Class: OcflTools::OcflDelta

Inherits:
Object
  • Object
show all
Defined in:
lib/ocfl_tools/ocfl_delta.rb

Overview

Given an inventory, show changes from previous versions. OcflDelta takes in an OCFL Inventory object and creates a delta hash containing the actions performed to assemble the requested version.

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(ocfl_object) ⇒ OcflDelta

Returns a new instance of OcflDelta.



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# File 'lib/ocfl_tools/ocfl_delta.rb', line 10

def initialize(ocfl_object)
  # Duck sanity check.
  ['@id', '@head', '@manifest', '@versions', '@fixity'].each do |var|
    unless ocfl_object.instance_variable_defined?(var)
      raise "Object #{ocfl_object} does not have instance var #{var} defined"
    end
  end

  %w[get_state version_id_list get_digest].each do |mthd|
    unless ocfl_object.respond_to?(mthd)
      raise "Object #{ocfl_object} does not respond to #{mthd}"
    end
  end

  @ocfl_object = ocfl_object
  @delta = {}
  # We need to get version format, for final report-out. Assume that the ocfl_object versions are
  # formatted correctly (starting with a 'v'). We can't trust the site config setting
  # for this, as there's no guarantee the inventory we are reading in was created at this site.
  first_version = @ocfl_object.versions.keys.min # should get us 'v0001' or 'v1'
  sliced_version = first_version.split('v')[1] # cut the leading 'v' from the string.
  if sliced_version.length == 1 # A length of 1 for the first version implies 'v1'
    @version_format = 'v%d'
  else
    @version_format = "v%0#{sliced_version.length}d"
  end
end

Instance Attribute Details

#delta ⇒ Object (readonly)

Returns the value of attribute delta.



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# File 'lib/ocfl_tools/ocfl_delta.rb', line 8

def delta
  @delta
end

Instance Method Details

#all ⇒ Object

Generates a complete delta hash for all versions of this object.



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# File 'lib/ocfl_tools/ocfl_delta.rb', line 39

def all
  @ocfl_object.version_id_list.each do |version|
    get_version_delta(version)
  end
  @delta
end

#previous(version) ⇒ Hash

Given a version, get the delta from the previous version.

Parameters:

  • version (Integer) —

    of object to get deltas for.

Returns:

  • (Hash) —

    of actions applied to previous version to create current version.



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# File 'lib/ocfl_tools/ocfl_delta.rb', line 49

def previous(version)
  # San check, does version exist in object?
  if version == 1
    get_first_version_delta
  else
    # verify version exists, then...
    unless @ocfl_object.version_id_list.include?(version)
      raise "Version #{version} not found in #{@ocfl_object}!"
    end
    get_version_delta(version)
  end
end