vm: implements CONVERT opcode

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.ISTYPE, opcode.NEWARRAYT:
+		opcode.CALL, opcode.ISTYPE, opcode.CONVERT, opcode.NEWARRAYT:
 		numtoread = 1
 	case opcode.JMPL, opcode.JMPIFL, opcode.JMPIFNOTL, opcode.JMPEQL, opcode.JMPNEL,
 		opcode.JMPGTL, opcode.JMPGEL, opcode.JMPLTL, opcode.JMPLEL,
@@ -192,6 +192,11 @@ func (c *Context) TryInteger() (*big.Int, error) {
 // Type implements StackItem interface.
 func (c *Context) Type() StackItemType { panic("Context cannot appear on evaluation stack") }
 
+// Convert implements StackItem interface.
+func (c *Context) Convert(_ StackItemType) (StackItem, error) {
+	panic("Context cannot be converted to anything")
+}
+
 // Equals implements StackItem interface.
 func (c *Context) Equals(s StackItem) bool {
 	return c == s

pkg/vm/opcode/opcode.go

@@ -161,8 +161,9 @@ const (
 	CLEARITEMS   Opcode = 0xD3
 
 	// Types
-	ISNULL Opcode = 0xD8
+	ISNULL  Opcode = 0xD8
-	ISTYPE Opcode = 0xD9
+	ISTYPE  Opcode = 0xD9
+	CONVERT Opcode = 0xDB
 
 	// Exceptions
 	THROW      Opcode = 0xF0

pkg/vm/opcode/opcode_string.go

@@ -141,11 +141,12 @@ func _() {
 	_ = x[CLEARITEMS-211]
 	_ = x[ISNULL-216]
 	_ = x[ISTYPE-217]
+	_ = x[CONVERT-219]
 	_ = x[THROW-240]
 	_ = x[THROWIFNOT-241]
 }
 
-const _Opcode_name = "PUSHINT8PUSHINT16PUSHINT32PUSHINT64PUSHINT128PUSHINT256PUSHNULLPUSHDATA1PUSHDATA2PUSHDATA4PUSHM1PUSH0PUSH1PUSH2PUSH3PUSH4PUSH5PUSH6PUSH7PUSH8PUSH9PUSH10PUSH11PUSH12PUSH13PUSH14PUSH15PUSH16NOPJMPJMPLJMPIFJMPIFLJMPIFNOTJMPIFNOTLJMPEQJMPEQLJMPNEJMPNELJMPGTJMPGTLJMPGEJMPGELJMPLTJMPLTLJMPLEJMPLELCALLCALLLOLDPUSH1RETAPPCALLSYSCALLTAILCALLDUPFROMALTSTACKTOALTSTACKFROMALTSTACKXDROPXSWAPXTUCKDEPTHDROPDUPNIPOVERPICKROLLROTSWAPTUCKCATSUBSTRLEFTRIGHTINVERTANDORXOREQUALINCDECSIGNNEGATEABSNOTNZADDSUBMULDIVMODSHLSHRBOOLANDBOOLORNUMEQUALNUMNOTEQUALLTGTLTEGTEMINMAXWITHINSHA1SHA256HASH160HASH256CHECKSIGVERIFYCHECKMULTISIGPACKUNPACKNEWARRAY0NEWARRAYNEWARRAYTNEWSTRUCT0NEWSTRUCTNEWMAPSIZEHASKEYKEYSVALUESPICKITEMAPPENDSETITEMREVERSEITEMSREMOVECLEARITEMSISNULLISTYPETHROWTHROWIFNOT"
+const _Opcode_name = "PUSHINT8PUSHINT16PUSHINT32PUSHINT64PUSHINT128PUSHINT256PUSHNULLPUSHDATA1PUSHDATA2PUSHDATA4PUSHM1PUSH0PUSH1PUSH2PUSH3PUSH4PUSH5PUSH6PUSH7PUSH8PUSH9PUSH10PUSH11PUSH12PUSH13PUSH14PUSH15PUSH16NOPJMPJMPLJMPIFJMPIFLJMPIFNOTJMPIFNOTLJMPEQJMPEQLJMPNEJMPNELJMPGTJMPGTLJMPGEJMPGELJMPLTJMPLTLJMPLEJMPLELCALLCALLLOLDPUSH1RETAPPCALLSYSCALLTAILCALLDUPFROMALTSTACKTOALTSTACKFROMALTSTACKXDROPXSWAPXTUCKDEPTHDROPDUPNIPOVERPICKROLLROTSWAPTUCKCATSUBSTRLEFTRIGHTINVERTANDORXOREQUALINCDECSIGNNEGATEABSNOTNZADDSUBMULDIVMODSHLSHRBOOLANDBOOLORNUMEQUALNUMNOTEQUALLTGTLTEGTEMINMAXWITHINSHA1SHA256HASH160HASH256CHECKSIGVERIFYCHECKMULTISIGPACKUNPACKNEWARRAY0NEWARRAYNEWARRAYTNEWSTRUCT0NEWSTRUCTNEWMAPSIZEHASKEYKEYSVALUESPICKITEMAPPENDSETITEMREVERSEITEMSREMOVECLEARITEMSISNULLISTYPECONVERTTHROWTHROWIFNOT"
 
