Encapsulate CLevelDB iterators cleanly

Conflicts:
	src/leveldb.cpp
	src/leveldb.h
	src/txdb.cpp

src/leveldbwrapper.h

@@ -60,7 +60,64 @@ public:
         batch.Delete(slKey);
     }
 };
+ 
+class CLevelDBIterator
+{
+private:
+    leveldb::Iterator *piter;
 
+public:
+    CLevelDBIterator(leveldb::Iterator *piterIn) : piter(piterIn) {}
+    ~CLevelDBIterator();
+
+    bool Valid();
+
+    void SeekToFirst();
+    void SeekToLast();
+
+    template<typename K> void Seek(const K& key) {
+        CDataStream ssKey(SER_DISK, CLIENT_VERSION);
+        ssKey.reserve(ssKey.GetSerializeSize(key));
+        ssKey << key;
+        leveldb::Slice slKey(&ssKey[0], ssKey.size());
+        piter->Seek(slKey);
+    }
+
+    void Next();
+    void Prev();
+
+    template<typename K> bool GetKey(K& key) {
+        leveldb::Slice slKey = piter->key();
+        try {
+            CDataStream ssKey(slKey.data(), slKey.data() + slKey.size(), SER_DISK, CLIENT_VERSION);
+            ssKey >> key;
+        } catch(std::exception &e) {
+            return false;
+        }
+        return true;
+    }
+
+    unsigned int GetKeySize() {
+        return piter->key().size();
+    }
+
+    template<typename V> bool GetValue(V& value) {
+        leveldb::Slice slValue = piter->value();
+        try {
+            CDataStream ssValue(slValue.data(), slValue.data() + slValue.size(), SER_DISK, CLIENT_VERSION);
+            ssValue >> value;
+        } catch(std::exception &e) {
+            return false;
+        }
+        return true;
+    }
+
+    unsigned int GetValueSize() {
+        return piter->value().size();
+    }
+
+};
+ 
 class CLevelDBWrapper
 {
 private:
@@ -169,11 +226,10 @@ public:
         return WriteBatch(batch, true);
     }
 
-    // not exactly clean encapsulation, but it's easiest for now
-    leveldb::Iterator* NewIterator()
+    CLevelDBIterator *NewIterator() 
+    {
+        return new CLevelDBIterator(pdb->NewIterator(iteroptions));
     {
-        return pdb->NewIterator(iteroptions);
-    }
 
     /**
      * Return true if the database managed by this class contains no entries.