| #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; | |
| } |