59 lines
1.2 KiB
Markdown
59 lines
1.2 KiB
Markdown
https://alloy.readthedocs.io/en/latest/language/signatures.html#relations
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>[!note]
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>Node.prox' = Node.prox
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!=
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all n:Node | n.prox' = n.prox
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=
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prox' = prox
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>[!note]
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>some b: Bucket | ...
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```c
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// Recall the hash table Alloy model,
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// now with mutable lists inside the buckets.
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sig Bucket {
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var head : lone Node
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}
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sig Node {
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key : one Key,
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var prox : lone Node
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}
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sig Key {
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hash : one Hash
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}
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sig Hash {}
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// Specify the operation of inserting a node
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// in the hash table. The node should be
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// inserted at the head of a bucket.
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// If the operation only works well when the
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// hash of the new node does not exist in the
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// table you get Two points. If it always
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// works well you get Five points. Use the
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// respective commands to check how many
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// points you have.
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pred insert[n : Node] {
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always n in ( Bucket.head + Bucket.head.prox)
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always n in Bucket.head or n in Node.prox
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//if hash empty -> node to head of bucket
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n.key.hash not in Hash implies
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(
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lone b:Bucket | b.head = none implies b.head' = n
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)
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//if hash empty -> bucket of desired hash, add to next
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n.key.hash in Hash implies
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(
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lone b: Bucket | b.head.key.hash = n.key.hash | b.head.*prox = n
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)
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}
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```
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