TreeTraversal (Unofficial IntelliJ Community Edition API docs)

java.lang.Object
- com.intellij.util.containers.TreeTraversal

```
public abstract class TreeTraversal
extends java.lang.Object
```
A redesigned version of com.google.common.collect.TreeTraversal.
The original JavaDoc:
Views elements of a type T as nodes in a tree, and provides methods to traverse the trees induced by this traverser.
For example, the tree
```
          h
        / | \
 *       /  e  \
 *      d       g
     /|\      |
    / | \     f
   a  b  c       
```
can be iterated over in pre-order (hdabcegf), post-order (abcdefgh), or breadth-first order (hdegabcf).
Null nodes are strictly forbidden.

Nested Class Summary

Nested Classes
Modifier and Type	Class and Description
`static class`	`TreeTraversal.GuidedIt<T>`
`static class`	`TreeTraversal.It<T>`
`static class`	`TreeTraversal.TracingIt<T>`
`static class`	`TreeTraversal.TraversalArgs<T>`
`static interface`	`TreeTraversal.TraversalInterceptor`

Field Summary

Fields
Modifier and Type	Field and Description
`static TreeTraversal`	`BI_ORDER_DFS` Returns an iterator over the nodes in a tree structure, using bi-order traversal.
`static TreeTraversal`	`INTERLEAVED_DFS` Returns an iterator over the nodes in a tree structure, using interlaced pre-order DFS traversal.
`static TreeTraversal`	`LEAVES_BFS` Returns an iterator over the leaf nodes only in a tree structure, using BFS traversal.
`static TreeTraversal`	`LEAVES_DFS` Returns an iterator over the leaf nodes only in a tree structure, using DFS traversal.
`static TreeTraversal`	`PLAIN_BFS` Returns an iterator over the nodes in a tree structure, using breadth-first traversal.
`static TreeTraversal`	`POST_ORDER_DFS` Returns an iterator over the nodes in a tree structure, using post-order DFS traversal.
`static TreeTraversal`	`PRE_ORDER_DFS` Returns an iterator over the nodes in a tree structure, using pre-order traversal.
`static TreeTraversal`	`TRACING_BFS` Same as `PLAIN_BFS` but with `TracingIt`.

Constructor Summary

Constructors
Modifier Constructor and Description

protected TreeTraversal(java.lang.String debugName)

Constructors
Modifier	Constructor and Description
`protected`	`TreeTraversal(java.lang.String debugName)`

Method Summary

All Methods Static Methods Instance Methods Abstract Methods Concrete Methods
Modifier and Type	Method and Description
`TreeTraversal`	`cached(java.util.Map<java.lang.Object,java.lang.Object> cache)` Configures the traversal to cache its structure.
`abstract <T> TreeTraversal.It<T>`	`createIterator(java.lang.Iterable<? extends T> roots, Function<? super T,? extends java.lang.Iterable<? extends T>> tree)` Creates a new iterator for this type of traversal.
`static TreeTraversal`	`GUIDED_TRAVERSAL(TreeTraversal.GuidedIt.Guide<?> guide)`
`TreeTraversal`	`intercept(java.lang.String debugName, TreeTraversal.TraversalInterceptor interceptor)`
`<T> TreeTraversal`	`onRange(Condition<T> rangeCondition)` Configures the traversal to expand and return the nodes within the range only.
`java.lang.String`	`toString()`
`<T> Function<T,JBIterable<T>>`	`traversal(Function<? super T,? extends java.lang.Iterable<? extends T>> tree)`
`<T> JBIterable<T>`	`traversal(java.lang.Iterable<? extends T> roots, Function<? super T,? extends java.lang.Iterable<? extends T>> tree)`
`<T> JBIterable<T>`	`traversal(T root, Function<? super T,? extends java.lang.Iterable<? extends T>> tree)`
`TreeTraversal`	`unique()` Configures the traversal to skip already visited nodes.
`TreeTraversal`	`unique(Function<?,?> identity)` Configures the traversal to skip already visited nodes.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

- Field Detail
  - BI_ORDER_DFS
```
public static final TreeTraversal BI_ORDER_DFS
```
    Returns an iterator over the nodes in a tree structure, using bi-order traversal. That is, each node returned before and after it's subtrees are traversed. Direction can be retrieved through TracingIt#isDescending()
    No guarantees are made about the behavior of the traversal when nodes change while iteration is in progress or when the iterators generated by tree are advanced.
  - PRE_ORDER_DFS
```
public static final TreeTraversal PRE_ORDER_DFS
```
    Returns an iterator over the nodes in a tree structure, using pre-order traversal. That is, each node's subtrees are traversed after the node itself is returned.
    No guarantees are made about the behavior of the traversal when nodes change while iteration is in progress or when the iterators generated by tree are advanced.
  - POST_ORDER_DFS
```
public static final TreeTraversal POST_ORDER_DFS
```
    Returns an iterator over the nodes in a tree structure, using post-order DFS traversal. That is, each node's subtrees are traversed before the node itself is returned.
    
