github.com/XiaoMi/Gaea@v1.2.5/parser/tidb-types/set.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  var zeroSet = Set{Name: "", Value: 0}
    24  
    25  // Set is for MySQL Set type.
    26  type Set struct {
    27  	Name  string
    28  	Value uint64
    29  }
    30  
    31  // String implements fmt.Stringer interface.
    32  func (e Set) String() string {
    33  	return e.Name
    34  }
    35  
    36  // ToNumber changes Set to float64 for numeric operation.
    37  func (e Set) ToNumber() float64 {
    38  	return float64(e.Value)
    39  }
    40  
    41  // ParseSetName creates a Set with name.
    42  func ParseSetName(elems []string, name string) (Set, error) {
    43  	if len(name) == 0 {
    44  		return zeroSet, nil
    45  	}
    46  
    47  	seps := strings.Split(name, ",")
    48  	marked := make(map[string]struct{}, len(seps))
    49  	for _, s := range seps {
    50  		marked[strings.ToLower(s)] = struct{}{}
    51  	}
    52  	items := make([]string, 0, len(seps))
    53  
    54  	value := uint64(0)
    55  	for i, n := range elems {
    56  		key := strings.ToLower(n)
    57  		if _, ok := marked[key]; ok {
    58  			value |= 1 << uint64(i)
    59  			delete(marked, key)
    60  			items = append(items, n)
    61  		}
    62  	}
    63  
    64  	if len(marked) == 0 {
    65  		return Set{Name: strings.Join(items, ","), Value: value}, nil
    66  	}
    67  
    68  	// name doesn't exist, maybe an integer?
    69  	if num, err := strconv.ParseUint(name, 0, 64); err == nil {
    70  		return ParseSetValue(elems, num)
    71  	}
    72  
    73  	return Set{}, errors.Errorf("item %s is not in Set %v", name, elems)
    74  }
    75  
    76  var (
    77  	setIndexValue       []uint64
    78  	setIndexInvertValue []uint64
    79  )
    80  
    81  func init() {
    82  	setIndexValue = make([]uint64, 64)
    83  	setIndexInvertValue = make([]uint64, 64)
    84  
    85  	for i := 0; i < 64; i++ {
    86  		setIndexValue[i] = 1 << uint64(i)
    87  		setIndexInvertValue[i] = ^setIndexValue[i]
    88  	}
    89  }
    90  
    91  // ParseSetValue creates a Set with special number.
    92  func ParseSetValue(elems []string, number uint64) (Set, error) {
    93  	if number == 0 {
    94  		return zeroSet, nil
    95  	}
    96  
    97  	value := number
    98  	var items []string
    99  	for i := 0; i < len(elems); i++ {
   100  		if number&setIndexValue[i] > 0 {
   101  			items = append(items, elems[i])
   102  			number &= setIndexInvertValue[i]
   103  		}
   104  	}
   105  
   106  	if number != 0 {
   107  		return Set{}, errors.Errorf("invalid number %d for Set %v", number, elems)
   108  	}
   109  
   110  	return Set{Name: strings.Join(items, ","), Value: value}, nil
   111  }