 var _Opcode_map = map[Opcode]string{
 	0:   _Opcode_name[0:8],
@@ -279,8 +280,9 @@ var _Opcode_map = map[Opcode]string{
 	211: _Opcode_name[731:741],
 	216: _Opcode_name[741:747],
 	217: _Opcode_name[747:753],
-	240: _Opcode_name[753:758],
+	219: _Opcode_name[753:760],
-	241: _Opcode_name[758:768],
+	240: _Opcode_name[760:765],
+	241: _Opcode_name[765:775],
 }
 
 func (i Opcode) String() string {

pkg/vm/stack.go

@@ -80,8 +80,7 @@ func (e *Element) BigInt() *big.Int {
 	return val
 }
 
-// Bool attempts to get the underlying value of the element as a boolean.
+// Bool converts an underlying value of the element to a boolean.
-// Will panic if the assertion failed which will be caught by the VM.
 func (e *Element) Bool() bool {
 	return e.value.Bool()
 }

pkg/vm/stack_item.go

@@ -32,8 +32,12 @@ type StackItem interface {
 	ToContractParameter(map[StackItem]bool) smartcontract.Parameter
 	// Type returns stack item type.
 	Type() StackItemType
+	// Convert converts StackItem to another type.
+	Convert(StackItemType) (StackItem, error)
 }
 
+var errInvalidConversion = errors.New("invalid conversion type")
+
 func makeStackItem(v interface{}) StackItem {
 	switch val := v.(type) {
 	case int:
@@ -108,6 +112,33 @@ func makeStackItem(v interface{}) StackItem {
 	}
 }
 
+// convertPrimitive converts primitive item to a specified type.
+func convertPrimitive(item StackItem, typ StackItemType) (StackItem, error) {
+	if item.Type() == typ {
+		return item, nil
+	}
+	switch typ {
+	case IntegerT:
+		bi, err := item.TryInteger()
+		if err != nil {
+			return nil, err
+		}
+		return NewBigIntegerItem(bi), nil
+	case ByteArrayT:
+		b, err := item.TryBytes()
+		if err != nil {
+			return nil, err
+		}
+		return NewByteArrayItem(b), nil
+	case BufferT:
+		panic("TODO") // #877
+	case BooleanT:
+		return NewBoolItem(item.Bool()), nil
+	default:
+		return nil, errInvalidConversion
+	}
+}
+
 // StructItem represents a struct on the stack.
 type StructItem struct {
 	value []StackItem
@@ -187,6 +218,20 @@ func (i *StructItem) ToContractParameter(seen map[StackItem]bool) smartcontract.
 // Type implements StackItem interface.
 func (i *StructItem) Type() StackItemType { return StructT }
 
+// Convert implements StackItem interface.
+func (i *StructItem) Convert(typ StackItemType) (StackItem, error) {
+	switch typ {
+	case StructT:
+		return i, nil
+	case ArrayT:
+		return NewArrayItem(i.value), nil
+	case BooleanT:
+		return NewBoolItem(i.Bool()), nil
+	default:
+		return nil, errInvalidConversion
+	}
+}
+
 // Clone returns a Struct with all Struct fields copied by value.
 // Array fields are still copied by reference.
 func (i *StructItem) Clone() *StructItem {
@@ -251,6 +296,14 @@ func (i NullItem) ToContractParameter(map[StackItem]bool) smartcontract.Paramete
 // Type implements StackItem interface.
 func (i NullItem) Type() StackItemType { return AnyT }
 
+// Convert implements StackItem interface.
+func (i NullItem) Convert(typ StackItemType) (StackItem, error) {
+	if typ == AnyT || !typ.IsValid() {
+		return nil, errInvalidConversion
+	}
+	return i, nil
+}
+
 // BigIntegerItem represents a big integer on the stack.
 type BigIntegerItem struct {
 	value *big.Int
@@ -324,6 +377,11 @@ func (i *BigIntegerItem) ToContractParameter(map[StackItem]bool) smartcontract.P
 // Type implements StackItem interface.
 func (i *BigIntegerItem) Type() StackItemType { return IntegerT }
 
