mes/string.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/>.
*/
scm *
string (scm *x) ///((arity . n))
{
return make_string (x);
}
scm *
string_append (scm *x) ///((arity . n))
{
scm *p = &scm_nil;
while (x != &scm_nil)
{
scm *s = car (x);
assert (s->type == STRING);
p = append2 (p, s->string);
x = cdr (x);
}
return make_string (p);
}
scm *
list_to_string (scm *x)
{
return make_string (x);
}
scm *
string_length (scm *x)
{
assert (x->type == STRING);
return make_number (length (x->string)->value);
}
scm *
string_ref (scm *x, scm *k)
{
assert (x->type == STRING);
assert (k->type == NUMBER);
scm n = {NUMBER, .value=k->value};
return make_char (list_ref (x->string, &n)->value);
}
scm *
substring (scm *x) ///((arity . n))
{
assert (x->type == PAIR);
assert (x->car->type == STRING);
scm *s = x->car->string;
assert (x->cdr->car->type == NUMBER);
int start = x->cdr->car->value;
int end = length (s)->value;
if (x->cdr->cdr->type == PAIR) {
assert (x->cdr->cdr->car->type == NUMBER);
assert (x->cdr->cdr->car->value <= end);
end = x->cdr->cdr->car->value;
}
int n = end - start;
while (start--) s = s->cdr;
scm *p = &scm_nil;
while (n-- && s != &scm_nil) {
p = append2 (p, cons (make_char (s->car->value), &scm_nil));
s = s->cdr;
}
return make_string (p);
}
scm *
number_to_string (scm *x)
{
assert (x->type == NUMBER);
int n = x->value;
scm *p = n < 0 ? cons (make_char ('-'), &scm_nil) : &scm_nil;
do {
p = cons (make_char (n % 10 + '0'), p);
n = n / 10;
} while (n);
return make_string (p);
}
scm *
string_to_symbol (scm *x)
{
assert (x->type == STRING);
return make_symbol (x->string);
}
scm *
symbol_to_string (scm *x)
{
assert (x->type == SYMBOL);
return make_string (x->string);
}