Class: TaliaCore::OrderedSource

Inherits:
ActiveSource
  • Object
show all
Defined in:
lib/talia_core/ordered_source.rb

Overview

This class provides an ordering on the related sources. It will load the related elements into an array. All changes made to the OrderedSource will reflect on the Array, and will only be persisted to the store on save.

The collection is contained in the ordered_objects - if you ever use that accessor all “ordering” relations for the object will be completely overwritten on saving. (You can still assign the predicates manually as long as the ordered_objects accesssor is not called before saving.)

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Methods inherited from ActiveSource

#[], #[]=, #add_additional_rdf_types, #add_semantic_attributes, #attach_files, #data, #db_attr?, #direct_predicates, #inverse, #inverse_predicates, #predicate, #predicate_replace, #predicate_set, #predicate_set_uniq, #rdf_selftype, #rewrite_attributes, #rewrite_attributes!, #short_uri, #to_rdf, #to_s, #to_uri, #to_xml, #update_attributes, #update_attributes!, #update_attributes_orig, #update_attributes_orig!, #update_source, #value_for, #write_predicate_direct

Methods included from ActiveSourceParts::ClassMethods

#additional_rdf_types, #create_from_xml, #create_multi_from, #create_source, #db_attr?, #exists?, #expand_uri, #new, #paginate, #rewrite, #split_attribute_hash, #update, #value_for

Methods included from ActiveSourceParts::Finders

#count, #find, #find_by_partial_local, #find_by_partial_uri, #find_by_uri_token

Methods included from ActiveSourceParts::SqlHelper

#default_inv_joins, #default_joins, #props_join, #sources_join

Methods included from ActiveSourceParts::PredicateHandler::ClassMethods

#prefetch_relations_for

Methods included from TaliaUtil::Progressable

#progressor, #progressor=, #run_with_progress

Methods included from ActiveSourceParts::Rdf

#autosave_rdf=, #autosave_rdf?, #create_rdf, #my_rdf, #to_rdf

Methods included from ActiveSourceParts::PredicateHandler

#each_cached_wrapper, #get_objects_on, #has_type?, #inject_predicate, #reset!, #save_wrappers, #types

Instance Attribute Details

#current_index ⇒ Object (readonly)

Returns the value of attribute current_index.



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# File 'lib/talia_core/ordered_source.rb', line 13

def current_index
  @current_index
end

Class Method Details

.index_to_predicate(index) ⇒ Object

return string for index



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# File 'lib/talia_core/ordered_source.rb', line 162

def self.index_to_predicate(index)
  'http://www.w3.org/1999/02/22-rdf-syntax-ns#_' << ("%06d" % index.to_i) 
end

.new(uri) ⇒ Object

Initialize SeqContainer



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# File 'lib/talia_core/ordered_source.rb', line 18

def self.new(uri)
  @resource = super(uri)
  #      @resource.save!
  #      @resource.types << RDF::Seq.uri
  #      @resource
end

.predicate_to_index(predicate) ⇒ Object

return index of predicate



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# File 'lib/talia_core/ordered_source.rb', line 167

def self.predicate_to_index(predicate)
  predicate.sub('http://www.w3.org/1999/02/22-rdf-syntax-ns#_', '').to_i
end

Instance Method Details

#add(object) ⇒ Object

Add new item to ordered source. This will add the object after the last element. ATTENTION: If you add on an empty collection, it will start at index 1 (One), for backwards compatability



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# File 'lib/talia_core/ordered_source.rb', line 99

def add(object)
  position = (size > 0) ? size : 1
  insert_at(position, object)
end

#at(index) ⇒ Object

return the item at position index.

* index: int
* return value: TaliaCore::ActiveSource



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# File 'lib/talia_core/ordered_source.rb', line 44

def at(index)
  @current_index = index
  ordered_objects.at(index)
end

#delete(index) ⇒ Object

remove an existing object to ordered source. This will reorder the existing positions if deleting from the middle! If you don’t want that use insert_at(index, nil)



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# File 'lib/talia_core/ordered_source.rb', line 107

def delete(index)
  ordered_objects.delete_at(index)
end

#delete_all ⇒ Object

remove all existing object to ordered source TODO: This will not reliably delete all elements, since the size

value is not reliable



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# File 'lib/talia_core/ordered_source.rb', line 114

def delete_all
  @ordered_objects = []
end

#elements ⇒ Object

Returns all elements (not the relations) in an ordered array. Unlike the ordered_objects accessor this will not include nil elements and the index will not have a 1:1 relation to the position of the elment.

