233 lines
7 KiB
Python
233 lines
7 KiB
Python
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"""
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Implementations for the history of a `Buffer`.
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NOTE: Notice that there is no `DynamicHistory`. This doesn't work well, because
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the `Buffer` needs to be able to attach an event handler to the event
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when a history entry is loaded. This loading can be done asynchronously
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and making the history swappable would probably break this.
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"""
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import datetime
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import os
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from abc import ABCMeta, abstractmethod
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from threading import Thread
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from typing import Callable, Iterable, List, Optional
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__all__ = [
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"History",
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"ThreadedHistory",
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"DummyHistory",
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"FileHistory",
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"InMemoryHistory",
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]
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class History(metaclass=ABCMeta):
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"""
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Base ``History`` class.
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This also includes abstract methods for loading/storing history.
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"""
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def __init__(self) -> None:
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# In memory storage for strings.
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self._loaded = False
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self._loaded_strings: List[str] = []
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#
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# Methods expected by `Buffer`.
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#
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def load(self, item_loaded_callback: Callable[[str], None]) -> None:
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"""
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Load the history and call the callback for every entry in the history.
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XXX: The callback can be called from another thread, which happens in
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case of `ThreadedHistory`.
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We can't assume that an asyncio event loop is running, and
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schedule the insertion into the `Buffer` using the event loop.
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The reason is that the creation of the :class:`.History` object as
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well as the start of the loading happens *before*
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`Application.run()` is called, and it can continue even after
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`Application.run()` terminates. (Which is useful to have a
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complete history during the next prompt.)
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Calling `get_event_loop()` right here is also not guaranteed to
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return the same event loop which is used in `Application.run`,
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because a new event loop can be created during the `run`. This is
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useful in Python REPLs, where we want to use one event loop for
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the prompt, and have another one active during the `eval` of the
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commands. (Otherwise, the user can schedule a while/true loop and
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freeze the UI.)
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"""
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if self._loaded:
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for item in self._loaded_strings[::-1]:
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item_loaded_callback(item)
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return
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try:
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for item in self.load_history_strings():
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self._loaded_strings.insert(0, item)
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item_loaded_callback(item)
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finally:
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self._loaded = True
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def get_strings(self) -> List[str]:
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"""
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Get the strings from the history that are loaded so far.
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"""
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return self._loaded_strings
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def append_string(self, string: str) -> None:
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" Add string to the history. "
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self._loaded_strings.append(string)
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self.store_string(string)
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#
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# Implementation for specific backends.
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#
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@abstractmethod
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def load_history_strings(self) -> Iterable[str]:
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"""
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This should be a generator that yields `str` instances.
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It should yield the most recent items first, because they are the most
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important. (The history can already be used, even when it's only
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partially loaded.)
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"""
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while False:
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yield
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@abstractmethod
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def store_string(self, string: str) -> None:
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"""
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Store the string in persistent storage.
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"""
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class ThreadedHistory(History):
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"""
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Wrapper that runs the `load_history_strings` generator in a thread.
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Use this to increase the start-up time of prompt_toolkit applications.
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History entries are available as soon as they are loaded. We don't have to
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wait for everything to be loaded.
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"""
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def __init__(self, history: History) -> None:
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self.history = history
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self._load_thread: Optional[Thread] = None
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self._item_loaded_callbacks: List[Callable[[str], None]] = []
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super().__init__()
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def load(self, item_loaded_callback: Callable[[str], None]) -> None:
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self._item_loaded_callbacks.append(item_loaded_callback)
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# Start the load thread, if we don't have a thread yet.
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if not self._load_thread:
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def call_all_callbacks(item: str) -> None:
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for cb in self._item_loaded_callbacks:
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cb(item)
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self._load_thread = Thread(
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target=self.history.load, args=(call_all_callbacks,)
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)
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self._load_thread.daemon = True
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self._load_thread.start()
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def get_strings(self) -> List[str]:
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return self.history.get_strings()
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def append_string(self, string: str) -> None:
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self.history.append_string(string)
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# All of the following are proxied to `self.history`.
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def load_history_strings(self) -> Iterable[str]:
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return self.history.load_history_strings()
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def store_string(self, string: str) -> None:
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self.history.store_string(string)
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def __repr__(self) -> str:
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return "ThreadedHistory(%r)" % (self.history,)
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class InMemoryHistory(History):
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"""
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:class:`.History` class that keeps a list of all strings in memory.
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"""
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def load_history_strings(self) -> Iterable[str]:
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return []
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def store_string(self, string: str) -> None:
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pass
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class DummyHistory(History):
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"""
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:class:`.History` object that doesn't remember anything.
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"""
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def load_history_strings(self) -> Iterable[str]:
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return []
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def store_string(self, string: str) -> None:
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pass
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def append_string(self, string: str) -> None:
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# Don't remember this.
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pass
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class FileHistory(History):
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"""
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:class:`.History` class that stores all strings in a file.
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"""
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def __init__(self, filename: str) -> None:
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self.filename = filename
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super(FileHistory, self).__init__()
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def load_history_strings(self) -> Iterable[str]:
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strings: List[str] = []
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lines: List[str] = []
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def add() -> None:
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if lines:
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# Join and drop trailing newline.
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string = "".join(lines)[:-1]
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strings.append(string)
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if os.path.exists(self.filename):
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with open(self.filename, "rb") as f:
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for line_bytes in f:
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line = line_bytes.decode("utf-8")
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if line.startswith("+"):
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lines.append(line[1:])
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else:
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add()
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lines = []
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add()
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# Reverse the order, because newest items have to go first.
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return reversed(strings)
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def store_string(self, string: str) -> None:
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# Save to file.
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with open(self.filename, "ab") as f:
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def write(t: str) -> None:
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f.write(t.encode("utf-8"))
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write("\n# %s\n" % datetime.datetime.now())
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for line in string.split("\n"):
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write("+%s\n" % line)
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