Topic: pointer rotation

topics > computer science > data > Group: access to data

dangling pointers
recursive data structures
safe use of pointers


Reduce problems caused by pointers and dangling references by performing rotations on pointer structures. This preserves the number of pointers in a record and its connectedness. A safe rotation can not lose records. (cbb 1/90)
Subtopic: pointer rotation up

Quote: pointer rotation preserves the number of pointers to a record; reference counts are preserved [»suzuN_1980]
Quote: pointer rotation is invariant to rotating its arguments [»suzuN_1980]
Quote: in pointer rotation, a record is lost if it is no longer reachable from the arguments; a rotation is safe if it can't lose records [»suzuN_1980]

Subtopic: preserves reference counts up

Quote: straight-line code that preserves reference counts and does not create records is implemented by a pointer rotation [»suzuN_1980]
Quote: linear lists and trees have reference counts of one; pointer rotation preserves this; prevents circularity or shared cells [»suzuN_1980]
Quote: if a computation preserves reference counts and number of reachable records, then is implemented solely by pointer rotations [»suzuN_1980]
Quote: there are only two distinct classes of 3-way rotations [»suzuN_1980]

Subtopic: pointer slide up

Quote: pointer slide is like an n-bit shift; can use for pointer assignment [»suzuN_1980]

Subtopic: swap up

Quote: a language should replace copying with swapping, and disallow pointers at the client level [»harmDE5_1991]

Subtopic: examples up

Quote: example of freeing a record explicitly with pointer rotation [»suzuN_1980]
Quote: example of moving a record from list to another using pointer rotation

Related Topics up

Topic: aliasing (28 items)
Topic: dangling pointers (13 items)
Topic: recursive data structures (18 items)
Topic: safe use of pointers
(102 items)

Updated barberCB 11/04
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Thesa is a trademark of C. Bradford Barber.