Added a trie iterator

ethutil/trie.go

@@ -70,6 +70,12 @@ func (cache *Cache) Get(key []byte) *Value {
 	return value
 }
 
+func (cache *Cache) Delete(key []byte) {
+	delete(cache.nodes, string(key))
+
+	cache.db.Delete(key)
+}
+
 func (cache *Cache) Commit() {
 	// Don't try to commit if it isn't dirty
 	if !cache.IsDirty {
@@ -413,3 +419,82 @@ func (t *Trie) Copy() *Trie {
 
 	return trie
 }
+
+type TrieIterator struct {
+	trie  *Trie
+	key   string
+	value string
+
+	shas   [][]byte
+	values []string
+}
+
+func (t *Trie) NewIterator() *TrieIterator {
+	return &TrieIterator{trie: t}
+}
+
+// Some time in the near future this will need refactoring :-)
+// XXX Note to self, IsSlice == inline node. Str == sha3 to node
+func (it *TrieIterator) workNode(currentNode *Value) {
+	if currentNode.Len() == 2 {
+		k := CompactDecode(currentNode.Get(0).Str())
+
+		if currentNode.Get(1).IsSlice() {
+			it.workNode(currentNode.Get(1))
+		} else {
+			if k[len(k)-1] == 16 {
+				it.values = append(it.values, currentNode.Get(1).Str())
+			} else {
+				it.shas = append(it.shas, currentNode.Get(1).Bytes())
+				it.getNode(currentNode.Get(1).Bytes())
+			}
+		}
+	} else {
+		for i := 0; i < currentNode.Len(); i++ {
+			if i == 16 && currentNode.Get(i).Len() != 0 {
+				it.values = append(it.values, currentNode.Get(i).Str())
+			} else {
+				if currentNode.Get(i).IsSlice() {
+					it.workNode(currentNode.Get(i))
+				} else {
+					val := currentNode.Get(i).Str()
+					if val != "" {
+						it.shas = append(it.shas, currentNode.Get(1).Bytes())
+						it.getNode([]byte(val))
+					}
+				}
+			}
+		}
+	}
+}
+
+func (it *TrieIterator) getNode(node []byte) {
+	currentNode := it.trie.cache.Get(node)
+	it.workNode(currentNode)
+}
+
+func (it *TrieIterator) Collect() [][]byte {
+	if it.trie.Root == "" {
+		return nil
+	}
+
+	it.getNode(NewValue(it.trie.Root).Bytes())
+
+	return it.shas
+}
+
+func (it *TrieIterator) Purge() int {
+	shas := it.Collect()
+	for _, sha := range shas {
+		it.trie.cache.Delete(sha)
+	}
+	return len(it.values)
+}
+
+func (it *TrieIterator) Key() string {
+	return ""
+}
+
+func (it *TrieIterator) Value() string {
+	return ""
+}

ethutil/trie_test.go

 package ethutil
 
 import (
+	"fmt"
 	"reflect"
 	"testing"
 )
@@ -21,6 +22,10 @@ func (db *MemDatabase) Put(key []byte, value []byte) {
 func (db *MemDatabase) Get(key []byte) ([]byte, error) {
 	return db.db[string(key)], nil
 }
+func (db *MemDatabase) Delete(key []byte) error {
+	delete(db.db, string(key))
+	return nil
+}
 func (db *MemDatabase) Print()              {}
 func (db *MemDatabase) Close()              {}
 func (db *MemDatabase) LastKnownTD() []byte { return nil }
@@ -148,3 +153,22 @@ func TestTrieDeleteWithValue(t *testing.T) {
 	}
 
 }
+
+func TestTrieIterator(t *testing.T) {
+	_, trie := New()
+	trie.Update("c", LONG_WORD)
+	trie.Update("ca", LONG_WORD)
+	trie.Update("cat", LONG_WORD)
+
+	it := trie.NewIterator()
+	fmt.Println("purging")
+	fmt.Println("len =", it.Purge())
+	/*
+		for it.Next() {
+			k := it.Key()
+			v := it.Value()
+
+			fmt.Println(k, v)
+		}
+	*/
+}