291 lines
9.0 KiB
C
291 lines
9.0 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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peek_char ()
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{
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return make_char (peekchar ());
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}
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SCM
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read_char ()
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{
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return make_char (getchar ());
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}
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SCM
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unread_char (SCM c)
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{
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return ungetchar (VALUE (c));
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}
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int
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read_block_comment (int s, int c)
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{
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if (c == s && peekchar () == '#') return getchar ();
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return read_block_comment (s, getchar ());
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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 lookup_char (int c, SCM a);
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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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#if READER
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if (c == '"' && w == cell_nil) return read_string ();
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if (c == '"') {ungetchar (c); return lookup (w, a);}
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if (c == ',' && peekchar () == '@') {getchar (); return cons (lookup (STRING (cell_symbol_unquote_splicing), a),
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cons (read_word (getchar (), w, a),
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cell_nil));}
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if ((c == '\''
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|| c == '`'
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|| c == ',')
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&& w == cell_nil) {return cons (lookup_char (c, a),
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cons (read_word (getchar (), w, a),
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cell_nil));}
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if (c == '#' && peekchar () == ',' && w == cell_nil) {
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getchar ();
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if (peekchar () == '@'){getchar (); return cons (lookup (STRING (cell_symbol_unsyntax_splicing), a),
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cons (read_word (getchar (), w, a),
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cell_nil));}
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return cons (lookup (STRING (cell_symbol_unsyntax), a), cons (read_word (getchar (), w, a), cell_nil));
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}
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if (c == '#' && (peekchar () == '\'' || peekchar () == '`') && w == cell_nil) {
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c = getchar ();
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return cons (lookup (cons (make_char ('#'), cons (make_char (c), cell_nil)), a),
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cons (read_word (getchar (), w, a), cell_nil));}
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if (c == '#' && peekchar () == 'x') {getchar (); return read_hex ();}
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if (c == '#' && peekchar () == '\\') {getchar (); return read_character ();}
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if (c == '#' && w == cell_nil && peekchar () == '(') {getchar (); return list_to_vector (read_list (a));}
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if (c == '#' && peekchar () == ';') {getchar (); read_word (getchar (), w, a); return read_word (getchar (), w, a);}
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if (c == '#' && (peekchar () == '!' || peekchar () == '|')) {c = getchar (); read_block_comment (c, getchar ()); return read_word (getchar (), w, a);}
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#endif //READER
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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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SCM
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read_character ()
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{
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int c = getchar ();
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if (c >= '0' && c <= '7'
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&& peekchar () >= '0' && peekchar () <= '7') {
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c = c - '0';
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while (peekchar () >= '0' && peekchar () <= '7') {
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c <<= 3;
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c += getchar () - '0';
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}
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}
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else if (c >= 'a' && c <= 'z'
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&& peekchar () >= 'a' && peekchar () <= 'z') {
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char buf[10];
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char *p = buf;
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*p++ = c;
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while (peekchar () >= 'a' && peekchar () <= 'z') {
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*p++ = getchar ();
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}
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*p = 0;
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if (!strcmp (buf, char_nul.name)) c = char_nul.value;
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else if (!strcmp (buf, char_backspace.name)) c = char_backspace.value;
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else if (!strcmp (buf, char_tab.name)) c = char_tab.value;
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else if (!strcmp (buf, char_newline.name)) c = char_newline.value;
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else if (!strcmp (buf, char_vt.name)) c = char_vt.value;
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else if (!strcmp (buf, char_page.name)) c = char_page.value;
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else if (!strcmp (buf, char_return.name)) c = char_return.value;
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else if (!strcmp (buf, char_space.name)) c = char_space.value;
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else {
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fprintf (stderr, "char not supported: %s\n", buf);
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assert (!"char not supported");
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}
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}
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return make_char (c);
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}
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SCM
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read_hex ()
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{
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int n = 0;
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int c = peekchar ();
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while ((c >= '0' && c <= '9')
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|| (c >= 'A' && c <= 'F')
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|| (c >= 'a' && c <= 'f')) {
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n <<= 4;
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if (c >= 'a') n += c - 'a' + 10;
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else if (c >= 'A') n += c - 'A' + 10;
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else n+= c - '0';
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getchar ();
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c = peekchar ();
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}
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return make_number (n);
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}
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SCM
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append_char (SCM x, int i)
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{
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return append2 (x, cons (make_char (i), cell_nil));
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}
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SCM
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read_string ()
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{
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SCM p = cell_nil;
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int c = getchar ();
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while (true) {
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if (c == '"') break;
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if (c == '\\' && peekchar () == '"') p = append_char (p, getchar ());
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else if (c == '\\' && peekchar () == 'n') {getchar (); p = append_char (p, '\n');}
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else if (c == EOF) assert (!"EOF in string");
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else p = append_char (p, c);
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c = getchar ();
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}
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return make_string (p);
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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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#if READER
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if (c == '#' && (peekchar () == '!' || peek_char () == '|')) {c=getchar (); read_block_comment (c, getchar ()); return eat_whitespace (getchar ());}
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#endif
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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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if (VALUE (car (s)) == '#' && VALUE (cadr (s)) == ':') return make_keyword (cddr (s));
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SCM x = internal_lookup_symbol (s);
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if (x) return x;
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if (cdr (s) == cell_nil) {
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if (VALUE (car (s)) == '\'') return cell_symbol_quote;
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if (VALUE (car (s)) == '`') return cell_symbol_quasiquote;
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if (VALUE (car (s)) == ',') return cell_symbol_unquote;
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}
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else if (cddr (s) == cell_nil) {
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if (VALUE (car (s)) == ',' && VALUE (cadr (s)) == '@') return cell_symbol_unquote_splicing;
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if (VALUE (car (s)) == '#' && VALUE (cadr (s)) == '\'') return cell_symbol_syntax;
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if (VALUE (car (s)) == '#' && VALUE (cadr (s)) == '`') return cell_symbol_quasisyntax;
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if (VALUE (car (s)) == '#' && VALUE (cadr (s)) == ',') return cell_symbol_unsyntax;
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}
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else if (cdddr (s) == cell_nil) {
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if (VALUE (car (s)) == '#' && VALUE (cadr (s)) == ',' && VALUE (caddr (s)) == '@') return cell_symbol_unsyntax_splicing;
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if (VALUE (car (s)) == 'E' && VALUE (cadr (s)) == 'O' && VALUE (caddr (s)) == 'F') {
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fprintf (stderr, "mes: got EOF\n");
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return cell_nil; // `EOF': eval program, which may read stdin
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}
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}
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return internal_make_symbol (s);
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}
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SCM
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lookup_char (int c, SCM a)
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{
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return lookup (cons (make_char (c), cell_nil), a);
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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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internal_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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// .string and .name is the same field; .name is used as a handy
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// static field initializer. A string can only be mistaken for a
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// cell with type == PAIR for the one character long, zero-padded
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// #\etx.
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SCM p = STRING (car (x));
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if (p < 0 || p >= g_free.value || TYPE (p) != PAIR)
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STRING (car (x)) = cstring_to_list (NAME (car (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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