49 lines
997 B
Ruby
49 lines
997 B
Ruby
# We transform objects into a tree of nodes
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module Sof
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#abstract base class for nodes in the tree
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class Node
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# must be able to output to a stream
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def out io ,level
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raise "abstract #{self}"
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end
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end
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class SimpleNode < Node
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def initialize head
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@head = head
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end
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attr_accessor :head
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def out io , level
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io.write(head) if head
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end
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end
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class NodeList < Node
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def initialize
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@children = []
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end
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attr_accessor :children
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def add child
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child = SimpleNode.new(child) if(child.is_a? String)
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@children << child
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end
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def out io , level = 0
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return if @children.empty?
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first = @children.first
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io.write "-"
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first.out(io , level + 1)
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indent = " " * level
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@children.each_with_index do |child , i|
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next if i == 0 # done already
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io.write "\n"
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io.write indent
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io.write "-"
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child.out(io , level + 1)
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end
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end
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end
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end
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