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%
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%  Copyright 1998-2021 Paulo Moura <pmoura@logtalk.org>
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%      http://www.apache.org/licenses/LICENSE-2.0
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:- object(grammar_rules_hook,
	implements(expanding)).

	:- info([
		version is 1:0:0,
		author is 'Paulo Moura',
		date is 2020-02-14,
		comment is 'This hook object expands grammar rules into clauses.',
		see_also is [
			backend_adapter_hook, default_workflow_hook,
			identity_hook, prolog_module_hook(_), object_wrapper_hook,
			write_to_stream_hook(_, _), write_to_stream_hook(_),
			print_goal_hook, suppress_goal_hook
		]
	]).

	term_expansion((GRHead --> GRBody), Clause) :-
		{	'$lgt_comp_ctx_mode'(CompilationContext, runtime),
			'$lgt_dcg_rule'((GRHead --> GRBody), Clause0, CompilationContext),
			(	Clause0 = (Head :- Body0) ->
				'$lgt_simplify_goal'(Body0, Body),
				(	Body == true ->
					Clause = Head
				;	Clause = (Head :- Body)
				)
			;	Clause = Clause0
			)
		}.

:- end_object.
