path: root/trie/iterator.go

// Copyright 2014 The go-ethereum Authors
// This file is part of the go-ethereum library.
//
// go-ethereum 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 {
    self.trie.mu.Lock()
    defer self.trie.mu.Unlock()

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

    key := RemTerm(CompactHexDecode(string(self.Key)))
    k := self.next(self.trie.root, key, isIterStart)

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

    return len(k) > 0
}

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

    switch node := node.(type) {
    case *FullNode:
        if len(key) > 0 {
            k := self.next(node.branch(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.branch(byte(i)))
            if k != nil {
                return append([]byte{i}, k...)
            }
        }

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

            var ret []byte
            skey := key[len(k):]
            if BeginsWith(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...)
            }
        }
    }

    return nil
}

func (self *Iterator) key(node Node) []byte {
    switch node := node.(type) {
    case *ShortNode:
        // Leaf node
        if vnode, ok := node.Value().(*ValueNode); ok {
            k := RemTerm(node.Key())
            self.Value = vnode.Val()

            return k
        } else {
            k := RemTerm(node.Key())
            return append(k, self.key(node.Value())...)
        }
    case *FullNode:
        if node.Value() != nil {
            self.Value = node.Value().(*ValueNode).Val()

            return []byte{16}
        }

        for i := 0; i < 16; i++ {
            k := self.key(node.branch(byte(i)))
            if k != nil {
                return append([]byte{byte(i)}, k...)
            }
        }
    }

    return nil
}