Class: Tree::TreeNode

Inherits:
Object
  • Object
show all
Includes:
Comparable, Enumerable, Utils::CamelCaseMethodHandler, Utils::HashConverter, Utils::JSONConverter, Utils::TreeMergeHandler, Utils::TreeMetricsHandler, Utils::TreePathHandler
Defined in:
lib/tree.rb

Overview

TreeNode Class Description

This class models the nodes for an N-ary tree data structure. The nodes are named, and have a place-holder for the node data (i.e., content of the node). The node names are required to be unique amongst the sibling/peer nodes. Note that the name is implicitly used as an ID within the data structure).

The node's content is not required to be unique across different nodes in the tree, and can be nil as well.

The class provides various methods to navigate the tree, traverse the structure, modify contents of the node, change position of the node in the tree, and to make structural changes to the tree.

A node can have any number of child nodes attached to it and hence can be used to create N-ary trees. Access to the child nodes can be made in order (with the conventional left to right access), or randomly.

The node also provides direct access to its parent node as well as other superior parents in the path to root of the tree. In addition, a node can also access its sibling nodes, if present.

Note that while this implementation does not explicitly support directed graphs, the class itself makes no restrictions on associating a node's content with multiple nodes in the tree. However, having duplicate nodes within the structure is likely to cause unpredictable behavior.

Example

#!/usr/bin/env ruby
#
# example_basic.rb:: Basic usage of the tree library.
#
# Author:  Anupam Sengupta
# Time-stamp: <2015-12-31 22:17:30 anupam>
# Copyright (C) 2013, 2015 Anupam Sengupta <anupamsg@gmail.com>
#
# The following example implements this tree structure:
#
#                    +------------+
#                    |    ROOT    |
#                    +-----+------+
#            +-------------+------------+
#            |                          |
#    +-------+-------+          +-------+-------+
#    |  CHILD 1      |          |  CHILD 2      |
#    +-------+-------+          +---------------+
#            |
#            |
#    +-------+-------+
#    | GRANDCHILD 1  |
#    +---------------+

# ..... Example starts.
require 'tree'                 # Load the library

# ..... Create the root node first.  Note that every node has a name and an optional content payload.
root_node = Tree::TreeNode.new("ROOT", "Root Content")
root_node.print_tree

# ..... Now insert the child nodes.  Note that you can "chain" the child insertions for a given path to any depth.
root_node << Tree::TreeNode.new("CHILD1", "Child1 Content") << Tree::TreeNode.new("GRANDCHILD1", "GrandChild1 Content")
root_node << Tree::TreeNode.new("CHILD2", "Child2 Content")

# ..... Lets print the representation to stdout.  This is primarily used for debugging purposes.
root_node.print_tree

# ..... Lets directly access children and grandchildren of the root.  The can be "chained" for a given path to any depth.
child1       = root_node["CHILD1"]
grand_child1 = root_node["CHILD1"]["GRANDCHILD1"]

# ..... Now lets retrieve siblings of the current node as an array.
siblings_of_child1 = child1.siblings

# ..... Lets retrieve immediate children of the root node as an array.
children_of_root = root_node.children

# ..... Retrieve the parent of a node.
parent = child1.parent

# ..... This is a depth-first and L-to-R pre-ordered traversal.
root_node.each { |node| node.content.reverse }

# ..... Lets remove a child node from the root node.
root_node.remove!(child1)

Author:

Direct Known Subclasses

BinaryTreeNode

Core Attributes (collapse)

Instance Attribute Summary (collapse)

Node Creation (collapse)

Structure Modification (collapse)

Tree Traversal (collapse)

Navigating the Child Nodes (collapse)

Navigating the Sibling Nodes (collapse)

Converting to/from JSON (collapse)

Merging Trees (collapse)

Instance Method Summary (collapse)

Constructor Details

- (TreeNode) initialize(name, content = nil)

Note:

If the name is an Integer, then the semantics of #[] access method can be surprising, as an Integer parameter to that method normally acts as an index to the children array, and follows the zero-based indexing convention.

Creates a new node with a name and optional content. The node name is expected to be unique within the tree.

The content can be of any type, and defaults to nil.

