417 lines
14 KiB
Python
417 lines
14 KiB
Python
"""
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Wrapper for the layout.
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"""
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from typing import Dict, Generator, Iterable, List, Optional, Union
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from prompt_toolkit.buffer import Buffer
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from .containers import (
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AnyContainer,
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ConditionalContainer,
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Container,
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Window,
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to_container,
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)
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from .controls import BufferControl, SearchBufferControl, UIControl
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__all__ = [
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"Layout",
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"InvalidLayoutError",
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"walk",
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]
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FocusableElement = Union[str, Buffer, UIControl, AnyContainer]
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class Layout:
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"""
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The layout for a prompt_toolkit
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:class:`~prompt_toolkit.application.Application`.
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This also keeps track of which user control is focused.
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:param container: The "root" container for the layout.
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:param focused_element: element to be focused initially. (Can be anything
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the `focus` function accepts.)
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"""
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def __init__(
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self,
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container: AnyContainer,
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focused_element: Optional[FocusableElement] = None,
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) -> None:
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self.container = to_container(container)
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self._stack: List[Window] = []
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# Map search BufferControl back to the original BufferControl.
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# This is used to keep track of when exactly we are searching, and for
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# applying the search.
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# When a link exists in this dictionary, that means the search is
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# currently active.
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# Map: search_buffer_control -> original buffer control.
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self.search_links: Dict[SearchBufferControl, BufferControl] = {}
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# Mapping that maps the children in the layout to their parent.
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# This relationship is calculated dynamically, each time when the UI
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# is rendered. (UI elements have only references to their children.)
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self._child_to_parent: Dict[Container, Container] = {}
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if focused_element is None:
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try:
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self._stack.append(next(self.find_all_windows()))
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except StopIteration as e:
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raise InvalidLayoutError(
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"Invalid layout. The layout does not contain any Window object."
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) from e
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else:
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self.focus(focused_element)
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# List of visible windows.
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self.visible_windows: List[Window] = [] # List of `Window` objects.
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def __repr__(self) -> str:
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return "Layout(%r, current_window=%r)" % (self.container, self.current_window)
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def find_all_windows(self) -> Generator[Window, None, None]:
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"""
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Find all the :class:`.UIControl` objects in this layout.
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"""
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for item in self.walk():
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if isinstance(item, Window):
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yield item
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def find_all_controls(self) -> Iterable[UIControl]:
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for container in self.find_all_windows():
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yield container.content
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def focus(self, value: FocusableElement) -> None:
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"""
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Focus the given UI element.
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`value` can be either:
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- a :class:`.UIControl`
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- a :class:`.Buffer` instance or the name of a :class:`.Buffer`
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- a :class:`.Window`
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- Any container object. In this case we will focus the :class:`.Window`
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from this container that was focused most recent, or the very first
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focusable :class:`.Window` of the container.
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"""
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# BufferControl by buffer name.
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if isinstance(value, str):
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for control in self.find_all_controls():
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if isinstance(control, BufferControl) and control.buffer.name == value:
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self.focus(control)
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return
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raise ValueError(
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"Couldn't find Buffer in the current layout: %r." % (value,)
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)
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# BufferControl by buffer object.
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elif isinstance(value, Buffer):
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for control in self.find_all_controls():
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if isinstance(control, BufferControl) and control.buffer == value:
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self.focus(control)
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return
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raise ValueError(
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"Couldn't find Buffer in the current layout: %r." % (value,)
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)
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# Focus UIControl.
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elif isinstance(value, UIControl):
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if value not in self.find_all_controls():
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raise ValueError(
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"Invalid value. Container does not appear in the layout."
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)
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if not value.is_focusable():
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raise ValueError("Invalid value. UIControl is not focusable.")
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self.current_control = value
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# Otherwise, expecting any Container object.
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else:
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value = to_container(value)
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if isinstance(value, Window):
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# This is a `Window`: focus that.
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if value not in self.find_all_windows():
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raise ValueError(
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"Invalid value. Window does not appear in the layout: %r"
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% (value,)
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)
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self.current_window = value
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else:
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# Focus a window in this container.
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# If we have many windows as part of this container, and some
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# of them have been focused before, take the last focused
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# item. (This is very useful when the UI is composed of more
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# complex sub components.)
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windows = []
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for c in walk(value, skip_hidden=True):
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if isinstance(c, Window) and c.content.is_focusable():
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windows.append(c)
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# Take the first one that was focused before.
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for w in reversed(self._stack):
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if w in windows:
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self.current_window = w
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return
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# None was focused before: take the very first focusable window.
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if windows:
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self.current_window = windows[0]
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return
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raise ValueError(
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"Invalid value. Container cannot be focused: %r" % (value,)
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)
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def has_focus(self, value: FocusableElement) -> bool:
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"""
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Check whether the given control has the focus.
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:param value: :class:`.UIControl` or :class:`.Window` instance.
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"""
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if isinstance(value, str):
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if self.current_buffer is None:
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return False
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return self.current_buffer.name == value
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if isinstance(value, Buffer):
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return self.current_buffer == value
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if isinstance(value, UIControl):
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return self.current_control == value
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else:
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value = to_container(value)
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if isinstance(value, Window):
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return self.current_window == value
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else:
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# Check whether this "container" is focused. This is true if
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# one of the elements inside is focused.
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for element in walk(value):
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if element == self.current_window:
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return True
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return False
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@property
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def current_control(self) -> UIControl:
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"""
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Get the :class:`.UIControl` to currently has the focus.
