:- module testb.

% Copyright (C) 2016 The Mercury Team

:- interface.

:- import_module string.

:- type loader.

:- func prefix_locator(loader) = string.

:- implementation.

:- type loader
    --->    loader(
		loader_prefix		:: string,
		loader_replay_prefix	:: string,
		loader_replay_options	:: replay_options
	    ).

:- type replay_options
    --->    replay_none
    ;	    replay_save(string)
    ;	    replay_load(string).

prefix_locator(Loader) = Prefix :-
    % Mercury is unable to properly detect the switch on Replay.  It works
    % if the a single deconstruction of Loader is made outside the switch
    % and unfication-asignments inside the switch.
    Replay = Loader ^ loader_replay_options,
    (
	( Replay = replay_none
	; Replay = replay_save(_)
	),
	Prefix = Loader ^ loader_prefix
    ;
	Replay = replay_load(_),
	Prefix = Loader ^ loader_replay_prefix
    ).