Trait datafusion::logical_plan::ExpressionVisitor [−][src]
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>>
[src]
Invoked before any children of expr
are visisted.
Provided methods
fn post_visit(self, _expr: &Expr) -> Result<Self>
[src]
Invoked after all children of expr
are visited. Default
implementation does nothing.