/*  $Id: am_match.pl,v 1.1.1.1 1992/05/26 11:51:32 jan Exp $

    Copyright (c) 1990 Jan Wielemaker. All rights reserved.
    jan@swi.psy.uva.nl

    Purpose: implement ambiguous matches
*/

:- module(am_match,
	[ am_match/1	% Does Atom matches previous compiled expression?
	, am_compile/1	% Compile expression represented by atomic argument
	, am_bagof/4	% Return alternatives of Var regarding
	]).		% Goal and matching Expr.


am_bagof(Var, Expression, Goal, Bag) :-
	am_compile(Expression), !, 
	am_bagof(Var, am_bagof_goal(Var, Goal), Bag), !.

am_bagof_goal(Var, Goal) :-
	Goal, 
	am_match(Var).

am_match(Atom) :-
	name(Atom, String), 
	recorded(am_compiled, goal(Goal, String), _), !, 
	Goal, !.

am_compile(Reg) :-
	am_compile(Reg, Goal, String), 
	(recorded(am_compiled, goal(_, _), Ref), erase(Ref) | true), 
	recorda(am_compiled, goal(Goal, String), _), !.

am_compile(Reg, Goal, String) :-
	name(Reg, RegString), 
	am_token_list(Tokens, RegString, ""), 
	am_comp(Tokens, Goal, String), !.

am_comp([], (Full = ""), Full) :- !.
am_comp([string(String)|Tokens], 
	 (append(String, Rest, Full), Goal), Full) :- !, 
	am_comp(Tokens, Goal, Rest).
am_comp([star|Tokens], 
	 (append(_, Rest, Full), Goal), Full) :- !, 
	am_comp(Tokens, Goal, Rest).
am_comp([any|Tokens], 
	 (append([_], Rest, Full), Goal), Full) :- !, 
	am_comp(Tokens, Goal, Rest).
am_comp([anychar(Chars)|Tokens], 
	 (append([C], Rest, Full), member(C, Chars), Goal), Full) :- !, 
	am_comp(Tokens, Goal, Rest).
am_comp([anyof(Strings)|Tokens], 
	 (OrGoal, Goal), Full) :- !, 
	am_anyof_goal(Strings, Rest, Full, OrGoal), 
	am_comp(Tokens, Goal, Rest).

am_anyof_goal([One], Rest, Full, append(One, Rest, Full) ) :- !.
am_anyof_goal([Head|Tail], Rest, Full, (append(Head, Rest, Full) | Goal)) :-
	am_anyof_goal(Tail, Rest, Full, Goal).

am_token_list([]) --> !.
am_token_list([Token|TokenList]) -->
	am_token(Token), 
	am_token_list(TokenList).

am_token(anyof([String|Rest])) -->
	am_next_char("{"), 
	am_any_string(String), 
	am_any_strings(Rest), 
	am_next_char("}"), !.
am_token(anychar(List) ) -->
	am_next_char("["), 
	am_anychar(List), 
	am_next_char("]"), !.
am_token(star) -->
	am_next_char("*"), !.
am_token(any) -->
	am_next_char("?"), !.
am_token(string(String) ) -->
	am_max_string(String), !.

am_any_strings([String|Rest]) -->
	am_next_char(", "), 
	am_any_string(String), 
	am_any_strings(Rest).
am_any_strings([]) --> { true }.

am_anychar([]) -->
	am_see_char("]"), !.
am_anychar(List) -->
	am_next_char([C1]), 
	am_next_char("-"), 
	am_next_char([C2]), { C2 \== 93, C2 > C1 }, 
	{ am_anylist(C1, C2, Sofar) }, 
	am_anychar(Rest), 
	{ append(Sofar, Rest, List) }, !.
am_anychar([C|Rest]) -->
	am_next_char([C]), !, 
	am_anychar(Rest).	

am_max_string([C|Rest]) -->
	am_next_char("\"), 
	am_next_char([C]), !, 
	am_max_string(Rest).
am_max_string([C|Rest]) -->
	am_next_char([C]), 
	{  \+ member(C, "[]{}?*") }, !, 
	am_max_string(Rest).
am_max_string([]) --> { true }.

am_any_string([]) -->
	am_see_char("}"), !.
am_any_string([]) -->
	am_see_char(", "), !.
am_any_string([C|Rest]) -->
	am_next_char("\"), 
	am_next_char([C]), !, 
	am_any_string(Rest).
am_any_string([C|Rest]) -->
	am_next_char([C]), !, 
	am_any_string(Rest).

am_next_char([C], [C|R], R).		% read next character
am_see_char(  [C], [C|R], [C|R]).	% line am_next_char, don't read

/*  fill a list with all characters between C1 and C2.
*/

am_anylist(C1, C1, []) :- !.
am_anylist(C1, C2, [C1|Rest]) :-
	succ(C1, CN), 
	am_anylist(CN, C2, Rest).