add new tests; create description;

Author: begmaroman

README.md

@@ -1,3 +1,108 @@
-# MPT - Merkle Patricia Tries
+# MPT - Modified Merkle Patricia Tries
 
-Simple implementation of Merkle Patricia Tries on GoLang.
+Simple implementation of Modified Merkle Patricia Tries on GoLang.
+
+## Usage
+
+1. Create the Trie:
+
+    - With empty root node:
+    
+    ```go
+    trie := mpt.NewEmptyTrie()
+    ```
+
+    - With branch root node:
+    
+    ```go
+    nd := node.NewBranchNode()
+    trie := mpt.NewTrie(nd)
+    ```
+
+    - With extension root node:
+    
+    ```go
+    nd := node.NewExtensionNode(nil, nil)
+    trie := mpt.NewTrie(nd)
+    ```
+    
+2. Add key/value pair:
+    
+```go
+key := []byte("key")
+val := []byte("val")
+
+// create new trie and try add key/value pair
+trie := mpt.NewEmptyTrie()
+if ok := trie.Put(key, val); !ok {
+	// key/pair not added
+}
+
+```
+
+3. Get data by key:
+    
+```go
+key := []byte("key")
+val := []byte("val")
+
+// create new trie and try add key/value pair
+trie := mpt.NewEmptyTrie()
+if ok := trie.Put(key, val); !ok {
+	// key/pair not added
+}
+
+// some logic...
+
+// try to get data by key
+getVal, ok := trie.Get(key)
+if !ok {
+	// key/pair not added
+}
+
+```
+    
+4. Update data by key:
+    
+```go
+// initialize data
+key := []byte("key")
+val := []byte("val")
+
+// create new trie and try add key/value pair
+trie := mpt.NewEmptyTrie()
+if ok := trie.Put(key, val); !ok {
+	// key/pair not added
+}
+
+// some logic...
+
+// try to update value by key
+newVal := []byte("updated value")
+if ok := trie.Update(key, newVal); !ok {
+	// data not updated
+}
+
+```
+    
+5. Delete data by key:
+    
+```go
+// initialize data
+key := []byte("key")
+val := []byte("val")
+
+// create new trie and try add key/value pair
+trie := mpt.NewEmptyTrie()
+if ok := trie.Put(key, val); !ok {
+	// key/pair not added
+}
+
+// some logic...
+
+// try to delete data by key
+if ok := trie.Delete(key, newVal); !ok {
+	// data not deleted
+}
+
+```

database.go

@@ -15,7 +15,7 @@ func NewDatabase() *Database {
 	return &Database{}
 }
 
-func (db *Database) GetNode(hash enc.Hash, cGen uint16) node.Node {
+func (db *Database) GetNode(hash enc.Hash) node.Node {
 	return nil
 }
 

node/branch_test.go

@@ -0,0 +1,55 @@
+package node
+
+import (
+	"bytes"
+	"reflect"
+	"testing"
+
+	"github.com/begmaroman/mpt/enc"
+)
+
+func TestBranchNode_Find(t *testing.T) {
+	key, value := enc.BytesToHex([]byte("key")), []byte("value")
+
+	nd := NewBranchNode()
+	nd.Children[key[0]] = NewExtensionNode(key[1:], NewLeafNode(value))
+
+	rVal, rNd, ok := nd.Find(key)
+	if !ok {
+		t.Error("added data not found")
+		return
+	}
+
+	if !bytes.Equal(rVal, value) {
+		t.Errorf("invalid value: expected %s got %s", value, rVal)
+	}
+
+	if !reflect.DeepEqual(nd, rNd) {
+		t.Errorf("invalid node: expected %#v got %#v", nd, rNd)
+	}
+}
+
+func TestBranchNode_PutAndCheck(t *testing.T) {
+	key, value := enc.BytesToHex([]byte("key")), []byte("value")
+
+	nd := NewBranchNode()
+	newNode, ok := nd.Put(key, NewLeafNode(value))
+	if !ok {
+		t.Error("put failed")
+		return
+	}
+
+	rVal, rNd, ok := newNode.Find(key)
+	if !ok {
+		t.Error("added data not found")
+		return
+	}
+
+	if !bytes.Equal(rVal, value) {
+		t.Errorf("invalid value: expected %s got %s", value, rVal)
+	}
+
+	if !reflect.DeepEqual(newNode, rNd) {
+		t.Errorf("invalid node: expected %#v got %#v", newNode, rNd)
+	}
+}

node/extension.go

@@ -44,7 +44,7 @@ func (e *ExtensionNode) Find(key []byte) ([]byte, Node, bool) {
 
 func (e *ExtensionNode) Put(key []byte, value Node) (Node, bool) {
 	if e.Key == nil {
-
+		return NewExtensionNode(key, value), true
 	}
 
 	matchKey := enc.PrefixLen(key, e.Key)

trie.go

@@ -14,8 +14,6 @@ var (
 type Trie struct {
 	db   *Database
 	node node.Node
-
-	cGen, cLimit uint16
 }
 
 func NewTrie(node node.Node) *Trie {
@@ -24,6 +22,10 @@ func NewTrie(node node.Node) *Trie {
 	}
 }
 
+func NewEmptyTrie() *Trie {
+	return &Trie{}
+}
+
 // Hash calculate and return hash of the tree
 func (t *Trie) Hash() (enc.Hash, error) {
 	bHash, cached, err := t.hashRoot(nil)
@@ -144,7 +146,7 @@ func (t *Trie) resolve(n node.Node, prefix []byte) (node.Node, error) {
 func (t *Trie) resolveHash(n node.HashNode, prefix []byte) (node.Node, error) {
 	hash := n.Hash() // get hash of HashNode
 
-	if nd := t.db.GetNode(hash, t.cGen); nd != nil { // lookup node.Node in database
+	if nd := t.db.GetNode(hash); nd != nil { // lookup node.Node in database
 		return nd, nil // return node.Node from database if exist
 	}
 

trie_test.go

@@ -246,7 +246,7 @@ func TestTrie_PutDeleteAndCheck(t *testing.T) {
 	}
 }
 
-func TestTrie_CustomStartNode(t *testing.T) {
+func TestTrie_CustomStartNode_BranchNode_Empty(t *testing.T) {
 	key, val := []byte("test"), []byte("test value")
 
 	trie := mpt.NewTrie(node.NewBranchNode())
@@ -262,6 +262,22 @@ func TestTrie_CustomStartNode(t *testing.T) {
 	}
 }
 
+func TestTrie_CustomStartNode_ExtensionNode_Empty(t *testing.T) {
+	key, val := []byte("test"), []byte("test value")
+
+	trie := mpt.NewTrie(node.NewExtensionNode(nil, nil))
+	trie.Put(key, val)
+
+	rVal, ok := trie.Get([]byte("test"))
+	if !ok {
+		t.Errorf("lookup failed for key %s", key)
+	}
+
+	if !bytes.Equal(rVal, val) {
+		t.Errorf("check added: invalid value: expected %s got %s", val, rVal)
+	}
+}
+
 // Benchmarks
 func BenchmarkTrie_Get(b *testing.B) {
 	key, val := []byte("tolongwseb;kjnwkjlevnoknbkomnrwobnwotrh34y6onyo"), []byte("lwebniopwjgnipwuhgpv wrhtpovm rhiopwerhgpowuihnopwrntgmopkrtmvport uiwthgipurthg puti")