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- #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;
- }
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