Stockfish/src/move.cpp

/*
  Stockfish, a UCI chess playing engine derived from Glaurung 2.1
  Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
  Copyright (C) 2008-2010 Marco Costalba, Joona Kiiski, Tord Romstad

  Stockfish is free software: you can redistribute it and/or modify
  it under the terms of the GNU General Public License as published by
  the Free Software Foundation, either version 3 of the License, or
  (at your option) any later version.

  Stockfish 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 General Public License for more details.

  You should have received a copy of the GNU General Public License
  along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/


////
//// Includes
////

#include <cassert>
#include <cstring>
#include <iomanip>
#include <string>
#include <sstream>

#include "move.h"
#include "movegen.h"
#include "search.h"

using std::string;

////
//// Local definitions
////

namespace {

  enum Ambiguity {
    AMBIGUITY_NONE, AMBIGUITY_FILE, AMBIGUITY_RANK, AMBIGUITY_BOTH
  };

  Ambiguity move_ambiguity(const Position& pos, Move m);
  const string time_string(int milliseconds);
  const string score_string(Value v);
}


////
//// Functions
////

/// move_to_uci() converts a move to a string in coordinate notation
/// (g1f3, a7a8q, etc.). The only special case is castling moves, where we
/// print in the e1g1 notation in normal chess mode, and in e1h1 notation in
/// Chess960 mode.

const std::string move_to_uci(Move m, bool chess960) {

  std::string promotion;
  Square from = move_from(m);
  Square to = move_to(m);

  if (m == MOVE_NONE)
      return "(none)";

  if (m == MOVE_NULL)
      return "0000";

  if (move_is_short_castle(m) && !chess960)
      return from == SQ_E1 ? "e1g1" : "e8g8";

  if (move_is_long_castle(m) && !chess960)
      return from == SQ_E1 ? "e1c1" : "e8c8";

  if (move_is_promotion(m))
      promotion = char(tolower(piece_type_to_char(move_promotion_piece(m))));

  return square_to_string(from) + square_to_string(to) + promotion;
}


/// move_from_uci() takes a position and a string representing a move in
/// simple coordinate notation and returns an equivalent Move.

Move move_from_uci(const Position& pos, const std::string& str) {

  MoveStack mlist[MOVES_MAX];
  MoveStack* last = generate<MV_LEGAL>(pos, mlist);

  for (MoveStack* cur = mlist; cur != last; cur++)
      if (str == move_to_uci(cur->move, pos.is_chess960()))
          return cur->move;

  return MOVE_NONE;
}


/// move_to_san() takes a position and a move as input, where it is assumed
/// that the move is a legal move from the position. The return value is
/// a string containing the move in short algebraic notation.

const string move_to_san(Position& pos, Move m) {

  assert(pos.is_ok());
  assert(move_is_ok(m));

  string san;
  Square from = move_from(m);
  Square to = move_to(m);
  PieceType pt = type_of_piece(pos.piece_on(from));

  if (m == MOVE_NONE)
      return "(none)";

  if (m == MOVE_NULL)
      return "(null)";

  if (move_is_long_castle(m))
      san = "O-O-O";
  else if (move_is_short_castle(m))
      san = "O-O";
  else
  {
      if (pt != PAWN)
      {
          san += piece_type_to_char(pt);

          switch (move_ambiguity(pos, m)) {
          case AMBIGUITY_NONE:
            break;
          case AMBIGUITY_FILE:
            san += file_to_char(square_file(from));
            break;
          case AMBIGUITY_RANK:
            san += rank_to_char(square_rank(from));
            break;
          case AMBIGUITY_BOTH:
            san += square_to_string(from);
            break;
          default:
            assert(false);
          }
      }

      if (pos.move_is_capture(m))
      {
          if (pt == PAWN)
              san += file_to_char(square_file(from));

          san += 'x';
      }
      san += square_to_string(to);

      if (move_is_promotion(m))
      {
          san += '=';
          san += piece_type_to_char(move_promotion_piece(m));
      }
  }

