73 lines
1.8 KiB
Prolog
73 lines
1.8 KiB
Prolog
/*
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Copyright 2018, 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 \= [61, 61], atom_codes(C, Chars)}.
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% Line is the next new-line delimited line from standard input stream as
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% a list of character codes.
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line(Line) :- get_code(X), line(X, Line).
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line(10, []) :- !. % break on new-lines.
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line(-1, [eof]) :- !. % break on EOF
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line(X, [X|Line]) :- get_code(Y), !, line(Y, Line).
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chars([Ch|Rest]) --> char(Ch), chars(Rest).
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chars([Ch]) --> char(Ch).
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char(Ch) --> [Ch], { Ch \== 0'[, Ch \== 0'], Ch >= 33, Ch =< 126 }.
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blanks --> blank, !, blanks.
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blanks --> [].
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blank --> [32] | [13] | [10].
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% TODO: negative numbers, floats, scientific notation.
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num(N) --> digits(Codes), !, { num(N, Codes) }.
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num(_, []) :- fail, !.
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num(N, [C|Codes]) :- number_codes(N, [C|Codes]).
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digits([H|T]) --> digit(H), !, digits(T).
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digits([]) --> [].
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digit(C) --> [C], { nonvar(C), C =< 57, C >= 48 }.
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