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feat: adds the Size() method to the nmt API #191

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merged 2 commits into from
May 4, 2023
Merged

feat: adds the Size() method to the nmt API #191

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ab2d666
adds the Size() method
staheri14 May 4, 2023
b78ba42
Merge branch 'master' into adds-size-method
staheri14 May 4, 2023
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27 changes: 16 additions & 11 deletions nmt.go
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Original file line number Diff line number Diff line change
Expand Up @@ -143,7 +143,7 @@ func New(h hash.Hash, setters ...Option) *NamespacedMerkleTree {
// Prove returns a NMT inclusion proof for the leaf at the supplied index. Note
// this is not really NMT specific but the tree supports inclusions proofs like
// any vanilla Merkle tree. Prove is a thin wrapper around the ProveRange.
// If the supplied index is invalid i.e., if index < 0 or index > len(n.leaves), then Prove returns an ErrInvalidRange error. Any other errors rather than this are irrecoverable and indicate an illegal state of the tree (n).
// If the supplied index is invalid i.e., if index < 0 or index > n.Size(), then Prove returns an ErrInvalidRange error. Any other errors rather than this are irrecoverable and indicate an illegal state of the tree (n).
func (n *NamespacedMerkleTree) Prove(index int) (Proof, error) {
return n.ProveRange(index, index+1)
}
Expand All @@ -164,7 +164,7 @@ func (n *NamespacedMerkleTree) Prove(index int) (Proof, error) {
// generated using a modified version of the namespace hash with a custom
// namespace ID range calculation. For more information on this, please refer to
// the HashNode method in the Hasher.
// If the supplied (start, end) range is invalid i.e., if start < 0 or end > len(n.leafHashes) or start >= end,
// If the supplied (start, end) range is invalid i.e., if start < 0 or end > n.Size() or start >= end,
// then ProveRange returns an ErrInvalidRange error. Any errors rather than ErrInvalidRange are irrecoverable and indicate an illegal state of the tree (n).
func (n *NamespacedMerkleTree) ProveRange(start, end int) (Proof, error) {
isMaxNsIgnored := n.treeHasher.IsMaxNamespaceIDIgnored()
Expand Down Expand Up @@ -248,7 +248,7 @@ func (n *NamespacedMerkleTree) ProveNamespace(nID namespace.ID) (Proof, error) {
// validateRange validates the range [start, end) against the size of the tree.
// start is inclusive and end is non-inclusive.
func (n *NamespacedMerkleTree) validateRange(start, end int) error {
if start < 0 || start >= end || end > len(n.leaves) {
if start < 0 || start >= end || end > n.Size() {
return ErrInvalidRange
}
return nil
Expand All @@ -268,12 +268,12 @@ func (n *NamespacedMerkleTree) buildRangeProof(proofStart, proofEnd int) ([][]by
}

// start, end are indices of leaves in the tree hence they should be within
// the size of the tree i.e., less than or equal to the len(n.leaves)
// the size of the tree i.e., less than or equal to n.Size()
// includeNode indicates whether the hash of the current subtree (covering
// the supplied range i.e., [start, end)) or one of its constituent subtrees
// should be part of the proof
recurse = func(start, end int, includeNode bool) ([]byte, error) {
if start >= len(n.leafHashes) {
if start >= n.Size() {
return nil, nil
}

Expand Down Expand Up @@ -341,7 +341,7 @@ func (n *NamespacedMerkleTree) buildRangeProof(proofStart, proofEnd int) ([][]by
return hash, nil
}

fullTreeSize := getSplitPoint(len(n.leafHashes)) * 2
fullTreeSize := getSplitPoint(n.Size()) * 2
if fullTreeSize < 1 {
fullTreeSize = 1
}
Expand Down Expand Up @@ -449,7 +449,7 @@ func (n *NamespacedMerkleTree) Push(namespacedData namespace.PrefixedData) error
// Any error returned by this method is irrecoverable and indicate an illegal state of the tree (n).
func (n *NamespacedMerkleTree) Root() ([]byte, error) {
if n.rawRoot == nil {
res, err := n.computeRoot(0, len(n.leaves))
res, err := n.computeRoot(0, n.Size())
if err != nil {
return nil, err // this should never happen since leaves are validated in the Push method
}
Expand Down Expand Up @@ -484,7 +484,7 @@ func (n *NamespacedMerkleTree) MaxNamespace() (namespace.ID, error) {
func (n *NamespacedMerkleTree) computeRoot(start, end int) ([]byte, error) {
// in computeRoot, start may be equal to end which indicates an empty tree hence empty root.
// Due to this, we need to perform custom range check instead of using validateRange() in which start=end is considered invalid.
if start < 0 || start > end || end > len(n.leaves) {
if start < 0 || start > end || end > n.Size() {
return nil, fmt.Errorf("failed to compute root [%d, %d): %w", start, end, ErrInvalidRange)
}
switch end - start {
Expand Down Expand Up @@ -533,8 +533,8 @@ func getSplitPoint(length int) int {
}

func (n *NamespacedMerkleTree) updateNamespaceRanges() {
if len(n.leaves) > 0 {
lastIndex := len(n.leaves) - 1
if n.Size() > 0 {
lastIndex := n.Size() - 1
lastPushed := n.leaves[lastIndex]
lastNsStr := string(lastPushed[:n.treeHasher.NamespaceSize()])
lastRange, found := n.namespaceRanges[lastNsStr]
Expand Down Expand Up @@ -570,7 +570,7 @@ func (n *NamespacedMerkleTree) validateAndExtractNamespace(ndata namespace.Prefi
nID := namespace.ID(ndata[:n.NamespaceSize()])
// ensure pushed data doesn't have a smaller namespace than the previous
// one:
curSize := len(n.leaves)
curSize := n.Size()
if curSize > 0 {
if nID.Less(n.leaves[curSize-1][:nidSize]) {
return nil, fmt.Errorf(
Expand Down Expand Up @@ -615,3 +615,8 @@ func MaxNamespace(hash []byte, size namespace.IDSize) []byte {
max := make([]byte, 0, size)
return append(max, hash[size:size*2]...)
}

// Size returns the number of leaves in the tree.
func (n *NamespacedMerkleTree) Size() int {
return len(n.leaves)
}