Class: Gaps

Inherits:
Object
  • Object
show all
Defined in:
lib/gaps.rb

Overview

This is used for finding the gaps between a subset of elements in an array and the original layout. We use this in Discourse to find gaps between posts.

Note that we will only return a gap as ‘before’ or ‘after’, not both. We only want to display the gap once.

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(subset, original) ⇒ Gaps

Returns a new instance of Gaps.



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# File 'lib/gaps.rb', line 13

def initialize(subset, original)
  @before = {}
  @after = {}
  @subset = subset
  @original = original

  find_gaps
end

Instance Attribute Details

#after ⇒ Object (readonly)

Returns the value of attribute after.



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# File 'lib/gaps.rb', line 11

def after
  @after
end

#before ⇒ Object (readonly)

Returns the value of attribute before.



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# File 'lib/gaps.rb', line 11

def before
  @before
end

Instance Method Details

#empty? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/gaps.rb', line 22

def empty?
  @before.size == 0 && @after.size == 0
end

#find_gaps ⇒ Object 



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# File 'lib/gaps.rb', line 26

def find_gaps
  return if @subset.nil? || @original.nil?

  i = j = 0
  gaps = {}
  current_gap = []

  while e1 = @subset[i]
    e2 = @original[j]

    if (e1 == e2)
      if current_gap.size > 0
        @before[e1] = current_gap.dup
        current_gap = []
      end

      i = i + 1
    else
      current_gap << e2
    end
    j = j + 1

    break if (i == @subset.size) || (j == @original.size)
  end

  @after[@subset[i - 1]] = @original[j..-1] if j < @original.size
end