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Abbrev

Calculate the set of unique abbreviations for a given set of strings.

require 'abbrev'
require 'pp'

pp Abbrev::abbrev(['ruby', 'rules']).sort

Generates:

[["rub", "ruby"],
 ["ruby", "ruby"],
 ["rul", "rules"],
 ["rule", "rules"],
 ["rules", "rules"]]

Also adds an abbrev method to class Array.

Public Class Methods

abbrev(words, pattern = nil) click to toggle source

Given a set of strings, calculate the set of unambiguous abbreviations for those strings, and return a hash where the keys are all the possible abbreviations and the values are the full strings. Thus, given input of “car” and “cone”, the keys pointing to “car” would be “ca” and “car”, while those pointing to “cone” would be “co”, “con”, and “cone”.

The optional pattern parameter is a pattern or a string. Only those input strings matching the pattern, or begging the string, are considered for inclusion in the output hash

 
               # File abbrev.rb, line 43
def abbrev(words, pattern = nil)
  table = {}
  seen = Hash.new(0)

  if pattern.is_a?(String)
    pattern = /^#{Regexp.quote(pattern)}/  # regard as a prefix
  end

  words.each do |word|
    next if (abbrev = word).empty?
    while (len = abbrev.rindex(/[\w\W]\z/)) > 0
      abbrev = word[0,len]

      next if pattern && pattern !~ abbrev

      case seen[abbrev] += 1
      when 1
        table[abbrev] = word
      when 2
        table.delete(abbrev)
      else
        break
      end
    end
  end

  words.each do |word|
    next if pattern && pattern !~ word

    table[word] = word
  end

  table
end

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