github.com/XiaoMi/Gaea@v1.2.5/parser/tidb-types/enum.go (about)

     1  // Copyright 2015 PingCAP, Inc.
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use this file except in compliance with the License.
     5  // You may obtain a copy of the License at
     6  //
     7  //     http://www.apache.org/licenses/LICENSE-2.0
     8  //
     9  // Unless required by applicable law or agreed to in writing, software
    10  // distributed under the License is distributed on an "AS IS" BASIS,
    11  // See the License for the specific language governing permissions and
    12  // limitations under the License.
    13  
    14  package types
    15  
    16  import (
    17  	"strconv"
    18  	"strings"
    19  
    20  	"github.com/pingcap/errors"
    21  )
    22  
    23  // Enum is for MySQL enum type.
    24  type Enum struct {
    25  	Name  string
    26  	Value uint64
    27  }
    28  
    29  // String implements fmt.Stringer interface.
    30  func (e Enum) String() string {
    31  	return e.Name
    32  }
    33  
    34  // ToNumber changes enum index to float64 for numeric operation.
    35  func (e Enum) ToNumber() float64 {
    36  	return float64(e.Value)
    37  }
    38  
    39  // ParseEnumName creates a Enum with item name.
    40  func ParseEnumName(elems []string, name string) (Enum, error) {
    41  	for i, n := range elems {
    42  		if strings.EqualFold(n, name) {
    43  			return Enum{Name: n, Value: uint64(i) + 1}, nil
    44  		}
    45  	}
    46  
    47  	// name doesn't exist, maybe an integer?
    48  	if num, err := strconv.ParseUint(name, 0, 64); err == nil {
    49  		return ParseEnumValue(elems, num)
    50  	}
    51  
    52  	return Enum{}, errors.Errorf("item %s is not in enum %v", name, elems)
    53  }
    54  
    55  // ParseEnumValue creates a Enum with special number.
    56  func ParseEnumValue(elems []string, number uint64) (Enum, error) {
    57  	if number == 0 || number > uint64(len(elems)) {
    58  		return Enum{}, errors.Errorf("number %d overflow enum boundary [1, %d]", number, len(elems))
    59  	}
    60  
    61  	return Enum{Name: elems[number-1], Value: number}, nil
    62  }