64 lines
2.1 KiB
Python
64 lines
2.1 KiB
Python
"""A stack-based naviation system.
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Maintains a stack of states through which a user can navigate.
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Think Android's back button model.
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Every screen is modeled as a function that takes one argument "state".
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It can modify state and should either return
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* None (which means go back one level)
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* A new function (which adds to the stack)
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* A keyword like NEXT_EXIT (exit nav) or NEXT_TOP (go to top of stack)
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Children get a a shallow clone of the current state, going back will
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lead to a screen with the original state.
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"""
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___dependencies___ = ["dialogs", "database"]
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___license___ = "MIT"
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import dialogs, database
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NEXT_EXIT = "exit" # Leave navigation
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NEXT_TOP = "init" # Go to top of stack
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def nav(init_fn, init_state={}):
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stack = [(init_fn, init_state)]
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while stack:
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(fn, state) = stack[-1] # peek
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next_state = state.copy()
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result = fn(next_state)
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if callable(result):
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stack.append((result, next_state))
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elif result == NEXT_TOP:
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stack = [(init_fn, init_state)]
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elif result == NEXT_EXIT:
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break
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else:
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stack.pop()
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# A simple menu. Format of items is [{"foo":fn}, ...]
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def selection(items, title="Settings", none_text="Back"):
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items = [{"title": t, "function": fn} for (t, fn) in items.items()]
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selection = dialogs.prompt_option(items, none_text=none_text, title=title)
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if selection:
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return selection["function"]
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else:
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return None
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# A wrapper for a simple string menu
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def change_string(title, getter_setter_function):
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def inner(state):
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value = getter_setter_function()
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value = dialogs.prompt_text(title, init_text=value, true_text="Change", false_text="Back")
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if value:
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getter_setter_function(value)
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return inner
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# A wrapper for a database key
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def change_database_string(title, key, default=""):
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def inner(state):
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value = database.get(key, default)
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value = dialogs.prompt_text(title, init_text=value, true_text="Change", false_text="Back")
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if value:
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database.set(key, value)
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return inner
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