    No guarantees are made about the behavior of the traversal when nodes change while iteration is in progress or when the iterators generated by tree are advanced.
  - LEAVES_DFS
```
public static final TreeTraversal LEAVES_DFS
```
    Returns an iterator over the leaf nodes only in a tree structure, using DFS traversal. That is, each node's subtrees are traversed before the node itself is returned.
  - INTERLEAVED_DFS
```
public static final TreeTraversal INTERLEAVED_DFS
```
    Returns an iterator over the nodes in a tree structure, using interlaced pre-order DFS traversal. That is, all paths are traversed in an interlaced manner that is suitable for infinite and cyclic graphs and each node's subtrees are traversed before the node itself is returned.
    
    No guarantees are made about the behavior of the traversal when nodes change while iteration is in progress or when the iterators generated by tree are advanced.
  - PLAIN_BFS
```
public static final TreeTraversal PLAIN_BFS
```
    Returns an iterator over the nodes in a tree structure, using breadth-first traversal. That is, all the nodes of depth 0 are returned, then depth 1, then 2, and so on.
    
    No guarantees are made about the behavior of the traversal when nodes change while iteration is in progress or when the iterators generated by tree are advanced.
  - TRACING_BFS
```
public static final TreeTraversal TRACING_BFS
```
    Same as PLAIN_BFS but with TracingIt. That is, a path to the current node can be retrieved during some traversal.
    
    See Also:
    
    TreeTraversal.TracingIt
  - LEAVES_BFS
```
public static final TreeTraversal LEAVES_BFS
```
    Returns an iterator over the leaf nodes only in a tree structure, using BFS traversal. That is, all the leaves of depth 0 are returned, then depth 1, then 2, and so on.
- Constructor Detail
  - TreeTraversal
```
protected TreeTraversal(java.lang.String debugName)
```
- Method Detail
  - createIterator
```
public abstract <T> TreeTraversal.It<T> createIterator(java.lang.Iterable<? extends T> roots,
                                                       Function<? super T,? extends java.lang.Iterable<? extends T>> tree)
```
    Creates a new iterator for this type of traversal.
    
    Parameters:
    
    roots - tree roots
    
    tree - tree structure the children for parent function. May return null (useful for map representation).
  - traversal
```
public final <T> JBIterable<T> traversal(java.lang.Iterable<? extends T> roots,
                                         Function<? super T,? extends java.lang.Iterable<? extends T>> tree)
```
  - traversal
```
public final <T> JBIterable<T> traversal(T root,
                                         Function<? super T,? extends java.lang.Iterable<? extends T>> tree)
```
  - traversal
```
public final <T> Function<T,JBIterable<T>> traversal(Function<? super T,? extends java.lang.Iterable<? extends T>> tree)
```
  - unique
```
public final TreeTraversal unique()
```
    Configures the traversal to skip already visited nodes.
    
    See Also:
    
    unique(Function)
  - unique
```
public final TreeTraversal unique(Function<?,?> identity)
```
    Configures the traversal to skip already visited nodes.
    
    Parameters:
    
    identity - function
  - cached
```
public final TreeTraversal cached(java.util.Map<java.lang.Object,java.lang.Object> cache)
```
    Configures the traversal to cache its structure.
  - onRange
```
public final <T> TreeTraversal onRange(Condition<T> rangeCondition)
```
    Configures the traversal to expand and return the nodes within the range only. It is an optimized version of expand-and-filter operation. It skips all the nodes "before" the rangeCondition return true for the first time, processes as usual the nodes while the condition return true and stops when the rangeCondition return false after that.
  - intercept
```
public final TreeTraversal intercept(java.lang.String debugName,
                                     TreeTraversal.TraversalInterceptor interceptor)
```
  - toString
```
public final java.lang.String toString()
```
    Overrides:
    
    toString in class java.lang.Object
  - GUIDED_TRAVERSAL
```
public static TreeTraversal GUIDED_TRAVERSAL(TreeTraversal.GuidedIt.Guide<?> guide)
```

Class TreeTraversal

Nested Class Summary

Field Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

BI_ORDER_DFS

PRE_ORDER_DFS

POST_ORDER_DFS

LEAVES_DFS

INTERLEAVED_DFS

PLAIN_BFS

TRACING_BFS

LEAVES_BFS

Constructor Detail

TreeTraversal

Method Detail

createIterator

traversal

traversal

traversal

unique

unique

cached

onRange

intercept

toString

GUIDED_TRAVERSAL