nullable Storage.Get

src/Neo.SmartContract.Framework/ByteString.cs

@@ -54,11 +54,6 @@ IEnumerator IEnumerable.GetEnumerator()
         [OpCode(OpCode.CONVERT, StackItemType.ByteString)]
         public static extern explicit operator ByteString(byte[] buffer);
 
-        [OpCode(OpCode.DUP)]
-        [OpCode(OpCode.ISNULL)]
-        [OpCode(OpCode.JMPIFNOT, "0x04")]
-        [OpCode(OpCode.DROP)]
-        [OpCode(OpCode.PUSH0)]
         [OpCode(OpCode.CONVERT, StackItemType.Integer)]
         public static extern explicit operator BigInteger(ByteString text);
 

src/Neo.SmartContract.Framework/Neo.SmartContract.Framework.csproj

@@ -1,6 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
+    <Nullable>enable</Nullable>
     <TargetFramework>net8.0</TargetFramework>
     <AssemblyTitle>Neo.SmartContract.Framework</AssemblyTitle>
     <AssemblyName>Neo.SmartContract.Framework</AssemblyName>

src/Neo.SmartContract.Framework/Nep17Token.cs

@@ -21,7 +21,7 @@ namespace Neo.SmartContract.Framework
     [ContractPermission(Permission.Any, Method.OnNEP17Payment)]
     public abstract class Nep17Token : TokenContract
     {
-        public delegate void OnTransferDelegate(UInt160 from, UInt160 to, BigInteger amount);
+        public delegate void OnTransferDelegate(UInt160? from, UInt160? to, BigInteger amount);
 
         [DisplayName("Transfer")]
         public static event OnTransferDelegate OnTransfer;
@@ -64,7 +64,7 @@ protected static void Burn(UInt160 account, BigInteger amount)
             PostTransfer(account, null, amount, null);
         }
 
-        protected static void PostTransfer(UInt160 from, UInt160 to, BigInteger amount, object data)
+        protected static void PostTransfer(UInt160? from, UInt160? to, BigInteger amount, object? data)
         {
             OnTransfer(from, to, amount);
             if (to is not null && ContractManagement.GetContract(to) is not null)

src/Neo.SmartContract.Framework/Services/Contract.cs

@@ -40,7 +40,7 @@ public class Contract
         public readonly ContractManifest Manifest;
 
         [Syscall("System.Contract.Call")]
-        public static extern object Call(UInt160 scriptHash, string method, CallFlags flags, params object[] args);
+        public static extern object Call(UInt160 scriptHash, string method, CallFlags flags, params object[]? args);
 
         [Syscall("System.Contract.GetCallFlags")]
         public static extern CallFlags GetCallFlags();

src/Neo.SmartContract.Framework/Services/Storage.cs

@@ -37,13 +37,13 @@ public static extern StorageContext CurrentReadOnlyContext
         /// Returns the value corresponding to the given key for Storage context (faster: generates opcode directly)
         /// </summary>
         [Syscall("System.Storage.Get")]
-        public static extern ByteString Get(StorageContext context, ByteString key);
+        public static extern ByteString? Get(StorageContext context, ByteString key);
 
         /// <summary>
         /// Returns the value corresponding to the given key for Storage context (faster: generates opcode directly)
         /// </summary>
         [Syscall("System.Storage.Get")]
-        public static extern ByteString Get(StorageContext context, byte[] key);
+        public static extern ByteString? Get(StorageContext context, byte[] key);
 
         /// <summary>
         /// Writes the key/value pair for the given Storage context (faster: generates opcode directly)
@@ -100,8 +100,8 @@ public static extern StorageContext CurrentReadOnlyContext
         public static extern Iterator Find(StorageContext context, byte[] prefix, FindOptions options = FindOptions.None);
 
         #region Interface with default Context
-        public static ByteString Get(ByteString key) => Get(CurrentReadOnlyContext, key);
-        public static ByteString Get(byte[] key) => Get(CurrentReadOnlyContext, key);
+        public static ByteString? Get(ByteString key) => Get(CurrentReadOnlyContext, key);
+        public static ByteString? Get(byte[] key) => Get(CurrentReadOnlyContext, key);
         public static void Put(ByteString key, ByteString value) => Put(CurrentContext, key, value);
         public static void Put(byte[] key, ByteString value) => Put(CurrentContext, key, value);
         public static void Put(byte[] key, byte[] value) => Put(CurrentContext, key, value);

src/Neo.SmartContract.Framework/Services/StorageMap.cs

@@ -23,7 +23,7 @@ public class StorageMap
         private readonly StorageContext context;
         private readonly byte[] prefix;
 
-        public extern ByteString this[ByteString key]
+        public extern ByteString? this[ByteString key]
         {
             [CallingConvention(CallingConvention.Cdecl)]
             [OpCode(OpCode.UNPACK)]
@@ -43,7 +43,7 @@ public extern ByteString this[ByteString key]
             set;
         }
 
