iteration.md

CurrentModule = AbstractTrees

Iteration

AbstractTrees.jl provides algorithms for iterating through the nodes of trees in certain ways.

Interface

Iterators can be constructed for any tree that implements The Abstract Tree Interface with a 1-argument constructor on the root. For example collect(Leaves(node)) returns a Vector containing the leaves of the tree of which node is the root.

Trees can define additional methods to simplify the iteration procedure. To guarantee to the compiler that all nodes connected to a node of type ExampleNode are of the same type

Base.IteratorEltype(::Type{<:TreeIterator{ExampleNode}}) = Base.HasEltype()
Base.eltype(::Type{<:TreeIterator{ExampleNode}}) = ExampleNode

!!! note

While AbstractTrees.jl does its best to infer types appropriately, it is usually not possible
to determine the types involved in iteration over a general tree.  For performance critical
trees it is crucial to define `Base.IteratorEltype` and `Base.eltype` for `TreeIterator`.

Iterators

All iterators provided by AbstractTrees.jl are of the TreeIterator abstract type.

TreeIterator
PreOrderDFS
PostOrderDFS
Leaves
Siblings
StatelessBFS
treemap

Iterator States

Any iterator with a state (that is, all except StatelessBFS) are wrappers around objects which by themselves contain all information needed for iteration. Such a state defines an alternative iteration protocol which can be iterated through by calling next(s).

IteratorState
PreOrderState
PostOrderState
LeavesState
SiblingState

IteratorState Functions

instance
initial
next
statetype