/*
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Computes a deterministic minimal height merkle tree hash.
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If the number of items is not a power of two, some leaves
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will be at different levels. Tries to keep both sides of
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the tree the same size, but the left may be one greater.
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Use this for short deterministic trees, such as the validator list.
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For larger datasets, use IAVLTree.
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*
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/ \
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/ \
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/ \
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/ \
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* *
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/ \ / \
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/ \ / \
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/ \ / \
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* * * h6
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/ \ / \ / \
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h0 h1 h2 h3 h4 h5
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*/
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package merkle
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import (
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"golang.org/x/crypto/ripemd160"
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"github.com/tendermint/go-wire"
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)
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func SimpleHashFromTwoHashes(left []byte, right []byte) []byte {
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var hasher = ripemd160.New()
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err := wire.EncodeByteSlice(hasher, left)
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err = wire.EncodeByteSlice(hasher, right)
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if err != nil {
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panic(err)
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}
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return hasher.Sum(nil)
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}
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func SimpleHashFromHashes(hashes [][]byte) []byte {
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// Recursive impl.
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switch len(hashes) {
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case 0:
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return nil
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case 1:
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return hashes[0]
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default:
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left := SimpleHashFromHashes(hashes[:(len(hashes)+1)/2])
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right := SimpleHashFromHashes(hashes[(len(hashes)+1)/2:])
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return SimpleHashFromTwoHashes(left, right)
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}
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}
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// NOTE: Do not implement this, use SimpleHashFromByteslices instead.
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// type Byteser interface { Bytes() []byte }
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// func SimpleHashFromBytesers(items []Byteser) []byte { ... }
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func SimpleHashFromByteslices(bzs [][]byte) []byte {
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hashes := make([][]byte, len(bzs))
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for i, bz := range bzs {
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hashes[i] = SimpleHashFromBytes(bz)
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}
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return SimpleHashFromHashes(hashes)
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}
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func SimpleHashFromBytes(bz []byte) []byte {
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hasher := ripemd160.New()
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hasher.Write(bz)
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return hasher.Sum(nil)
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}
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func SimpleHashFromHashers(items []Hasher) []byte {
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hashes := make([][]byte, len(items))
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for i, item := range items {
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hash := item.Hash()
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hashes[i] = hash
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}
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return SimpleHashFromHashes(hashes)
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}
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func SimpleHashFromMap(m map[string]Hasher) []byte {
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sm := NewSimpleMap()
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for k, v := range m {
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sm.Set(k, v)
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}
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return sm.Hash()
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}
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