mes/quasiquote.c

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/* -*-comment-start: "//";comment-end:""-*-
* Mes --- Maxwell Equations of Software
* Copyright © 2016 Jan Nieuwenhuizen <janneke@gnu.org>
*
* This file is part of Mes.
*
* Mes 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.
*
* Mes 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 Mes. If not, see <http://www.gnu.org/licenses/>.
*/
#if QUASIQUOTE
scm *add_environment (scm *a, char const *name, scm *x);
scm *
unquote (scm *x) ///((no-environment))
{
return cons (&symbol_unquote, x);
}
scm *
unquote_splicing (scm *x) ///((no-environment))
{
return cons (&symbol_unquote_splicing, x);
}
scm *
eval_quasiquote (scm *e, scm *a)
{
if (e == &scm_nil) return e;
else if (atom_p (e) == &scm_t) return e;
else if (eq_p (car (e), &symbol_unquote) == &scm_t)
return builtin_eval (cadr (e), a);
else if (e->type == PAIR && e->car->type == PAIR
&& eq_p (caar (e), &symbol_unquote_splicing) == &scm_t)
return append2 (builtin_eval (cadar (e), a), eval_quasiquote (cdr (e), a));
return cons (eval_quasiquote (car (e), a), eval_quasiquote (cdr (e), a));
}
scm *
the_unquoters = &scm_nil;
scm *
add_unquoters (scm *a)
{
if (the_unquoters == &scm_nil)
the_unquoters = cons (cons (&symbol_unquote, &scm_unquote),
cons (cons (&symbol_unquote_splicing, &scm_unquote_splicing),
&scm_nil));
return append2 (the_unquoters, a);
}
#else // !QUASIQUOTE
scm*add_unquoters (scm *a){}
scm*eval_quasiquote (scm *e, scm *a){}
#endif // QUASIQUOTE
#if QUASISYNTAX
scm *
syntax (scm *x)
{
return cons (&symbol_syntax, x);
}
scm *
unsyntax (scm *x) ///((no-environment))
{
return cons (&symbol_unsyntax, x);
}
scm *
unsyntax_splicing (scm *x) ///((no-environment))
{
return cons (&symbol_unsyntax_splicing, x);
}
scm *
eval_quasisyntax (scm *e, scm *a)
{
if (e == &scm_nil) return e;
else if (atom_p (e) == &scm_t) return e;
else if (eq_p (car (e), &symbol_unsyntax) == &scm_t)
return builtin_eval (cadr (e), a);
else if (e->type == PAIR && e->car->type == PAIR
&& eq_p (caar (e), &symbol_unsyntax_splicing) == &scm_t)
return append2 (builtin_eval (cadar (e), a), eval_quasisyntax (cdr (e), a));
return cons (eval_quasisyntax (car (e), a), eval_quasisyntax (cdr (e), a));
}
scm *
add_unsyntaxers (scm *a)
{
a = cons (cons (&symbol_unsyntax, &scm_unsyntax), a);
a = cons (cons (&symbol_unsyntax_splicing, &scm_unsyntax_splicing), a);
return a;
}
#else // !QUASISYNTAX
scm*syntax (scm *x){}
scm*unsyntax (scm *x){}
scm*unsyntax_splicing (scm *x){}
scm*add_unsyntaxers (scm *a){}
scm*eval_unsyntax (scm *e, scm *a){}
scm*eval_quasisyntax (scm *e, scm *a){}
#endif // !QUASISYNTAX