urbit/jets/b/skid.c
2015-09-19 10:03:13 -07:00

45 lines
905 B
C

/* j/2/skid.c
**
*/
#include "all.h"
/* functions
*/
u3_noun
u3qb_skid(u3_noun a,
u3_noun b)
{
if ( 0 == a ) {
return u3nc(u3_nul, u3_nul);
}
else if ( c3n == u3du(a) ) {
return u3m_bail(c3__exit);
} else {
u3_noun acc = u3qb_skid(u3t(a), b);
u3_noun hoz = u3n_slam_on(u3k(b), u3k(u3h(a)));
switch ( hoz ) {
case c3y: acc = u3nc(u3nc(u3k(u3h(a)), u3h(acc)), u3t(acc));
break;
case c3n: acc = u3nc(u3h(acc), u3nc(u3k(u3h(a)), u3t(acc)));
break;
default: u3z(hoz);
return u3m_bail(c3__exit);
}
u3z(hoz);
return acc;
}
}
u3_noun
u3wb_skid(u3_noun cor)
{
u3_noun a, b;
if ( c3n == u3r_mean(cor, u3x_sam_2, &a, u3x_sam_3, &b, 0) ) {
return u3m_bail(c3__exit);
} else {
return u3qb_skid(a, b);
}
}