Parameters:

  • name (Object)

    Name of the node. Conventional usage is to pass a String (Integer names may cause surprises)

  • content (Object) (defaults to: nil)

    Content of the node.

Raises:

  • (ArgumentError)

    Raised if the node name is empty.

See Also:



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# File 'lib/tree.rb', line 217

def initialize(name, content = nil)
  raise ArgumentError, "Node name HAS to be provided!" if name == nil
  @name, @content = name, content

  if name.kind_of?(Integer)
    warn StandardWarning,
         "Using integer as node name."\
         " Semantics of TreeNode[] may not be what you expect!"\
         " #{name} #{content}"
  end

  self.set_as_root!
  @children_hash = Hash.new
  @children = []
end

Dynamic Method Handling

This class handles dynamic methods through the method_missing method in the class Tree::Utils::CamelCaseMethodHandler

Instance Attribute Details

- (Integer) breadth (readonly) Originally defined in module Utils::TreeMetricsHandler

Breadth of the tree at this node's level. A single node without siblings has a breadth of 1.

Breadth is defined to be:

Breadth

Number of sibling nodes to this node + 1 (this node itself),

i.e., the number of children the parent of this node has.

Returns:

  • (Integer)

    breadth of the node's level.

- (Object) content

Content of this node. Can be nil. Note that there is no uniqueness constraint related to this attribute.

See Also:

  • name


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# File 'lib/tree.rb', line 122

def content
  @content
end

- (Integer) depth (readonly) Originally defined in module Utils::TreeMetricsHandler

Deprecated.

This method returns an incorrect value. Use the

Depth of the tree from this node. A single leaf node has a depth of 1.

This method is DEPRECATED and may be removed in the subsequent releases. Note that the value returned by this method is actually the:

height + 1 of the node, NOT the depth.

For correct and conventional behavior, please use #node_depth and #node_height methods instead.

#node_depth method instead.

Returns:

  • (Integer)

    depth of the node.

See Also:

- (Boolean) has_children? (readonly)

true if the this node has any child node.

Returns:

  • (Boolean)

    true if child nodes exist.

See Also:



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# File 'lib/tree.rb', line 193

def has_children?
  @children.length != 0
end

- (Boolean) has_content? (readonly)

true if this node has content.

Returns:

  • (Boolean)

    true if the node has content.



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# File 'lib/tree.rb', line 152

def has_content?
  @content != nil
end

- (Integer) in_degree (readonly) Originally defined in module Utils::TreeMetricsHandler

The incoming edge-count of this node.

In-degree is defined as:

In-degree

Number of edges arriving at the node (0 for root, 1 for

all other nodes)

  • In-degree = 0 for a root or orphaned node

  • In-degree = 1 for a node which has a parent

Returns:

  • (Integer)

    The in-degree of this node.

- (Boolean) is_leaf? (readonly)

true if this node is a leaf - i.e., one without any children.

Returns:

  • (Boolean)

    true if this is a leaf node.

See Also:



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# File 'lib/tree.rb', line 163

def is_leaf?
  !has_children?
end

- (Boolean) is_root? (readonly)

Returns true if this is a root node. Note that orphaned children will also be reported as root nodes.

Returns:

  • (Boolean)

    true if this is a root node.



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# File 'lib/tree.rb', line 144

def is_root?
  @parent.nil?
end

- (Integer) length (readonly) Originally defined in module Utils::TreeMetricsHandler

Deprecated.

This method name is ambiguous and may be removed. Use

Convenience synonym for #size.

#size instead.

Returns:

  • (Integer)

    The total number of nodes in this (sub)tree.

See Also:

- (Object) level (readonly) Originally defined in module Utils::TreeMetricsHandler

Alias for #node_depth

See Also:

- (Object) name

Name of this node. Expected to be unique within the tree.

Note that the name attribute really functions as an ID within the tree structure, and hence the uniqueness constraint is required.

This may be changed in the future, but for now it is best to retain unique names within the tree structure, and use the content attribute for any non-unique node requirements.

If you want to change the name, you probably want to call rename instead.

See Also:

  • content
  • rename


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# File 'lib/tree.rb', line 115

def name
  @name
end

- (Integer) node_depth (readonly) Originally defined in module Utils::TreeMetricsHandler

Depth of this node in its tree. Depth of a node is defined as:

Depth

Length of the node's path to its root. Depth of a root node is

zero.

