83 lines
2.2 KiB
Prolog
83 lines
2.2 KiB
Prolog
/*
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Copyright 2019 Simon Forman
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This file is part of Thun
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Thun is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation, either version 3 of the License, or
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(at your option) any later version.
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Thun is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with Thun. If not see <http://www.gnu.org/licenses/>.
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Parser
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*/
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:- set_prolog_flag(double_quotes, codes).
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joy_parse([T|J]) --> blanks, joy_term(T), blanks, joy_parse(J).
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joy_parse([]) --> [].
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joy_term(N) --> num(N), !.
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joy_term(J) --> "[", !, joy_parse(J), "]".
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joy_term(C) --> symbol(C).
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symbol(C) --> chars(Chars), !, { Chars \= "==", atom_codes(C, Chars) }.
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num(N) --> number_digits(Codes), { number_codes(N, Codes) }.
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number_digits(Codes) --> signed_float_or_integer(Codes), !, end_num.
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end_num, [Ch] --> [Ch], { [Ch] = "[" ; is_space(Ch) }.
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end_num([], []).
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/*
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Print state.
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*/
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format_state(Stack, Expression, Codes) :-
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reverse(Stack, RStack),
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phrase(format_joy(RStack), RStackCodes),
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phrase(format_joy(Expression), ExpressionCodes),
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append(RStackCodes, [32, 46, 32|ExpressionCodes], Codes).
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frump(Stack, Expression) :-
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format_state(Stack, Expression, Codes),
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maplist(put_code, Codes), nl.
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print_stack(Stack) :-
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reverse(Stack, RStack),
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phrase(format_joy(RStack), Codes),
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maplist(put_code, Codes).
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% Print Joy expressions as text.
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format_joy(Tail) --> {var(Tail)}, !, [46, 46, 46].
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format_joy([T]) --> format_term(T), !.
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format_joy([T|S]) --> format_term(T), " ", format_joy(S).
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format_joy([]) --> [].
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format_term(N) --> {number(N), number_codes(N, Codes)}, Codes.
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format_term(A) --> { atom(A), atom_codes(A, Codes)}, Codes.
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format_term(V) --> { var(V), write_to_codes(Codes, V)}, Codes.
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format_term([A|As]) --> "[", format_joy([A|As]), "]".
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format_term(F) --> { write_to_codes(Codes, F)}, Codes.
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