vm: implement ISTYPE opcode

Also make StackItemType public and reorder it according to NEO3.

pkg/vm/context.go

@@ -101,7 +101,7 @@ func (c *Context) Next() (opcode.Opcode, []byte, error) {
 		}
 	case opcode.JMP, opcode.JMPIF, opcode.JMPIFNOT, opcode.JMPEQ, opcode.JMPNE,
 		opcode.JMPGT, opcode.JMPGE, opcode.JMPLT, opcode.JMPLE,
-		opcode.CALL:
+		opcode.CALL, opcode.ISTYPE:
 		numtoread = 1
 	case opcode.JMPL, opcode.JMPIFL, opcode.JMPIFNOTL, opcode.JMPEQL, opcode.JMPNEL,
 		opcode.JMPGTL, opcode.JMPGEL, opcode.JMPLTL, opcode.JMPLEL,
@@ -186,6 +186,9 @@ func (c *Context) TryInteger() (*big.Int, error) {
 	return nil, errors.New("can't convert Context to Integer")
 }
 
+// Type implements StackItem interface.
+func (c *Context) Type() StackItemType { panic("Context cannot appear on evaluation stack") }
+
 // Equals implements StackItem interface.
 func (c *Context) Equals(s StackItem) bool {
 	return c == s

pkg/vm/opcode/opcode.go

@@ -162,6 +162,9 @@ const (
 	REMOVE       Opcode = 0xD2
 	CLEARITEMS   Opcode = 0xD3
 
+	// Types
+	ISTYPE Opcode = 0xD9
+
 	// Exceptions
 	THROW      Opcode = 0xF0
 	THROWIFNOT Opcode = 0xF1

pkg/vm/serialization.go

@@ -7,17 +7,61 @@ import (
 	"github.com/nspcc-dev/neo-go/pkg/vm/emit"
 )
 
-type stackItemType byte
+// StackItemType represents type of the stack item.
+type StackItemType byte
 
+// This block defines all known stack item types.
 const (
-	byteArrayT stackItemType = 0x00
-	booleanT   stackItemType = 0x01
-	integerT   stackItemType = 0x02
-	arrayT     stackItemType = 0x80
-	structT    stackItemType = 0x81
-	mapT       stackItemType = 0x82
+	AnyT       StackItemType = 0x00
+	PointerT   StackItemType = 0x10
+	BooleanT   StackItemType = 0x20
+	IntegerT   StackItemType = 0x21
+	ByteArrayT StackItemType = 0x28
+	BufferT    StackItemType = 0x30
+	ArrayT     StackItemType = 0x40
+	StructT    StackItemType = 0x41
+	MapT       StackItemType = 0x48
+	InteropT   StackItemType = 0x60
 )
 
+// String implements fmt.Stringer interface.
+func (t StackItemType) String() string {
+	switch t {
+	case AnyT:
+		return "Any"
+	case PointerT:
+		return "Pointer"
+	case BooleanT:
+		return "Boolean"
+	case IntegerT:
+		return "Integer"
+	case ByteArrayT:
+		return "ByteArray"
+	case BufferT:
+		return "Buffer"
+	case ArrayT:
+		return "Array"
+	case StructT:
+		return "Struct"
+	case MapT:
+		return "Map"
+	case InteropT:
+		return "Interop"
+	default:
+		return "INVALID"
+	}
+}
+
+// IsValid checks if s is a well defined stack item type.
+func (t StackItemType) IsValid() bool {
+	switch t {
+	case AnyT, PointerT, BooleanT, IntegerT, ByteArrayT, BufferT, ArrayT, StructT, MapT, InteropT:
+		return true
+	default:
+		return false
+	}
+}
+
 // SerializeItem encodes given StackItem into the byte slice.
 func SerializeItem(item StackItem) ([]byte, error) {
 	w := io.NewBufBinWriter()
@@ -43,13 +87,13 @@ func serializeItemTo(item StackItem, w *io.BinWriter, seen map[StackItem]bool) {
 
 	switch t := item.(type) {
 	case *ByteArrayItem:
-		w.WriteBytes([]byte{byte(byteArrayT)})
+		w.WriteBytes([]byte{byte(ByteArrayT)})
 		w.WriteVarBytes(t.value)
 	case *BoolItem:
-		w.WriteBytes([]byte{byte(booleanT)})
+		w.WriteBytes([]byte{byte(BooleanT)})
 		w.WriteBool(t.value)
 	case *BigIntegerItem:
-		w.WriteBytes([]byte{byte(integerT)})
+		w.WriteBytes([]byte{byte(IntegerT)})
 		w.WriteVarBytes(emit.IntToBytes(t.value))
 	case *InteropItem:
 		w.Err = errors.New("interop item can't be serialized")
@@ -58,9 +102,9 @@ func serializeItemTo(item StackItem, w *io.BinWriter, seen map[StackItem]bool) {
 
