Chess: Refactor en passant implementation
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Wuzzy
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@ -224,6 +224,23 @@ local function can_castle(meta, board, from_list, from_idx, to_idx)
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end
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-- Checks if a square to check if there is a piece that can be captured en passant. Returns true if this
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-- is the case, false otherwise.
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-- Parameters:
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-- * meta: chessboard node metadata
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-- * victim_color: color of the opponent to capture a piece from. "white" or "black". (so in White's turn, pass "black" here)
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-- * victim_index: board index of the square where you expect the victim to be
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local function can_capture_en_passant(meta, victim_color, victim_index)
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local inv = meta:get_inventory()
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local victimPiece = inv:get_stack("board", victim_index)
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local double_step_index = meta:get_int("prevDoublePawnStepTo")
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local victim_name = victimPiece:get_name()
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if double_step_index ~= 0 and double_step_index == victim_index and victim_name:find(victim_color) and victim_name:sub(11,14) == "pawn" then
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return true
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end
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return false
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end
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-- Returns all theoretically possible moves from a given
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-- square, according to the piece it occupies. Ignores restrictions like check, etc.
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-- If the square is empty, no moves are returned.
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@ -271,18 +288,9 @@ local function get_theoretical_moves_from(meta, board, from_idx)
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can_capture = true
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else
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-- en passant
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local inv = meta:get_inventory()
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local enPassantPiece = inv:get_stack("board", xy_to_index(to_x, from_y))
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local epp_meta = enPassantPiece:get_meta()
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local epp_name = enPassantPiece:get_name()
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if epp_name:find("black") and epp_name:sub(11,14) == "pawn" then
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local pawn_no = epp_name:sub(-1)
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local double_step_halfmove = meta:get_int("doublePawnStepB"..pawn_no)
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local current_halfmove = get_current_halfmove(meta)
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if double_step_halfmove ~= 0 and double_step_halfmove == current_halfmove then
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can_capture = true
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en_passant = true
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end
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if can_capture_en_passant(meta, "black", xy_to_index(to_x, from_y)) then
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can_capture = true
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en_passant = true
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end
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end
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if not can_capture then
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@ -335,18 +343,9 @@ local function get_theoretical_moves_from(meta, board, from_idx)
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can_capture = true
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else
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-- en passant
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local inv = meta:get_inventory()
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local enPassantPiece = inv:get_stack("board", xy_to_index(to_x, from_y))
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local epp_meta = enPassantPiece:get_meta()
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local epp_name = enPassantPiece:get_name()
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if epp_name:find("white") and epp_name:sub(11,14) == "pawn" then
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local pawn_no = epp_name:sub(-1)
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local double_step_halfmove = meta:get_int("doublePawnStepW"..pawn_no)
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local current_halfmove = get_current_halfmove(meta)
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if double_step_halfmove ~= 0 and double_step_halfmove == current_halfmove then
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can_capture = true
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en_passant = true
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end
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if can_capture_en_passant(meta, "white", xy_to_index(to_x, from_y)) then
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can_capture = true
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en_passant = true
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end
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end
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if not can_capture then
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@ -1398,6 +1397,7 @@ function realchess.init(pos)
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meta:set_int("castlingWhiteR", 1)
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meta:set_int("promotionPawnFromIdx", 0)
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meta:set_int("promotionPawnToIdx", 0)
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meta:set_int("prevDoublePawnStepTo", 0)
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meta:set_string("moves_raw", "")
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meta:set_string("eaten", "")
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@ -1499,6 +1499,7 @@ function realchess.move(pos, from_list, from_index, to_list, to_index, player)
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local to_x, to_y = index_to_xy(to_index)
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local promotion = false
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local doublePawnStep = nil
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-- PAWN
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if pieceFrom:sub(11,14) == "pawn" then
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@ -1533,12 +1534,8 @@ function realchess.move(pos, from_list, from_index, to_list, to_index, player)
