with Generic_Set ;

generic

	----------------------------------------------------------------------------
	--  T y p e s
	--
	type Symbol               is ( <> )                                     ;
	type Phrase               is array  ( Positive range <> ) of Symbol     ;
	type To_Phrase            is access                          Phrase     ;
	type Phrases              is array  ( Positive range <> ) of To_Phrase  ;
	type To_Phrases           is access                          Phrases    ;
	type Context_Free_Grammar is array  ( Symbol   range <> ) of To_Phrases ;

	----------------------------------------------------------------------------
	--  C o n s t a n t s
	--
	Terminal_First : Symbol               ;
	Terminal_Last  : Symbol               ;
	Productions    : Context_Free_Grammar ;
	Start          : Symbol               ;
	Follow_Start   : Symbol               ;

package Generic_CFG_to_NFA is

	----------------------------------------------------------------------------
	--  T y p e s
	--
	subtype Terminal    is Symbol range Terminal_First..Terminal_Last ;
	subtype Nonterminal is Symbol range Productions'Range             ;

	type Item is

		record
			A     : Nonterminal ;
			Dot   : Positive    ;
			Alpha : To_Phrase   ;
		end record;

	type Item_Order is ( '<', '=', '>' ) ;

	function Compare   ( Left, Right : Item       ) return Item_Order ;
	function Equal     ( Compare     : Item_Order ) return Boolean    ;
	function Less_Than ( Compare     : Item_Order ) return Boolean    ;

	package Items is new Generic_Set ( Item, Item_Order ) ;

	----------------------------------------------------------------------------
	--  O p e r a t i o n s
	--
	function Start_Item                                             return Item       ;
	function Alphabet_Transition ( From : Items.Set ; On : Symbol ) return Items.Set  ;
	function Epsilon_Closure     ( From : Items.Set               ) return Items.Set  ;
	function Final               ( From : Items.Set               ) return Boolean    ;
	function Handles             ( From : Items.Set               ) return Items.Set  ;

end Generic_CFG_to_NFA;