Function merge_event_handlers

src/py/reactpy/reactpy/core/events.py:165–200

Merge multiple event handlers into one Raises a ValueError if any handlers have conflicting :attr:`~reactpy.core.proto.EventHandlerType.stop_propagation` or :attr:`~reactpy.core.proto.EventHandlerType.prevent_default` attributes.

(
    event_handlers: Sequence[EventHandlerType],
)

def merge_event_handlers(
    event_handlers: Sequence[EventHandlerType],
) -> EventHandlerType:
    """Merge multiple event handlers into one

    Raises a ValueError if any handlers have conflicting
    :attr:`~reactpy.core.proto.EventHandlerType.stop_propagation` or
    :attr:`~reactpy.core.proto.EventHandlerType.prevent_default` attributes.
    """
    if not event_handlers:
        msg = "No event handlers to merge"
        raise ValueError(msg)
    elif len(event_handlers) == 1:
        return event_handlers[0]

    first_handler = event_handlers[0]

    stop_propagation = first_handler.stop_propagation
    prevent_default = first_handler.prevent_default
    target = first_handler.target

    for handler in event_handlers:
        if (
            handler.stop_propagation != stop_propagation
            or handler.prevent_default != prevent_default
            or handler.target != target
        ):
            msg = "Cannot merge handlers - 'stop_propagation', 'prevent_default' or 'target' mismatch."
            raise ValueError(msg)

    return EventHandler(
        merge_event_handler_funcs([h.function for h in event_handlers]),
        stop_propagation,
        prevent_default,
        target,
    )


def merge_event_handler_funcs(