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Contents
# frozen_string_literal: true
module Katalyst
module Navigation
module HasTree
# Constructs a tree from an ordered list of items with depth.
# * items that have higher depth than their predecessor are nested as `children`.
# * items with the same depth become siblings.
def tree
items.reduce(Builder.new, &:add).tree
end
class Builder
attr_reader :current, :depth, :children, :tree
def initialize
@depth = 0
@children = @tree = []
end
def add(node)
if node.depth == depth
node.parent = current
children << node
self
elsif node.depth > depth
push(children.last)
add(node)
else
pop
add(node)
end
end
private
attr_writer :current, :depth, :children
# Add node to the top of builder stacks
def push(node)
self.depth += 1
self.current = node
self.children = node.children = []
node
end
# Remove current from builder stack
def pop
previous = current
self.depth -= 1
if depth.zero?
self.current = nil
self.children = tree
else
self.current = previous.parent
self.children = current.children
end
previous
end
end
end
end
end
Version data entries
25 entries across 25 versions & 1 rubygems