tidb enum 源码
tidb enum 代码
文件路径：/types/enum.go
// Copyright 2015 PingCAP, 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 (
"fmt"
"strconv"
"github.com/pingcap/errors"
"github.com/pingcap/tidb/util/collate"
"github.com/pingcap/tidb/util/stringutil"
)
// Enum is for MySQL enum type.
type Enum struct {
Name string
Value uint64
}
// Copy deep copy an Enum.
func (e Enum) Copy() Enum {
return Enum{
Name: stringutil.Copy(e.Name),
Value: e.Value,
}
}
// String implements fmt.Stringer interface.
func (e Enum) String() string {
return e.Name
}
// ToNumber changes enum index to float64 for numeric operation.
func (e Enum) ToNumber() float64 {
return float64(e.Value)
}
// ParseEnum creates a Enum with item name or value.
func ParseEnum(elems []string, name string, collation string) (Enum, error) {
if enumName, err := ParseEnumName(elems, name, collation); err == nil {
return enumName, nil
}
// name doesn't exist, maybe an integer?
if num, err := strconv.ParseUint(name, 0, 64); err == nil {
return ParseEnumValue(elems, num)
}
errMsg := fmt.Sprintf("convert to MySQL enum failed: item %s is not in enum %v", name, elems)
return Enum{}, errors.Wrap(ErrTruncated, errMsg)
}
// ParseEnumName creates a Enum with item name.
func ParseEnumName(elems []string, name string, collation string) (Enum, error) {
ctor := collate.GetCollator(collation)
for i, n := range elems {
if ctor.Compare(n, name) == 0 {
return Enum{Name: n, Value: uint64(i) + 1}, nil
}
}
errMsg := fmt.Sprintf("convert to MySQL enum failed: item %s is not in enum %v", name, elems)
return Enum{}, errors.Wrap(ErrTruncated, errMsg)
}
// ParseEnumValue creates a Enum with special number.
func ParseEnumValue(elems []string, number uint64) (Enum, error) {
if number == 0 || number > uint64(len(elems)) {
errMsg := fmt.Sprintf("convert to MySQL enum failed: number %d overflow enum boundary [1, %d]", number, len(elems))
return Enum{}, errors.Wrap(ErrTruncated, errMsg)
}
return Enum{Name: elems[number-1], Value: number}, nil
}
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