171 lines
3.4 KiB
Go
171 lines
3.4 KiB
Go
// Copyright 2015 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 ast
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import "fmt"
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// Cloner is an ast visitor that clones a node.
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type Cloner struct {
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}
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// Enter implements Visitor Enter interface.
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func (c *Cloner) Enter(node Node) (Node, bool) {
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return copyStruct(node), false
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}
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// Leave implements Visitor Leave interface.
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func (c *Cloner) Leave(in Node) (out Node, ok bool) {
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return in, true
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}
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// copyStruct copies a node's struct value, if the struct has slice member,
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// make a new slice and copy old slice value to new slice.
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func copyStruct(in Node) (out Node) {
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switch v := in.(type) {
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case *ValueExpr:
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nv := *v
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out = &nv
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case *BetweenExpr:
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nv := *v
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out = &nv
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case *BinaryOperationExpr:
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nv := *v
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out = &nv
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case *WhenClause:
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nv := *v
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out = &nv
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case *CaseExpr:
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nv := *v
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nv.WhenClauses = make([]*WhenClause, len(v.WhenClauses))
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copy(nv.WhenClauses, v.WhenClauses)
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out = &nv
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case *SubqueryExpr:
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nv := *v
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out = &nv
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case *CompareSubqueryExpr:
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nv := *v
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out = &nv
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case *ColumnName:
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nv := *v
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out = &nv
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case *ColumnNameExpr:
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nv := *v
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out = &nv
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case *DefaultExpr:
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nv := *v
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out = &nv
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case *ExistsSubqueryExpr:
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nv := *v
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out = &nv
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case *PatternInExpr:
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nv := *v
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nv.List = make([]ExprNode, len(v.List))
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copy(nv.List, v.List)
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out = &nv
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case *IsNullExpr:
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nv := *v
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out = &nv
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case *IsTruthExpr:
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nv := *v
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out = &nv
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case *PatternLikeExpr:
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nv := *v
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out = &nv
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case *ParamMarkerExpr:
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nv := *v
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out = &nv
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case *ParenthesesExpr:
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nv := *v
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out = &nv
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case *PositionExpr:
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nv := *v
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out = &nv
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case *PatternRegexpExpr:
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nv := *v
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out = &nv
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case *RowExpr:
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nv := *v
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nv.Values = make([]ExprNode, len(v.Values))
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copy(nv.Values, v.Values)
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out = &nv
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case *UnaryOperationExpr:
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nv := *v
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out = &nv
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case *ValuesExpr:
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nv := *v
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out = &nv
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case *VariableExpr:
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nv := *v
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out = &nv
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case *Join:
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nv := *v
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out = &nv
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case *TableName:
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nv := *v
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out = &nv
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case *TableSource:
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nv := *v
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out = &nv
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case *OnCondition:
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nv := *v
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out = &nv
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case *WildCardField:
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nv := *v
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out = &nv
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case *SelectField:
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nv := *v
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out = &nv
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case *FieldList:
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nv := *v
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nv.Fields = make([]*SelectField, len(v.Fields))
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copy(nv.Fields, v.Fields)
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out = &nv
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case *TableRefsClause:
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nv := *v
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out = &nv
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case *ByItem:
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nv := *v
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out = &nv
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case *GroupByClause:
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nv := *v
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nv.Items = make([]*ByItem, len(v.Items))
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copy(nv.Items, v.Items)
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out = &nv
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case *HavingClause:
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nv := *v
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out = &nv
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case *OrderByClause:
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nv := *v
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nv.Items = make([]*ByItem, len(v.Items))
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copy(nv.Items, v.Items)
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out = &nv
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case *SelectStmt:
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nv := *v
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out = &nv
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case *UnionSelectList:
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nv := *v
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nv.Selects = make([]*SelectStmt, len(v.Selects))
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copy(nv.Selects, v.Selects)
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out = &nv
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case *UnionStmt:
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nv := *v
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out = &nv
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default:
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// We currently only handle expression and select statement.
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// Will add more when we need to.
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panic("unknown ast Node type " + fmt.Sprintf("%T", v))
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}
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return
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}
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