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join.go
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join.go
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/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You 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 ast
import (
"strings"
)
import (
"github.com/pkg/errors"
)
var (
_ Node = (*JoinNode)(nil)
_ Restorer = (*JoinNode)(nil)
)
const (
_ JoinType = iota
LeftJoin
RightJoin
InnerJoin
)
var _joinTypeNames = [...]string{
LeftJoin: "LEFT",
RightJoin: "RIGHT",
InnerJoin: "INNER",
}
type JoinType uint8
func (j JoinType) String() string {
return _joinTypeNames[j]
}
type JoinNode struct {
Target *TableSourceItem
On ExpressionNode
Typ JoinType
Natural bool
}
func (jn *JoinNode) Accept(visitor Visitor) (interface{}, error) {
return visitor.VisitJoin(jn)
}
func (jn *JoinNode) Restore(flag RestoreFlag, sb *strings.Builder, args *[]int) error {
if jn.Natural {
sb.WriteString(" NATURAL")
}
sb.WriteByte(' ')
sb.WriteString(jn.Typ.String())
sb.WriteString(" JOIN ")
if err := jn.Target.Restore(flag, sb, args); err != nil {
return errors.WithStack(err)
}
sb.WriteString(" ON ")
if err := jn.On.Restore(flag, sb, args); err != nil {
return errors.WithStack(err)
}
return nil
}