core, trie: new trie

trie/node.go

@@ -16,46 +16,172 @@
 
 package trie
 
-import "fmt"
+import (
+	"fmt"
+	"io"
+	"strings"
+
+	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/rlp"
+)
 
 var indices = []string{"0", "1", "2", "3", "4", "5", "6", "7", "8", "9", "a", "b", "c", "d", "e", "f", "[17]"}
 
-type Node interface {
-	Value() Node
-	Copy(*Trie) Node // All nodes, for now, return them self
-	Dirty() bool
+type node interface {
 	fstring(string) string
-	Hash() interface{}
-	RlpData() interface{}
-	setDirty(dirty bool)
 }
 
-// Value node
-func (self *ValueNode) String() string            { return self.fstring("") }
-func (self *FullNode) String() string             { return self.fstring("") }
-func (self *ShortNode) String() string            { return self.fstring("") }
-func (self *ValueNode) fstring(ind string) string { return fmt.Sprintf("%x ", self.data) }
+type (
+	fullNode  [17]node
+	shortNode struct {
+		Key []byte
+		Val node
+	}
+	hashNode  []byte
+	valueNode []byte
+)
 
-//func (self *HashNode) fstring(ind string) string  { return fmt.Sprintf("< %x > ", self.key) }
-func (self *HashNode) fstring(ind string) string {
-	return fmt.Sprintf("%v", self.trie.trans(self))
-}
+// Pretty printing.
+func (n fullNode) String() string  { return n.fstring("") }
+func (n shortNode) String() string { return n.fstring("") }
+func (n hashNode) String() string  { return n.fstring("") }
+func (n valueNode) String() string { return n.fstring("") }
 
-// Full node
-func (self *FullNode) fstring(ind string) string {
+func (n fullNode) fstring(ind string) string {
 	resp := fmt.Sprintf("[\n%s  ", ind)
-	for i, node := range self.nodes {
+	for i, node := range n {
 		if node == nil {
 			resp += fmt.Sprintf("%s: <nil> ", indices[i])
 		} else {
 			resp += fmt.Sprintf("%s: %v", indices[i], node.fstring(ind+"  "))
 		}
 	}
-
 	return resp + fmt.Sprintf("\n%s] ", ind)
 }
-
-// Short node
-func (self *ShortNode) fstring(ind string) string {
-	return fmt.Sprintf("[ %x: %v ] ", self.key, self.value.fstring(ind+"  "))
+func (n shortNode) fstring(ind string) string {
+	return fmt.Sprintf("{%x: %v} ", n.Key, n.Val.fstring(ind+"  "))
+}
+func (n hashNode) fstring(ind string) string {
+	return fmt.Sprintf("<%x> ", []byte(n))
+}
+func (n valueNode) fstring(ind string) string {
+	return fmt.Sprintf("%x ", []byte(n))
+}
+
+func mustDecodeNode(dbkey, buf []byte) node {
+	n, err := decodeNode(buf)
+	if err != nil {
+		panic(fmt.Sprintf("node %x: %v", dbkey, err))
+	}
+	return n
+}
+
+// decodeNode parses the RLP encoding of a trie node.
+func decodeNode(buf []byte) (node, error) {
+	if len(buf) == 0 {
+		return nil, io.ErrUnexpectedEOF
+	}
+	elems, _, err := rlp.SplitList(buf)
+	if err != nil {
+		return nil, fmt.Errorf("decode error: %v", err)
+	}
+	switch c, _ := rlp.CountValues(elems); c {
+	case 2:
+		n, err := decodeShort(elems)
+		return n, wrapError(err, "short")
+	case 17:
+		n, err := decodeFull(elems)
+		return n, wrapError(err, "full")
+	default:
+		return nil, fmt.Errorf("invalid number of list elements: %v", c)
+	}
+}
+
+func decodeShort(buf []byte) (node, error) {
+	kbuf, rest, err := rlp.SplitString(buf)
+	if err != nil {
+		return nil, err
+	}
+	key := compactDecode(kbuf)
+	if key[len(key)-1] == 16 {
+		// value node
+		val, _, err := rlp.SplitString(rest)
+		if err != nil {
+			return nil, fmt.Errorf("invalid value node: %v", err)
+		}
+		return shortNode{key, valueNode(val)}, nil
+	}
+	r, _, err := decodeRef(rest)
+	if err != nil {
+		return nil, wrapError(err, "val")
+	}
+	return shortNode{key, r}, nil
+}
+
+func decodeFull(buf []byte) (fullNode, error) {
+	var n fullNode
+	for i := 0; i < 16; i++ {
+		cld, rest, err := decodeRef(buf)
+		if err != nil {
+			return n, wrapError(err, fmt.Sprintf("[%d]", i))
+		}
+		n[i], buf = cld, rest
+	}
+	val, _, err := rlp.SplitString(buf)
+	if err != nil {
+		return n, err
+	}
+	if len(val) > 0 {
+		n[16] = valueNode(val)
+	}
+	return n, nil
+}
+
+const hashLen = len(common.Hash{})
+
+func decodeRef(buf []byte) (node, []byte, error) {
+	kind, val, rest, err := rlp.Split(buf)
+	if err != nil {
+		return nil, buf, err
+	}
+	switch {
+	case kind == rlp.List:
+		// 'embedded' node reference. The encoding must be smaller
+		// than a hash in order to be valid.
+		if size := len(buf) - len(rest); size > hashLen {
+			err := fmt.Errorf("oversized embedded node (size is %d bytes, want size < %d)", size, hashLen)
+			return nil, buf, err
+		}
+		n, err := decodeNode(buf)
+		return n, rest, err
+	case kind == rlp.String && len(val) == 0:
+		// empty node
+		return nil, rest, nil
+	case kind == rlp.String && len(val) == 32:
+		return hashNode(val), rest, nil
+	default:
+		return nil, nil, fmt.Errorf("invalid RLP string size %d (want 0 or 32)", len(val))
+	}
+}
+
+// wraps a decoding error with information about the path to the
+// invalid child node (for debugging encoding issues).
+type decodeError struct {
+	what  error
+	stack []string
+}
+
+func wrapError(err error, ctx string) error {
+	if err == nil {
+		return nil
+	}
+	if decErr, ok := err.(*decodeError); ok {
+		decErr.stack = append(decErr.stack, ctx)
+		return decErr
+	}
+	return &decodeError{err, []string{ctx}}
+}
+
+func (err *decodeError) Error() string {
+	return fmt.Sprintf("%v (decode path: %s)", err.what, strings.Join(err.stack, "<-"))
 }