Thun/thun/gnu-prolog/parser.pl

111 lines
3.1 KiB
Prolog

/*
Copyright 2019 Simon Forman
This file is part of Thun
Thun is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
Thun is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with Thun. If not see <http://www.gnu.org/licenses/>.
Parser
*/
:- set_prolog_flag(double_quotes, codes).
joy_parse([T|J]) --> blanks, joy_term(T), blanks, joy_parse(J).
joy_parse([]) --> [].
joy_term(N) --> num(N), !.
joy_term(J) --> "[", !, joy_parse(J), "]".
joy_term(C) --> symbol(C).
symbol(C) --> chars(Chars), !, { Chars \= "==", atom_codes(C, Chars) }.
num(N) --> number_digits(Codes), { number_codes(N, Codes) }.
number_digits(Codes) --> signed_float_or_integer(Codes), !, end_num.
% TODO: floats, scientific notation.
signed_float_or_integer(Codes) --> signed_digits(J), ".", !, digits(I),
{ append(J, [0'.|I], Codes) }.
signed_float_or_integer(Codes) --> signed_digits(Codes).
signed_digits([45|Codes]) --> "-", !, digits(Codes).
signed_digits( Codes ) --> digits(Codes).
end_num, [Ch] --> [Ch], { [Ch] = "[" ; is_space(Ch) }.
end_num([], []).
% Groups of characters.
chars(Chars) --> one_or_more(char, Chars).
blanks --> blank, !, blanks | [].
digits(Digits) --> one_or_more(digit, Digits).
% Character types.
char(Ch) --> [Ch], { nonvar(Ch), is_glyph(Ch) }.
blank --> [Ch], { nonvar(Ch), is_space(Ch) }.
digit(Ch) --> [Ch], { nonvar(Ch), between(0'0, 0'9, Ch) }.
is_glyph(Ch) :- Ch =\= 0'[, Ch =\= 0'], between(0'!, 0'~, Ch).
is_space(Ch) :- Ch =:= 32 ; between(9, 13, Ch).
one_or_more(E, List) --> one_or_more_(List, E).
one_or_more_([Ch|Rest], P) --> call(P, Ch), one_or_more_(Rest, P).
one_or_more_([Ch], P) --> call(P, Ch).
/*
Print state.
*/
format_state(Stack, Expression, Codes) :-
reverse(Stack, RStack),
phrase(format_joy(RStack), RStackCodes),
phrase(format_joy(Expression), ExpressionCodes),
append(RStackCodes, [32, 46, 32|ExpressionCodes], Codes).
frump(Stack, Expression) :-
format_state(Stack, Expression, Codes),
maplist(put_code, Codes), nl.
print_stack(Stack) :-
reverse(Stack, RStack),
phrase(format_joy(RStack), Codes),
maplist(put_code, Codes).
% Print Joy expressions as text.
format_joy(Tail) --> {var(Tail)}, !, [46, 46, 46].
format_joy([T]) --> format_term(T), !.
format_joy([T|S]) --> format_term(T), " ", format_joy(S).
format_joy([]) --> [].
format_term(N) --> {number(N), number_codes(N, Codes)}, Codes.
format_term(A) --> { atom(A), atom_codes(A, Codes)}, Codes.
format_term(V) --> { var(V), write_to_codes(Codes, V)}, Codes.
format_term([A|As]) --> "[", format_joy([A|As]), "]".
format_term(F) --> { write_to_codes(Codes, F)}, Codes.