Module: Abbrev

Defined in:
lib/abbrev.rb

Overview

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.

Class Method Summary collapse

Class Method Details

.abbrev(words, pattern = nil) ⇒ Object

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



43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
 
# File 'lib/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