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# Natural Language Toolkit: Text Trees
#
# Copyright (C) 2001-2023 NLTK Project
# Author: Edward Loper <[email protected]>
# Steven Bird <[email protected]>
# Peter Ljunglöf <[email protected]>
# Tom Aarsen <>
# URL: <https://www.nltk.org/>
# For license information, see LICENSE.TXT
import re
from nltk.tree.tree import Tree
######################################################################
## Parsing
######################################################################
def bracket_parse(s):
"""
Use Tree.read(s, remove_empty_top_bracketing=True) instead.
"""
raise NameError("Use Tree.read(s, remove_empty_top_bracketing=True) instead.")
def sinica_parse(s):
"""
Parse a Sinica Treebank string and return a tree. Trees are represented as nested brackettings,
as shown in the following example (X represents a Chinese character):
S(goal:NP(Head:Nep:XX)|theme:NP(Head:Nhaa:X)|quantity:Dab:X|Head:VL2:X)#0(PERIODCATEGORY)
:return: A tree corresponding to the string representation.
:rtype: Tree
:param s: The string to be converted
:type s: str
"""
tokens = re.split(r"([()| ])", s)
for i in range(len(tokens)):
if tokens[i] == "(":
tokens[i - 1], tokens[i] = (
tokens[i],
tokens[i - 1],
) # pull nonterminal inside parens
elif ":" in tokens[i]:
fields = tokens[i].split(":")
if len(fields) == 2: # non-terminal
tokens[i] = fields[1]
else:
tokens[i] = "(" + fields[-2] + " " + fields[-1] + ")"
elif tokens[i] == "|":
tokens[i] = ""
treebank_string = " ".join(tokens)
return Tree.fromstring(treebank_string, remove_empty_top_bracketing=True)
# s = re.sub(r'^#[^\s]*\s', '', s) # remove leading identifier
# s = re.sub(r'\w+:', '', s) # remove role tags
# return s
__all__ = [
"bracket_parse",
"sinica_parse",
]
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