The ordering of the elements will be preserved, though.



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# File 'lib/talia_core/ordered_source.rb', line 30

def elements
  # execute query
  ordered_objects.compact
end

#find_position_by_object(object) ⇒ Object

Find the position index of the given object. This will always find the first occurence



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# File 'lib/talia_core/ordered_source.rb', line 127

def find_position_by_object(object)
  ordered_objects.index(object)
end

#first ⇒ Object

Returns the first element of the collection



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# File 'lib/talia_core/ordered_source.rb', line 36

def first
  ordered_objects.find { |el| !el.nil? }
end

#index_to_predicate(index) ⇒ Object

return string for index



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# File 'lib/talia_core/ordered_source.rb', line 132

def index_to_predicate(index)
  self.class.index_to_predicate(index)
end

#insert_at(index, object) ⇒ Object

Inserts an element at the given index.



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# File 'lib/talia_core/ordered_source.rb', line 92

def insert_at(index, object)
  write_for_index(ordered_objects, index, object)
end

#next(current_element = nil) ⇒ Object

return next item

  • current_element: int or string. Current element. If nil, the index is the last integer used with at method



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# File 'lib/talia_core/ordered_source.rb', line 51

def next(current_element = nil)
  set_current_index_for(current_element)
  
  # if current element is nil, next must return first value
  @current_index ||= 0

  if (@current_index < (size - 1))
    return at(@current_index + 1) # TODO: Current is not increased, is this intentional? Do we need this method at all?
  else
  raise "Last item reached"
end
end

#ordered_objects ⇒ Object

Returns all the objects that are ordered in an array where the array index equals the position of the object in the ordered set. The array is zero-based, position that don’t have an object attached will be set to nil.



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# File 'lib/talia_core/ordered_source.rb', line 145

def ordered_objects
  return @ordered_objects if(@ordered_objects)
  relations = query
  # Let's assume the follwing is a sane assumption ;-)
  # Even if a one-base collection comes in, we need to push just one element
  @ordered_objects = Array.new(relations.size)
  # Now add the elements so that the relation property is reflected
  # on the position in the array
  relations.each do |rel|
    index = rel.rel_order
    write_for_index(@ordered_objects, index, rel.object)
  end

  @ordered_objects
end

#predicate_to_index(predicate) ⇒ Object

return index of predicate



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# File 'lib/talia_core/ordered_source.rb', line 137

def predicate_to_index(predicate)
  self.class.predicate_to_index(predicate)
end

#previous(current_element = nil) ⇒ Object

return previous item

  • current_element: int or string. Current element. If nil, the index is the last integer used with at method



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# File 'lib/talia_core/ordered_source.rb', line 66

def previous(current_element = nil)
  set_current_index_for(current_element)
  
  # if current element is nil, next must return first value
  @current_index = (size + 1) if @current_index.nil?

  if (@current_index > 1) # TODO: This assumes a one-base array, not really useful
    return at(@current_index - 1) # TODO: See above
  else
  raise "First item reached"
end
end

#replace(index, object) ⇒ Object

replace item as position index with object

  • index: int

  • object: TaliaCore::ActiveSource



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# File 'lib/talia_core/ordered_source.rb', line 121

def replace(index, object)
  replace_for_index(ordered_objects, index, object)
end

#size ⇒ Object

Return the “size” of the collection. This is actually the maximum position index that is used. The value is cached internally and will be increased on insert_at (only if inserting at a value larger at the current size) and on the add operation. If elements are added in another way, the count may be off, but in that case it would be off anyway. Delete will decrease the size by 1, if the index removed equals the size (this is a rough guess which may be off!) The cached counter will be reset on saving.



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# File 'lib/talia_core/ordered_source.rb', line 87

def size
ordered_objects.size
end