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if pieceTo ~= "" or from_y < 6 or pawnWhiteMove ~= "" then
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return
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end
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-- store this double step in meta (needed for en passant check)
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local pawn_no = pieceFrom:sub(-1)
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local moves_raw = meta:get_string("moves_raw")
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local mrsplit = string.split(moves_raw, ";")
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local halfmove_no = #mrsplit + 1
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meta:set_int("doublePawnStepW"..pawn_no, halfmove_no)
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-- store the destination of this double step in meta (needed for en passant check)
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doublePawnStep = to_index
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else
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return
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end
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@ -1564,17 +1561,9 @@ function realchess.move(pos, from_list, from_index, to_list, to_index, player)
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can_capture = true
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else
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-- en passant
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local enPassantPiece = inv:get_stack(to_list, xy_to_index(to_x, from_y))
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local epp_meta = enPassantPiece:get_meta()
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local epp_name = enPassantPiece:get_name()
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if epp_name:find("black") and epp_name:sub(11,14) == "pawn" then
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local pawn_no = epp_name:sub(-1)
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local double_step_halfmove = meta:get_int("doublePawnStepB"..pawn_no)
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local current_halfmove = get_current_halfmove(meta)
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if double_step_halfmove ~= 0 and double_step_halfmove == current_halfmove then
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can_capture = true
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inv:set_stack(to_list, xy_to_index(to_x, from_y), "")
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end
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if can_capture_en_passant(meta, "black", xy_to_index(to_x, from_y)) then
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can_capture = true
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inv:set_stack(to_list, xy_to_index(to_x, from_y), "")
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end
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end
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if not can_capture then
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@ -1615,12 +1604,8 @@ function realchess.move(pos, from_list, from_index, to_list, to_index, player)
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if pieceTo ~= "" or from_y > 1 or pawnBlackMove ~= "" then
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return
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end
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-- store this double step in meta (needed for en passant check)
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local pawn_no = pieceFrom:sub(-1)
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local moves_raw = meta:get_string("moves_raw")
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local mrsplit = string.split(moves_raw, ";")
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local halfmove_no = #mrsplit + 1
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meta:set_int("doublePawnStepB"..pawn_no, halfmove_no)
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-- store the destination of this double step in meta (needed for en passant check)
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doublePawnStep = to_index
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else
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return
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end
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@ -1646,17 +1631,9 @@ function realchess.move(pos, from_list, from_index, to_list, to_index, player)
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can_capture = true
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else
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-- en passant
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local enPassantPiece = inv:get_stack(to_list, xy_to_index(to_x, from_y))
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local epp_meta = enPassantPiece:get_meta()
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local epp_name = enPassantPiece:get_name()
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if epp_name:find("white") and epp_name:sub(11,14) == "pawn" then
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local pawn_no = epp_name:sub(-1)
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local double_step_halfmove = meta:get_int("doublePawnStepW"..pawn_no)
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local current_halfmove = get_current_halfmove(meta)
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if double_step_halfmove ~= 0 and double_step_halfmove == current_halfmove then
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can_capture = true
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inv:set_stack(to_list, xy_to_index(to_x, from_y), "")
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end
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if can_capture_en_passant(meta, "white", xy_to_index(to_x, from_y)) then
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can_capture = true
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inv:set_stack(to_list, xy_to_index(to_x, from_y), "")
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end
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end
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if not can_capture then
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@ -1961,6 +1938,11 @@ function realchess.move(pos, from_list, from_index, to_list, to_index, player)
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if not promotion then
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realchess.update_state(meta, from_index, to_index, thisMove)
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end
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if doublePawnStep then
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meta:set_int("prevDoublePawnStepTo", doublePawnStep)
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else
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meta:set_int("prevDoublePawnStepTo", 0)
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end
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if meta:get_string("playerWhite") == "" then
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meta:set_string("playerWhite", playerWhite)
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