Note that the deprecated method #depth was incorrectly computing this value. Please replace all calls to the old method with #node_depth instead.

#level is an alias for this method.

Returns:

  • (Integer)

    Depth of this node.

- (Integer) node_height (readonly) Originally defined in module Utils::TreeMetricsHandler

Height of the (sub)tree from this node. Height of a node is defined as:

Height

Length of the longest downward path to a leaf from the node.

  • Height from a root node is height of the entire tree.

  • The height of a leaf node is zero.

Returns:

  • (Integer)

    Height of the node.

- (Integer) out_degree (readonly) Originally defined in module Utils::TreeMetricsHandler

The outgoing edge-count of this node.

Out-degree is defined as:

Out-degree

Number of edges leaving the node (zero for leafs)

Returns:

  • (Integer)

    The out-degree of this node.

- (Object) parent

Parent of this node. Will be nil for a root node.



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# File 'lib/tree.rb', line 126

def parent
  @parent
end

- (Array<Tree::TreeNode>?) parentage (readonly)

An array of ancestors of this node in reversed order (the first element is the immediate parent of this node).

Returns nil if this is a root node.

Returns:

  • (Array<Tree::TreeNode>)

    An array of ancestors of this node

  • (nil)

    if this is a root node.



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# File 'lib/tree.rb', line 175

def parentage
  return nil if is_root?

  parentage_array = []
  prev_parent = self.parent
  while (prev_parent)
    parentage_array << prev_parent
    prev_parent = prev_parent.parent
  end
  parentage_array
end

- (Tree::TreeNode) root (readonly)

Root node for the (sub)tree to which this node belongs. A root node's root is itself.

Returns:



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# File 'lib/tree.rb', line 133

def root
  root = self
  root = root.parent while !root.is_root?
  root
end

- (Integer) size (readonly) Originally defined in module Utils::TreeMetricsHandler

Total number of nodes in this (sub)tree, including this node.

Size of the tree is defined as:

Size

Total number nodes in the subtree including this node.

Returns:

  • (Integer)

    Total number of nodes in this (sub)tree.

Instance Method Details

- (Tree::TreeNode) <<(child)

Convenience synonym for #add method.

This method allows an easy mechanism to add node hierarchies to the tree on a given path via chaining the method calls to successive child nodes.

Examples:

Add a child and grand-child to the root

root << child << grand_child

Parameters:

Returns:

See Also:



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# File 'lib/tree.rb', line 333

def <<(child)
  add(child)
end

- (Integer) <=>(other)

Provides a comparision operation for the nodes.

Comparision is based on the natural ordering of the node name objects.

Parameters:

Returns:

  • (Integer)

    +1 if this node is a 'successor', 0 if equal and -1 if this node is a 'predecessor'. Returns 'nil' if the other object is not a 'Tree::TreeNode'.



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# File 'lib/tree.rb', line 927

def <=>(other)
  return nil if other == nil || other.class != Tree::TreeNode
  self.name <=> other.name
end

- (Tree::TreeNode) [](name_or_index, num_as_name = false)

Note:

The use of Integer names is allowed by using the optional num_as_name flag.

Returns the requested node from the set of immediate children.

  • If the name argument is an Integer, then the in-sequence array of children is accessed using the argument as the index (zero-based). However, if the second optional num_as_name argument is true, then the name is used literally as a name, and NOT as an index

  • If the name argument is NOT an Integer, then it is taken to be the name of the child node to be returned.

If a non-Integer name is passed, and the num_as_name parameter is also true, then a warning is thrown (as this is a redundant use of the num_as_name flag.)

Parameters:

  • name_or_index (String|Number)

    Name of the child, or its positional index in the array of child nodes.

  • num_as_name (Boolean) (defaults to: false)

    Whether to treat the Integer name argument as an actual name, and NOT as an index to the children array.

Returns:

  • (Tree::TreeNode)

    the requested child node. If the index in not in range, or the name is not present, then a nil is returned.

Raises:

  • (ArgumentError)

    Raised if the name_or_index argument is nil.

