ruby 操作字符串 实现关键字搜索功能

class Song
  def initialize(format, name, title, duration)
    @format=format
    @name=name
    @title=title
    @duration=duration
  end
  
  attr_accessor :format, :name, :title, :duration
  
end

class WordIndex
  def initialize
    @index={}
  end
  
  def add_to_index(obj, *phrases)
    phrases.each do|phrase|
      phrase.scan(/\w[-\w'']+/) do |word|
        word.downcase!
        @index[word]=[] if @index[word].nil?
        @index[word].push(obj)
      end
    end
  end
  
  def lookup(word)
    @index[word.downcase]
  end
end

class SongList
  def initialize
    @songs=Array. new
     @index=WordIndex. new
  end
  
  def append(song)
    @songs.push(song)
     @index.add_to_index(song, song.title, song.name)
    self
  end
  
  def [](index)
    @songs[index]
  end
  
  def length
    @songs.length
  end
  
  def lookup(word)
    @index.lookup(word)
  end
end

f=File.open('test')
songs=SongList. new
f.each  do |line|
  format, duration, name, title= line.split(/\s*\|\s*/)
  song=Song. new(format, name, title, duration)
  songs.append(song)
end

(0..songs.length-1).each  do  |n|
 puts   "#{songs[n].format}--#{songs[n].name}--#{songs[n].duration}--#{songs[n].title}"
end
puts songs.lookup('fats')
puts songs[0].name