Method: JSI::JSON::Pointer#modified_document_copy

Defined in:

lib/jsi/json/pointer.rb

#modified_document_copy(document) {|Object| ... } ⇒ Object

takes a document and a block. the block is yielded the content of the given document at this pointer's location. the block must result a modified copy of that content (and MUST NOT modify the object it is given). this modified copy of that content is incorporated into a modified copy of the given document, which is then returned. the structure and contents of the document outside the path pointed to by this pointer is not modified.

Parameters:

• document (Object) —

  the document to apply this pointer to

Yields:

• (Object) —

  the content this pointer applies to in the given document the block must result in the new content which will be placed in the modified document copy.

Returns:

• (Object) —

  a copy of the given document, with the content this pointer applies to replaced by the result of the block

# File 'lib/jsi/json/pointer.rb', line 209

def modified_document_copy(document, &block)
  # we need to preserve the rest of the document, but modify the content at our path.
  #
  # this is actually a bit tricky. we can't modify the original document, obviously.
  # we could do a deep copy, but that's expensive. instead, we make a copy of each array
  # or hash in the path above this node. this node's content is modified by the caller, and
  # that is recursively merged up to the document root. the recursion is done with a
  # y combinator, for no other reason than that was a fun way to implement it.
  modified_document = JSI::Util.ycomb do |rec|
    proc do |subdocument, subpath|
      if subpath == []
        Typelike.modified_copy(subdocument, &block)
      else
        car = subpath[0]
        cdr = subpath[1..-1]
        if subdocument.respond_to?(:to_hash)
          subdocument_car = (subdocument.respond_to?(:[]) ? subdocument : subdocument.to_hash)[car]
          car_object = rec.call(subdocument_car, cdr)
          if car_object.object_id == subdocument_car.object_id
            subdocument
          else
            (subdocument.respond_to?(:merge) ? subdocument : subdocument.to_hash).merge({car => car_object})
          end
        elsif subdocument.respond_to?(:to_ary)
          if car.is_a?(String) && car =~ /\A\d+\z/
            car = car.to_i
          end
          unless car.is_a?(Integer)
            raise(TypeError, "bad subscript #{car.pretty_inspect.chomp} with remaining subpath: #{cdr.inspect} for array: #{subdocument.pretty_inspect.chomp}")
          end
          subdocument_car = (subdocument.respond_to?(:[]) ? subdocument : subdocument.to_ary)[car]
          car_object = rec.call(subdocument_car, cdr)
          if car_object.object_id == subdocument_car.object_id
            subdocument
          else
            (subdocument.respond_to?(:[]=) ? subdocument : subdocument.to_ary).dup.tap do |arr|
              arr[car] = car_object
            end
          end
        else
          raise(TypeError, "bad subscript: #{car.pretty_inspect.chomp} with remaining subpath: #{cdr.inspect} for content: #{subdocument.pretty_inspect.chomp}")
        end
      end
    end
  end.call(document, reference_tokens)
  modified_document
end