See Also:



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# File 'lib/tree.rb', line 606

def [](name_or_index, num_as_name=false)
  raise ArgumentError,
        "Name_or_index needs to be provided!" if name_or_index == nil

  if name_or_index.kind_of?(Integer) and not num_as_name
    @children[name_or_index]
  else
    if num_as_name and not name_or_index.kind_of?(Integer)
      warn StandardWarning,
         "Redundant use of the `num_as_name` flag for non-integer node name"
    end
    @children_hash[name_or_index]
  end
end

- (Tree::TreeNode) add(child, at_index = -1))

Adds the specified child node to this node.

This method can also be used for grafting a subtree into this node's tree, if the specified child node is the root of a subtree (i.e., has child nodes under it).

this node becomes parent of the node passed in as the argument, and the child is added as the last child (“right most”) in the current set of children of this node.

Additionally you can specify a insert position. The new node will be inserted BEFORE that position. If you don't specify any position the node will be just appended. This feature is provided to make implementation of node movement within the tree very simple.

If an insertion position is provided, it needs to be within the valid range of:

-children.size..children.size

This is to prevent nil nodes being created as children if a non-existant position is used.

If the new node being added has an existing parent node, then it will be removed from this pre-existing parent prior to being added as a child to this node. I.e., the child node will effectively be moved from its old parent to this node. In this situation, after the operation is complete, the node will no longer exist as a child for its old parent.

Parameters:

  • child (Tree::TreeNode)

    The child node to add.

  • at_index (optional, Number) (defaults to: -1))

    The optional position where the node is to be inserted.

Returns:

Raises:

  • (RuntimeError)

    This exception is raised if another child node with the same name exists, or if an invalid insertion position is specified.

  • (ArgumentError)

    This exception is raised if a nil node is passed as the argument.

See Also:



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# File 'lib/tree.rb', line 381

def add(child, at_index = -1)
  # Only handles the immediate child scenario
  raise ArgumentError,
        "Attempting to add a nil node" unless child
  raise ArgumentError,
        "Attempting add node to itself" if self.equal?(child)
  raise ArgumentError,
        "Attempting add root as a child" if child.equal?(root)

  # Lazy mans unique test, won't test if children of child are unique in
  # this tree too.
  raise "Child #{child.name} already added!"\
        if @children_hash.include?(child.name)

  child.parent.remove! child if child.parent # Detach from the old parent

  if insertion_range.include?(at_index)
    @children.insert(at_index, child)
  else
    raise "Attempting to insert a child at a non-existent location"\
          " (#{at_index}) "\
          "when only positions from "\
          "#{insertion_range.min} to #{insertion_range.max} exist."
  end

  @children_hash[child.name]  = child
  child.parent = self
  return child
end

- (Array) add_from_hash(children) Originally defined in module Utils::HashConverter

Instantiate and insert child nodes from data in a Ruby Hash

This method is used in conjunction with from_hash to provide a convenient way of building and inserting child nodes present in a Ruby hashes.

This method will instantiate a node instance for each top- level key of the input hash, to be inserted as children of the receiver instance.

Nested hashes are expected and further child nodes will be created and added accordingly. If a hash key is a single value that value will be used as the name for the node. If a hash key is an Array, both node name and content will be populated.

A leaf element of the tree should be represented as a hash key with corresponding value nil or {}.

Examples:

root = Tree::TreeNode.new(:A, "Root content!")
root.add_from_hash({:B => {:D => {}}, [:C, "C content!"] => {}})

Parameters:

  • children (Hash)

    The hash of child subtrees.

Returns:

  • (Array)

    Array of child nodes added

Raises:

  • (ArgumentError)

    This exception is raised if a non-hash is passed.

See Also:

Author:

- (Object) as_json(options = {}) Originally defined in module Utils::JSONConverter

Creates a JSON ready Hash for the #to_json method.

Rails uses JSON in ActiveSupport, and all Rails JSON encoding goes through as_json.

Returns:

  • A hash based representation of the JSON

See Also:

Author:

Since:

  • 0.8.3

- (Tree::TreeNode, Enumerator) breadth_each {|node| ... }

Performs breadth-first traversal of the (sub)tree rooted at this node. The traversal at a given level is from left-to-right. this node itself is the first node to be traversed.

