NGFile.txt用のActiveRecordのModel (Ruby 1.9.2)

20110812042641_create_ng_files.rb

class CreateNgFiles < ActiveRecord::Migration
  def self.up
    create_table :ng_files do |t|
      t.string :ng_hash
      t.string :memo
      t.timestamps
    end
    add_index :ng_files, :ng_hash, :unique => true
  end
  def self.down
    drop_table :ng_files
  end
end

NgFile.rb

# -*- coding: utf-8 -*-
class NgFile < ActiveRecord::Base
  
  def self.find_by_file(filename)
    find_by_ng_hash(hash_from_file(filename))
  end
  def self.find_by_blob(blob)
    find_by_ng_hash(hash_from_blob(blob))
  end
  def self.find_by_md5(md5str)
    md5digest = [md5str].pack("H*")
    find_by_ng_hash(hash_from_md5digest(md5digest))
  end

  def self.pull(data_file)
    transaction do 
      File.open(data_file, "r:windows-31j:utf-8") do |f|
        until (f.eof?)
          line = f.readline.chomp
          hash, memo = line.split("=")
          memo = memo.gsub(/^\*/, '')
          
          NgFile.find_or_create_by_ng_hash(hash) do |ngfile|
            ngfile.memo = memo
          end
        end
      end
    end
  end

  private
  NGHASH_CHAR =
    [
     '0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
     'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J',
     'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T',
     'U', 'V'
    ]
  NGHASH_LEN = 26
  
  def self.hash_from_file(filename)
    hash_from_blob(File.read(filename))
  end
  def self.hash_from_blob(blob)
    hash_from_md5digest(Digest::MD5.digest(blob))
  end
  def self.make_word(lo, hi)
    lo + (hi << 8)
  end
  def self.hash_from_md5digest(md5digest)
    hash = []
    md5 = Array.new
    
    (0 ... md5digest.length).each{|i|
      md5.push(md5digest[i].unpack('C')[0])
    }
    md5.push(0)
    
    (0 ... NGHASH_LEN).each do |i|
      hash[i] = NGHASH_CHAR[(make_word(md5[5 * i / 8], md5[5 * i / 8 + 1]) >> (5 * i % 8)) & 0x1F]
    end
    
    return hash.join
  end
end