vm: move Bool method to the StackItem interface

pkg/consensus/payload.go

@@ -222,9 +222,7 @@ func (p *Payload) Verify(scriptHash util.Uint160) bool {
 		return false
 	}
 
-	res, err := v.Estack().Pop().TryBool()
-
-	return err == nil && res
+	return v.Estack().Pop().Bool()
 }
 
 // DecodeBinaryUnsigned reads payload from w excluding signature.

pkg/core/blockchain.go

@@ -1978,11 +1978,7 @@ func (bc *Blockchain) verifyHashAgainstScript(hash util.Uint160, witness *transa
 	}
 	resEl := vm.Estack().Pop()
 	if resEl != nil {
-		res, err := resEl.TryBool()
-		if err != nil {
-			return err
-		}
-		if !res {
+		if !resEl.Bool() {
 			return errors.Errorf("signature check failed")
 		}
 		if useKeys {

pkg/vm/context.go

@@ -176,6 +176,9 @@ func (c *Context) Dup() StackItem {
 	return c
 }
 
+// Bool implements StackItem interface.
+func (c *Context) Bool() bool { panic("can't convert Context to Bool") }
+
 // TryBytes implements StackItem interface.
 func (c *Context) TryBytes() ([]byte, error) {
 	return nil, errors.New("can't convert Context to ByteArray")

pkg/vm/stack.go

@@ -80,38 +80,10 @@ func (e *Element) BigInt() *big.Int {
 	return val
 }
 
-// TryBool attempts to get the underlying value of the element as a boolean.
-// Returns error if can't convert value to boolean type.
-func (e *Element) TryBool() (bool, error) {
-	switch t := e.value.(type) {
-	case *BigIntegerItem:
-		return t.value.Int64() != 0, nil
-	case *BoolItem:
-		return t.value, nil
-	case *ArrayItem, *StructItem:
-		return true, nil
-	case *ByteArrayItem:
-		for _, b := range t.value {
-			if b != 0 {
-				return true, nil
-			}
-		}
-		return false, nil
-	case *InteropItem:
-		return t.value != nil, nil
-	default:
-		return false, fmt.Errorf("can't convert to bool: " + t.String())
-	}
-}
-
 // Bool attempts to get the underlying value of the element as a boolean.
 // Will panic if the assertion failed which will be caught by the VM.
 func (e *Element) Bool() bool {
-	val, err := e.TryBool()
-	if err != nil {
-		panic(err)
-	}
-	return val
+	return e.value.Bool()
 }
 
 // Bytes attempts to get the underlying value of the element as a byte array.

pkg/vm/stack_item.go

@@ -20,6 +20,8 @@ type StackItem interface {
 	Value() interface{}
 	// Dup duplicates current StackItem.
 	Dup() StackItem
+	// Bool converts StackItem to a boolean value.
+	Bool() bool
 	// TryBytes converts StackItem to a byte slice.
 	TryBytes() ([]byte, error)
 	// TryInteger converts StackItem to an integer.
@@ -133,6 +135,9 @@ func (i *StructItem) Dup() StackItem {
 	return i
 }
 
+// Bool implements StackItem interface.
+func (i *StructItem) Bool() bool { return true }
+
 // TryBytes implements StackItem interface.
 func (i *StructItem) TryBytes() ([]byte, error) {
 	return nil, errors.New("can't convert Struct to ByteArray")
@@ -217,6 +222,9 @@ func (i NullItem) Dup() StackItem {
 	return i
 }
 
+// Bool implements StackItem interface.
+func (i NullItem) Bool() bool { return false }
+
 // TryBytes implements StackItem interface.
 func (i NullItem) TryBytes() ([]byte, error) {
 	return nil, errors.New("can't convert Null to ByteArray")
@@ -260,6 +268,11 @@ func (i *BigIntegerItem) Bytes() []byte {
 	return emit.IntToBytes(i.value)
 }
 
+// Bool implements StackItem interface.
+func (i *BigIntegerItem) Bool() bool {
+	return i.value.Sign() != 0
+}
+
 // TryBytes implements StackItem interface.
 func (i *BigIntegerItem) TryBytes() ([]byte, error) {
 	return i.Bytes(), nil
@@ -347,6 +360,9 @@ func (i *BoolItem) Dup() StackItem {
 	return &BoolItem{i.value}
 }
 
+// Bool implements StackItem interface.
+func (i *BoolItem) Bool() bool { return i.value }
+
 // Bytes converts BoolItem to bytes.
 func (i *BoolItem) Bytes() []byte {
 	if i.value {
@@ -420,6 +436,19 @@ func (i *ByteArrayItem) String() string {
 	return "ByteArray"
 }
 
+// Bool implements StackItem interface.
+func (i *ByteArrayItem) Bool() bool {
+	if len(i.value) > MaxBigIntegerSizeBits/8 {
+		return true
+	}
+	for _, b := range i.value {
+		if b != 0 {
+			return true
+		}
+	}
+	return false
+}
+
 // TryBytes implements StackItem interface.
 func (i *ByteArrayItem) TryBytes() ([]byte, error) {
 	return i.value, nil
@@ -485,6 +514,9 @@ func (i *ArrayItem) String() string {
 	return "Array"
 }
 
+// Bool implements StackItem interface.
+func (i *ArrayItem) Bool() bool { return true }
+
 // TryBytes implements StackItem interface.
 func (i *ArrayItem) TryBytes() ([]byte, error) {
 	return nil, errors.New("can't convert Array to ByteArray")
@@ -553,6 +585,9 @@ func (i *MapItem) Value() interface{} {
 	return i.value
 }
 
+// Bool implements StackItem interface.
+func (i *MapItem) Bool() bool { return true }
+
 // TryBytes implements StackItem interface.
 func (i *MapItem) TryBytes() ([]byte, error) {
 	return nil, errors.New("can't convert Map to ByteArray")
@@ -672,6 +707,9 @@ func (i *InteropItem) Dup() StackItem {
 	return i
 }
 
+// Bool implements StackItem interface.
+func (i *InteropItem) Bool() bool { return true }
+
 // TryBytes implements StackItem interface.
 func (i *InteropItem) TryBytes() ([]byte, error) {
 	return nil, errors.New("can't convert Interop to ByteArray")