+// Convert implements StackItem interface.
+func (i *BigIntegerItem) Convert(typ StackItemType) (StackItem, error) {
+	return convertPrimitive(i, typ)
+}
+
 // MarshalJSON implements the json.Marshaler interface.
 func (i *BigIntegerItem) MarshalJSON() ([]byte, error) {
 	return json.Marshal(i.value)
@@ -410,6 +468,11 @@ func (i *BoolItem) ToContractParameter(map[StackItem]bool) smartcontract.Paramet
 // Type implements StackItem interface.
 func (i *BoolItem) Type() StackItemType { return BooleanT }
 
+// Convert implements StackItem interface.
+func (i *BoolItem) Convert(typ StackItemType) (StackItem, error) {
+	return convertPrimitive(i, typ)
+}
+
 // ByteArrayItem represents a byte array on the stack.
 type ByteArrayItem struct {
 	value []byte
@@ -488,6 +551,11 @@ func (i *ByteArrayItem) ToContractParameter(map[StackItem]bool) smartcontract.Pa
 // Type implements StackItem interface.
 func (i *ByteArrayItem) Type() StackItemType { return ByteArrayT }
 
+// Convert implements StackItem interface.
+func (i *ByteArrayItem) Convert(typ StackItemType) (StackItem, error) {
+	return convertPrimitive(i, typ)
+}
+
 // ArrayItem represents a new ArrayItem object.
 type ArrayItem struct {
 	value []StackItem
@@ -558,6 +626,20 @@ func (i *ArrayItem) ToContractParameter(seen map[StackItem]bool) smartcontract.P
 // Type implements StackItem interface.
 func (i *ArrayItem) Type() StackItemType { return ArrayT }
 
+// Convert implements StackItem interface.
+func (i *ArrayItem) Convert(typ StackItemType) (StackItem, error) {
+	switch typ {
+	case ArrayT:
+		return i, nil
+	case StructT:
+		return NewStructItem(i.value), nil
+	case BooleanT:
+		return NewBoolItem(i.Bool()), nil
+	default:
+		return nil, errInvalidConversion
+	}
+}
+
 // MapElement is a key-value pair of StackItems.
 type MapElement struct {
 	Key   StackItem
@@ -649,6 +731,18 @@ func (i *MapItem) ToContractParameter(seen map[StackItem]bool) smartcontract.Par
 // Type implements StackItem interface.
 func (i *MapItem) Type() StackItemType { return MapT }
 
+// Convert implements StackItem interface.
+func (i *MapItem) Convert(typ StackItemType) (StackItem, error) {
+	switch typ {
+	case MapT:
+		return i, nil
+	case BooleanT:
+		return NewBoolItem(i.Bool()), nil
+	default:
+		return nil, errInvalidConversion
+	}
+}
+
 // Add adds key-value pair to the map.
 func (i *MapItem) Add(key, value StackItem) {
 	if !isValidMapKey(key) {
@@ -742,6 +836,18 @@ func (i *InteropItem) ToContractParameter(map[StackItem]bool) smartcontract.Para
 // Type implements StackItem interface.
 func (i *InteropItem) Type() StackItemType { return InteropT }
 
+// Convert implements StackItem interface.
+func (i *InteropItem) Convert(typ StackItemType) (StackItem, error) {
+	switch typ {
+	case InteropT:
+		return i, nil
+	case BooleanT:
+		return NewBoolItem(i.Bool()), nil
+	default:
+		return nil, errInvalidConversion
+	}
+}
+
 // MarshalJSON implements the json.Marshaler interface.
 func (i *InteropItem) MarshalJSON() ([]byte, error) {
 	return json.Marshal(i.value)

pkg/vm/vm.go

@@ -569,6 +569,15 @@ func (v *VM) execute(ctx *Context, op opcode.Opcode, parameter []byte) (err erro
 		res := v.estack.Pop().Item()
 		v.estack.PushVal(res.Type() == StackItemType(parameter[0]))
 
+	case opcode.CONVERT:
+		typ := StackItemType(parameter[0])
+		item := v.estack.Pop().Item()
+		result, err := item.Convert(typ)
+		if err != nil {
+			panic(err)
+		}
+		v.estack.PushVal(result)
+
 	// Stack operations.
 	case opcode.TOALTSTACK:
 		v.astack.Push(v.estack.Pop())

pkg/vm/vm_test.go

@@ -4,6 +4,7 @@ import (
 	"bytes"
 	"encoding/binary"
 	"encoding/hex"
+	"fmt"
 	"math/big"
 	"math/rand"
 	"testing"
@@ -256,6 +257,128 @@ func TestISTYPE(t *testing.T) {
 	})
 }
 
