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system_enumtype.go
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/
system_enumtype.go
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// Copyright 2021 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 sql
import (
"strings"
"github.com/dolthub/vitess/go/sqltypes"
"github.com/dolthub/vitess/go/vt/proto/query"
)
// systemEnumType is an internal enum type ONLY for system variables.
type systemEnumType struct {
varName string
valToIndex map[string]int
indexToVal []string
}
var _ SystemVariableType = systemEnumType{}
// NewSystemEnumType returns a new systemEnumType.
func NewSystemEnumType(varName string, values ...string) SystemVariableType {
if len(values) > 65535 { // system variables should NEVER hit this
panic(varName + " somehow has more than 65535 values")
}
valToIndex := make(map[string]int)
for i, value := range values {
valToIndex[strings.ToLower(value)] = i
}
return systemEnumType{varName, valToIndex, values}
}
// Compare implements Type interface.
func (t systemEnumType) Compare(a interface{}, b interface{}) (int, error) {
as, err := t.Convert(a)
if err != nil {
return 0, err
}
bs, err := t.Convert(b)
if err != nil {
return 0, err
}
ai := as.(string)
bi := bs.(string)
if ai == bi {
return 0, nil
}
if ai < bi {
return -1, nil
}
return 1, nil
}
// Convert implements Type interface.
func (t systemEnumType) Convert(v interface{}) (interface{}, error) {
// Nil values are not accepted
switch value := v.(type) {
case int:
if value >= 0 && value < len(t.indexToVal) {
return t.indexToVal[value], nil
}
case uint:
return t.Convert(int(value))
case int8:
return t.Convert(int(value))
case uint8:
return t.Convert(int(value))
case int16:
return t.Convert(int(value))
case uint16:
return t.Convert(int(value))
case int32:
return t.Convert(int(value))
case uint32:
return t.Convert(int(value))
case int64:
return t.Convert(int(value))
case uint64:
return t.Convert(int(value))
case float32:
return t.Convert(float64(value))
case float64:
// Float values aren't truly accepted, but the engine will give them when it should give ints.
// Therefore, if the float doesn't have a fractional portion, we treat it as an int.
if value == float64(int(value)) {
return t.Convert(int(value))
}
case string:
if idx, ok := t.valToIndex[strings.ToLower(value)]; ok {
return t.indexToVal[idx], nil
}
}
return nil, ErrInvalidSystemVariableValue.New(t.varName, v)
}
// MustConvert implements the Type interface.
func (t systemEnumType) MustConvert(v interface{}) interface{} {
value, err := t.Convert(v)
if err != nil {
panic(err)
}
return value
}
// Promote implements the Type interface.
func (t systemEnumType) Promote() Type {
return t
}
// SQL implements Type interface.
func (t systemEnumType) SQL(v interface{}) (sqltypes.Value, error) {
if v == nil {
return sqltypes.NULL, nil
}
v, err := t.Convert(v)
if err != nil {
return sqltypes.Value{}, err
}
return sqltypes.MakeTrusted(t.Type(), []byte(v.(string))), nil
}
// String implements Type interface.
func (t systemEnumType) String() string {
return "SYSTEM_ENUM"
}
// Type implements Type interface.
func (t systemEnumType) Type() query.Type {
return sqltypes.VarChar
}
// Zero implements Type interface.
func (t systemEnumType) Zero() interface{} {
return ""
}
// EncodeValue implements SystemVariableType interface.
func (t systemEnumType) EncodeValue(val interface{}) (string, error) {
expectedVal, ok := val.(string)
if !ok {
return "", ErrSystemVariableCodeFail.New(val, t.String())
}
return expectedVal, nil
}
// DecodeValue implements SystemVariableType interface.
func (t systemEnumType) DecodeValue(val string) (interface{}, error) {
outVal, err := t.Convert(val)
if err != nil {
return nil, ErrSystemVariableCodeFail.New(val, t.String())
}
return outVal, nil
}