217 lines
6.9 KiB
Python
217 lines
6.9 KiB
Python
"""
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Minimal and functional version of CPython's argparse module.
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"""
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import sys
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from ucollections import namedtuple
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class _ArgError(BaseException):
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pass
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class _Arg:
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def __init__(self, names, dest, action, nargs, const, default, help):
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self.names = names
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self.dest = dest
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self.action = action
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self.nargs = nargs
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self.const = const
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self.default = default
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self.help = help
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def parse(self, optname, args):
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# parse args for this arg
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if self.action == "store":
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if self.nargs is None:
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if args:
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return args.pop(0)
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else:
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raise _ArgError("expecting value for %s" % optname)
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elif self.nargs == "?":
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if args:
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return args.pop(0)
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else:
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return self.default
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else:
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if self.nargs == "*":
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n = -1
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elif self.nargs == "+":
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if not args:
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raise _ArgError("expecting value for %s" % optname)
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n = -1
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else:
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n = int(self.nargs)
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ret = []
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stop_at_opt = True
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while args and n != 0:
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if stop_at_opt and args[0].startswith("-") and args[0] != "-":
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if args[0] == "--":
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stop_at_opt = False
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args.pop(0)
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else:
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break
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else:
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ret.append(args.pop(0))
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n -= 1
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if n > 0:
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raise _ArgError("expecting value for %s" % optname)
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return ret
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elif self.action == "store_const":
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return self.const
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else:
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assert False
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def _dest_from_optnames(opt_names):
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dest = opt_names[0]
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for name in opt_names:
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if name.startswith("--"):
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dest = name
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break
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return dest.lstrip("-").replace("-", "_")
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class ArgumentParser:
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def __init__(self, *, description=""):
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self.description = description
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self.opt = []
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self.pos = []
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def add_argument(self, *args, **kwargs):
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action = kwargs.get("action", "store")
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if action == "store_true":
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action = "store_const"
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const = True
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default = kwargs.get("default", False)
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elif action == "store_false":
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action = "store_const"
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const = False
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default = kwargs.get("default", True)
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else:
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const = kwargs.get("const", None)
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default = kwargs.get("default", None)
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if args and args[0].startswith("-"):
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list = self.opt
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dest = kwargs.get("dest")
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if dest is None:
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dest = _dest_from_optnames(args)
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else:
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list = self.pos
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dest = kwargs.get("dest")
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if dest is None:
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dest = args[0]
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if not args:
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args = [dest]
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list.append(
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_Arg(args, dest, action, kwargs.get("nargs", None),
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const, default, kwargs.get("help", "")))
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def usage(self, full):
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# print short usage
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print("usage: %s [-h]" % sys.argv[0], end="")
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def render_arg(arg):
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if arg.action == "store":
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if arg.nargs is None:
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return " %s" % arg.dest
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if isinstance(arg.nargs, int):
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return " %s(x%d)" % (arg.dest, arg.nargs)
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else:
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return " %s%s" % (arg.dest, arg.nargs)
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else:
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return ""
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for opt in self.opt:
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print(" [%s%s]" % (', '.join(opt.names), render_arg(opt)), end="")
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for pos in self.pos:
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print(render_arg(pos), end="")
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print()
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if not full:
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return
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# print full information
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print()
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if self.description:
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print(self.description)
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if self.pos:
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print("\npositional args:")
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for pos in self.pos:
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print(" %-16s%s" % (pos.names[0], pos.help))
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print("\noptional args:")
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print(" -h, --help show this message and exit")
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for opt in self.opt:
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print(" %-16s%s" % (', '.join(opt.names) + render_arg(opt), opt.help))
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def parse_args(self, args=None):
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return self._parse_args_impl(args, False)
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def parse_known_args(self, args=None):
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return self._parse_args_impl(args, True)
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def _parse_args_impl(self, args, return_unknown):
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if args is None:
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args = sys.argv[1:]
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else:
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args = args[:]
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try:
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return self._parse_args(args, return_unknown)
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except _ArgError as e:
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self.usage(False)
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print("error:", e)
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sys.exit(2)
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def _parse_args(self, args, return_unknown):
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# add optional args with defaults
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arg_dest = []
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arg_vals = []
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for opt in self.opt:
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arg_dest.append(opt.dest)
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arg_vals.append(opt.default)
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# deal with unknown arguments, if needed
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unknown = []
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def consume_unknown():
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while args and not args[0].startswith("-"):
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unknown.append(args.pop(0))
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# parse all args
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parsed_pos = False
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while args or not parsed_pos:
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if args and args[0].startswith("-") and args[0] != "-" and args[0] != "--":
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# optional arg
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a = args.pop(0)
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if a in ("-h", "--help"):
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self.usage(True)
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sys.exit(0)
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found = False
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for i, opt in enumerate(self.opt):
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if a in opt.names:
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arg_vals[i] = opt.parse(a, args)
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found = True
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break
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if not found:
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if return_unknown:
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unknown.append(a)
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consume_unknown()
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else:
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raise _ArgError("unknown option %s" % a)
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else:
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# positional arg
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if parsed_pos:
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if return_unknown:
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unknown = unknown + args
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break
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else:
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raise _ArgError("extra args: %s" % " ".join(args))
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for pos in self.pos:
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arg_dest.append(pos.dest)
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arg_vals.append(pos.parse(pos.names[0], args))
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parsed_pos = True
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if return_unknown:
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consume_unknown()
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# build and return named tuple with arg values
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values = namedtuple("args", arg_dest)(*arg_vals)
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return (values, unknown) if return_unknown else values
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