<m_nWidth; j+=2){ //for each pair of channels
    size_t x = m_cMatching[level][j]; //channel at left end of comparator
    size_t y = m_cMatching[level][j + 1]; //channel at the other end
 
    if(y == m_nWidth) //if the rightmost channel is the last one in a comparator network with an odd number of inputs
      m_nComparator[level][x] = x; //it's empty
 
    else{ //make the testable representation
      m_nComparator[level][x] = y; //x goes to y
      m_nComparator[level][y] = x; //y goes to x
    } //else
  } //for
} //SynchMatchingRepresentations
 
 
void CSearchable::InitMatchingRepresentations(size_t level){
  m_cMatching[level].Initialize();  //initialize the generatable form
  m_nStack[level] = 0; //and its stack
 
  for(size_t j=0; j<m_nWidth; j++) //initialize the testable form
    m_nComparator[level][j] = j^1;
 
  if(odd(m_nWidth)) //one extra one if n is odd
    m_nComparator[level][m_nWidth - 1] = m_nWidth - 1;
} //InitMatchingRepresentations
 
 
bool CSearchable::NextComparatorNetwork(){
  SetToS(); //set top of stack
 
  m_nStack[m_nToS]++;
 
  if(m_cMatching[m_nToS].Next())
    SynchMatchingRepresentations(m_nToS);
 
  while((m_nToS >= m_nTop) && (m_nStack[m_nToS] == m_nNumMatchings)){
    InitMatchingRepresentations(m_nToS);
 
    if(--m_nToS >= m_nTop){
      m_nStack[m_nToS]++;
 
      if(m_nStack[m_nToS] < m_nNumMatchings && m_cMatching[m_nToS].Next())
        SynchMatchingRepresentations(m_nToS);
    } //if
  } //while
 
  return m_nToS >= m_nTop; //there are no more if we blow the top of the stack
} //NextComparatorNetwork
 
 
const size_t CSearchable::GetCount() const{
  return m_nCount;
} //GetCount