def __init__(self, value: str, board: Board):
"""Helper class to parse moves on a given board status
The base class from python-chess miss information like piece value, capture and checkmate
Used across the library to standardize move parsing and evaluation
Args:
value (str): The input move as string (SAN, LAN) or chess Move object
board (Board): The board status at the right moment, moves and notations depend on the context
"""
# Parse the string input if input value is not already a move object
if isinstance(value, str):
self.move = board.parse_san(value)
else:
self.move = value
# Convert to real SAN value to have a uniformed string version
self.move_str = board.san(self.move)
# Store board and future board
self.board_from = board.deepcopy()
self.board_to = board.deepcopy()
self.board_to.push_san(self.move_str)
# Evaluate move characteristics, capture, from and to square
self.trajectory = (self.move.from_square, self.move.to_square)
self.is_capture = board.is_capture(self.move)
self.from_piece = parse_piece(board.piece_at(self.from_square))
# Prepare features for display and evaluation
self.color = self.from_piece["color"].upper()
self.color_factor = 1 if self.color == "WHITE" else -1
self.name = self.from_piece["name"].upper()
# Capture rules
# Parse piece value of the capture
if self.is_capture:
try:
self.to_piece = parse_piece(board.piece_at(self.to_square))
self.value = self.to_piece["value"]
except:
self.to_piece = {}
self.value = 0
else:
self.to_piece = {}
self.value = 0
# Use SAN to determine is the move is a checkmate
# Modify move value if there is a checkmate
self.checkmate = "#" in self.move_str
if self.checkmate:
self.value = CHECKMATE_VALUE
# Promotion rules
# Parsing the SAN name to get promotion piece (With a check the san value is appended by +)
# Move value increased by the promotion piece minus the pawn value we exchanged
if "=" in self.move_str:
self.promoted_piece = PROMOTED_PIECES[self.move_str.split(
"=")[-1].replace("+", "").replace("#", "")]
bonus_promotion = PIECE_VALUES_BY_NAME[self.promoted_piece] - 1
self.value += bonus_promotion