Yield Parameters:

Returns:

  • (Tree::TreeNode)

    this node, if a block if given

  • (Enumerator)

    an enumerator on this tree, if a block is not given

See Also:



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# File 'lib/tree.rb', line 711

def breadth_each(&block)
  return self.to_enum(:breadth_each) unless block_given?

  node_queue = [self]       # Create a queue with self as the initial entry

  # Use a queue to do breadth traversal
  until node_queue.empty?
    node_to_traverse = node_queue.shift
    yield node_to_traverse
    # Enqueue the children from left to right.
    node_to_traverse.children { |child| node_queue.push child }
  end

  return self if block_given?
end

- (Tree::TreeNode+) children {|child| ... }

An array of all the immediate children of this node. The child nodes are ordered “left-to-right” in the returned array.

If a block is given, yields each child node to the block traversing from left to right.

Yield Parameters:

Returns:



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# File 'lib/tree.rb', line 739

def children
  if block_given?
    @children.each {|child| yield child}
    return self
  else
    return @children.clone
  end
end

- (Tree::TreeNode) detached_copy

Returns a copy of this node, with its parent and children links removed. The original node remains attached to its tree.

Returns:



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# File 'lib/tree.rb', line 237

def detached_copy
  self.class.new(@name, @content ? @content.clone : nil)
end

- (Tree::TreeNode) detached_subtree_copy Also known as: dup

Returns a copy of entire (sub-)tree from this node.

Returns:

Author:

  • Vincenzo Farruggia

Since:

  • 0.8.0



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# File 'lib/tree.rb', line 247

def detached_subtree_copy
  new_node = detached_copy
  children { |child| new_node << child.detached_subtree_copy }
  new_node
end

- (Tree::TreeNode, Enumerator) each {|node| ... }

Traverses each node (including this node) of the (sub)tree rooted at this node by yielding the nodes to the specified block.

The traversal is depth-first and from left-to-right in pre-ordered sequence.

Yield Parameters:

Returns:

  • (Tree::TreeNode)

    this node, if a block if given

  • (Enumerator)

    an enumerator on this tree, if a block is not given

See Also:



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# File 'lib/tree.rb', line 634

def each(&block)             # :yields: node

 return self.to_enum unless block_given?

  node_stack = [self]   # Start with this node

  until node_stack.empty?
    current = node_stack.shift    # Pop the top-most node
    if current                    # Might be 'nil' (esp. for binary trees)
      yield current               # and process it
      # Stack children of the current node at top of the stack
      node_stack = current.children.concat(node_stack)
    end
  end

  return self if block_given?
end

- (Tree::TreeNode+) each_leaf {|node| ... }

Yields every leaf node of the (sub)tree rooted at this node to the specified block.

May yield this node as well if this is a leaf node. Leaf traversal is depth-first and left-to-right.

Yield Parameters:

Returns:

See Also:



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# File 'lib/tree.rb', line 761

def each_leaf &block
  if block_given?
    self.each { |node| yield(node) if node.is_leaf? }
    return self
  else
    self.select { |node| node.is_leaf?}
  end
end

- (Tree::TreeNode) first_child

First child of this node. Will be nil if no children are present.

Returns:



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# File 'lib/tree.rb', line 778

def first_child
  children.first
end

- (Tree::TreeNode) first_sibling

First sibling of this node. If this is the root node, then returns itself.

'First' sibling is defined as follows:

First sibling

The left-most child of this node's parent, which may be

this node itself

Returns:

See Also:



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# File 'lib/tree.rb', line 804

def first_sibling
  is_root? ? self : parent.children.first
end

- (Object) freeze_tree!

Freezes all nodes in the (sub)tree rooted at this node.

The nodes become immutable after this operation. In effect, the entire tree's structure and contents become read-only and cannot be changed.



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# File 'lib/tree.rb', line 565

def freeze_tree!
  each {|node| node.freeze}
end

- (Boolean) is_first_sibling?

Returns true if this node is the first sibling at its level.

Returns:

  • (Boolean)

    true if this is the first sibling.