-        public extern ByteString this[byte[] key]
+        public extern ByteString? this[byte[] key]
         {
             [CallingConvention(CallingConvention.Cdecl)]
             [OpCode(OpCode.UNPACK)]
@@ -112,7 +112,9 @@ public extern ByteString this[byte[] key]
         [OpCode(OpCode.CAT)]
         [OpCode(OpCode.SWAP)]
         [Syscall("System.Storage.Get")]
-        public extern ByteString Get(ByteString key);
+#pragma warning disable CS8632 // The annotation for nullable reference types should only be used in code within a '#nullable' annotations context.
+        public extern ByteString? Get(ByteString key);
+#pragma warning restore CS8632 // The annotation for nullable reference types should only be used in code within a '#nullable' annotations context.
 
         [CallingConvention(CallingConvention.Cdecl)]
         [OpCode(OpCode.UNPACK)]
@@ -204,7 +206,9 @@ public extern ByteString this[byte[] key]
         [OpCode(OpCode.CAT)]
         [OpCode(OpCode.SWAP)]
         [Syscall("System.Storage.Get")]
-        public extern ByteString Get(byte[] key);
+#pragma warning disable CS8632 // The annotation for nullable reference types should only be used in code within a '#nullable' annotations context.
+        public extern ByteString? Get(byte[] key);
+#pragma warning restore CS8632 // The annotation for nullable reference types should only be used in code within a '#nullable' annotations context.
 
         [CallingConvention(CallingConvention.Cdecl)]
         [OpCode(OpCode.UNPACK)]
@@ -289,16 +293,16 @@ public extern ByteString this[byte[] key]
         [OpCode(OpCode.CONVERT, StackItemType.Integer)]
         public extern BigInteger GetIntegerOrZero(byte[] key);
 
-        public object GetObject(ByteString key)
+        public object? GetObject(ByteString key)
         {
-            ByteString value = Get(key);
+            ByteString? value = Get(key);
             if (value is null) return null;
             return StdLib.Deserialize(value);
         }
 
-        public object GetObject(byte[] key)
+        public object? GetObject(byte[] key)
         {
-            ByteString value = Get(key);
+            ByteString? value = Get(key);
             if (value is null) return null;
             return StdLib.Deserialize(value);
         }

src/Neo.SmartContract.Framework/TokenContract.cs

@@ -17,35 +17,49 @@ namespace Neo.SmartContract.Framework
 {
     public abstract class TokenContract : SmartContract
     {
-        protected const byte Prefix_TotalSupply = 0x00;
-        protected const byte Prefix_Balance = 0x01;
+        protected static readonly ByteString Prefix_TotalSupply = "\x00";
+        protected static readonly ByteString Prefix_Balance = "\x01";
 
         public abstract string Symbol { [Safe] get; }
 
         public abstract byte Decimals { [Safe] get; }
 
-        [Stored(Prefix_TotalSupply)]
-        public static BigInteger TotalSupply { [Safe] get; protected set; }
+        public static BigInteger TotalSupply
+        {
+            [Safe]
+            get
+            {
+                ByteString? stored = Storage.Get(Prefix_TotalSupply);
+                return stored != null ? (BigInteger)stored : 0;
+            }
+            protected set
+            {
+                Storage.Put(Prefix_TotalSupply, value);
+            }
+        }
 
         [Safe]
         public static BigInteger BalanceOf(UInt160 owner)
         {
             if (owner is null || !owner.IsValid)
                 throw new Exception("The argument \"owner\" is invalid.");
-            StorageMap balanceMap = new(Storage.CurrentContext, Prefix_Balance);
-            return (BigInteger)balanceMap[owner];
+            ByteString? balanceStored = Storage.Get(Prefix_Balance + owner);
+            return balanceStored != null ? (BigInteger)balanceStored : 0;
         }
 
         protected static bool UpdateBalance(UInt160 owner, BigInteger increment)
         {
-            StorageMap balanceMap = new(Storage.CurrentContext, Prefix_Balance);
-            BigInteger balance = (BigInteger)balanceMap[owner];
+            StorageContext currentContext = Storage.CurrentContext;
+            ByteString ownerKey = Prefix_Balance + owner;
+            ByteString? balanceStored = Storage.Get(currentContext, ownerKey);
+            BigInteger balance = balanceStored != null ? (BigInteger)balanceStored : 0;
             balance += increment;
-            if (balance < 0) return false;
-            if (balance.IsZero)
-                balanceMap.Delete(owner);
+            if (balance < 0)
+                return false;
+            if (balance == 0)
+                Storage.Delete(currentContext, ownerKey);
             else
-                balanceMap.Put(owner, balance);
+                Storage.Put(currentContext, ownerKey, balance);
             return true;
         }
     }