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/*
* Program: pgn-extract: a Portable Game Notation (PGN) extractor.
* Copyright (C) 1994-2005 David Barnes
* This program 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 1, 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 General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*
* David Barnes may be contacted as D.J.Barnes@kent.ac.uk
* http://www.cs.kent.ac.uk/people/staff/djb/
*
*/
/* This file contains functions concerned with decoding
* the original text of a move in order to determine
* which MoveClass it is in,
* any start and end square information.
* It extracts this information purely from the move text
* rather than analysing the move within the context of
* a board position.
* This information is later refined by the semantic analysis
* phase of the program as part of the checking of a game score.
*/
#include <stdio.h>
#include <string.h>
#include "bool.h"
#include "mymalloc.h"
#include "defs.h"
#include "typedef.h"
#include "decode.h"
#include "tokens.h"
#include "taglist.h"
#include "lex.h"
/* Does the character represent a column of the board? */
Boolean
is_col(char c)
{
return (FIRSTCOL <= c) && (c <= LASTCOL);
}
/* Does the character represent a rank of the board? */
Boolean
is_rank(char c)
{
return (FIRSTRANK <= c) && (c <= LASTRANK);
}
/* What kind of piece is *move likely to represent?
* Note, the provision for double-character pieces,
* like a Russian King, means we need access to a
* string rather than a single char.
*/
Piece
is_piece(const unsigned char *move)
{ Piece piece = EMPTY;
switch(*move){
case 'K': case 'k':
piece = KING;
break;
case 'Q': case 'q':
case 'D': /* Dutch/German. */
case RUSSIAN_QUEEN:
piece = QUEEN;
break;
case 'R': case 'r':
case 'T': /* Dutch/German. */
case RUSSIAN_ROOK:
piece = ROOK;
break;
case 'N': case 'n':
case 'P': /* Dutch. */
case 'S': /* German. */
piece = KNIGHT;
break;
case 'B':
case 'L': /* Dutch/German. */
case RUSSIAN_BISHOP:
/* Lower case 'b' is most likely to be a pawn reference. */
piece = BISHOP;
break;
case RUSSIAN_KNIGHT_OR_KING:
if(RUSSIAN_PIECE_CHECK(*(move+1)) == RUSSIAN_KING_SECOND_LETTER){
piece = KING;
}
else{
piece = KNIGHT;
}
break;
}
return piece;
}
/* Is the symbol a capturing one?
* In fact, this is used to recognise any general separator
* between two parts of a move, e.g.:
* Nxc3, e2-e4, etc.
*/
static Boolean
is_capture(char c)
{
return (c == 'x') || (c == 'X') || (c == ':') || (c == '-');
}
static Boolean
is_castling_character(char c)
{
return (c == 'O') || (c == '0') || (c == 'o');
}
Boolean
is_check(char c)
{
return (c == '+') || (c == '#');
}
/* Allocate space in which to return the information that
* has been gleaned from the move.
*/
Move *
new_move_structure(void)
{ Move *move = (Move *)MallocOrDie(sizeof(Move));
move->terminating_result = NULL;
move->epd = NULL;
move->Nags = NULL;
move->Comment = NULL;
move->Variants = NULL;
move->next = NULL;
return move;
}
/* Work out whatever can be gleaned from move_string of
* the starting and ending points of the given move.
* The move may be any legal string.
* The scanning here is libertarian, so it relies heavily on
* illegal moves having already been filtered out by the process
* of lexical analysis.
*/
Move *
decode_move(const unsigned char *move_string)
{ /* The four components of the co-ordinates when known. */
Rank from_rank = 0, to_rank = 0;
Col from_col = 0, to_col = 0;
MoveClass class;
Boolean Ok = TRUE;
/* Temporary locations until known whether they are from_ or to_. */
Col col = 0;
Rank rank = 0;
/* A pointer to move along the move string. */
const unsigned char *move = move_string;
/* A pointer to the structure containing the details to be returned. */
Move *move_details;
Piece piece_to_move = EMPTY;
/* Make an initial distinction between pawn moves and piece moves. */
if(is_col(*move)){
/* Pawn move. */
class = PAWN_MOVE;
piece_to_move = PAWN;
col = *move;
move++;
if(is_rank(*move)){
/* e4, e2e4 */
rank = *move;
move++;
if(is_capture(*move)){
move++;
}
if(is_col(*move)){
from_col = col;
from_rank = rank;
to_col = *move;
move++;
if(is_rank(*move)){
to_rank = *move;
move++;
}
}
else{
to_col = col;
to_rank = rank;
}
}
else{
if(is_capture(*move)){
/* axb */
move++;
}
if(is_col(*move)){
/* ab, or bg8 for liberal bishop moves. */
from_col = col;
to_col = *move;
move++;
if(is_rank(*move)){
to_rank = *move;
move++;
/* Check the sanity of this. */
if((from_col != 'b') &&
(from_col != (to_col+1)) && (from_col != (to_col-1))){
Ok = FALSE;
}
}
else{
/* Check the sanity of this. */
if((from_col != (to_col+1)) && (from_col != (to_col-1))){
Ok = FALSE;
}
}
}
else{
print_error_context(GlobalState.logfile);
fprintf(GlobalState.logfile,"Unknown pawn move %s.\n",move_string);
Ok = FALSE;
}
}
if(Ok){
/* Look for promotions. */
if(*move == '='){
move++;
}
if(is_piece(move) != EMPTY){
class = PAWN_MOVE_WITH_PROMOTION;
/* @@@ Strictly speaking, if the piece is a RUSSIAN_KING
* then we should skip two chars.
