135 lines
3.5 KiB
C
135 lines
3.5 KiB
C
/* -*-comment-start: "//";comment-end:""-*-
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* Mes --- Maxwell Equations of Software
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* Copyright © 2016 Jan Nieuwenhuizen <janneke@gnu.org>
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*
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* This file is part of Mes.
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*
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* Mes is free software; you can redistribute it and/or modify it
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* 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 (at
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* your option) any later version.
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*
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* Mes is distributed in the hope that it will be useful, but
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* 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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*
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* You should have received a copy of the GNU General Public License
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* along with Mes. If not, see <http://www.gnu.org/licenses/>.
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*/
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SCM
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read_input_file_env_ (SCM e, SCM a)
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{
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if (e == cell_nil) return e;
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return cons (e, read_input_file_env_ (read_env (a), a));
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}
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SCM
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read_input_file_env (SCM a)
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{
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r0 = a;
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if (assq_ref_cache (cell_symbol_read_input_file, r0) != cell_undefined)
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return apply_env (cell_symbol_read_input_file, cell_nil, r0);
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return read_input_file_env_ (read_env (r0), r0);
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}
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int
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read_line_comment (int c)
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{
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if (c == '\n') return c;
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return read_line_comment (getchar ());
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}
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SCM
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read_word (int c, SCM w, SCM a)
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{
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if (c == EOF && w == cell_nil) return cell_nil;
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if (c == '\t') return read_word ('\n', w, a);
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if (c == '\f') return read_word ('\n', w, a);
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if (c == '\n' && w == cell_nil) return read_word (getchar (), w, a);
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if (c == '\n' && VALUE (car (w)) == '.' && cdr (w) == cell_nil) return cell_dot;
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if (c == EOF || c == '\n') return lookup_ (w, a);
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if (c == ' ') return read_word ('\n', w, a);
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if (c == '(' && w == cell_nil) return read_list (a);
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if (c == '(') {ungetchar (c); return lookup_ (w, a);}
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if (c == ')' && w == cell_nil) {ungetchar (c); return cell_nil;}
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if (c == ')') {ungetchar (c); return lookup_ (w, a);}
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if (c == ';') {read_line_comment (c); return read_word ('\n', w, a);}
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return read_word (getchar (), append2 (w, cons (MAKE_CHAR (c), cell_nil)), a);
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}
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int
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eat_whitespace (int c)
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{
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while (c == ' ' || c == '\t' || c == '\n' || c == '\f') c = getchar ();
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if (c == ';') return eat_whitespace (read_line_comment (c));
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return c;
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}
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SCM
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read_list (SCM a)
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{
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int c = getchar ();
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c = eat_whitespace (c);
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if (c == ')') return cell_nil;
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SCM w = read_word (c, cell_nil, a);
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if (w == cell_dot)
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return car (read_list (a));
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return cons (w, read_list (a));
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}
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SCM
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read_env (SCM a)
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{
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return read_word (getchar (), cell_nil, a);
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}
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SCM
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lookup_ (SCM s, SCM a)
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{
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if (isdigit (VALUE (car (s))) || (VALUE (car (s)) == '-' && cdr (s) != cell_nil)) {
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SCM p = s;
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int sign = 1;
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if (VALUE (car (s)) == '-') {
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sign = -1;
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p = cdr (s);
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}
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int n = 0;
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while (p != cell_nil && isdigit (VALUE (car (p)))) {
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n *= 10;
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n += VALUE (car (p)) - '0';
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p = cdr (p);
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}
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if (p == cell_nil) return MAKE_NUMBER (n * sign);
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}
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SCM x = lookup_symbol_ (s);
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return x ? x : make_symbol_ (s);
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}
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SCM
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list_of_char_equal_p (SCM a, SCM b)
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{
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while (a != cell_nil && b != cell_nil && VALUE (car (a)) == VALUE (car (b))) {
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assert (TYPE (car (a)) == CHAR);
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assert (TYPE (car (b)) == CHAR);
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a = cdr (a);
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b = cdr (b);
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}
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return (a == cell_nil && b == cell_nil) ? cell_t : cell_f;
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}
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SCM
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lookup_symbol_ (SCM s)
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{
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SCM x = g_symbols;
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while (x) {
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if (list_of_char_equal_p (STRING (car (x)), s) == cell_t) break;
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x = cdr (x);
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}
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if (x) x = car (x);
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return x;
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}
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