+func testCONVERT(isErr bool, to StackItemType, item, res StackItem) func(t *testing.T) {
+	return func(t *testing.T) {
+		prog := []byte{byte(opcode.CONVERT), byte(to)}
+		v := load(prog)
+		v.estack.PushVal(item)
+		if isErr {
+			checkVMFailed(t, v)
+			return
+		}
+		runVM(t, v)
+		require.Equal(t, 1, v.estack.Len())
+		require.Equal(t, res, v.estack.Pop().value)
+	}
+}
+
+func TestCONVERT(t *testing.T) {
+	type convertTC struct {
+		item, res StackItem
+	}
+	arr := []StackItem{
+		NewBigIntegerItem(big.NewInt(7)),
+		NewByteArrayItem([]byte{4, 8, 15}),
+	}
+	m := NewMapItem()
+	m.Add(NewByteArrayItem([]byte{1}), NewByteArrayItem([]byte{2}))
+
+	getName := func(item StackItem, typ StackItemType) string { return fmt.Sprintf("%s->%s", item, typ) }
+
+	t.Run("->Bool", func(t *testing.T) {
+		testBool := func(a, b StackItem) func(t *testing.T) {
+			return testCONVERT(false, BooleanT, a, b)
+		}
+
+		trueCases := []StackItem{
+			NewBoolItem(true), NewBigIntegerItem(big.NewInt(11)), NewByteArrayItem([]byte{1, 2, 3}),
+			NewArrayItem(arr), NewArrayItem(nil),
+			NewStructItem(arr), NewStructItem(nil),
+			NewMapItem(), m, NewInteropItem(struct{}{}),
+		}
+		for i := range trueCases {
+			t.Run(getName(trueCases[i], BooleanT), testBool(trueCases[i], NewBoolItem(true)))
+		}
+
+		falseCases := []StackItem{
+			NewBigIntegerItem(big.NewInt(0)), NewByteArrayItem([]byte{0, 0}), NewBoolItem(false),
+		}
+		for i := range falseCases {
+			testBool(falseCases[i], NewBoolItem(false))
+		}
+	})
+
+	t.Run("compound/interop -> basic", func(t *testing.T) {
+		types := []StackItemType{IntegerT, ByteArrayT}
+		items := []StackItem{NewArrayItem(nil), NewStructItem(nil), NewMapItem(), NewInteropItem(struct{}{})}
+		for _, typ := range types {
+			for j := range items {
+				t.Run(getName(items[j], typ), testCONVERT(true, typ, items[j], nil))
+			}
+		}
+	})
+
+	t.Run("primitive -> Integer/ByteArray", func(t *testing.T) {
+		n := big.NewInt(42)
+		b := emit.IntToBytes(n)
+
+		itemInt := NewBigIntegerItem(n)
+		itemBytes := NewByteArrayItem(b)
+
+		trueCases := map[StackItemType][]convertTC{
+			IntegerT: {
+				{itemInt, itemInt},
+				{itemBytes, itemInt},
+				{NewBoolItem(true), NewBigIntegerItem(big.NewInt(1))},
+				{NewBoolItem(false), NewBigIntegerItem(big.NewInt(0))},
+			},
+			ByteArrayT: {
+				{itemInt, itemBytes},
+				{itemBytes, itemBytes},
+				{NewBoolItem(true), NewByteArrayItem([]byte{1})},
+				{NewBoolItem(false), NewByteArrayItem([]byte{0})},
+			},
+		}
+
+		for typ := range trueCases {
+			for _, tc := range trueCases[typ] {
+				t.Run(getName(tc.item, typ), testCONVERT(false, typ, tc.item, tc.res))
+			}
+		}
+	})
+
+	t.Run("Struct<->Array", func(t *testing.T) {
+		arrayItem := NewArrayItem(arr)
+		structItem := NewStructItem(arr)
+		t.Run("Array->Array", testCONVERT(false, ArrayT, arrayItem, arrayItem))
+		t.Run("Array->Struct", testCONVERT(false, StructT, arrayItem, structItem))
+		t.Run("Struct->Array", testCONVERT(false, ArrayT, structItem, arrayItem))
+		t.Run("Struct->Struct", testCONVERT(false, StructT, structItem, structItem))
+	})
+
+	t.Run("Map->Map", testCONVERT(false, MapT, m, m))
+
+	t.Run("Null->", func(t *testing.T) {
+		types := []StackItemType{
+			BooleanT, ByteArrayT, IntegerT, ArrayT, StructT, MapT, InteropT,
+		}
+		for i := range types {
+			t.Run(types[i].String(), testCONVERT(false, types[i], NullItem{}, NullItem{}))
+		}
+	})
+
+	t.Run("->Any", func(t *testing.T) {
+		items := []StackItem{
+			NewBigIntegerItem(big.NewInt(1)), NewByteArrayItem([]byte{1}), NewBoolItem(true),
+			NewArrayItem(arr), NewStructItem(arr), m, NewInteropItem(struct{}{}),
+		}
+
+		for i := range items {
+			t.Run(items[i].String(), testCONVERT(true, AnyT, items[i], nil))
+		}
+	})
+}
+
 // appendBigStruct returns a program which:
 // 1. pushes size Structs on stack
 // 2. packs them into a new struct