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#!/usr/bin/python
import argparse
from nltk.parse.generate import generate
from nltk import CFG
from os.path import exists
from sys import exit as sys_exit
DEMO_GRAMMAR = """
S -> 'import ' ImportList ';' | 'static import ' ImportList ';'
ImportList -> Import | ImportBindings | Import ', ' ImportList
Import -> ModuleFullyQualifiedName | ModuleAliasIdentifier ' = ' ModuleFullyQualifiedName
ImportBindings -> Import ' : ' ImportBindList
ImportBindList -> ImportBind | ImportBind ', ' ImportBindList
ImportBind -> Identifier | Identifier ' = ' Identifier
ModuleAliasIdentifier -> Identifier
Packages -> PackageName | Packages '.' PackageName
ModuleFullyQualifiedName -> ModuleName | Packages '.' ModuleName
PackageName -> Identifier
ModuleName -> Identifier
Identifier -> 'x'
"""
def valid_file(arg_parser, *args):
"""
checks if on of the provided paths is a file
Parameters
----------------------------------------------------------------------------
:param arg_parser:
argument parser object that is called if no file is found
:param args: list< str >
a list of file path that is going to be checked
:return: str
----------------------------------------------------------------------------
path to an existing file
"""
arg = None
found_flag = False
for arg in args:
if exists(arg):
found_flag = True
break
if not found_flag:
arg_parser.error("file(s) do not exist: %s" % args)
return arg
def main(args):
grammar_string = DEMO_GRAMMAR
if args.input_file_path:
with open(args.input_file_path, 'r') as f:
grammar_string = f.read()
grammar = CFG.fromstring(grammar_string)
for sentence in generate(grammar, depth=args.depth):
print(''.join(sentence))
return 0
if __name__ == "__main__":
arg_parser = argparse.ArgumentParser()
arg_parser.add_argument(
'-i', '--input_file_path',
metavar='<path>',
type=lambda x: valid_file(arg_parser, x),
help="Path to the grammar file",
required=False
)
arg_parser.add_argument(
'-d', '--depth',
metavar='<nr>',
type=int,
default=9,
help='Max depth of grammar tree.'
)
FLAGS, unparsed = arg_parser.parse_known_args()
sys_exit(main(FLAGS))
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