Class: Marc4R::MarcStreamReader

Inherits:
Object
  • Object
show all
Includes:
Enumerable
Defined in:
lib/marc4r/marc_stream_reader.rb

Instance Method Summary collapse

Constructor Details

#initialize(io, enc = nil) ⇒ MarcStreamReader

Returns a new instance of MarcStreamReader.



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# File 'lib/marc4r/marc_stream_reader.rb', line 3

def initialize(io, enc=nil)
  @io = io
  @encoding = enc ? Encoding.find(enc) : nil
end

Instance Method Details

#close ⇒ Object 



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# File 'lib/marc4r/marc_stream_reader.rb', line 7

def close
  @io.close
end

#data_field(tag, field_content) ⇒ Object

Raises:



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# File 'lib/marc4r/marc_stream_reader.rb', line 67

def data_field(tag, field_content)
  raise Marc4R::MarcException.new("malformed data data field content") if field_content.size < 2
  ind1 = field_content[0]
  ind2 = field_content[1]

  data_field = Marc4R::Fields::DataField.new(tag, ind1, ind2)
  if field_content[2] == Marc4R::Terminators::SUBFIELD_TERMINATOR
    subfields = field_content[3..-1].split(Marc4R::Terminators::SUBFIELD_TERMINATOR)
    subfields = subfields.collect {|x| [x[0], x.slice(1..-1).force_encoding(@encoding)]}
    subfields.flatten!
  else
    subfields = []
  end
  return Marc4R::Fields::DataField.new(tag, ind1, ind2, *subfields)
end

#each ⇒ Object 



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# File 'lib/marc4r/marc_stream_reader.rb', line 10

def each
  until @io.eof? do
    leader = @io.read(24)
    record = Marc4R::Record.new(leader)
    record_body = @io.read(record.leader.record_length - 24)
    load_record(record, record_body)
    yield record
  end
end

#load_record(record, content) ⇒ Object

Raises:



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# File 'lib/marc4r/marc_stream_reader.rb', line 19

def load_record(record, content)
  leader = record.leader
  dir_length = leader.data_base_address - 25
  raise Marc4R::MarcException.new("invalid directory length #{dir_length}\n#{leader.to_s}\n#{content}") unless (dir_length % 12) == 0
  size = dir_length / 12

  # if MARC 21 then check encoding
  unless @encoding
    if leader.char_coding_scheme.eql? ' '
      @encoding = Encoding.find("ISO-8859-1")
    elsif leader.char_coding_scheme.eql? 'a'
      @encoding = Encoding.find("UTF-8")
    end
  end
  
  tags = []
  lengths = []
  starts = []
  offset = 0
  size.times do
    tags << content.slice(offset,3)
    lengths << content.slice(offset+3,4).to_i
    offset += 12
  end

  unless content[offset] == Marc4R::Terminators::FIELD_TERMINATOR
    raise Marc4R::MarcException.new("expected field terminator at end of directory")
  else
    offset += 1
  end

  (0...size).each do |i|
    field_content = content.slice(offset,lengths[i])
    offset += lengths[i]
    unless field_content[-1] == Marc4R::Terminators::FIELD_TERMINATOR
      raise Marc4R::MarcException.new("expected field terminator at end of field #{field_content}")
    end
    if Marc4R::Fields::ControlField.accepts_tag(tags[i])
      data = field_content[0...-1].force_encoding(@encoding)
      record.control_fields << Marc4R::Fields::ControlField.new(tags[i], data)
    else # read a data field
      record.data_fields << data_field(tags[i],field_content[0...-1])
    end
  end
  unless content[offset] == Marc4R::Terminators::RECORD_TERMINATOR
    raise Marc4R::MarcException.new("expected record terminator")
  end
end