sentence_truncate helper

sentence_truncate_helper.rb

  # Based on http://stackoverflow.com/questions/1293573/rails-smart-text-truncation
  def sentence_truncate(string, num_sentences, enforce_max_length=true)
    pattern   = /[\.\?\!]{1,}\s/
    matches   = string.scan(pattern)
    sentences = string.split(pattern)
    num_sentences = matches.length if matches.length < num_sentences
    
    truncated_sentence = sentences[0...num_sentences].map do |sentence|
      sentence << matches[sentences.index(sentence)]
    end.join("").chop
    
    # optionally enforce max length in case of really long sentences
    if enforce_max_length
      max_length = num_sentences*100
      truncated_sentence = truncate(truncated_sentence, :length => max_length) if truncated_sentence.length > max_length
    end

    truncated_sentence
  end



  # rspec test
  it "should split a text block on sentences" do
    text = "I am a sentence about radio station 95.5 WHOT. What a hot station! I love that one. Don't you? Well, onto other things, my friend. Like the fourth sentence with a period. And the fifth."
    sentence_truncate(text, 4).should == "I am a sentence about radio station 95.5 WHOT. What a hot station! I love that one. Don't you?"
  end