Class: HexaPDF::Importer

Inherits:
Object
  • Object
show all
Defined in:
lib/hexapdf/importer.rb

Overview

The Importer class manages the process of copying objects from one Document to another.

It may seem unnecessary using an importer containing state for the task. However, by retaining some information about the already copied objects we can make sure that already imported objects don’t get imported again.

Two types of indirect objects are never imported from one document to another: the catalog and page tree nodes. If the catalog was imported, the whole source document would be imported. And if one page tree node would imported, the whole page tree would be imported.

See: Document#import

Defined Under Namespace

Classes: NullableWeakRef

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(source:, destination:) ⇒ Importer

Initializes a new importer that can import objects from the source document to the destination document.



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# File 'lib/hexapdf/importer.rb', line 74

def initialize(source:, destination:)
  @source = source
  @destination = destination
  @mapper = {}
end

Instance Attribute Details

#destination ⇒ Object (readonly)

:nodoc:



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# File 'lib/hexapdf/importer.rb', line 70

def destination
  @destination
end

#source ⇒ Object (readonly)

:nodoc:



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# File 'lib/hexapdf/importer.rb', line 70

def source
  @source
end

Class Method Details

.for(source:, destination:) ⇒ Object

Returns the Importer object for copying objects from the source to the destination document.



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# File 'lib/hexapdf/importer.rb', line 60

def self.for(source:, destination:)
  @map ||= {}
  @map.keep_if {|_, v| v.source.weakref_alive? && v.destination.weakref_alive?}
  source = NullableWeakRef.new(source)
  destination = NullableWeakRef.new(destination)
  @map[[source.hash, destination.hash]] ||= new(source: source, destination: destination)
end

Instance Method Details

#import(object) ⇒ Object

Imports the given object from the source to the destination object and returns the imported object.

Note: Indirect objects are automatically added to the destination document but direct or simple objects are not.

An error is raised if the object doesn’t belong to the source document.



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# File 'lib/hexapdf/importer.rb', line 87

def import(object)
  mapped_object = @mapper[object.data] if object.kind_of?(HexaPDF::Object)
  if object.kind_of?(HexaPDF::Object) && object.document? && @source != object.document
    raise HexaPDF::Error, "Import error: Incorrect document object for importer"
  elsif mapped_object && mapped_object == @destination.object(mapped_object)
    mapped_object
  else
    duplicate(object)
  end
end