fix: provide a safe way to obtain leaf index from mmrIndex #19
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When the merklebuilder is adding a node it is guaranteed that the before and after mmrIndex are also valid mmrSizes. This lets it use LeafCount to directly obtain the leafIndex of the item just added. This led to the regular use of LeafCount as the way to get the leaf index. It is not safe to do this in general. This change adds FirstMMRSize which returns the size of the smallest valid MMR which containes the node identified by mmrIndex To provide a clear idiom for safely getting the leaf index from a node index (mmrIndex), LeafIndex(mmrIndex) is additionaly provided as a convenience for LeafCount(FirstMMRSize(mmrIndex)) - 1 AB#9551
honourfish
approved these changes
Jun 5, 2024
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When the merklebuilder is adding a node it is guaranteed that the before and after mmrIndex are also valid mmrSizes. This lets it use LeafCount to directly obtain the leafIndex of the item just added.
This led to the regular use of LeafCount as the way to get the leaf index. It is not safe to do this in general.
This change adds FirstMMRSize which returns the size of the smallest valid MMR which containes the node identified by mmrIndex
To provide a clear idiom for safely getting the leaf index from a node index (mmrIndex), LeafIndex(mmrIndex) is additionaly provided as a convenience for
LeafCount(FirstMMRSize(mmrIndex)) - 1
AB#9551