99 lines
2.4 KiB
Python
99 lines
2.4 KiB
Python
"""Base classes for states."""
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from __future__ import annotations
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from typing import Protocol, TypeAlias
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import attrs
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import tcod.console
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import tcod.event
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import g
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class State(Protocol):
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"""An abstract game state."""
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__slots__ = ()
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def on_event(self, event: tcod.event.Event) -> StateResult:
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"""Called on events."""
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def on_draw(self, console: tcod.console.Console) -> None:
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"""Called when the state is being drawn."""
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@attrs.define()
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class Push:
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"""Push a new state on top of the stack."""
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state: State
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@attrs.define()
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class Pop:
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"""Remove the current state from the stack."""
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@attrs.define()
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class Reset:
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"""Replace the entire stack with a new state."""
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state: State
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StateResult: TypeAlias = "Push | Pop | Reset | None"
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"""Union of state results."""
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def main_draw() -> None:
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"""Render and present the active state."""
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if not g.states:
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return
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g.console.clear()
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g.states[-1].on_draw(g.console)
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g.context.present(g.console)
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def apply_state_result(result: StateResult) -> None:
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"""Apply a StateResult to `g.states`."""
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match result:
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case Push(state=state):
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g.states.append(state)
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case Pop():
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g.states.pop()
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case Reset(state=state):
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while g.states:
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apply_state_result(Pop())
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apply_state_result(Push(state))
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case None:
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pass
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case _:
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raise TypeError(result)
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def main_loop() -> None:
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"""Run the active state forever."""
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while g.states:
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main_draw()
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for event in tcod.event.wait():
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tile_event = g.context.convert_event(event)
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if g.states:
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apply_state_result(g.states[-1].on_event(tile_event))
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def get_previous_state(state: State) -> State | None:
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"""Return the state before `state` in the stack if it exists."""
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current_index = next(index for index, value in enumerate(g.states) if value is state)
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return g.states[current_index - 1] if current_index > 0 else None
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def draw_previous_states(state: State, console: tcod.console.Console, dim: bool = True) -> None:
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"""Draw previous states, optionally dimming all but the active state."""
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prev_state = get_previous_state(state)
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if prev_state is None:
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return
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prev_state.on_draw(console)
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if dim and state is g.states[-1]:
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console.rgb["fg"] //= 4
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console.rgb["bg"] //= 4
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