Trait datafusion::logical_plan::ExpressionVisitor
source · [−]pub trait ExpressionVisitor<E: ExprVisitable = Expr>: Sized {
fn pre_visit(self, expr: &E) -> Result<Recursion<Self>>
where
Self: ExpressionVisitor;
fn post_visit(self, _expr: &E) -> Result<Self> { ... }
}
Expand description
Encode the traversal of an expression tree. When passed to
Expr::accept
, ExpressionVisitor::visit
is invoked
recursively on all nodes of an expression tree. See the comments
on Expr::accept
for details on its use
Required methods
Provided methods
fn post_visit(self, _expr: &E) -> Result<Self>
fn post_visit(self, _expr: &E) -> Result<Self>
Invoked after all children of expr
are visited. Default
implementation does nothing.