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#include "Fen.hpp"
namespace chessarbiter {
std::string FENParser::normalize_rank(const std::string &fen_rank) {
std::string normalized;
for (const char &c : fen_rank) {
if (IS_DIGIT(c)) {
for (char i = 0; i < (c - '0'); i++) {
normalized += ' ';
}
} else {
// Check validity
char c2 = std::tolower(c);
if (!(c2 == 'p' || c2 == 'r' || c2 == 'n' || c2 == 'b' || c2 == 'q' ||
c2 == 'k' || c2 == ' ')) {
throw InvalidFEN();
}
// Add
normalized += c;
}
}
// Check validity
if (normalized.size() != 8) {
throw InvalidFEN();
}
return (normalized);
}
char FENParser::NextToken(const std::string &fen, char loc) {
while (loc < fen.size() && IS_BLANK(fen[loc])) {
loc++;
}
return (loc);
}
char FENParser::NextRank(const std::string &fen, char loc) {
loc++;
while (loc < fen.size() && fen[loc] != '/' && fen[loc] != ' ') {
loc++;
}
return (loc);
}
std::string FENParser::Serialize(const FEN &fen) {
std::string s;
char skip = 0;
char rank = 0;
for (const char &c : fen.board) {
rank++;
if (c == ' ') {
skip++;
} else {
if (skip > 0) {
s += std::to_string(skip);
skip = 0;
}
s += c;
}
if (rank == 8) {
if (skip != 0) {
s += std::to_string(skip);
skip = 0;
}
s += '/';
rank = 0;
}
}
// Remove last /
s = s.substr(0, s.size() - 1);
s += " ";
// Player
if (fen.player) {
s += "b ";
} else {
s += "w ";
}
// Castle
if (!(fen.white_castle_short || fen.white_castle_long ||
fen.black_castle_short || fen.black_castle_long)) {
s += "-";
} else {
if (fen.white_castle_short) {
s += "K";
}
if (fen.white_castle_long) {
s += "Q";
}
if (fen.black_castle_short) {
s += "k";
}
if (fen.black_castle_long) {
s += "q";
}
}
// Remaining
s += " " + fen.en_passant + " " + std::to_string(fen.halfmove) + " " +
std::to_string(fen.move);
return (s);
}
FEN FENParser::Parse(const std::string &fen) {
FEN parsed;
// Parse board
char loc = 0;
for (char rank = 0; rank < 8; rank++) {
CHECK_LOC();
char newloc = NextRank(fen, loc);
parsed.board += normalize_rank(fen.substr(loc, newloc - loc));
loc = newloc + 1;
}
// Parse player to move
loc = NextToken(fen, loc);
if (!(fen[loc] == 'w' || fen[loc] == 'b')) {
throw InvalidFEN();
}
parsed.player = fen[loc] == 'b';
CHECK_LOC();
// Parse castling
loc = NextToken(fen, loc + 1);
char length = 0;
char cur_loc = loc;
while (!IS_BLANK(fen[cur_loc])) {
length++;
cur_loc++;
CHECK_LOC();
}
parsed.white_castle_short = false;
parsed.white_castle_long = false;
parsed.black_castle_short = false;
parsed.black_castle_long = false;
std::string castle = fen.substr(loc, length);
for (char i = 0; i < length; i++) {
switch (fen[loc + i]) {
case 'K':
parsed.white_castle_short = true;
break;
case 'Q':
parsed.white_castle_long = true;
break;
case 'k':
parsed.black_castle_short = true;
break;
case 'q':
parsed.black_castle_long = true;
break;
case '-':
break;
default:
throw InvalidFEN();
}
}
// Parse en passant
loc = NextToken(fen, loc + length);
if (fen[loc] != '-') {
parsed.en_passant = fen.substr(loc, 2);
loc++;
// Check format
char f = parsed.en_passant[0];
char r = parsed.en_passant[1];
if (!((f >= 'a' && f <= 'h') && (r >= '1' && r <= '8'))) {
throw InvalidFEN();
}
}
loc++;
CHECK_LOC();
// Parse half move counter
loc = NextToken(fen, loc);
std::string halfmove;
while (!IS_BLANK(fen[loc])) {
if (!IS_DIGIT(fen[loc])) {
throw InvalidFEN();
}
halfmove += fen[loc];
loc++;
CHECK_LOC();
}
parsed.halfmove = stoi(halfmove);
// Parse move counter
loc = NextToken(fen, loc);
std::string move;
while (loc < fen.size() && !IS_BLANK(fen[loc])) {
if (!IS_DIGIT(fen[loc])) {
throw InvalidFEN();
}
CHECK_LOC();
move += fen[loc];
loc++;
}
parsed.move = stoi(move);
return (parsed);
}
} // namespace chessarbiter
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