/
null.go
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/
null.go
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// Copyright 2022 Dolthub, Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package types
import (
"reflect"
"github.com/dolthub/vitess/go/sqltypes"
"github.com/dolthub/vitess/go/vt/proto/query"
"gopkg.in/src-d/go-errors.v1"
"github.com/dolthub/go-mysql-server/sql"
)
var (
Null sql.NullType = nullType{}
// ErrValueNotNil is thrown when a value that was expected to be nil, is not
ErrValueNotNil = errors.NewKind("value not nil: %#v")
)
type nullType struct{}
// Compare implements Type interface. Note that while this returns 0 (equals)
// for ordering purposes, in SQL NULL != NULL.
func (t nullType) Compare(a interface{}, b interface{}) (int, error) {
return 0, nil
}
// Convert implements Type interface.
func (t nullType) Convert(v interface{}) (interface{}, sql.ConvertInRange, error) {
if v != nil {
return nil, sql.InRange, ErrValueNotNil.New(v)
}
return nil, sql.InRange, nil
}
// MaxTextResponseByteLength implements the Type interface
func (t nullType) MaxTextResponseByteLength(_ *sql.Context) uint32 {
return 0
}
// MustConvert implements the Type interface.
func (t nullType) MustConvert(v interface{}) interface{} {
value, _, err := t.Convert(v)
if err != nil {
panic(err)
}
return value
}
// Equals implements the Type interface.
func (t nullType) Equals(otherType sql.Type) bool {
_, ok := otherType.(nullType)
return ok
}
// Promote implements the Type interface.
func (t nullType) Promote() sql.Type {
return t
}
// SQL implements Type interface.
func (t nullType) SQL(*sql.Context, []byte, interface{}) (sqltypes.Value, error) {
return sqltypes.NULL, nil
}
// String implements Type interface.
func (t nullType) String() string {
return "null"
}
// Type implements Type interface.
func (t nullType) Type() query.Type {
return sqltypes.Null
}
// ValueType implements Type interface.
func (t nullType) ValueType() reflect.Type {
return nil
}
// Zero implements Type interface.
func (t nullType) Zero() interface{} {
return nil
}
// CollationCoercibility implements sql.CollationCoercible interface.
func (nullType) CollationCoercibility(ctx *sql.Context) (collation sql.CollationID, coercibility byte) {
return sql.Collation_binary, 6
}