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Improve FEN parser

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Loic Guegan 2022-01-30 07:44:55 +01:00
parent 41107b6890
commit 851f31e7ae
3 changed files with 112 additions and 46 deletions
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46
src/Fen.cpp
View file

@ -5,19 +5,30 @@ namespace chessarbiter {
std::string FENParser::normalize_rank(std::string fen_rank) {
std::string normalized;
for (char &c : fen_rank) {
if (IS_DIGIT(c)) {
if (FEN__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(std::string fen, char loc) {
while (loc < fen.size() && IS_BLANK(fen[loc])) {
while (loc < fen.size() && FEN__IS_BLANK(fen[loc])) {
loc++;
}
return (loc);
@ -99,6 +110,7 @@ FEN FENParser::Parse(std::string fen) {
// Parse board
char loc = 0;
for (char rank = 0; rank < 8; rank++) {
FEN__CHECK_LOC();
char newloc = NextRank(fen, loc);
parsed.board += normalize_rank(fen.substr(loc, newloc - loc));
loc = newloc + 1;
@ -106,15 +118,20 @@ FEN FENParser::Parse(std::string fen) {
// Parse player to move
loc = NextToken(fen, loc);
if (!(fen[loc] == 'w' || fen[loc] == 'b')) {
throw InvalidFEN();
}
parsed.player = fen[loc] == 'b';
FEN__CHECK_LOC();
// Parse castling
loc = NextToken(fen, loc + 1);
char length = 0;
char cur_loc = loc;
while (!IS_BLANK(fen[cur_loc])) {
while (!FEN__IS_BLANK(fen[cur_loc])) {
length++;
cur_loc++;
FEN__CHECK_LOC();
}
parsed.white_castle_short = false;
parsed.white_castle_long = false;
@ -135,6 +152,10 @@ FEN FENParser::Parse(std::string fen) {
case 'q':
parsed.black_castle_long = true;
break;
case '-':
break;
default:
throw InvalidFEN();
}
}
@ -143,22 +164,37 @@ FEN FENParser::Parse(std::string fen) {
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++;
FEN__CHECK_LOC();
// Parse half move counter
loc = NextToken(fen, loc);
std::string halfmove;
while (!IS_BLANK(fen[loc])) {
while (!FEN__IS_BLANK(fen[loc])) {
if (!FEN__IS_DIGIT(fen[loc])) {
throw InvalidFEN();
}
halfmove += fen[loc];
loc++;
FEN__CHECK_LOC();
}
parsed.halfmove = stoi(halfmove);
// Parse move counter
loc = NextToken(fen, loc);
std::string move;
while (loc < fen.size() && !IS_BLANK(fen[loc])) {
while (loc < fen.size() && !FEN__IS_BLANK(fen[loc])) {
if (!FEN__IS_DIGIT(fen[loc])) {
throw InvalidFEN();
}
FEN__CHECK_LOC();
move += fen[loc];
loc++;
}

11
src/Fen.hpp
View file

@ -2,10 +2,11 @@
#include <sstream>
#include <string>
#define IS_DIGIT(c) \
#define FEN__IS_DIGIT(c) \
(c == '0' || c == '1' || c == '2' || c == '3' || c == '4' || c == '5' || \
c == '6' || c == '7' || c == '8' || c == '9')
#define IS_BLANK(c) (c == ' ' || c == '\n' || c == '\t' || c == '\r')
#define FEN__IS_BLANK(c) (c == ' ' || c == '\n' || c == '\t' || c == '\r')
#define FEN__CHECK_LOC() {if(loc>=fen.size()){throw InvalidFEN();}}
namespace chessarbiter {
@ -33,9 +34,13 @@ private:
static char NextRank(std::string fen, char loc);
public:
/// @brief Parse a FEN from a string
/// @brief Parse a FEN from a string (can throw InvalidFEN)
static FEN Parse(std::string);
/// @brief Generate a fen string from the FEN object
static std::string Serialize(FEN fen);
};
struct InvalidFEN : public std::exception {
const char *what() const throw() { return "No piece found"; }
};
} // namespace chessarbiter