  // The move gives check ? We don't use pos.move_is_check() here
  // because we need to test for mate after the move is done.
  StateInfo st;
  pos.do_move(m, st);
  if (pos.is_check())
      san += pos.is_mate() ? "#" : "+";
  pos.undo_move(m);

  return san;
}


/// pretty_pv() creates a human-readable string from a position and a PV.
/// It is used to write search information to the log file (which is created
/// when the UCI parameter "Use Search Log" is "true").

const string pretty_pv(Position& pos, int time, int depth,
                       Value score, ValueType type, Move pv[]) {

  const int64_t K = 1000;
  const int64_t M = 1000000;
  const int startColumn = 29;
  const size_t maxLength = 80 - startColumn;
  const string lf = string("\n") + string(startColumn, ' ');

  StateInfo state[PLY_MAX_PLUS_2], *st = state;
  Move* m = pv;
  std::stringstream s;
  string san;
  size_t length = 0;

  // First print depth, score, time and searched nodes...
  s << std::setw(2) << depth
    << (type == VALUE_TYPE_LOWER ? " >" : type == VALUE_TYPE_UPPER ? " <" : "  ")
    << std::setw(7) << score_string(score)
    << std::setw(8) << time_string(time);

  if (pos.nodes_searched() < M)
      s << std::setw(8) << pos.nodes_searched() / 1 << "  ";
  else if (pos.nodes_searched() < K * M)
      s << std::setw(7) << pos.nodes_searched() / K << " K ";
  else
      s << std::setw(7) << pos.nodes_searched() / M << " M ";

  // ...then print the full PV line in short algebraic notation
  while (*m != MOVE_NONE)
  {
      san = move_to_san(pos, *m);
      length += san.length() + 1;

      if (length > maxLength)
      {
          length = san.length() + 1;
          s << lf;
      }
      s << san << ' ';

      pos.do_move(*m++, *st++);
  }

  // Restore original position before to leave
  while (m != pv) pos.undo_move(*--m);

  return s.str();
}


namespace {

  Ambiguity move_ambiguity(const Position& pos, Move m) {

    MoveStack mlist[MOVES_MAX], *last;
    Move candidates[8];
    Square from = move_from(m);
    Square to = move_to(m);
    Piece pc = pos.piece_on(from);
    int matches = 0, f = 0, r = 0;

    // If there is only one piece 'pc' then move cannot be ambiguous
    if (pos.piece_count(pos.side_to_move(), type_of_piece(pc)) == 1)
        return AMBIGUITY_NONE;

    // Collect all legal moves of piece 'pc' with destination 'to'
    last = generate<MV_LEGAL>(pos, mlist);
    for (MoveStack* cur = mlist; cur != last; cur++)
        if (move_to(cur->move) == to && pos.piece_on(move_from(cur->move)) == pc)
            candidates[matches++] = cur->move;

    if (matches == 1)
        return AMBIGUITY_NONE;

    for (int i = 0; i < matches; i++)
    {
        if (square_file(move_from(candidates[i])) == square_file(from))
            f++;

        if (square_rank(move_from(candidates[i])) == square_rank(from))
            r++;
    }

    return f == 1 ? AMBIGUITY_FILE : r == 1 ? AMBIGUITY_RANK : AMBIGUITY_BOTH;
  }


  const string time_string(int millisecs) {

    const int MSecMinute = 1000 * 60;
    const int MSecHour   = 1000 * 60 * 60;

    std::stringstream s;
    s << std::setfill('0');

    int hours = millisecs / MSecHour;
    int minutes = (millisecs - hours * MSecHour) / MSecMinute;
    int seconds = (millisecs - hours * MSecHour - minutes * MSecMinute) / 1000;

    if (hours)
        s << hours << ':';

    s << std::setw(2) << minutes << ':' << std::setw(2) << seconds;
    return s.str();
  }


  const string score_string(Value v) {

    std::stringstream s;

    if (v >= VALUE_MATE - 200)
        s << "#" << (VALUE_MATE - v + 1) / 2;
    else if (v <= -VALUE_MATE + 200)
        s << "-#" << (VALUE_MATE + v) / 2;
    else
    {
        float floatScore = float(v) / float(PawnValueMidgame);
        if (v >= 0)
            s << '+';

        s << std::setprecision(2) << std::fixed << floatScore;
    }
    return s.str();
  }
}