*/
move++;
}
}
}
else if((piece_to_move = is_piece(move)) != EMPTY){
class = PIECE_MOVE;
/* Check for a two-character piece. */
if((RUSSIAN_PIECE_CHECK(*move) == RUSSIAN_KNIGHT_OR_KING) &&
(piece_to_move == KING)){
move++;
}
move++;
if(is_rank(*move)){
/* A disambiguating rank.
* R1e1, R1xe3.
*/
from_rank = *move;
move++;
if(is_capture(*move)){
move++;
}
if(is_col(*move)){
to_col = *move;
move++;
if(is_rank(*move)){
to_rank = *move;
move++;
}
}
else{
Ok = FALSE;
print_error_context(GlobalState.logfile);
fprintf(GlobalState.logfile,"Unknown piece move %s.\n",move_string);
}
}
else{
if(is_capture(*move)){
/* Rxe1 */
move++;
if(is_col(*move)){
to_col = *move;
move++;
if(is_rank(*move)){
to_rank = *move;
move++;
}
else{
Ok = FALSE;
print_error_context(GlobalState.logfile);
fprintf(GlobalState.logfile,
"Unknown piece move %s.\n",move_string);
}
}
else{
Ok = FALSE;
print_error_context(GlobalState.logfile);
fprintf(GlobalState.logfile,"Unknown piece move %s.\n",move_string);
}
}
else if(is_col(*move)){
col = *move;
move++;
if(is_capture(*move)){
move++;
}
if(is_rank(*move)){
/* Re1, Re1d1, Re1xd1 */
rank = *move;
move++;
if(is_capture(*move)){
move++;
}
if(is_col(*move)){
/* Re1d1 */
from_col = col;
from_rank = rank;
to_col = *move;
move++;
if(is_rank(*move)){
to_rank = *move;
move++;
}
else{
Ok = FALSE;
print_error_context(GlobalState.logfile);
fprintf(GlobalState.logfile,
"Unknown piece move %s.\n",move_string);
}
}
else{
to_col = col;
to_rank = rank;
}
}
else if(is_col(*move)){
/* Rae1 */
from_col = col;
to_col = *move;
move++;
if(is_rank(*move)){
to_rank = *move;
move++;
}
}
else{
Ok = FALSE;
print_error_context(GlobalState.logfile);
fprintf(GlobalState.logfile,"Unknown piece move %s.\n",move_string);
}
}
else{
Ok = FALSE;
print_error_context(GlobalState.logfile);
fprintf(GlobalState.logfile,"Unknown piece move %s.\n",move_string);
}
}
}
else if(is_castling_character(*move)){
/* Some form of castling. */
move++;
/* Allow separators to be optional. */
if(*move == '-'){
move++;
}
if(is_castling_character(*move)){
move++;
if(*move == '-'){
move++;
}
if(is_castling_character(*move)){
class = QUEENSIDE_CASTLE;
move++;
}
else{
class = KINGSIDE_CASTLE;
}
}
else{
print_error_context(GlobalState.logfile);
fprintf(GlobalState.logfile,"Unknown castling move %s.\n",move_string);
Ok = FALSE;
}
}
else{
print_error_context(GlobalState.logfile);
fprintf(GlobalState.logfile,"Unknown move %s.\n",move_string);
Ok = FALSE;
}
if(Ok){
/* Allow trailing checks. */
while(is_check(*move)){
move++;
}
if(*move == '\0'){
/* Nothing more to check. */
}
else if(((strcmp((const char *) move,"ep") == 0) ||
(strcmp((const char *) move,"e.p.") == 0)) &&
(class == PAWN_MOVE)){
/* These are ok. */
class = ENPASSANT_PAWN_MOVE;
}
else{
Ok = FALSE;
print_error_context(GlobalState.logfile);
fprintf(GlobalState.logfile,
"Unknown text trailing move %s <%s>.\n",move_string,move);
}
}
/* Store all of the details gathered, even if the move is illegal. */
if(!Ok){
class = UNKNOWN_MOVE;
}
move_details = new_move_structure();
strcpy((char *) move_details->move,(const char *) move_string);
move_details->class = class;
move_details->piece_to_move = piece_to_move;
move_details->from_col = from_col;
move_details->from_rank = from_rank;
move_details->to_col = to_col;
move_details->to_rank = to_rank;
move_details->captured_piece = EMPTY;
move_details->check_status = NOCHECK;
return move_details;
}
Move *
decode_algebraic(Move *move_details, Board *board)
{ short from_r = RankConvert(move_details->from_rank);
short from_c = ColConvert(move_details->from_col);
Piece piece_to_move = EXTRACT_PIECE(board->board[from_r][from_c]);
if(piece_to_move != EMPTY){
/* Check for the special case of castling. */
if((piece_to_move == KING) && (move_details->from_col == 'e')){
if(move_details->to_col == 'g'){
move_details->class = KINGSIDE_CASTLE;
}
else if(move_details->to_col == 'c'){
move_details->class = QUEENSIDE_CASTLE;
}
else{
move_details->class = PIECE_MOVE;
move_details->piece_to_move = piece_to_move;
}
}
else{
if(piece_to_move == PAWN){
move_details->class = PAWN_MOVE;
}
else{
move_details->class = PIECE_MOVE;
}
move_details->piece_to_move = piece_to_move;
}
move_details->captured_piece = EMPTY;
move_details->check_status = NOCHECK;
}
return move_details;
}
/* See if move_string seems to represent the text of a valid move.
