tidb field_name 源码
tidb field_name 代码
文件路径：/types/field_name.go
// Copyright 2019 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 (
"strings"
"github.com/pingcap/tidb/parser/ast"
"github.com/pingcap/tidb/parser/model"
"github.com/pingcap/tidb/util/size"
)
// FieldName records the names used for mysql protocol.
type FieldName struct {
OrigTblName model.CIStr
OrigColName model.CIStr
DBName model.CIStr
TblName model.CIStr
ColName model.CIStr
Hidden bool
// NotExplicitUsable is used for mark whether a column can be explicit used in SQL.
// update stmt can write `writeable` column implicitly but cannot use non-public columns explicit.
// e.g. update t set a = 10 where b = 10; which `b` is in `writeOnly` state
NotExplicitUsable bool
Redundant bool
}
const emptyName = "EMPTY_NAME"
// String implements Stringer interface.
func (name *FieldName) String() string {
builder := strings.Builder{}
if name.Hidden {
return emptyName
}
if name.DBName.L != "" {
builder.WriteString(name.DBName.L + ".")
}
if name.TblName.L != "" {
builder.WriteString(name.TblName.L + ".")
}
builder.WriteString(name.ColName.L)
return builder.String()
}
// MemoryUsage return the memory usage of FieldName
func (name *FieldName) MemoryUsage() (sum int64) {
if name == nil {
return
}
sum = name.OrigTblName.MemoryUsage() + name.OrigColName.MemoryUsage() + name.DBName.MemoryUsage() +
name.TblName.MemoryUsage() + name.ColName.MemoryUsage() + size.SizeOfBool*3
return
}
// NameSlice is the slice of the *fieldName
type NameSlice []*FieldName
// Shallow is a shallow copy, only making a new slice.
func (s NameSlice) Shallow() NameSlice {
ret := make(NameSlice, len(s))
copy(ret, s)
return ret
}
// EmptyName is to occupy the position in the name slice. If it's set, that column's name is hidden.
var EmptyName = &FieldName{Hidden: true}
// FindAstColName checks whether the given ast.ColumnName is appeared in this slice.
func (s NameSlice) FindAstColName(name *ast.ColumnName) bool {
for _, fieldName := range s {
if (name.Schema.L == "" || name.Schema.L == fieldName.DBName.L) &&
(name.Table.L == "" || name.Table.L == fieldName.TblName.L) &&
name.Name.L == fieldName.ColName.L {
return true
}
}
return false
}
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