Module: Unnatural::Scan

Defined in:
lib/unnatural/scan.rb

Overview

Compares strings using a ‘StringScanner`. Pure ruby. Tends to be outperformed by `Unnatural::Substitution` and `Unnatural::Split` when sorting short strings via the global sort function, but its comparison function is the fastest of the pure-ruby algorithms.

Class Method Summary collapse

Class Method Details

.compare(a_string, b_string) ⇒ Object

rubocop: disable Metrics/AbcSize rubocop: disable Metrics/CyclomaticComplexity rubocop: disable Metrics/MethodLength rubocop: disable Metrics/PerceivedComplexity



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# File 'lib/unnatural/scan.rb', line 25

def self.compare(a_string, b_string)
  if a_string.is_a?(Array) && b_string.is_a?(Array)
    a_string = a_string.first
    b_string = b_string.first
  end

  a = StringScanner.new(a_string)
  b = StringScanner.new(b_string)

  loop do
    a_number = a.scan(/\d+/)
    b_number = b.scan(/\d+/)

    if a_number.nil? && b_number.nil?
    # move on
    elsif a_number.nil?
      return +1
    elsif b_number.nil?
      return -1
    else
      compare = a_number.to_i <=> b_number.to_i
      return compare unless compare == 0
    end

    a_segment = a.scan(/\D+/)
    b_segment = b.scan(/\D+/)

    if a_segment.nil? && b_segment.nil?
    # move on
    elsif a_segment.nil?
      return -1
    elsif b_segment.nil?
      return +1
    else
      compare = a_segment.casecmp(b_segment)
      return compare unless compare == 0
    end

    return 0 if a.eos? && b.eos?
    return -1 if a.eos?
    return +1 if b.eos?
  end
end

.sort(enumerable) ⇒ Object 



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# File 'lib/unnatural/scan.rb', line 9

def self.sort(enumerable)
  enumerable.sort { |a, b| compare(a, b) }
end

.sort_by(enumerable) ⇒ Object

Raises:

  • (ArgumentError) 


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# File 'lib/unnatural/scan.rb', line 13

def self.sort_by(enumerable)
  raise ArgumentError, 'Block expected but none given' unless block_given?
  enumerable
    .map { |e| [(yield e), e] }
    .sort { |a, b| compare(a, b) }
    .map { |ary| ary[1] }
end