* Don't print any error messages, just return TRUE or FALSE.
*/
Boolean
move_seems_valid(const unsigned char *move_string)
{ MoveClass class;
Boolean Ok = TRUE;
/* A pointer to move along the move string. */
unsigned const char *move = move_string;
/* Make an initial distinction between pawn moves and piece moves. */
if(is_col(*move)){
/* Pawn move. */
class = PAWN_MOVE;
move++;
if(is_rank(*move)){
/* e4, e2e4 */
move++;
if(is_capture(*move)){
move++;
}
if(is_col(*move)){
move++;
if(is_rank(*move)){
move++;
}
}
else{
}
}
else{
if(is_capture(*move)){
/* axb */
move++;
}
if(is_col(*move)){
/* ab */
move++;
if(is_rank(*move)){
move++;
}
}
else{
Ok = FALSE;
}
}
if(Ok){
/* Look for promotions. */
if(*move == '='){
move++;
}
if(is_piece(move) != EMPTY){
class = PAWN_MOVE_WITH_PROMOTION;
/* @@@ Strictly speaking, if the piece is a RUSSIAN_KING
* then we should skip two chars.
*/
move++;
}
}
}
else if(is_piece(move) != EMPTY){
class = PIECE_MOVE;
/* Check for a two-character piece. */
if((RUSSIAN_PIECE_CHECK(*move) == RUSSIAN_KNIGHT_OR_KING) &&
(is_piece(move) == KING)){
move++;
}
move++;
if(is_rank(*move)){
/* A disambiguating rank.
* R1e1, R1xe3.
*/
move++;
if(is_capture(*move)){
move++;
}
if(is_col(*move)){
move++;
if(is_rank(*move)){
move++;
}
}
else{
Ok = FALSE;
}
}
else{
if(is_capture(*move)){
/* Rxe1 */
move++;
if(is_col(*move)){
move++;
if(is_rank(*move)){
move++;
}
else{
Ok = FALSE;
}
}
else{
Ok = FALSE;
}
}
else if(is_col(*move)){
move++;
if(is_capture(*move)){
move++;
}
if(is_rank(*move)){
/* Re1, Re1d1, Re1xd1 */
move++;
if(is_capture(*move)){
move++;
}
if(is_col(*move)){
/* Re1d1 */
move++;
if(is_rank(*move)){
move++;
}
else{
Ok = FALSE;
}
}
}
else if(is_col(*move)){
/* Rae1 */
move++;
if(is_rank(*move)){
move++;
}
else{
Ok = FALSE;
}
}
else{
Ok = FALSE;
}
}
else{
Ok = FALSE;
}
}
}
else if(is_castling_character(*move)){
/* Some form of castling. */
move++;
/* Allow separators to be optional. */
if(*move == '-'){
move++;
}
if(is_castling_character(*move)){
move++;
if(*move == '-'){
move++;
}
if(is_castling_character(*move)){
class = QUEENSIDE_CASTLE;
move++;
}
else{
class = KINGSIDE_CASTLE;
}
}
else{
Ok = FALSE;
}
}
else{
Ok = FALSE;
}
if(Ok){
/* Allow trailing checks. */
while(is_check(*move)){
move++;
}
if(*move == '\0'){
/* Nothing more to check. */
}
else if(((strcmp((const char *) move,"ep") == 0) ||
(strcmp((const char *) move,"e.p.") == 0)) &&
(class == PAWN_MOVE)){
/* These are ok. */
class = ENPASSANT_PAWN_MOVE;
}
else{
Ok = FALSE;
}
}
return Ok;
}
|
