Class: KeyTree::Forest

Inherits:
Array
  • Object
show all
Includes:
MetaData
Defined in:
lib/key_tree/forest.rb

Overview

A forest is a (possibly nested) collection of trees

Class Method Summary collapse

Instance Method Summary collapse

Methods included from MetaData

#meta_data, #with_meta_data

Class Method Details

.[](*contents) ⇒ Object 



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# File 'lib/key_tree/forest.rb', line 11

def self.[](*contents)
  contents.reduce(Forest.new) do |result, content|
    result << KeyTree[content]
  end
end

Instance Method Details

#[](key, &merger) ⇒ Object

For a numeric key, return the n:th tree in the forest

For a key path convertable key, return the closest match in the forest

When a closer tree contains a prefix of the key, this shadows any key path matches in trees further away, returning nil. This preserves the constraints that only leaves may contain a value.



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# File 'lib/key_tree/forest.rb', line 25

def [](key, &merger)
  return super(key) if key.is_a?(Numeric)
  fetch(key, &merger)
rescue KeyError
  nil
end

#fetch(key) ⇒ Object 



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# File 'lib/key_tree/forest.rb', line 32

def fetch(key)
  return tree_with_key(key).fetch(key) unless block_given?

  values = trees_with_key(key).map { |tree| tree.fetch(key) }
  values.reverse.reduce { |left, right| yield(key, left, right) }
end

#flatten(&merger) ⇒ Object

Flattening a forest produces a tree with the equivalent view of key paths



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# File 'lib/key_tree/forest.rb', line 60

def flatten(&merger)
  trees.reverse_each.reduce(Tree[]) do |result, tree|
    result.merge!(tree, &merger)
  end
end

#key?(key) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/key_tree/forest.rb', line 50

def key?(key)
  trees.any? { |tree| tree.key?(key) }
end

#prefix?(key) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/key_tree/forest.rb', line 54

def prefix?(key)
  trees.any? { |tree_or_forest| tree_or_forest.prefix?(key) }
end

#tree_with_key(key) ⇒ Object 



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# File 'lib/key_tree/forest.rb', line 39

def tree_with_key(key)
  result = trees.detect { |tree| tree.prefix?(key) }
  result || raise(KeyError, "key not found: #{key}")
end

#trees ⇒ Object

Return a breadth-first Enumerator for all the trees in the forest, and any nested forests



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# File 'lib/key_tree/forest.rb', line 68

def trees
  Enumerator.new do |yielder|
    remaining = [self]
    remaining.each do |woods|
      next yielder << woods if woods.is_a?(Tree)
      woods.each { |wood| remaining << wood }
    end
  end
end

#trees_with_key(key) ⇒ Object

Raises:

  • (KeyError) 


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# File 'lib/key_tree/forest.rb', line 44

def trees_with_key(key)
  result = trees.select { |tree| tree.prefix?(key) }
  raise(KeyError, "key not found: #{key}") if result.empty?
  result
end