Trait datafusion::logical_plan::ExpressionVisitor

pub trait ExpressionVisitor: Sized {
    fn pre_visit(self, expr: &Expr) -> Result<Recursion<Self>>;

    fn post_visit(self, _expr: &Expr) -> Result<Self> { ... }
}

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

fn pre_visit(self, expr: &Expr) -> Result<Recursion<Self>>

Invoked before any children of expr are visisted.

Provided methods

fn post_visit(self, _expr: &Expr) -> Result<Self>

Invoked after all children of expr are visited. Default implementation does nothing.

Implementors