SentenceParser.rb

#slightly modified
#made it part of a module for your using pleasure

module SentenceParser
  #finds the earliest sentence-ending punctuation in the given String
  #i realize this isn't pretty
  #finds the earliest sentence-ending punctuation in the given String
  def find_partition_pos(line)
    found = false
    pos = nil #the position of the valid sentence ending punctuation
    puncs = %w[. ! ?]
    puncs.each do |punc|
      temp = line.index(punc)
      if temp != nil and temp < pos
        pos = temp 
        found = true
      end
    end
    pos = nil if not found
    return pos
  end

  def read_file(filename)
    lines = [] #an array to store the parsed sentences
    if File.exist? filename      
      file = File.open(filename, "r")
      line = ""
      until file.eof do
        line << " " << file.gets.chomp.strip #appends next line to the incomplete sentence before it
        pos = find_partition_pos(line) #finds the position of the earliest sentence-ending punctuation
        unless pos == nil #extract a complete sentence
          tokens = line.partition(line[pos])
          lines << (tokens[0] << tokens[1]) #fuse the punctuation back to the sentence first
          line = tokens[2].lstrip #save the remaining line for the next pass
        end #else, skip to the next line read
      end #until
      #get the stragglers. there may be sentences left over in 'line' even after file reading is done
      done = false
      until done do
        pos = find_partition_pos(line)
        unless pos == nil
          if pos == line.size-1 #if the only valid punctuation appears at the end, there's only one sentence
            lines << line
            done = true
          else #keep going
            tokens = line.partition(line[pos])
            lines << (tokens[0] << tokens[1])
            line = tokens[2].lstrip
          end
        else #pos == nil because there's no sentence-ending punctuation left in 'line'
          lines << line #prevents infinite loop if no punctuation in last line
          done = true
        end
      end #until
      puts lines #print a copy of the inputted text as a whole, split by sentences
   else
     puts "#{filename} is an invalid file."
  return lines
  end #read_file
end #SentenceParser