See Also:



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# File 'lib/tree.rb', line 814

def is_first_sibling?
  first_sibling == self
end

- (Boolean) is_last_sibling?

Returns true if this node is the last sibling at its level.

Returns:

  • (Boolean)

    true if this is the last sibling.

See Also:



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# File 'lib/tree.rb', line 840

def is_last_sibling?
  last_sibling == self
end

- (Boolean) is_only_child?

true if this node is the only child of its parent.

As a special case, a root node will always return true.

Returns:

  • (Boolean)

    true if this is the only child of its parent.

See Also:



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# File 'lib/tree.rb', line 878

def is_only_child?
  is_root? ? true : parent.children.size == 1
end

- (Tree::TreeNode) last_child

Last child of this node. Will be nil if no children are present.

Returns:



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# File 'lib/tree.rb', line 786

def last_child
  children.last
end

- (Tree::TreeNode) last_sibling

Last sibling of this node. If this is the root node, then returns itself.

'Last' sibling is defined as follows:

Last sibling

The right-most child of this node's parent, which may be

this node itself

Returns:

See Also:



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# File 'lib/tree.rb', line 830

def last_sibling
  is_root? ? self : parent.children.last
end

- (Object) marshal_dump

Returns a marshal-dump represention of the (sub)tree rooted at this node.



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# File 'lib/tree.rb', line 261

def marshal_dump
  self.collect { |node| node.create_dump_rep }
end

- (Object) marshal_load(dumped_tree_array)

TODO:

This method probably should be a class method. It currently clobbers self and makes itself the root.

Loads a marshalled dump of a tree and returns the root node of the reconstructed tree. See the Marshal class for additional details.



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# File 'lib/tree.rb', line 285

def marshal_load(dumped_tree_array)
  nodes = { }
  dumped_tree_array.each do |node_hash|
    name        = node_hash[:name]
    parent_name = node_hash[:parent]
    content     = Marshal.load(node_hash[:content])

    if parent_name then
      nodes[name] = current_node = Tree::TreeNode.new(name, content)
      nodes[parent_name].add current_node
    else
      # This is the root node, hence initialize self.
      initialize(name, content)

      nodes[name] = self    # Add self to the list of nodes
    end
  end
end

- (Tree::TreeNode) merge(other_tree) Originally defined in module Utils::TreeMergeHandler

Merge two trees that share the same root node and returns a new tree.

The new tree contains the contents of the merge between other_tree and self. Duplicate nodes (coming from other_tree) will NOT be overwritten in self.

Parameters:

Returns:

Raises:

  • (TypeError)

    This exception is raised if other_tree is not a TreeNode.

  • (ArgumentError)

    This exception is raised if other_tree does not have the same root node as self.

Author:

Since:

  • 0.9.0

- (Object) merge!(other_tree) Originally defined in module Utils::TreeMergeHandler

Merge in another tree (that shares the same root node) into this tree. Duplicate nodes (coming from other_tree) will NOT be overwritten in self.

Parameters:

Raises:

  • (TypeError)

    This exception is raised if other_tree is not a TreeNode.

  • (ArgumentError)

    This exception is raised if other_tree does not have the same root node as self.

Author:

Since:

  • 0.9.0

- (Tree::treeNode) next_sibling

Next sibling for this node. The next node is defined as the node to right of this node.

Will return nil if no subsequent node is present, or if this is a root node.

Returns:

  • (Tree::treeNode)

    the next sibling node, if present.

See Also:



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# File 'lib/tree.rb', line 892

def next_sibling
  return nil if is_root?

  myidx = parent.children.index(self)
  parent.children.at(myidx + 1) if myidx
end

- (Array) path_as_array Originally defined in module Utils::TreePathHandler

Returns the node-names from this node to the root as an array. The first element is the root node name, and the last element is this node's name.

node

Returns:

  • (Array)

    The array containing the node names for the path to this

- (String) path_as_string(separator = '=>') Originally defined in module Utils::TreePathHandler

Returns the path of this node from the root as a string, with the node names separated using the specified separator. The path is listed left to right from the root node.

Parameters:

  • separator (defaults to: '=>')

    The optional separator to use. The default separator is '+=>+'.

Returns:

  • (String)

    The node path with names separated using the specified separator.

