com.almworks.jira.structure.api.util

Class RowTree

Object

RowTree

Direct Known Subclasses:

IndexedRowTree

public class RowTree
extends Object

RowTree is another representation of the Forest concept. It is implemented as a tree structure and is an alternative to ArrayForest when it comes to manipulating the forest.

RowTree is far more heavy on memory and GC - each row is a separate object + 52 bytes of payload. However, it is very fast with the modification operations.

Suggested use:

• Do not use for long-term forest storage!
• Do not use when ArrayForest is sufficient for the modifications you need.
• Do not use when you can arrange the modifications you need in a bulk array-creation fashion.
• DO use as a temporary object when you need a (potentially big) number of random changes with a forest and none of the above applies.

Additional concepts and terms:

• Super-root is the "hidden" node that all root nodes are children of.
• There's no concept of depth! Depth can be calculated by going up the parent chain, if needed. But it shouldn't be needed.
• Flags field lets you store temporary bitmask data in each node to help your algorithms. Semantics is up to you.

Note that this class does not check invariants (like uniqueness of row IDs).

Not thread-safe.

This method does not and should not implement Forest because it does not provide indexed access.

See Also:

RowTree.Node, IndexedRowTree

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	RowTree.Node Represents a single node or a RowTree.

Constructor Summary

Constructors

Constructor and Description
RowTree()

Method Summary

Modifier and Type	Method and Description
void	appendForest(Forest forest) Appends forest to the end of the tree.
void	appendForest(Forest forest, RowTree.Node underNode, RowTree.Node afterNode) Appends forest at the specified place.
int	appendForest(Forest forest, RowTree.Node parentNode, RowTree.Node afterNode, int parentIndex, int flags, LongPredicate rowFilter) Generic utility method for adding the forest to the RowTree, with parameters for optimization.
protected RowTree.Node	createNode(long rowId, int flags) Called always to create a new node for insertion in this tree.
protected void	forgetNode(RowTree.Node node) Called always when a node is removed (with its sub-nodes).
RowTree.Node	getSuperRoot()
RowTree.Node	insertNode(long rowId, int flags, RowTree.Node parentNode, RowTree.Node afterNode) Adds a node to the tree at the specified position.
RowTree.Node	moveNode(RowTree.Node node, RowTree.Node parentNode, RowTree.Node afterNode) Moves node within a tree
void	remove(RowTree.Node node) Removes node and its sub-tree from the tree.
ArrayForest	toForest() Creates Forest representing this RowTree.
String	toString()

Methods inherited from class Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Constructor Detail

RowTree

public RowTree()

Method Detail

getSuperRoot

public RowTree.Node getSuperRoot()

toString

public String toString()

Overrides:

toString in class Object

appendForest

public void appendForest(@NotNull
                         Forest forest)

Appends forest to the end of the tree. Forest roots also become roots in the RowTree.

Parameters:

forest - the forest

appendForest

public void appendForest(@NotNull
                         Forest forest,
                         @NotNull
                         RowTree.Node underNode,
                         @Nullable
                         RowTree.Node afterNode)

Appends forest at the specified place.

Parameters:

forest - the forest

underNode - the would-be parent

afterNode - the would-be preceding sibling, or null if the inserted nodes should come first under underNode

appendForest

public int appendForest(@NotNull
                        Forest forest,
                        @NotNull
                        RowTree.Node parentNode,
                        @Nullable
                        RowTree.Node afterNode,
                        int parentIndex,
                        int flags,
                        @Nullable
                        LongPredicate rowFilter)

Generic utility method for adding the forest to the RowTree, with parameters for optimization.

Parameters:

forest - the source forest

parentNode - the would-be parent

afterNode - the would-be preceding sibling, or null if the inserted nodes should come first under underNode

parentIndex - the index of the source row in forest - only children of of that row and their sub-trees are added (the row itself is not added); use -1 to insert the whole forest

flags - initial flags for all created nodes

rowFilter - when not null, each node is tested with this predicate; failed nodes and their sub-trees are skipped (even if some row in the sub-tree passes the filter)

Returns:

the index in the forest where iteration stopped (subtreeEnd for the parentNode)

insertNode

public RowTree.Node insertNode(long rowId,
                               int flags,
                               RowTree.Node parentNode,
                               RowTree.Node afterNode)

Adds a node to the tree at the specified position.

Parameters:

rowId - row ID

parentNode - the would-be parent

afterNode - the would-be preceding sibling, or null if the inserted nodes should come first under underNode

flags - initial flags for all created nodes

Returns:

inserted node

moveNode

public RowTree.Node moveNode(RowTree.Node node,
                             RowTree.Node parentNode,
                             RowTree.Node afterNode)

Moves node within a tree

Parameters:

node - node to move

parentNode - the would-be parent

afterNode - the would-be preceding sibling, or null if the inserted nodes should come first under underNode

Returns:

node

remove

public void remove(RowTree.Node node)

Removes node and its sub-tree from the tree.

Parameters:

node - node

toForest

public ArrayForest toForest()

Creates Forest representing this RowTree.

Returns:

ArrayForest

createNode

protected RowTree.Node createNode(long rowId,
                                  int flags)

Called always to create a new node for insertion in this tree. Intended to be overridden with additional checks and maintaining state.

forgetNode

protected void forgetNode(RowTree.Node node)

Called always when a node is removed (with its sub-nodes). Not called for sub-nodes explicitly. Intended to be overridden with additional checks and maintaining state.