RememberLayout Sublime Text 3 Plugin

import sublime, sublime_plugin
from collections import defaultdict

class RememberLayout(sublime_plugin.EventListener):
    """Remembers where views are located in a layout,
    so they can be restored correctly when you revert to that specific layout."""

    # Per window, per layout, which view as active.
    active_view_cache = defaultdict(dict)

    # Per window, per layout, per group, the views.
    views_cache = defaultdict(lambda: defaultdict(lambda: defaultdict(list)))

    def on_window_command(self, window, command_name, args):
        if command_name == 'set_layout':
            # Before the layout changes.
            self.remember_views(window)

            # After the layout changes.
            sublime.set_timeout(lambda: self.restore_views(window), 0)

    def get_layout_repr(self, window):
        # We need some kind of identifier for layouts, and the cells attribute seems a safe choice.
        return repr(window.get_layout()['cells'])

    def remember_views(self, window):
        layout = self.get_layout_repr(window)

        self.active_view_cache[window.id()][layout] = window.active_view().id()

        groups = self.views_cache[window.id()][layout]
        for v in window.views():
            self.update_view(groups, v)

    def update_view(self, groups, view):
        # The group and view index can potentially be -1 according to the API.
        window = view.window()
        group_idx, view_idx = window.get_view_index(view)
        if group_idx == -1 or view_idx == -1:
            return

        # Only alter if necessary.
        view_ids = groups[group_idx]
        view_id = view.id()
        if view_id in view_ids and view_ids.index(view_id) == view_idx:
            return

        self.remove_view_id(groups, view_id)
        view_ids.insert(view_idx, view_id)

    def remove_view_id(self, groups, view_id):
        for group_idx in groups:
            if view_id in groups[group_idx]:
                groups[group_idx].remove(view_id)
                return

    def restore_views(self, window):
        # There might be nothing to restore from.
        layout = self.get_layout_repr(window)
        if layout not in self.views_cache[window.id()]:
            return

        view_lookup = dict([(v.id(), v) for v in window.views()])

        groups = self.views_cache[window.id()][layout]
        for group_idx in groups:
            for view_idx, view_id in enumerate(groups[group_idx]):
                window.set_view_index(view_lookup[view_id], group_idx, view_idx)

        window.focus_view(view_lookup[self.active_view_cache[window.id()][layout]])