- (Tree::TreeNode, Enumerator) postordered_each {|node| ... }

Traverses the (sub)tree rooted at this node in post-ordered sequence.

Yield Parameters:

Returns:

  • (Tree::TreeNode)

    this node, if a block if given

  • (Enumerator)

    an enumerator on this tree, if a block is not given

See Also:



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# File 'lib/tree.rb', line 674

def postordered_each(&block)
  return self.to_enum(:postordered_each) unless block_given?

  # Using a marked node in order to skip adding the children of nodes that
  # have already been visited. This allows the stack depth to be controlled,
  # and also allows stateful backtracking.
  markednode = Struct.new(:node, :visited)
  node_stack = [markednode.new(self, false)] # Start with self

  until node_stack.empty?
    peek_node = node_stack[0]
    if peek_node.node.has_children? and not peek_node.visited
      peek_node.visited = true
      # Add the children to the stack. Use the marking structure.
      marked_children =
        peek_node.node.children.map {|node| markednode.new(node, false)}
      node_stack = marked_children.concat(node_stack)
      next
    else
      yield node_stack.shift.node           # Pop and yield the current node
    end
  end

  return self if block_given?
end

- (Tree::TreeNode, Enumerator) preordered_each {|node| ... }

Traverses the (sub)tree rooted at this node in pre-ordered sequence. This is a synonym of #each.

Yield Parameters:

Returns:

  • (Tree::TreeNode)

    this node, if a block if given

  • (Enumerator)

    an enumerator on this tree, if a block is not given

See Also:



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# File 'lib/tree.rb', line 662

def preordered_each(&block)  # :yields: node
  each(&block)
end

- (Tree::treeNode) previous_sibling

Previous sibling of this node. Previous node is defined to be the node to left of this node.

Will return nil if no predecessor node is present, or if this is a root node.

Returns:

  • (Tree::treeNode)

    the previous sibling node, if present.

See Also:



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# File 'lib/tree.rb', line 909

def previous_sibling
  return nil if is_root?

  myidx = parent.children.index(self)
  parent.children.at(myidx - 1) if myidx && myidx > 0
end

Pretty prints the (sub)tree rooted at this node.

Parameters:

  • level (Integer) (defaults to: node_depth)

    The indentation level (4 spaces) to start with.

  • max_depth (Integer) (defaults to: nil)

    optional maximum depth at which the printing with stop.

  • block (Proc) (defaults to: lambda { |node, prefix| puts "#{prefix} #{node.name}" })

    optional block to use for rendering



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# File 'lib/tree.rb', line 938

def print_tree(level = node_depth, max_depth = nil,
               block = lambda { |node, prefix|
                 puts "#{prefix} #{node.name}" })
  prefix = ''

  if is_root?
    prefix << '*'
  else
    prefix << '|' unless parent.is_last_sibling?
    prefix << (' ' * (level - 1) * 4)
    prefix << (is_last_sibling? ? '+' : '|')
    prefix << '---'
    prefix << (has_children? ? '+' : '>')
  end

  block.call(self, prefix)

  # Exit if the max level is defined, and reached.
  return unless max_depth.nil? || level < max_depth

  children { |child|
    child.print_tree(level + 1,
                     max_depth, block) if child } # Child might be 'nil'
end

- (Tree::TreeNode) remove!(child)

Removes the specified child node from this node.

This method can also be used for pruning a sub-tree, in cases where the removed child node is the root of the sub-tree to be pruned.

The removed child node is orphaned but accessible if an alternate reference exists. If accessible via an alternate reference, the removed child will report itself as a root node for its sub-tree.

Parameters:

Returns:

  • (Tree::TreeNode)

    The removed child node, or nil if a nil was passed in as argument.

See Also:



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# File 'lib/tree.rb', line 501

def remove!(child)
  return nil unless child

  @children_hash.delete(child.name)
  @children.delete(child)
  child.set_as_root!
  child
end

- (Tree::TreeNode) remove_all!

Removes all children from this node. If an independent reference exists to the child nodes, then these child nodes report themselves as roots after this operation.

Returns:

See Also:



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# File 'lib/tree.rb', line 544

def remove_all!
  @children.each { |child| child.set_as_root! }

  @children_hash.clear
  @children.clear
  self
end

- (Tree:TreeNode) remove_from_parent!

