Class: YPetri::Net::State::Feature::Delta

Inherits:
YPetri::Net::State::Feature show all
Defined in:
lib/y_petri/net/state/feature/delta.rb

Overview

Change of a Petri net place caused by a certain set of transitions.

Class Attribute Summary collapse

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Methods inherited from YPetri::Net::State::Feature

#%, Assignment, Delta, Firing, Flux, Gradient, Marking, infer_from_node

Constructor Details

#initialize(place, transitions: net.tt) ⇒ Delta

The constructor of a delta feature takes one ordered argument (place identifier), and one named argument, :transitions, expecting an array of transition identifiers, whose contribution is taken into account in this delta feature.


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# File 'lib/y_petri/net/state/feature/delta.rb', line 101

def initialize place, transitions: net.tt
  @place = net.place( place )
  @transitions = net.Transitions( transitions )
end

Class Attribute Details

.instancesObject (readonly)

def parametrize


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# File 'lib/y_petri/net/state/feature/delta.rb', line 53

def instances
  @instances
end

Instance Attribute Details

#placeObject (readonly)

Returns the value of attribute place


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# File 'lib/y_petri/net/state/feature/delta.rb', line 6

def place
  @place
end

#transitionsObject (readonly) Also known as: tt

Returns the value of attribute transitions


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# File 'lib/y_petri/net/state/feature/delta.rb', line 6

def transitions
  @transitions
end

Class Method Details

.__new__Object


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# File 'lib/y_petri/net/state/feature/delta.rb', line 55

alias __new__ new

.new(*args) ⇒ Object Also known as: of

Constructor #new is redefined to use instance cache.


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# File 'lib/y_petri/net/state/feature/delta.rb', line 89

def new *args
  return instances[ *args ] if args.size == 1
  instances[ args ]
end

.parametrize(*args) ⇒ Object

Customization of the Class#parametrize method.


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# File 'lib/y_petri/net/state/feature/delta.rb', line 12

def parametrize *args
  Class.instance_method( :parametrize ).bind( self ).( *args ).tap do |ç|
    # First, prepare the instance registry.
    hsh = Hash.new do |, id|
      if id.is_a? self then # missing key "id" is a Delta instance
        [ [ id.place, transitions: id.transitions.sort_by( &:object_id ) ] ]
      else
        p = id.fetch( 0 )
        tt = id.fetch( 1 ).fetch( :transitions ) # value of :transitions key
        tt_array = Array( tt )
        if tt == tt_array then
          if p.is_a? ç.net.Place and tt.all? { |t| t.is_a? ç.net.Transition }
            if tt == tt.sort_by( &:object_id ) then
              # Cache the instance.
              [ id ] = if tt.all? &:timed? then
                          ç.timed( *id )
                        elsif tt.all? &:timeless? then
                          fail TypeError, "Net::State::Feature::Delta does " +
                            "not admit A transitions!" if tt.any? &:A?
                          ç.timeless( *id )
                        else
                          fail TypeError, "Net::State::Feature::Delta only " +
                            "admits the transition sets that are either " +
                            "all timed, or all timeless!"
                        end
            else
              [ [ p, transitions: tt.sort_by( &:object_id ) ] ]
            end
          else # convert place and transition ids to places and transitions
            [ [ ç.net.place( p ), transitions: ç.net.Transitions( tt ) ] ]
          end
        else
          [ [ p, transitions: tt_array ] ]
        end
      end
    end    # Then, assign it to the :@instances variable.

    ç.instance_variable_set :@instances, hsh
  end # tap
end

.timed(place, transitions: net.T_tt) ⇒ Object

Timed delta feature constructor. Takes a place, and an array of timed transition identifiers supplied as +:transitions: parameter.


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# File 'lib/y_petri/net/state/feature/delta.rb', line 60

def timed place, transitions: net.T_tt
  tt = begin
         net.T_Transitions( transitions )
       rescue TypeError => err
         msg = "Transitions #{transitions} not recognized as timed " +
           "transitions in #{net}! (%s)"
         raise TypeError, msg % err
       end
  __new__( place, transitions: tt )
    .tap { |inst| inst.instance_variable_set :@timed, true }
end

.timeless(place, transitions: net.t_tt) ⇒ Object

Timeless delta feature constructor. Takes a place, and an array of timeless transition identifiers as +:transitions: parameter.


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# File 'lib/y_petri/net/state/feature/delta.rb', line 75

def timeless place, transitions: net.t_tt
  tt = begin
         net.t_Transitions( transitions )
       rescue TypeError => err
         msg = "Transitions #{transitions} not recognized as timed " +
           "transitions in #{net}! (%s)"
         raise TypeError, msg % err
       end
  __new__( place, transitions: net.t_Transitions( transitions ) )
    .tap { |inst| inst.instance_variable_set :@timed, false }
end

Instance Method Details

#==(other) ⇒ Object

Delta features are equal if they are of equal PS and refer to the same place and transition set.


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# File 'lib/y_petri/net/state/feature/delta.rb', line 169

def == other
  other.is_a? net.State.Feature.Delta and
    place == other.place && transitions == other.transitions
end

#extract_from(arg, **named_args) ⇒ Object

Extracts the value of this feature from the target (eg. a simulation). If the receiver delta feature is timed, this method requires an additional named argument :delta_time, alias :Δt.


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# File 'lib/y_petri/net/state/feature/delta.rb', line 110

def extract_from arg, **named_args
  case arg
  when YPetri::Simulation then
    if timed? then
      arg.send( :T_Transitions, transitions )
        .delta( named_args.must_have :delta_time, syn!: :Δt ).fetch( place )
    else
      arg.send( :t_Transitions, transitions ).delta.fetch( place )
    end
  else
    fail TypeError, "Argument type not supported!"
  end
end

#inspectObject

Inspect string of the delta feature.


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# File 'lib/y_petri/net/state/feature/delta.rb', line 161

def inspect
  "<Feature::Delta Δ:#{place.name || place}:[%s]>" %
    transitions.names( true ).join( ', ' )
end

#labelObject

Label for the delta feature (to use in graphics etc.)


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# File 'lib/y_petri/net/state/feature/delta.rb', line 150

def label
  "Δ:#{place.name}:%s" %
    if transitions.size == 1 then
      transitions.first.name || transitions.first
    else
      "#{transitions.size}tt"
    end
end

#timed?Boolean

Is the delta feature timed?

Returns:

  • (Boolean)

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# File 'lib/y_petri/net/state/feature/delta.rb', line 126

def timed?
  @timed
end

#timeless?Boolean

Opposite of #timed?.

Returns:

  • (Boolean)

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# File 'lib/y_petri/net/state/feature/delta.rb', line 132

def timeless?
  ! timed?
end

#to_sObject

A string briefly describing this delta feature.


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# File 'lib/y_petri/net/state/feature/delta.rb', line 144

def to_s
  label
end

#typeObject

Type of this feature.


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# File 'lib/y_petri/net/state/feature/delta.rb', line 138

def type
  :delta
end