Module: Pairtree

Defined in:
lib/pairtree.rb,
lib/pairtree/obj.rb,
lib/pairtree/path.rb,
lib/pairtree/root.rb,
lib/pairtree/identifier.rb

Defined Under Namespace

Classes: Identifier, IdentifierError, Obj, Path, PathError, Root, VersionMismatch

Constant Summary collapse

SPEC_VERSION = 
0.1

Class Method Summary collapse

Class Method Details

.at(path, args = {}) ⇒ Object

Instantiate a pairtree at a given path location

Parameters:

  • path (String) —

    The path in which the pairtree resides

  • args (Hash) (defaults to: {}) —

    Pairtree options

Options Hash (args):

  • :prefix (String) — default: nil —

    the identifier prefix used throughout the pairtree

  • :version (String) — default: Pairtree::SPEC_VERSION —

    the version of the pairtree spec that this tree conforms to

  • :create (Boolean) — default: false —

    if true, create the pairtree and its directory structure if it doesn’t already exist



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# File 'lib/pairtree.rb', line 22

def self.at path, args = {}
  args = { :prefix => nil, :version => nil, :create => false }.merge(args)
  args[:version] ||= SPEC_VERSION
  args[:version] = args[:version].to_f
  
  root_path = File.join(path, 'pairtree_root')
  prefix_file = File.join(path, 'pairtree_prefix')
  version_file = File.join(path, pairtree_version_filename(args[:version]))
  existing_version_file = Dir[File.join(path, "pairtree_version*")].sort.last
  
  if args.delete(:create)
    if File.exists?(path) and not File.directory?(path)
      raise PathError, "#{path} exists, but is not a valid pairtree root"
    end
    FileUtils.mkdir_p(root_path)

    unless File.exists? prefix_file
      File.open(prefix_file, 'w') { |f| f.write(args[:prefix].to_s) }
    end
    
    if existing_version_file
      if existing_version_file != version_file
        stored_version = existing_version_file.scan(/([0-9]+)_([0-9]+)/).flatten.join('.').to_f
        raise VersionMismatch, "Version #{args[:version]} specified, but #{stored_version} found."
      end
    else
      args[:version] ||= SPEC_VERSION
      version_file = File.join(path, pairtree_version_filename(args[:version]))
      File.open(version_file, 'w') { |f| f.write %{This directory conforms to Pairtree Version #{args[:version]}. Updated spec: http://www.cdlib.org/inside/diglib/pairtree/pairtreespec.html} }
      existing_version_file = version_file
    end
  else
    unless File.directory? root_path
      raise PathError, "#{path} does not point to an existing pairtree"
    end
  end

  stored_prefix = File.read(prefix_file)
  unless args[:prefix].nil? or args[:prefix].to_s == stored_prefix
    raise IdentifierError, "Specified prefix #{args[:prefix].inspect} does not match stored prefix #{stored_prefix.inspect}"
  end
  args[:prefix] = stored_prefix

  stored_version = existing_version_file.scan(/([0-9]+)_([0-9]+)/).flatten.join('.').to_f
  args[:version] ||= stored_version
  unless args[:version] == stored_version
    raise VersionMismatch, "Version #{args[:version]} specified, but #{stored_version} found."
  end
      
  Pairtree::Root.new(File.join(path, 'pairtree_root'), args)
end