54 lines
1.4 KiB
Prolog
54 lines
1.4 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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Main Loop
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*/
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% :- debug.
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% :- spy(thun).
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:- initialization(loop).
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loop :- prompt, line(Line), loop(Line, [], _Out).
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loop([eof], S, S) :- !.
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loop( Line, In, Out) :-
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do_line(Line, In, S),
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show_stack(S),
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prompt,
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line(NextLine), !,
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loop(NextLine, S, Out).
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do_line(Line, In, Out) :- phrase(joy_parse(E), Line), thun(E, In, Out).
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do_line(_Line, S, S) :- write('Err'), nl.
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prompt :- write(`joy? `).
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show_stack(S) :- nl, print_stack(S), write(` <-top`), nl, nl.
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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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