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