sgf_wrapper.py

# Copyright 2018 Google LLC
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#      http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

'''
Code to extract a series of positions + their next moves from an SGF.

Most of the complexity here is dealing with two features of SGF:
- Stones can be added via "play move" or "add move", the latter being used
  to configure L+D puzzles, but also for initial handicap placement.
- Plays don't necessarily alternate colors; they can be repeated B or W moves
  This feature is used to handle free handicap placement.
'''
import numpy as np
import itertools

import coords
import go
from go import Position, PositionWithContext
import utils
import sgf

SGF_TEMPLATE = '''(;GM[1]FF[4]CA[UTF-8]AP[Minigo_sgfgenerator]RU[{ruleset}]
SZ[{boardsize}]KM[{komi}]PW[{white_name}]PB[{black_name}]RE[{result}]
{game_moves})'''

PROGRAM_IDENTIFIER = "Minigo"


def translate_sgf_move(player_move, comment):
    if player_move.color not in (go.BLACK, go.WHITE):
        raise ValueError("Can't translate color %s to sgf" % player_move.color)
    c = coords.to_sgf(player_move.move)
    color = 'B' if player_move.color == go.BLACK else 'W'
    if comment is not None:
        comment = comment.replace(']', r'\]')
        comment_node = "C[{}]".format(comment)
    else:
        comment_node = ""
    return ";{color}[{coords}]{comment_node}".format(
        color=color, coords=c, comment_node=comment_node)


def make_sgf(
    move_history,
    result_string,
    ruleset="Chinese",
    komi=7.5,
    white_name=PROGRAM_IDENTIFIER,
    black_name=PROGRAM_IDENTIFIER,
    comments=[]
):
    '''Turn a game into SGF.

    Doesn't handle handicap games or positions with incomplete history.

    Args:
        move_history: iterable of PlayerMoves
        result_string: "B+R", "W+0.5", etc.
        comments: iterable of string/None. Will be zipped with move_history.
    '''
    boardsize = go.N
    game_moves = ''.join(translate_sgf_move(*z)
                         for z in itertools.zip_longest(move_history, comments))
    result = result_string
    return SGF_TEMPLATE.format(**locals())


def sgf_prop(value_list):
    'Converts raw sgf library output to sensible value'
    if value_list is None:
        return None
    if len(value_list) == 1:
        return value_list[0]
    else:
        return value_list


def sgf_prop_get(props, key, default):
    return sgf_prop(props.get(key, default))


def handle_node(pos, node):
    'A node can either add B+W stones, play as B, or play as W.'
    props = node.properties
    black_stones_added = [coords.from_sgf(
        c) for c in props.get('AB', [])]
    white_stones_added = [coords.from_sgf(
        c) for c in props.get('AW', [])]
    if black_stones_added or white_stones_added:
        return add_stones(pos, black_stones_added, white_stones_added)
    # If B/W props are not present, then there is no move. But if it is present and equal to the empty string, then the move was a pass.
    elif 'B' in props:
        black_move = coords.from_sgf(props.get('B', [''])[0])
        return pos.play_move(black_move, color=go.BLACK)
    elif 'W' in props:
        white_move = coords.from_sgf(props.get('W', [''])[0])
        return pos.play_move(white_move, color=go.WHITE)
    else:
        return pos


def add_stones(pos, black_stones_added, white_stones_added):
    working_board = np.copy(pos.board)
    go.place_stones(working_board, go.BLACK, black_stones_added)
    go.place_stones(working_board, go.WHITE, white_stones_added)
    new_position = Position(board=working_board, n=pos.n, komi=pos.komi,
                            caps=pos.caps, ko=pos.ko, recent=pos.recent, to_play=pos.to_play)
    return new_position


def get_next_move(node):
    props = node.next.properties
    if 'W' in props:
        return coords.from_sgf(props['W'][0])
    else:
        return coords.from_sgf(props['B'][0])


def maybe_correct_next(pos, next_node):
    if (('B' in next_node.properties and not pos.to_play == go.BLACK) or
            ('W' in next_node.properties and not pos.to_play == go.WHITE)):
        pos.flip_playerturn(mutate=True)


def get_sgf_root_node(sgf_contents):
    collection = sgf.parse(sgf_contents)
    game = collection.children[0]
    return game.root


def replay_sgf(sgf_contents):
    '''
    Wrapper for sgf files, returning go.PositionWithContext instances.

    It does NOT return the very final position, as there is no follow up.
    To get the final position, call pwc.position.play_move(pwc.next_move)
    on the last PositionWithContext returned.

    Example usage:
    with open(filename) as f:
        for position_w_context in replay_sgf(f.read()):
            print(position_w_context.position)
    '''
    root_node = get_sgf_root_node(sgf_contents)
    props = root_node.properties
    assert int(sgf_prop(props.get('GM', ['1']))) == 1, "Not a Go SGF!"

    komi = 0
    if props.get('KM') is not None:
        komi = float(sgf_prop(props.get('KM')))
    result = utils.parse_game_result(sgf_prop(props.get('RE', '')))

    pos = Position(komi=komi)
    current_node = root_node
    while pos is not None and current_node.next is not None:
        pos = handle_node(pos, current_node)
        maybe_correct_next(pos, current_node.next)
        next_move = get_next_move(current_node)
        yield PositionWithContext(pos, next_move, result)
        current_node = current_node.next


def replay_sgf_file(sgf_file):
    with open(sgf_file) as f:
        for pwc in replay_sgf(f.read()):
            yield pwc