github.com/rohankumardubey/aresdb@v0.0.2-0.20190517170215-e54e3ca06b9c/query/sql/tree/Join.go (about)

     1  //  Copyright (c) 2017-2018 Uber Technologies, 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  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    12  // See the License for the specific language governing permissions and
    13  // limitations under the License.
    14  
    15  package tree
    16  
    17  import (
    18  	"fmt"
    19  
    20  	"github.com/uber/aresdb/query/sql/util"
    21  )
    22  
    23  // Join is Join
    24  type Join struct {
    25  	// IRelation is interface
    26  	IRelation
    27  	// Type is join type
    28  	Type JoinType
    29  	// Left is IRelation
    30  	Left IRelation
    31  	// Right is IRelation
    32  	Right IRelation
    33  	// Criteria is on condition
    34  	Criteria IJoinCriteria
    35  }
    36  
    37  // JoinType is join type
    38  type JoinType int
    39  
    40  const (
    41  	// CROSS is CROSS
    42  	CROSS JoinType = iota
    43  	// INNER is INNER
    44  	INNER
    45  	// LEFT is LEFT
    46  	LEFT
    47  	// RIGHT is RIGHT
    48  	RIGHT
    49  	// FULL is FULL
    50  	FULL
    51  	// IMPLICIT is IMPLICIT
    52  	IMPLICIT
    53  )
    54  
    55  // JoinTypes is join type strings
    56  var JoinTypes = [...]string{
    57  	"CROSS",
    58  	"INNER",
    59  	"LEFT",
    60  	"RIGHT",
    61  	"FULL",
    62  	"IMPLICIT",
    63  }
    64  
    65  // NewJoin creates Join
    66  func NewJoin(location *NodeLocation, joinType JoinType, left, right IRelation, criteria IJoinCriteria) *Join {
    67  	errMsg := fmt.Sprintf("left is null at (line:%d, col:%d)", location.Line, location.CharPosition)
    68  	util.RequireNonNull(left, errMsg)
    69  	errMsg = fmt.Sprintf("right is null at (line:%d, col:%d)", location.Line, location.CharPosition)
    70  	util.RequireNonNull(right, errMsg)
    71  
    72  	if joinType != LEFT {
    73  		panic(fmt.Errorf("only support left join at (line:%d, col:%d)", location.Line, location.CharPosition))
    74  	}
    75  
    76  	return &Join{
    77  		NewRelation(location),
    78  		joinType,
    79  		left,
    80  		right,
    81  		criteria,
    82  	}
    83  }
    84  
    85  // Accept accepts visitor
    86  func (e *Join) Accept(visitor AstVisitor, ctx interface{}) interface{} {
    87  	return visitor.VisitJoin(e, ctx)
    88  }