def __init__(self):
super(Game, self).__init__()
self.headers = collections.OrderedDict()
self.headers["Event"] = "?"
self.headers["Site"] = "?"
self.headers["Date"] = "????.??.??"
self.headers["Round"] = "?"
self.headers["White"] = "?"
self.headers["Black"] = "?"
self.headers["Result"] = "*"
self.errors = []
def scan_headers(handle):
"""
Scan a PGN file opened in text mode for game offsets and headers.
Yields a tuple for each game. The first element is the offset. The second
element is an ordered dictionary of game headers.
Since actually parsing many games from a big file is relatively expensive,
this is a better way to look only for specific games and seek and parse
them later.
This example scans for the first game with Kasparov as the white player.
>>> pgn = open("mega.pgn")
>>> for offset, headers in chess.pgn.scan_headers(pgn):
... if "Kasparov" in headers["White"]:
... kasparov_offset = offset
... break
Then it can later be seeked an parsed.
>>> pgn.seek(kasparov_offset)
>>> game = chess.pgn.read_game(pgn)
This also works nicely with generators, scanning lazily only when the next
offset is required.
>>> white_win_offsets = (offset for offset, headers in chess.pgn.scan_headers(pgn)
... if headers["Result"] == "1-0")
>>> first_white_win = next(white_win_offsets)
>>> second_white_win = next(white_win_offsets)
:warning: Be careful when seeking a game in the file while more offsets are
being generated.
"""
in_comment = False
game_headers = None
game_pos = None
last_pos = handle.tell()
line = handle.readline()
while line:
# Skip single line comments.
if line.startswith("%"):
last_pos = handle.tell()
line = handle.readline()
continue
# Reading a header tag. Parse it and add it to the current headers.
if not in_comment and line.startswith("["):
tag_match = TAG_REGEX.match(line)
if tag_match:
if game_pos is None:
game_headers = collections.OrderedDict()
game_headers["Event"] = "?"
game_headers["Site"] = "?"
game_headers["Date"] = "????.??.??"
game_headers["Round"] = "?"
game_headers["White"] = "?"
game_headers["Black"] = "?"
game_headers["Result"] = "*"
game_pos = last_pos
game_headers[tag_match.group(1)] = tag_match.group(2)
last_pos = handle.tell()
line = handle.readline()
continue
# Reading movetext. Update parser state in_comment in order to skip
# comments that look like header tags.
if (not in_comment and "{" in line) or (in_comment and "}" in line):
in_comment = line.rfind("{") > line.rfind("}")
# Reading movetext. If there were headers, previously, those are now
# complete and can be yielded.
if game_pos is not None:
yield game_pos, game_headers
game_pos = None
last_pos = handle.tell()
line = handle.readline()
# Yield the headers of the last game.
if game_pos is not None:
yield game_pos, game_headers
