Class: MARC::ControlField

Inherits:
Object
  • Object
show all
Defined in:
lib/marc/controlfield.rb

Overview

MARC records contain control fields, each of which has a tag and value. Tags for control fields must be in the 001-009 range or be specially added to the @@control_tags Set

Constant Summary collapse

@@control_tags =

Initially, control tags are the numbers 1 through 9 or the string ‘000’

Set.new( (1..9).to_a)

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(tag, value = '') ⇒ ControlField

The constructor which must be passed a tag value and an optional value for the field.



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# File 'lib/marc/controlfield.rb', line 37

def initialize(tag,value='')
  @tag = tag
  @value = value
  if not MARC::ControlField.control_tag?(@tag)
    raise MARC::Exception.new(), "tag must be in 001-009 or in the MARC::ControlField.control_tags set"
  end
end

Instance Attribute Details

#tag ⇒ Object

the tag value (007, 008, etc)



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# File 'lib/marc/controlfield.rb', line 29

def tag
  @tag
end

#value ⇒ Object

the value of the control field



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# File 'lib/marc/controlfield.rb', line 32

def value
  @value
end

Class Method Details

.control_tag?(tag) ⇒ Boolean

A tag is a control tag if it is a member of the @@control_tags set as either a string (e.g., ‘FMT’) or in its .to_i representation (e.g., ‘008’.to_i == 3 is in @@control_tags by default)

Returns:

  • (Boolean) 


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# File 'lib/marc/controlfield.rb', line 23

def self.control_tag?(tag)
  return (@@control_tags.include?(tag.to_i) or @@control_tags.include?(tag))
end

.control_tags ⇒ Object 



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# File 'lib/marc/controlfield.rb', line 15

def self.control_tags
  return @@control_tags
end

Instance Method Details

#==(other) ⇒ Object

Two control fields are equal if their tags and values are equal.



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# File 'lib/marc/controlfield.rb', line 47

def ==(other)
  if @tag != other.tag
    return false 
  elsif @value != other.value
    return false
  end
  return true
end

#=~(regex) ⇒ Object 



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# File 'lib/marc/controlfield.rb', line 70

def =~(regex)
  return self.to_s =~ regex
end

#to_hash ⇒ Object

Turn the control field into a hash for MARC-in-JSON



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# File 'lib/marc/controlfield.rb', line 62

def to_hash
  return {@tag=>@value}
end

#to_marchash ⇒ Object

turning it into a marc-hash element



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# File 'lib/marc/controlfield.rb', line 57

def to_marchash
  return [@tag, @value]
end

#to_s ⇒ Object 



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# File 'lib/marc/controlfield.rb', line 66

def to_s
  return "#{tag} #{value}" 
end