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"""
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return self._stack[-1].content
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@current_control.setter
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def current_control(self, control: UIControl) -> None:
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"""
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Set the :class:`.UIControl` to receive the focus.
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"""
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for window in self.find_all_windows():
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if window.content == control:
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self.current_window = window
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return
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raise ValueError("Control not found in the user interface.")
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@property
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def current_window(self) -> Window:
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" Return the :class:`.Window` object that is currently focused. "
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return self._stack[-1]
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@current_window.setter
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def current_window(self, value: Window):
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" Set the :class:`.Window` object to be currently focused. "
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self._stack.append(value)
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@property
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def is_searching(self) -> bool:
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" True if we are searching right now. "
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return self.current_control in self.search_links
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@property
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def search_target_buffer_control(self) -> Optional[BufferControl]:
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"""
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Return the :class:`.BufferControl` in which we are searching or `None`.
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"""
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# Not every `UIControl` is a `BufferControl`. This only applies to
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# `BufferControl`.
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control = self.current_control
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if isinstance(control, SearchBufferControl):
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return self.search_links.get(control)
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else:
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return None
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def get_focusable_windows(self) -> Iterable[Window]:
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"""
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Return all the :class:`.Window` objects which are focusable (in the
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'modal' area).
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"""
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for w in self.walk_through_modal_area():
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if isinstance(w, Window) and w.content.is_focusable():
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yield w
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def get_visible_focusable_windows(self) -> List[Window]:
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"""
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Return a list of :class:`.Window` objects that are focusable.
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"""
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# focusable windows are windows that are visible, but also part of the
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# modal container. Make sure to keep the ordering.
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visible_windows = self.visible_windows
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return [w for w in self.get_focusable_windows() if w in visible_windows]
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@property
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def current_buffer(self) -> Optional[Buffer]:
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"""
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The currently focused :class:`~.Buffer` or `None`.
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"""
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ui_control = self.current_control
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if isinstance(ui_control, BufferControl):
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return ui_control.buffer
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return None
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def get_buffer_by_name(self, buffer_name: str) -> Optional[Buffer]:
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"""
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Look in the layout for a buffer with the given name.
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Return `None` when nothing was found.
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"""
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for w in self.walk():
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if isinstance(w, Window) and isinstance(w.content, BufferControl):
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if w.content.buffer.name == buffer_name:
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return w.content.buffer
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return None
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@property
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def buffer_has_focus(self) -> bool:
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"""
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Return `True` if the currently focused control is a
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:class:`.BufferControl`. (For instance, used to determine whether the
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default key bindings should be active or not.)
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"""
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ui_control = self.current_control
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return isinstance(ui_control, BufferControl)
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@property
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def previous_control(self) -> UIControl:
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"""
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Get the :class:`.UIControl` to previously had the focus.
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"""
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try:
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return self._stack[-2].content
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except IndexError:
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return self._stack[-1].content
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def focus_last(self) -> None:
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"""
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Give the focus to the last focused control.
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"""
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if len(self._stack) > 1:
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self._stack = self._stack[:-1]
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def focus_next(self) -> None:
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"""
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Focus the next visible/focusable Window.
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"""
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windows = self.get_visible_focusable_windows()
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if len(windows) > 0:
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try:
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index = windows.index(self.current_window)
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except ValueError:
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index = 0
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else:
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index = (index + 1) % len(windows)
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self.focus(windows[index])
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def focus_previous(self) -> None:
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"""
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Focus the previous visible/focusable Window.
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"""
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windows = self.get_visible_focusable_windows()
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if len(windows) > 0:
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try:
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index = windows.index(self.current_window)
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except ValueError:
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index = 0
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else:
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index = (index - 1) % len(windows)
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self.focus(windows[index])
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def walk(self) -> Iterable[Container]:
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"""
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Walk through all the layout nodes (and their children) and yield them.
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"""
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for i in walk(self.container):
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yield i
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def walk_through_modal_area(self) -> Iterable[Container]:
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"""
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Walk through all the containers which are in the current 'modal' part
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of the layout.
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"""
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# Go up in the tree, and find the root. (it will be a part of the
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# layout, if the focus is in a modal part.)
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root: Container = self.current_window
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while not root.is_modal() and root in self._child_to_parent:
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root = self._child_to_parent[root]
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for container in walk(root):
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yield container
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def update_parents_relations(self) -> None:
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"""
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Update child->parent relationships mapping.
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"""
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parents = {}
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def walk(e: Container) -> None:
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for c in e.get_children():
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parents[c] = e
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walk(c)
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walk(self.container)
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self._child_to_parent = parents
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def reset(self) -> None:
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# Remove all search links when the UI starts.
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# (Important, for instance when control-c is been pressed while
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# searching. The prompt cancels, but next `run()` call the search
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# links are still there.)
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self.search_links.clear()
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self.container.reset()
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def get_parent(self, container: Container) -> Optional[Container]:
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"""
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Return the parent container for the given container, or ``None``, if it
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wasn't found.
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"""
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try:
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return self._child_to_parent[container]
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except KeyError:
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return None
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class InvalidLayoutError(Exception):
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pass
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def walk(container: Container, skip_hidden: bool = False) -> Iterable[Container]:
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"""
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Walk through layout, starting at this container.
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"""
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# When `skip_hidden` is set, don't go into disabled ConditionalContainer containers.
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if (
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skip_hidden
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and isinstance(container, ConditionalContainer)
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and not container.filter()
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):
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return
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yield container
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for c in container.get_children():
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# yield from walk(c)
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yield from walk(c, skip_hidden=skip_hidden)
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