 		_, isArray := t.(*ArrayItem)
 		if isArray {
-			w.WriteBytes([]byte{byte(arrayT)})
+			w.WriteBytes([]byte{byte(ArrayT)})
 		} else {
-			w.WriteBytes([]byte{byte(structT)})
+			w.WriteBytes([]byte{byte(StructT)})
 		}
 
 		arr := t.Value().([]StackItem)
@@ -71,7 +115,7 @@ func serializeItemTo(item StackItem, w *io.BinWriter, seen map[StackItem]bool) {
 	case *MapItem:
 		seen[item] = true
 
-		w.WriteBytes([]byte{byte(mapT)})
+		w.WriteBytes([]byte{byte(MapT)})
 		w.WriteVarUint(uint64(len(t.value)))
 		for i := range t.value {
 			serializeItemTo(t.value[i].Key, w, seen)
@@ -100,31 +144,31 @@ func DecodeBinaryStackItem(r *io.BinReader) StackItem {
 		return nil
 	}
 
-	switch stackItemType(t) {
-	case byteArrayT:
+	switch StackItemType(t) {
+	case ByteArrayT:
 		data := r.ReadVarBytes()
 		return NewByteArrayItem(data)
-	case booleanT:
+	case BooleanT:
 		var b = r.ReadBool()
 		return NewBoolItem(b)
-	case integerT:
+	case IntegerT:
 		data := r.ReadVarBytes()
 		num := emit.BytesToInt(data)
 		return &BigIntegerItem{
 			value: num,
 		}
-	case arrayT, structT:
+	case ArrayT, StructT:
 		size := int(r.ReadVarUint())
 		arr := make([]StackItem, size)
 		for i := 0; i < size; i++ {
 			arr[i] = DecodeBinaryStackItem(r)
 		}
 
-		if stackItemType(t) == arrayT {
+		if StackItemType(t) == ArrayT {
 			return &ArrayItem{value: arr}
 		}
 		return &StructItem{value: arr}
-	case mapT:
+	case MapT:
 		size := int(r.ReadVarUint())
 		m := NewMapItem()
 		for i := 0; i < size; i++ {

pkg/vm/stack_item.go

@@ -28,6 +28,8 @@ type StackItem interface {
 	Equals(s StackItem) bool
 	// ToContractParameter converts StackItem to smartcontract.Parameter
 	ToContractParameter(map[StackItem]bool) smartcontract.Parameter
+	// Type returns stack item type.
+	Type() StackItemType
 }
 
 func makeStackItem(v interface{}) StackItem {
@@ -177,6 +179,9 @@ func (i *StructItem) ToContractParameter(seen map[StackItem]bool) smartcontract.
 	}
 }
 
+// Type implements StackItem interface.
+func (i *StructItem) Type() StackItemType { return StructT }
+
 // Clone returns a Struct with all Struct fields copied by value.
 // Array fields are still copied by reference.
 func (i *StructItem) Clone() *StructItem {
@@ -235,6 +240,9 @@ func (i NullItem) ToContractParameter(map[StackItem]bool) smartcontract.Paramete
 	}
 }
 
+// Type implements StackItem interface.
+func (i NullItem) Type() StackItemType { return AnyT }
+
 // BigIntegerItem represents a big integer on the stack.
 type BigIntegerItem struct {
 	value *big.Int
@@ -300,6 +308,9 @@ func (i *BigIntegerItem) ToContractParameter(map[StackItem]bool) smartcontract.P
 	}
 }
 
+// Type implements StackItem interface.
+func (i *BigIntegerItem) Type() StackItemType { return IntegerT }
+
 // MarshalJSON implements the json.Marshaler interface.
 func (i *BigIntegerItem) MarshalJSON() ([]byte, error) {
 	return json.Marshal(i.value)
@@ -380,6 +391,9 @@ func (i *BoolItem) ToContractParameter(map[StackItem]bool) smartcontract.Paramet
 	}
 }
 
+// Type implements StackItem interface.
+func (i *BoolItem) Type() StackItemType { return BooleanT }
+
 // ByteArrayItem represents a byte array on the stack.
 type ByteArrayItem struct {
 	value []byte
@@ -442,6 +456,9 @@ func (i *ByteArrayItem) ToContractParameter(map[StackItem]bool) smartcontract.Pa
 	}
 }
 
