48 lines
1.3 KiB
Go
48 lines
1.3 KiB
Go
// Copyright 2017 PingCAP, Inc.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package plan
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import (
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"github.com/pingcap/tidb/ast"
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)
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// AggregateFuncExtractor visits Expr tree.
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// It converts ColunmNameExpr to AggregateFuncExpr and collects AggregateFuncExpr.
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type AggregateFuncExtractor struct {
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inAggregateFuncExpr bool
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// AggFuncs is the collected AggregateFuncExprs.
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AggFuncs []*ast.AggregateFuncExpr
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}
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// Enter implements Visitor interface.
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func (a *AggregateFuncExtractor) Enter(n ast.Node) (ast.Node, bool) {
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switch n.(type) {
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case *ast.AggregateFuncExpr:
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a.inAggregateFuncExpr = true
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case *ast.SelectStmt, *ast.UnionStmt:
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return n, true
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}
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return n, false
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}
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// Leave implements Visitor interface.
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func (a *AggregateFuncExtractor) Leave(n ast.Node) (ast.Node, bool) {
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switch v := n.(type) {
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case *ast.AggregateFuncExpr:
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a.inAggregateFuncExpr = false
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a.AggFuncs = append(a.AggFuncs, v)
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}
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return n, true
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}
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