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sgf.py

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""" SGF grammar: FF4 allows subtree
https://www.red-bean.com/sgf/sgf4.html
Collection = GameTree+ # alternatives
GameTree = "(" Sequence GameTree* ")" # a common seq, followed by 0 or more variations
Sequence = Node+
Node = ";" Property*
GameTree is a tree: multiple variations may not converge
Terminology:
Node -> Move
"""
# map from numerical coordinates to letters used by SGF
SGF_POS = " abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"
class Collection:
def __init__(self, parser=None):
self.parser = parser
if parser:
self.setup()
self.children = []
def setup(self):
self.parser.start_gametree = self.my_start_gametree
def my_start_gametree(self):
self.children.append(GameTree(self, self.parser))
def __len__(self):
return len(self.children)
def __getitem__(self, k):
return self.children[k]
def __iter__(self):
return iter(self.children)
def output(self, f):
for child in self.children:
child.output(f)
class GameTree(object):
def __init__(self, parent, parser=None):
self.parent = parent
self.parser = parser
if parser:
self.setup()
self.nodes = []
self.children = []
def setup(self):
self.parser.start_gametree = self.my_start_gametree
self.parser.end_gametree = self.my_end_gametree
self.parser.start_node = self.my_start_node
def my_start_node(self):
if len(self.nodes) > 0:
previous = self.nodes[-1]
elif self.parent.__class__ == GameTree:
previous = self.parent.nodes[-1]
else:
previous = None
node = Node(self, previous, self.parser)
if len(self.nodes) == 0:
node.first = True
if self.parent.__class__ == GameTree:
if len(previous.variations) > 0:
previous.variations[-1].next_variation = node
node.previous_variation = previous.variations[-1]
previous.variations.append(node)
else:
if len(self.parent.children) > 1:
node.previous_variation = self.parent.children[-2].nodes[0]
self.parent.children[-2].nodes[0].next_variation = node
self.nodes.append(node)
def my_start_gametree(self):
self.children.append(GameTree(self, self.parser))
def my_end_gametree(self):
self.parent.setup()
def __iter__(self):
return NodeIterator(self.nodes[0])
@property
def root(self):
# @@@ technically for this to be root, self.parent must be a Collection
return self.nodes[0]
@property
def rest(self):
class _:
def __iter__(_):
return NodeIterator(self.nodes[0].next)
if self.nodes[0].next:
return _()
else:
return None
def output(self, f):
f.write("(")
for node in self.nodes:
node.output(f)
for child in self.children:
child.output(f)
f.write(")")
class Node:
def __init__(self, parent, previous, parser=None):
self.parent = parent
self.previous = previous
self.parser = parser
if parser:
self.setup()
self.properties = {}
self.next = None
self.previous_variation = None
self.next_variation = None
self.first = False
self.variations = []
if previous and not previous.next:
previous.next = self
def setup(self):
self.parser.start_property = self.my_start_property
self.parser.add_prop_value = self.my_add_prop_value
self.parser.end_property = self.my_end_property
self.parser.end_node = self.my_end_node
def my_start_property(self, identifier):
# @@@ check for duplicates
self.current_property = identifier
self.current_prop_value = []
def my_add_prop_value(self, value):
self.current_prop_value.append(value)
def my_end_property(self):
self.properties[self.current_property] = self.current_prop_value
def my_end_node(self):
self.parent.setup()
def output(self, f):
f.write(";")
for key, values in sorted(self.properties.items()):
f.write(key)
for value in values:
if "\\" in value:
value = "\\\\".join(value.split("\\"))
if "]" in value:
value = "\\]".join(value.split("]"))
f.write("[%s]" % value)
class NodeIterator:
def __init__(self, start_node):
self.node = start_node
def __next__(self):
if self.node:
node = self.node
self.node = node.next
return node
else:
raise StopIteration()
next = __next__ # Python 2
class ParseException(Exception):
pass
class Parser:
def parse(self, sgf_string):
def whitespace(ch):
return ch in " \t\r\n"
def ucletter(ch):
return ch in "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
state = 0
for ch in sgf_string:
if state == 0:
if whitespace(ch):
state = 0
elif ch == '(':
self.start_gametree()
state = 1
else:
state = 0 # ignore everything up to first (
# raise ParseException(ch, state)
elif state == 1:
if whitespace(ch):
state = 1
elif ch == ";":
self.start_node()
state = 2
else:
raise ParseException(ch, state)
elif state == 2:
if whitespace(ch):
state = 2
elif ucletter(ch):
prop_ident = ch
state = 3
elif ch == ";":
self.end_node()
self.start_node()
state = 2
elif ch == "(":
self.end_node()
self.start_gametree()
state = 1
elif ch == ")":
self.end_node()
self.end_gametree()
state = 4
else:
raise ParseException(ch, state)
elif state == 3:
if ucletter(ch):
prop_ident = prop_ident + ch
state = 3
elif ch == "[":
self.start_property(prop_ident)
prop_value = ""
state = 5
else:
raise ParseException(ch, state)
elif state == 4:
if ch == ")":
self.end_gametree()
state = 4
elif whitespace(ch):
state = 4
elif ch == "(":
self.start_gametree()
state = 1
else:
raise ParseException(ch, state)
elif state == 5:
if ch == "\\":
state = 6
elif ch == "]":
self.add_prop_value(prop_value)
state = 7
else:
prop_value = prop_value + ch
elif state == 6:
prop_value = prop_value + ch
state = 5
elif state == 7:
if whitespace(ch):
state = 7
elif ch == "[":
prop_value = ""
state = 5
elif ch == ";":
self.end_property()
self.end_node()
self.start_node()
state = 2
elif ucletter(ch):
self.end_property()
prop_ident = ch
state = 3
elif ch == ")":
self.end_property()
self.end_node()
self.end_gametree()
state = 4
elif ch == "(":
self.end_property()
self.end_node()
self.start_gametree()
state = 1
else:
raise ParseException(ch, state)
else:
# only a programming error could get here
raise Exception(state) # pragma: no cover
if state != 4:
raise ParseException(ch, state)
def parse(sgf_string) -> Collection:
parser = Parser()
collection = Collection(parser)
parser.parse(sgf_string)
return collection
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