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gitea/vendor/github.com/pingcap/tidb/ast/flag.go

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// Copyright 2015 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 ast
const preEvaluable = FlagHasParamMarker | FlagHasFunc | FlagHasVariable | FlagHasDefault
// IsPreEvaluable checks if the expression can be evaluated before execution.
func IsPreEvaluable(expr ExprNode) bool {
return expr.GetFlag()|preEvaluable == preEvaluable
}
// IsConstant checks if the expression is constant.
// A constant expression is safe to be rewritten to value expression.
func IsConstant(expr ExprNode) bool {
return expr.GetFlag() == FlagConstant
}
// HasAggFlag checks if the expr contains FlagHasAggregateFunc.
func HasAggFlag(expr ExprNode) bool {
return expr.GetFlag()&FlagHasAggregateFunc > 0
}
// SetFlag sets flag for expression.
func SetFlag(n Node) {
var setter flagSetter
n.Accept(&setter)
}
type flagSetter struct {
}
func (f *flagSetter) Enter(in Node) (Node, bool) {
return in, false
}
func (f *flagSetter) Leave(in Node) (Node, bool) {
switch x := in.(type) {
case *AggregateFuncExpr:
f.aggregateFunc(x)
case *BetweenExpr:
x.SetFlag(x.Expr.GetFlag() | x.Left.GetFlag() | x.Right.GetFlag())
case *BinaryOperationExpr:
x.SetFlag(x.L.GetFlag() | x.R.GetFlag())
case *CaseExpr:
f.caseExpr(x)
case *ColumnNameExpr:
x.SetFlag(FlagHasReference)
case *CompareSubqueryExpr:
x.SetFlag(x.L.GetFlag() | x.R.GetFlag())
case *DefaultExpr:
x.SetFlag(FlagHasDefault)
case *ExistsSubqueryExpr:
x.SetFlag(x.Sel.GetFlag())
case *FuncCallExpr:
f.funcCall(x)
case *FuncCastExpr:
x.SetFlag(FlagHasFunc | x.Expr.GetFlag())
case *IsNullExpr:
x.SetFlag(x.Expr.GetFlag())
case *IsTruthExpr:
x.SetFlag(x.Expr.GetFlag())
case *ParamMarkerExpr:
x.SetFlag(FlagHasParamMarker)
case *ParenthesesExpr:
x.SetFlag(x.Expr.GetFlag())
case *PatternInExpr:
f.patternIn(x)
case *PatternLikeExpr:
f.patternLike(x)
case *PatternRegexpExpr:
f.patternRegexp(x)
case *PositionExpr:
x.SetFlag(FlagHasReference)
case *RowExpr:
f.row(x)
case *SubqueryExpr:
x.SetFlag(FlagHasSubquery)
case *UnaryOperationExpr:
x.SetFlag(x.V.GetFlag())
case *ValueExpr:
case *ValuesExpr:
x.SetFlag(FlagHasReference)
case *VariableExpr:
x.SetFlag(FlagHasVariable)
}
return in, true
}
func (f *flagSetter) caseExpr(x *CaseExpr) {
var flag uint64
if x.Value != nil {
flag |= x.Value.GetFlag()
}
for _, val := range x.WhenClauses {
flag |= val.Expr.GetFlag()
flag |= val.Result.GetFlag()
}
if x.ElseClause != nil {
flag |= x.ElseClause.GetFlag()
}
x.SetFlag(flag)
}
func (f *flagSetter) patternIn(x *PatternInExpr) {
flag := x.Expr.GetFlag()
for _, val := range x.List {
flag |= val.GetFlag()
}
if x.Sel != nil {
flag |= x.Sel.GetFlag()
}
x.SetFlag(flag)
}
func (f *flagSetter) patternLike(x *PatternLikeExpr) {
flag := x.Pattern.GetFlag()
if x.Expr != nil {
flag |= x.Expr.GetFlag()
}
x.SetFlag(flag)
}
func (f *flagSetter) patternRegexp(x *PatternRegexpExpr) {
flag := x.Pattern.GetFlag()
if x.Expr != nil {
flag |= x.Expr.GetFlag()
}
x.SetFlag(flag)
}
func (f *flagSetter) row(x *RowExpr) {
var flag uint64
for _, val := range x.Values {
flag |= val.GetFlag()
}
x.SetFlag(flag)
}
func (f *flagSetter) funcCall(x *FuncCallExpr) {
flag := FlagHasFunc
for _, val := range x.Args {
flag |= val.GetFlag()
}
x.SetFlag(flag)
}
func (f *flagSetter) aggregateFunc(x *AggregateFuncExpr) {
flag := FlagHasAggregateFunc
for _, val := range x.Args {
flag |= val.GetFlag()
}
x.SetFlag(flag)
}