// EvalDatum evaluates an expression to a datum.
func EvalDatum(ctx context.Context, expr ast.ExprNode) (d types.Datum, err error) {
e := &Evaluator{ctx: ctx}
expr.Accept(e)
if e.err != nil {
return d, errors.Trace(e.err)
}
return *expr.GetDatum(), nil
}
// Eval evaluates an expression to a datum.
func Eval(ctx context.Context, expr ast.ExprNode) (d types.Datum, err error) {
if ast.IsEvaluated(expr) {
return *expr.GetDatum(), nil
}
e := &Evaluator{ctx: ctx}
expr.Accept(e)
if e.err != nil {
return d, errors.Trace(e.err)
}
if ast.IsPreEvaluable(expr) && (expr.GetFlag()&ast.FlagHasFunc == 0) {
expr.SetFlag(expr.GetFlag() | ast.FlagPreEvaluated)
}
return *expr.GetDatum(), nil
}
// exprToPBExpr converts an ast.ExprNode to a tipb.Expr, if not supported, nil will be returned.
func (b *executorBuilder) exprToPBExpr(client kv.Client, expr ast.ExprNode, tn *ast.TableName) *tipb.Expr {
switch x := expr.(type) {
case *ast.ValueExpr, *ast.ParamMarkerExpr:
return b.datumToPBExpr(client, *expr.GetDatum())
case *ast.ColumnNameExpr:
return b.columnNameToPBExpr(client, x, tn)
case *ast.BinaryOperationExpr:
return b.binopToPBExpr(client, x, tn)
case *ast.ParenthesesExpr:
return b.exprToPBExpr(client, x.Expr, tn)
case *ast.PatternLikeExpr:
return b.likeToPBExpr(client, x, tn)
case *ast.UnaryOperationExpr:
return b.unaryToPBExpr(client, x, tn)
case *ast.PatternInExpr:
return b.patternInToPBExpr(client, x, tn)
case *ast.SubqueryExpr:
return b.subqueryToPBExpr(client, x)
case *ast.AggregateFuncExpr:
return b.aggFuncToPBExpr(client, x, tn)
default:
return nil
}
}