Class: Signalize::Computed

Inherits:
Signal
  • Object
show all
Defined in:
lib/signalize.rb

Instance Attribute Summary collapse

Attributes inherited from Signal

#_node, #_targets, #_version

Instance Method Summary collapse

Methods inherited from Signal

#inspect, #subscribe, #to_s, #value=

Constructor Details

#initialize(compute) ⇒ Computed

Returns a new instance of Computed.



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# File 'lib/signalize.rb', line 461

def initialize(compute)
  super(nil)

  @_compute = compute
  @_sources = nil
  # @_global_version = Signalize.global_version - 1
  @_flags = OUTDATED
end

Instance Attribute Details

#_compute ⇒ Object

Returns the value of attribute _compute.



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# File 'lib/signalize.rb', line 459

def _compute
  @_compute
end

#_flags ⇒ Object

Returns the value of attribute _flags.



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# File 'lib/signalize.rb', line 459

def _flags
  @_flags
end

#_sources ⇒ Object

Returns the value of attribute _sources.



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# File 'lib/signalize.rb', line 459

def _sources
  @_sources
end

Instance Method Details

#_notify ⇒ Object 



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# File 'lib/signalize.rb', line 557

def _notify
  unless (@_flags & NOTIFIED).nonzero?
    @_flags |= OUTDATED | NOTIFIED

    node = @_targets
    while node.nil?.!
      node._target._notify
      node = node._next_target
    end
  end
end

#_refresh ⇒ Object 



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# File 'lib/signalize.rb', line 470

def _refresh
  @_flags &= ~NOTIFIED

  return false if (@_flags & RUNNING).nonzero?

  # If this computed signal has subscribed to updates from its dependencies
  # (TRACKING flag set) and none of them have notified about changes (OUTDATED
  # flag not set), then the computed value can't have changed.
  return true if (@_flags & (OUTDATED | TRACKING)) == TRACKING

  @_flags &= ~OUTDATED

  # NOTE: performance optimization removed.
  #
  # if @_global_version == Signalize.global_version
  #   return true
  # end
  # @_global_version = Signalize.global_version

  # Mark this computed signal running before checking the dependencies for value
  # changes, so that the RUNNING flag can be used to notice cyclical dependencies.
  @_flags |= RUNNING
  if @_version > 0 && !Signalize.needs_to_recompute(self)
    @_flags &= ~RUNNING
    return true
  end

  prev_context = Signalize.eval_context
  begin
    Signalize.prepare_sources(self)
    Signalize.eval_context = self
    value = @_compute.()
    if (@_flags & HAS_ERROR).nonzero? || @value != value || @_version == 0
      @value = value
      @_flags &= ~HAS_ERROR
      @_version += 1
    end
  rescue StandardError => err
    @value = err;
    @_flags |= HAS_ERROR
    @_version += 1
  end
  Signalize.eval_context = prev_context
  Signalize.cleanup_sources(self)
  @_flags &= ~RUNNING

  true
end

#_subscribe(node) ⇒ Object 



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# File 'lib/signalize.rb', line 519

def (node)
  if @_targets.nil?
    @_flags |= OUTDATED | TRACKING

    # A computed signal subscribes lazily to its dependencies when the it
    # gets its first subscriber.

    # RUBY NOTE: if we redefine `node`` here, it messes with `node` top method scope!
    # So we'll use a new variable name `snode`
    snode = @_sources
    while snode.nil?.!
      snode._source.(snode)
      snode = snode._next_source
    end
  end
  super(node)
end

#_unsubscribe(node) ⇒ Object 



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# File 'lib/signalize.rb', line 537

def _unsubscribe(node)
  # Only run the unsubscribe step if the computed signal has any subscribers.
  unless @_target.nil?
    super(node)

    # Computed signal unsubscribes from its dependencies when it loses its last subscriber.
    # This makes it possible for unreferences subgraphs of computed signals to get garbage collected.
    if @_targets.nil?
      @_flags &= ~TRACKING

      node = @_sources

      while node.nil?.!
        node._source._unsubscribe(node)
        node = node._next_source
      end
    end
  end
end

#peek ⇒ Object

Raises:



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# File 'lib/signalize.rb', line 569

def peek
  Signalize.cycle_detected unless _refresh

  raise @value if (@_flags & HAS_ERROR).nonzero?

  @value
end

#value ⇒ Object

Raises:



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# File 'lib/signalize.rb', line 577

def value
  Signalize.cycle_detected if (@_flags & RUNNING).nonzero?

  node = Signalize.add_dependency(self)
  _refresh

  node._version = @_version unless node.nil?

  raise @value if (@_flags & HAS_ERROR).nonzero?

  @value
end