Removes this node from its parent. This node becomes the new root for its subtree.

If this is the root node, then does nothing.

Returns:

  • (Tree:TreeNode)

    self (the removed node) if the operation is successful, nil otherwise.

See Also:



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# File 'lib/tree.rb', line 532

def remove_from_parent!
  @parent.remove!(self) unless is_root?
end

- (Object) rename(new_name)

Renames the node and updates the parent's reference to it

Parameters:

  • new_name (Object)

    Name of the node. Conventional usage is to pass a String (Integer names may cause surprises)

Returns:

  • (Object)

    The old name



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# File 'lib/tree.rb', line 426

def rename(new_name)
  old_name = @name

  if is_root?
    self.name=(new_name)
  else
    @parent.rename_child old_name, new_name
  end

  old_name
end

- (Object) rename_child(old_name, new_name)

Renames the specified child node

Parameters:

  • old_name (Object)

    old Name of the node. Conventional usage is to pass a String (Integer names may cause surprises)

  • new_name (Object)

    new Name of the node. Conventional usage is to pass a String (Integer names may cause surprises)

Raises:

  • (ArgumentError)


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# File 'lib/tree.rb', line 445

def rename_child(old_name, new_name)
  raise ArgumentError, "Invalid child name specified: #{old_name}"\
        unless @children_hash.has_key?(old_name)

  @children_hash[new_name] = @children_hash.delete(old_name)
  @children_hash[new_name].name=(new_name)
end

- (Tree::TreeNode) replace!(old_child, new_child)

Replaces the specified child node with another child node on this node.

Parameters:

Returns:



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# File 'lib/tree.rb', line 469

def replace!(old_child, new_child)
  child_index = @children.find_index(old_child)

  old_child = remove! old_child
  add new_child, child_index

  return old_child
end

- (Tree::TreeNode) replace_with(node)

Replaces the node with another node

Parameters:

Returns:



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# File 'lib/tree.rb', line 483

def replace_with(node)
  @parent.replace!(self, node)
end

- (Array<Tree::TreeNode>, Tree::TreeNode) siblings {|sibling| ... }

An array of siblings for this node. This node is excluded.

If a block is provided, yields each of the sibling nodes to the block. The root always has nil siblings.

Yield Parameters:

Returns:

  • (Array<Tree::TreeNode>)

    Array of siblings of this node. Will return an empty array for root

  • (Tree::TreeNode)

    This node, if no block is given

See Also:



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# File 'lib/tree.rb', line 858

def siblings
  if block_given?
    parent.children.each { |sibling| yield sibling if sibling != self }
    return self
  else
    return [] if is_root?
    siblings = []
    parent.children {|my_sibling|
                     siblings << my_sibling if my_sibling != self}
    siblings
  end
end

- (Hash) to_h Originally defined in module Utils::HashConverter

Convert a node and its subtree into a Ruby hash.

Examples:

root = Tree::TreeNode.new(:root, "root content")
root << Tree::TreeNode.new(:child1, "child1 content")
root << Tree::TreeNode.new(:child2, "child2 content")
root.to_h # => {[:root, "root content"] =>
                     { [:child1, "child1 content"] =>
                                {}, [:child2, "child2 content"] => {}}}

Returns:

  • (Hash)

    Hash representation of tree.

Author:

- (Object) to_json(*a) Originally defined in module Utils::JSONConverter

Creates a JSON representation of this node including all it's children. This requires the JSON gem to be available, or else the operation fails with a warning message. Uses the Hash output of #as_json method.

Returns:

  • The JSON representation of this subtree.

See Also:

Author:

Since:

  • 0.7.0

- (String) to_s

Returns string representation of this node. This method is primarily meant for debugging purposes.

Returns:

  • (String)

    A string representation of the node.



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# File 'lib/tree.rb', line 310

def to_s
  "Node Name: #{@name}" +
    " Content: " + (@content.to_s || "<Empty>") +
    " Parent: " + (is_root?()  ? "<None>" : @parent.name.to_s) +
    " Children: #{@children.length}" +
    " Total Nodes: #{size()}"
end