TreeNodeVisitor

datafusion_python::datafusion_common::tree_node

Trait TreeNodeVisitor 

Source 
pub trait TreeNodeVisitor<'n>: Sized {
    type Node: TreeNode;

    // Provided methods
    fn f_down(
        &mut self,
        _node: &'n Self::Node,
    ) -> Result<TreeNodeRecursion, DataFusionError> { ... }
    fn f_up(
        &mut self,
        _node: &'n Self::Node,
    ) -> Result<TreeNodeRecursion, DataFusionError> { ... }
}
Expand description

A Visitor for recursively inspecting TreeNodes via TreeNode::visit.

See TreeNode for more details on available APIs

When passed to TreeNode::visit, TreeNodeVisitor::f_down and TreeNodeVisitor::f_up are invoked recursively on the tree. See TreeNodeRecursion for more details on controlling the traversal.

§Return Value

The returns value of f_up and f_down specifies how the tree walk should proceed. See TreeNodeRecursion for details. If an Err is returned, the recursion stops immediately.

Note: If using the default implementations of TreeNodeVisitor::f_up or TreeNodeVisitor::f_down that do nothing, consider using TreeNode::apply instead.

§See Also:

Required Associated Types§

Source

type Node: TreeNode

The node type which is visitable.

Provided Methods§

Source

fn f_down( &mut self, _node: &'n Self::Node, ) -> Result<TreeNodeRecursion, DataFusionError>

Invoked while traversing down the tree, before any children are visited. Default implementation continues the recursion.

Source

fn f_up( &mut self, _node: &'n Self::Node, ) -> Result<TreeNodeRecursion, DataFusionError>

Invoked while traversing up the tree after children are visited. Default implementation continues the recursion.

Dyn Compatibility§

This trait is not dyn compatible.

In older versions of Rust, dyn compatibility was called "object safety", so this trait is not object safe.

Implementors§