312 lines
7.9 KiB
Python
312 lines
7.9 KiB
Python
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import os
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import signal
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import sys
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import threading
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from collections import deque
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from typing import (
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Callable,
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ContextManager,
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Deque,
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Dict,
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Generator,
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Generic,
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List,
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Optional,
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TypeVar,
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Union,
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)
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from wcwidth import wcwidth
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__all__ = [
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"Event",
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"DummyContext",
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"get_cwidth",
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"suspend_to_background_supported",
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"is_conemu_ansi",
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"is_windows",
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"in_main_thread",
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"take_using_weights",
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"to_str",
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"to_int",
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"AnyFloat",
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"to_float",
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"is_dumb_terminal",
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]
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_Sender = TypeVar("_Sender", covariant=True)
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class Event(Generic[_Sender]):
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"""
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Simple event to which event handlers can be attached. For instance::
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class Cls:
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def __init__(self):
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# Define event. The first parameter is the sender.
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self.event = Event(self)
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obj = Cls()
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def handler(sender):
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pass
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# Add event handler by using the += operator.
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obj.event += handler
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# Fire event.
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obj.event()
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"""
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def __init__(
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self, sender: _Sender, handler: Optional[Callable[[_Sender], None]] = None
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):
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self.sender = sender
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self._handlers: List[Callable[[_Sender], None]] = []
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if handler is not None:
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self += handler
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def __call__(self) -> None:
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" Fire event. "
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for handler in self._handlers:
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handler(self.sender)
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def fire(self) -> None:
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" Alias for just calling the event. "
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self()
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def add_handler(self, handler: Callable[[_Sender], None]) -> None:
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"""
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Add another handler to this callback.
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(Handler should be a callable that takes exactly one parameter: the
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sender object.)
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"""
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# Add to list of event handlers.
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self._handlers.append(handler)
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def remove_handler(self, handler: Callable[[_Sender], None]) -> None:
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"""
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Remove a handler from this callback.
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"""
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if handler in self._handlers:
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self._handlers.remove(handler)
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def __iadd__(self, handler: Callable[[_Sender], None]) -> "Event[_Sender]":
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"""
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`event += handler` notation for adding a handler.
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"""
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self.add_handler(handler)
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return self
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def __isub__(self, handler: Callable[[_Sender], None]) -> "Event[_Sender]":
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"""
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`event -= handler` notation for removing a handler.
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"""
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self.remove_handler(handler)
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return self
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class DummyContext(ContextManager[None]):
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"""
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(contextlib.nested is not available on Py3)
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"""
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def __enter__(self) -> None:
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pass
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def __exit__(self, *a: object) -> None:
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pass
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class _CharSizesCache(Dict[str, int]):
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"""
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Cache for wcwidth sizes.
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"""
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LONG_STRING_MIN_LEN = 64 # Minimum string length for considering it long.
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MAX_LONG_STRINGS = 16 # Maximum number of long strings to remember.
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def __init__(self) -> None:
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super().__init__()
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# Keep track of the "long" strings in this cache.
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self._long_strings: Deque[str] = deque()
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def __missing__(self, string: str) -> int:
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# Note: We use the `max(0, ...` because some non printable control
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# characters, like e.g. Ctrl-underscore get a -1 wcwidth value.
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# It can be possible that these characters end up in the input
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# text.
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result: int
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if len(string) == 1:
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result = max(0, wcwidth(string))
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else:
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result = sum(self[c] for c in string)
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# Store in cache.
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self[string] = result
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# Rotate long strings.
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# (It's hard to tell what we can consider short...)
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if len(string) > self.LONG_STRING_MIN_LEN:
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long_strings = self._long_strings
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long_strings.append(string)
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if len(long_strings) > self.MAX_LONG_STRINGS:
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key_to_remove = long_strings.popleft()
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if key_to_remove in self:
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del self[key_to_remove]
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return result
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_CHAR_SIZES_CACHE = _CharSizesCache()
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def get_cwidth(string: str) -> int:
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"""
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Return width of a string. Wrapper around ``wcwidth``.
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"""
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return _CHAR_SIZES_CACHE[string]
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def suspend_to_background_supported() -> bool:
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"""
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Returns `True` when the Python implementation supports
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suspend-to-background. This is typically `False' on Windows systems.
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"""
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return hasattr(signal, "SIGTSTP")
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def is_windows() -> bool:
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"""
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True when we are using Windows.
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"""
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return sys.platform.startswith("win") # E.g. 'win32', not 'darwin' or 'linux2'
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def is_windows_vt100_supported() -> bool:
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"""
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True when we are using Windows, but VT100 escape sequences are supported.
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"""
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# Import needs to be inline. Windows libraries are not always available.
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from prompt_toolkit.output.windows10 import is_win_vt100_enabled
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return is_windows() and is_win_vt100_enabled()
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def is_conemu_ansi() -> bool:
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"""
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True when the ConEmu Windows console is used.
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"""
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return is_windows() and os.environ.get("ConEmuANSI", "OFF") == "ON"
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def in_main_thread() -> bool:
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"""
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True when the current thread is the main thread.
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"""
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return threading.current_thread().__class__.__name__ == "_MainThread"
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def get_term_environment_variable() -> str:
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" Return the $TERM environment variable. "
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return os.environ.get("TERM", "")
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_T = TypeVar("_T")
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def take_using_weights(
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items: List[_T], weights: List[int]
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) -> Generator[_T, None, None]:
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"""
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Generator that keeps yielding items from the items list, in proportion to
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their weight. For instance::
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# Getting the first 70 items from this generator should have yielded 10
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# times A, 20 times B and 40 times C, all distributed equally..
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take_using_weights(['A', 'B', 'C'], [5, 10, 20])
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:param items: List of items to take from.
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:param weights: Integers representing the weight. (Numbers have to be
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integers, not floats.)
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"""
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assert len(items) == len(weights)
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assert len(items) > 0
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# Remove items with zero-weight.
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items2 = []
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weights2 = []
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for item, w in zip(items, weights):
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if w > 0:
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items2.append(item)
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weights2.append(w)
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items = items2
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weights = weights2
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# Make sure that we have some items left.
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if not items:
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raise ValueError("Did't got any items with a positive weight.")
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#
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already_taken = [0 for i in items]
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item_count = len(items)
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max_weight = max(weights)
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i = 0
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while True:
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# Each iteration of this loop, we fill up until by (total_weight/max_weight).
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adding = True
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while adding:
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adding = False
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for item_i, item, weight in zip(range(item_count), items, weights):
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if already_taken[item_i] < i * weight / float(max_weight):
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yield item
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already_taken[item_i] += 1
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adding = True
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i += 1
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def to_str(value: Union[Callable[[], str], str]) -> str:
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" Turn callable or string into string. "
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if callable(value):
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return to_str(value())
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else:
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return str(value)
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def to_int(value: Union[Callable[[], int], int]) -> int:
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" Turn callable or int into int. "
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if callable(value):
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return to_int(value())
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else:
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return int(value)
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AnyFloat = Union[Callable[[], float], float]
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def to_float(value: AnyFloat) -> float:
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" Turn callable or float into float. "
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if callable(value):
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return to_float(value())
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else:
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return float(value)
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def is_dumb_terminal(term: Optional[str] = None) -> bool:
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"""
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True if this terminal type is considered "dumb".
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If so, we should fall back to the simplest possible form of line editing,
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without cursor positioning and color support.
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"""
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if term is None:
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term = os.environ.get("TERM", "")
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return term in ["dumb", "unknown"]
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