core: vm: sqlvm: ast: rename DataTypeUnknown to DataTypePending

SQL uses three-valued logic which includes an unknown state. To prevent
the reader of the code from confusing the unknown value with the unknown
data type defined here, we rename 'unknown' data type to 'pending'
because it is intended to be used by nodes whose type has not been
determined.

3 files changed, 19 insertions, 14 deletions

diff --git a/core/vm/sqlvm/ast/ast.go b/core/vm/sqlvm/ast/ast.go
index 672770b84..80daacfe1 100644
--- a/core/vm/sqlvm/ast/ast.go
+++ b/core/vm/sqlvm/ast/ast.go
@@ -341,15 +341,15 @@ func (n *IntTypeNode) GetType() (DataType, errors.ErrorCode, string) {
 			code = errors.ErrorCodeInvalidUintSize
 		}
 		if !isMultiple {
-			return DataTypeUnknown, code, fmt.Sprintf(
+			return DataTypeBad, code, fmt.Sprintf(
 				"%s size %d is not a multiple of 8", name, n.Size)
 		}
 		if !isNotZero {
-			return DataTypeUnknown, code, fmt.Sprintf(
+			return DataTypeBad, code, fmt.Sprintf(
 				"%s size cannot be zero", name)
 		}
 		if !isInRange {
-			return DataTypeUnknown, code, fmt.Sprintf(
+			return DataTypeBad, code, fmt.Sprintf(
 				"%s size %d cannot be larger than 256", name, n.Size)
 		}
 		panic("unreachable")
@@ -395,15 +395,15 @@ func (n *FixedTypeNode) GetType() (DataType, errors.ErrorCode, string) {
 			code = errors.ErrorCodeInvalidFixedSize
 		}
 		if !sizeIsMultiple {
-			return DataTypeUnknown, code, fmt.Sprintf(
+			return DataTypeBad, code, fmt.Sprintf(
 				"%s size %d is not a multiple of 8", name, n.Size)
 		}
 		if !sizeIsNotZero {
-			return DataTypeUnknown, code, fmt.Sprintf(
+			return DataTypeBad, code, fmt.Sprintf(
 				"%s size cannot be zero", name)
 		}
 		if !sizeIsInRange {
-			return DataTypeUnknown, code, fmt.Sprintf(
+			return DataTypeBad, code, fmt.Sprintf(
 				"%s size %d cannot be larger than 256", name, n.Size)
 		}
 		code = errors.ErrorCodeInvalidFixedFractionalDigits
@@ -411,7 +411,7 @@ func (n *FixedTypeNode) GetType() (DataType, errors.ErrorCode, string) {
 			code = errors.ErrorCodeInvalidUfixedFractionalDigits
 		}
 		if !fractionalDigitsInRange {
-			return DataTypeUnknown, code, fmt.Sprintf(
+			return DataTypeBad, code, fmt.Sprintf(
 				"%s fractional digits %d cannot be larger than 80",
 				name, n.FractionalDigits)
 		}
@@ -467,10 +467,10 @@ func (n *FixedBytesTypeNode) GetType() (DataType, errors.ErrorCode, string) {
 	if !isNotZero || !isInRange {
 		code := errors.ErrorCodeInvalidBytesSize
 		if !isNotZero {
-			return DataTypeUnknown, code, "bytes size cannot be zero"
+			return DataTypeBad, code, "bytes size cannot be zero"
 		}
 		if !isInRange {
-			return DataTypeUnknown, code, fmt.Sprintf(
+			return DataTypeBad, code, fmt.Sprintf(
 				"bytes size %d cannot be larger than 32", n.Size)
 		}
 		panic("unreachable")
@@ -881,7 +881,7 @@ func (n *CastOperatorNode) GetType() DataType {
 	if dt, code, _ := n.TargetType.GetType(); code == errors.ErrorCodeNil {
 		return dt
 	}
-	return DataTypeUnknown
+	return DataTypeBad
 }
 
 // ---------------------------------------------------------------------------
diff --git a/core/vm/sqlvm/ast/types.go b/core/vm/sqlvm/ast/types.go
index 41c35ac78..9d7efc430 100644
--- a/core/vm/sqlvm/ast/types.go
+++ b/core/vm/sqlvm/ast/types.go
@@ -2,6 +2,7 @@ package ast
 
 import (
 	"fmt"
+	"math"
 	"math/big"
 
 	"github.com/shopspring/decimal"
@@ -27,7 +28,7 @@ type DataType uint16
 
 // DataTypeMajor enums.
 const (
-	DataTypeMajorUnknown DataTypeMajor = iota
+	DataTypeMajorPending DataTypeMajor = iota
 	DataTypeMajorSpecial
 	DataTypeMajorBool
 	DataTypeMajorAddress
@@ -47,8 +48,11 @@ const (
 	DataTypeMinorSpecialDefault DataTypeMinor = 0x02
 )
 
-// DataTypeUnknown for unknown data type.
-const DataTypeUnknown DataType = 0
+// Special data types which are commonly used.
+const (
+	DataTypePending DataType = (DataType(DataTypeMajorPending) << 8) | DataType(DataTypeMinorDontCare)
+	DataTypeBad     DataType = math.MaxUint16
+)
 
 // DecomposeDataType to major and minor part with given data type.
 func DecomposeDataType(t DataType) (DataTypeMajor, DataTypeMinor) {
diff --git a/core/vm/sqlvm/ast/types_test.go b/core/vm/sqlvm/ast/types_test.go
index b44f818cb..89a000251 100644
--- a/core/vm/sqlvm/ast/types_test.go
+++ b/core/vm/sqlvm/ast/types_test.go
@@ -82,7 +82,8 @@ func (s *TypesTestSuite) TestEncodeDataTypeError() {
 }
 
 func (s *TypesTestSuite) TestDecodeDataTypeError() {
-	s.requireDecodeDataTypeError(DataTypeUnknown)
+	s.requireDecodeDataTypeError(DataTypePending)
+	s.requireDecodeDataTypeError(DataTypeBad)
 	s.requireDecodeDataTypeError(ComposeDataType(DataTypeMajorInt, 0x20))
 	s.requireDecodeDataTypeError(ComposeDataType(DataTypeMajorUint, 0x20))
 	s.requireDecodeDataTypeError(ComposeDataType(DataTypeMajorFixedBytes, 0x20))