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add peek-char

This commit is contained in:
Yuichi Nishiwaki 2014-01-13 01:34:26 +09:00
parent 4a87120eb6
commit 70f6b59856
1 changed files with 30 additions and 6 deletions
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36
src/port.c
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@ -352,6 +352,15 @@ pic_port_close_port(pic_state *pic)
return pic_none_value();
}
#define assert_port_profile(port, flgs, stat, caller) do { \
if ((port->flags & flgs) != flgs) { \
pic_error(pic, caller ": expected input port"); \
} \
if (port->status != stat) { \
pic_error(pic, caller ": expected open port"); \
} \
} while (0)
static pic_value
pic_port_read_char(pic_state *pic)
{
@ -360,12 +369,7 @@ pic_port_read_char(pic_state *pic)
pic_get_args(pic, "|p", &port);
if ((port->flags & PIC_PORT_IN) == 0) {
pic_error(pic, "read-char: expected input-port");
}
if (port->status != PIC_PORT_OPEN) {
pic_error(pic, "read-char: expected open port");
}
assert_port_profile(port, PIC_PORT_IN, PIC_PORT_OPEN, "read-char");
if ((c = fgetc(port->file)) == EOF) {
return pic_eof_object();
@ -375,6 +379,25 @@ pic_port_read_char(pic_state *pic)
}
}
static pic_value
pic_port_peek_char(pic_state *pic)
{
char c;
struct pic_port *port = pic_stdin(pic);
pic_get_args(pic, "|p", &port);
assert_port_profile(port, PIC_PORT_IN, PIC_PORT_OPEN, "peek-char");
if ((c = fgetc(port->file)) == EOF) {
return pic_eof_object();
}
else {
ungetc(c, port->file);
return pic_char_value(c);
}
}
void
pic_init_port(pic_state *pic)
{
@ -397,6 +420,7 @@ pic_init_port(pic_state *pic)
/* input */
pic_defun(pic, "read-char", pic_port_read_char);
pic_defun(pic, "peek-char", pic_port_peek_char);
/* write */
pic_defun(pic, "newline", pic_port_newline);