/
transformation_rules.go
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/
transformation_rules.go
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// Copyright 2018 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,
// See the License for the specific language governing permissions and
// limitations under the License.
package cascades
import (
plannercore "github.com/daiguadaidai/tidb/planner/core"
"github.com/daiguadaidai/tidb/planner/memo"
)
// Transformation defines the interface for the transformation rules.
type Transformation interface {
GetPattern() *memo.Pattern
Match(expr *memo.ExprIter) (matched bool)
OnTransform(old *memo.ExprIter) (new *memo.GroupExpr, eraseOld bool, err error)
}
// GetTransformationRules gets the all the candidate transformation rules based
// on the logical plan node.
func GetTransformationRules(node plannercore.LogicalPlan) []Transformation {
return transformationMap[memo.GetOperand(node)]
}
var transformationMap = map[memo.Operand][]Transformation{
/**
operandSelect: []Transformation{
nil,
},
operandProject: []Transformation{
nil,
},
*/
}