+// Type implements StackItem interface.
+func (i *ByteArrayItem) Type() StackItemType { return ByteArrayT }
+
 // ArrayItem represents a new ArrayItem object.
 type ArrayItem struct {
 	value []StackItem
@@ -506,6 +523,9 @@ func (i *ArrayItem) ToContractParameter(seen map[StackItem]bool) smartcontract.P
 	}
 }
 
+// Type implements StackItem interface.
+func (i *ArrayItem) Type() StackItemType { return ArrayT }
+
 // MapElement is a key-value pair of StackItems.
 type MapElement struct {
 	Key   StackItem
@@ -591,6 +611,9 @@ func (i *MapItem) ToContractParameter(seen map[StackItem]bool) smartcontract.Par
 	}
 }
 
+// Type implements StackItem interface.
+func (i *MapItem) Type() StackItemType { return MapT }
+
 // Add adds key-value pair to the map.
 func (i *MapItem) Add(key, value StackItem) {
 	if !isValidMapKey(key) {
@@ -678,6 +701,9 @@ func (i *InteropItem) ToContractParameter(map[StackItem]bool) smartcontract.Para
 	}
 }
 
+// Type implements StackItem interface.
+func (i *InteropItem) Type() StackItemType { return InteropT }
+
 // MarshalJSON implements the json.Marshaler interface.
 func (i *InteropItem) MarshalJSON() ([]byte, error) {
 	return json.Marshal(i.value)

pkg/vm/vm.go

@@ -565,6 +565,10 @@ func (v *VM) execute(ctx *Context, op opcode.Opcode, parameter []byte) (err erro
 		res := v.estack.Pop().value.Equals(NullItem{})
 		v.estack.PushVal(res)
 
+	case opcode.ISTYPE:
+		res := v.estack.Pop().Item()
+		v.estack.PushVal(res.Type() == StackItemType(parameter[0]))
+
 	// Stack operations.
 	case opcode.TOALTSTACK:
 		v.astack.Push(v.estack.Pop())

pkg/vm/vm_test.go

@@ -216,6 +216,46 @@ func TestISNULL(t *testing.T) {
 	})
 }
 
+func testISTYPE(t *testing.T, result bool, typ StackItemType, item StackItem) {
+	prog := []byte{byte(opcode.ISTYPE), byte(typ)}
+	v := load(prog)
+	v.estack.PushVal(item)
+	runVM(t, v)
+	require.Equal(t, 1, v.estack.Len())
+	require.Equal(t, result, v.estack.Pop().Bool())
+}
+
+func TestISTYPE(t *testing.T) {
+	t.Run("Integer", func(t *testing.T) {
+		testISTYPE(t, true, IntegerT, NewBigIntegerItem(big.NewInt(42)))
+		testISTYPE(t, false, IntegerT, NewByteArrayItem([]byte{}))
+	})
+	t.Run("Boolean", func(t *testing.T) {
+		testISTYPE(t, true, BooleanT, NewBoolItem(true))
+		testISTYPE(t, false, BooleanT, NewByteArrayItem([]byte{}))
+	})
+	t.Run("ByteArray", func(t *testing.T) {
+		testISTYPE(t, true, ByteArrayT, NewByteArrayItem([]byte{}))
+		testISTYPE(t, false, ByteArrayT, NewBigIntegerItem(big.NewInt(42)))
+	})
+	t.Run("Array", func(t *testing.T) {
+		testISTYPE(t, true, ArrayT, NewArrayItem([]StackItem{}))
+		testISTYPE(t, false, ArrayT, NewByteArrayItem([]byte{}))
+	})
+	t.Run("Struct", func(t *testing.T) {
+		testISTYPE(t, true, StructT, NewStructItem([]StackItem{}))
+		testISTYPE(t, false, StructT, NewByteArrayItem([]byte{}))
+	})
+	t.Run("Map", func(t *testing.T) {
+		testISTYPE(t, true, MapT, NewMapItem())
+		testISTYPE(t, false, MapT, NewByteArrayItem([]byte{}))
+	})
+	t.Run("Interop", func(t *testing.T) {
+		testISTYPE(t, true, InteropT, NewInteropItem(42))
+		testISTYPE(t, false, InteropT, NewByteArrayItem([]byte{}))
+	})
+}
+
 // appendBigStruct returns a program which:
 // 1. pushes size Structs on stack
 // 2. packs them into a new struct
@@ -685,7 +725,7 @@ func TestSerializeMap(t *testing.T) {
 }
 
 func TestSerializeMapCompat(t *testing.T) {
-	resHex := "820100036b6579000576616c7565"
+	resHex := "480128036b6579280576616c7565"
 	res, err := hex.DecodeString(resHex)
 	require.NoError(t, err)