path: root/trie/iterator.go

// Copyright 2014 The go-ethereum Authors
// This file is part of the go-ethereum library.
//
// The go-ethereum library is free software: you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// The go-ethereum library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.

package trie

import "bytes"

type Iterator struct {
    trie *Trie

    Key   []byte
    Value []byte
}

func NewIterator(trie *Trie) *Iterator {
    return &Iterator{trie: trie, Key: nil}
}

func (self *Iterator) Next() bool {
    isIterStart := false
    if self.Key == nil {
        isIterStart = true
        self.Key = make([]byte, 32)
    }

    key := remTerm(compactHexDecode(self.Key))
    k := self.next(self.trie.root, key, isIterStart)

    self.Key = []byte(decodeCompact(k))

    return len(k) > 0
}

func (self *Iterator) next(node interface{}, key []byte, isIterStart bool) []byte {
    if node == nil {
        return nil
    }

    switch node := node.(type) {
    case fullNode:
        if len(key) > 0 {
            k := self.next(node[key[0]], key[1:], isIterStart)
            if k != nil {
                return append([]byte{key[0]}, k...)
            }
        }

        var r byte
        if len(key) > 0 {
            r = key[0] + 1
        }

        for i := r; i < 16; i++ {
            k := self.key(node[i])
            if k != nil {
                return append([]byte{i}, k...)
            }
        }

    case shortNode:
        k := remTerm(node.Key)
        if vnode, ok := node.Val.(valueNode); ok {
            switch bytes.Compare([]byte(k), key) {
            case 0:
                if isIterStart {
                    self.Value = vnode
                    return k
                }
            case 1:
                self.Value = vnode
                return k
            }
        } else {
            cnode := node.Val

            var ret []byte
            skey := key[len(k):]
            if bytes.HasPrefix(key, k) {
                ret = self.next(cnode, skey, isIterStart)
            } else if bytes.Compare(k, key[:len(k)]) > 0 {
                return self.key(node)
            }

            if ret != nil {
                return append(k, ret...)
            }
        }

    case hashNode:
        return self.next(self.trie.resolveHash(node), key, isIterStart)
    }
    return nil
}

func (self *Iterator) key(node interface{}) []byte {
    switch node := node.(type) {
    case shortNode:
        // Leaf node
        k := remTerm(node.Key)
        if vnode, ok := node.Val.(valueNode); ok {
            self.Value = vnode
            return k
        }
        return append(k, self.key(node.Val)...)
    case fullNode:
        if node[16] != nil {
            self.Value = node[16].(valueNode)
            return []byte{16}
        }
        for i := 0; i < 16; i++ {
            k := self.key(node[i])
            if k != nil {
                return append([]byte{byte(i)}, k...)
            }
        }
    case hashNode:
        return self.key(self.trie.resolveHash(node))
    }

    return nil
}