| #include <u.h> |
| #include <libc.h> |
| #include <bio.h> |
| #include <ndb.h> |
| |
| /* replace a in t with b, the line structure in b is lost, c'est la vie */ |
| Ndbtuple* |
| ndbsubstitute(Ndbtuple *t, Ndbtuple *a, Ndbtuple *b) |
| { |
| Ndbtuple *nt; |
| |
| if(a == b) |
| return t; |
| if(b == nil) |
| return ndbdiscard(t, a); |
| |
| /* all pointers to a become pointers to b */ |
| for(nt = t; nt != nil; nt = nt->entry){ |
| if(nt->line == a) |
| nt->line = b; |
| if(nt->entry == a) |
| nt->entry = b; |
| } |
| |
| /* end of b chain points to a's successors */ |
| for(nt = b; nt->entry; nt = nt->entry){ |
| nt->line = nt->entry; |
| } |
| nt->line = a->line; |
| nt->entry = a->entry; |
| |
| a->entry = nil; |
| ndbfree(a); |
| |
| if(a == t) |
| return b; |
| else |
| return t; |
| } |
