feat(mpt): list all states in a tree

Libplanet.Tests/ImmutableArrayEqualityComparer.cs

@@ -0,0 +1,26 @@
+using System.Collections.Generic;
+using System.Collections.Immutable;
+using System.Linq;
+
+namespace Libplanet.Tests
+{
+    public class ImmutableArrayEqualityComparer<T> : IEqualityComparer<ImmutableArray<T>>
+    {
+        public bool Equals(ImmutableArray<T> x, ImmutableArray<T> y)
+            => x.Length == y.Length && x.SequenceEqual(y);
+
+        public int GetHashCode(ImmutableArray<T> obj)
+        {
+            int code = 0;
+            unchecked
+            {
+                foreach (T el in obj)
+                {
+                    code = (code * 397) ^ el.GetHashCode();
+                }
+            }
+
+            return code;
+        }
+    }
+}

Libplanet.Tests/Store/Trie/MerkleTrieExtensionsTest.cs

@@ -1,4 +1,5 @@
 using System.Collections.Generic;
+using System.Collections.Immutable;
 using System.Linq;
 using System.Security.Cryptography;
 using Bencodex.Types;
@@ -39,5 +40,38 @@ public void DifferentNodes()
             Assert.Equal(trieA.Hash, differentNodes["03"][0].Root);
             Assert.Equal(trieB.Hash, differentNodes["04"][0].Root);
         }
+
+        [Fact]
+        public void ListAllStates()
+        {
+            IKeyValueStore keyValueStore = new MemoryKeyValueStore();
+            MerkleTrie trie = new MerkleTrie(keyValueStore);
+
+            trie.Set(new byte[] { 0x01, }, default(Null));
+            trie.Set(new byte[] { 0x02, }, default(Null));
+            trie.Set(new byte[] { 0x03, }, default(Null));
+            trie.Set(new byte[] { 0x04, }, default(Null));
+            trie.Set(new byte[] { 0xbe, 0xef }, Dictionary.Empty);
+
+            Dictionary<ImmutableArray<byte>, IValue> states =
+                new Dictionary<ImmutableArray<byte>, IValue>(
+                    trie.ListAllStates(), new ImmutableArrayEqualityComparer<byte>());
+            Assert.Equal(5, states.Count);
+            Assert.Equal(default(Null), states[ImmutableArray<byte>.Empty.Add(0x01)]);
+            Assert.Equal(default(Null), states[ImmutableArray<byte>.Empty.Add(0x02)]);
+            Assert.Equal(default(Null), states[ImmutableArray<byte>.Empty.Add(0x03)]);
+            Assert.Equal(default(Null), states[ImmutableArray<byte>.Empty.Add(0x04)]);
+            Assert.Equal(Dictionary.Empty, states[ImmutableArray<byte>.Empty.Add(0xbe).Add(0xef)]);
+
+            trie = (MerkleTrie)trie.Commit();
+            states = new Dictionary<ImmutableArray<byte>, IValue>(
+                trie.ListAllStates(), new ImmutableArrayEqualityComparer<byte>());
+            Assert.Equal(5, states.Count);
+            Assert.Equal(default(Null), states[ImmutableArray<byte>.Empty.Add(0x01)]);
+            Assert.Equal(default(Null), states[ImmutableArray<byte>.Empty.Add(0x02)]);
+            Assert.Equal(default(Null), states[ImmutableArray<byte>.Empty.Add(0x03)]);
+            Assert.Equal(default(Null), states[ImmutableArray<byte>.Empty.Add(0x04)]);
+            Assert.Equal(Dictionary.Empty, states[ImmutableArray<byte>.Empty.Add(0xbe).Add(0xef)]);
+        }
     }
 }

Libplanet/Store/Trie/MerkleTrieExtensions.cs

@@ -40,6 +40,20 @@ public static class MerkleTrieExtensions
                     group.Count() == 1 || !group.All(v => v.Value.Equals(group.First().Value)));
         }
 
+        /// <summary>
+        /// Lists the all states key and the all states in the given <paramref name="merkleTrie"/>.
+        /// </summary>
+        /// <param name="merkleTrie">A trie to discover.</param>
+        /// <returns>All state keys and the all states.</returns>
+        public static IEnumerable<KeyValuePair<ImmutableArray<byte>, IValue>> ListAllStates(
+            this MerkleTrie merkleTrie)
+        {
+            return merkleTrie.IterateNodes().Where(pair => pair.Node is ValueNode).Select(pair =>
+                new KeyValuePair<ImmutableArray<byte>, IValue>(
+                    FromKey(pair.Path),
+                    ((ValueNode)pair.Node).Value));
+        }
+
         private static ImmutableArray<byte> FromKey(ImmutableArray<byte> bytes)
         {
             if (bytes.Length % 2 == 1)