Class: ContextManager

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

Constant Summary collapse

@@default = 
nil

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize ⇒ ContextManager

Returns a new instance of ContextManager.



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# File 'lib/context_manager.rb', line 9

def initialize
  @directory = Hash.new
  @adaptations = Array.new
  @total_activations = 0
  @activation_stamps = Hash.new
  self.resolution_policy= self.age_resolution_policy
end

Instance Attribute Details

#adaptations ⇒ Object

Returns the value of attribute adaptations.



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# File 'lib/context_manager.rb', line 7

def adaptations
  @adaptations
end

#directory ⇒ Object

Returns the value of attribute directory.



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# File 'lib/context_manager.rb', line 7

def directory
  @directory
end

Instance Method Details

#activate_adaptation(context_adaptation) ⇒ Object 



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# File 'lib/context_manager.rb', line 24

def activate_adaptation(context_adaptation)
  @adaptations.push(context_adaptation)
  self.deploy_best_adaptation_for(context_adaptation.adapted_class, context_adaptation.adapted_selector)
end

#adaptation_chain(a_class, a_symbol) ⇒ Object

Raises:

  • (Exception) 


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# File 'lib/context_manager.rb', line 38

def adaptation_chain(a_class, a_symbol)
  a = @adaptations.select do |adaptation|
    adaptation.adapts_class? a_class, a_symbol
  end
  raise Exception, "no adaptation found for #{a_class.to_s}.#{a_symbol.to_s}" if a.empty?
  a.sort do |a1, a2|
    @resolution_policy.call(a1.context, a2.context)
  end
end

#age_resolution_policy ⇒ Object 



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# File 'lib/context_manager.rb', line 55

def age_resolution_policy
  Proc.new { |a1, a2|
    (self.context_activation_age(a1) < self.context_activation_age(a2)) ? -1 : 1
  }
end

#context_activation_age(context) ⇒ Object 



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# File 'lib/context_manager.rb', line 61

def context_activation_age(context)
  @total_activations - (@activation_stamps[context].nil? ? 0 : @activation_stamps[context])
end

#deactivate_adaptation(context_adaptation) ⇒ Object

Raises:

  • (Exception) 


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# File 'lib/context_manager.rb', line 29

def deactivate_adaptation(context_adaptation)
  raise Exception, "can't deactivate unmanaged adaptation" if @adaptations.delete(context_adaptation).nil?
  self.deploy_best_adaptation_for(context_adaptation.adapted_class, context_adaptation.adapted_selector) unless @adaptations.empty?
end

#deploy_best_adaptation_for(a_class, a_symbol) ⇒ Object 



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# File 'lib/context_manager.rb', line 34

def deploy_best_adaptation_for(a_class, a_symbol)
  self.adaptation_chain(a_class, a_symbol).first.deploy
end

#discard_context(context) ⇒ Object

Raises:

  • (Exception) 


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# File 'lib/context_manager.rb', line 17

def discard_context(context)
  raise Exception "can't discard outside context manager" if context.manager != self
  raise Exception, "can't discard an active context" if context.active?
  @directory.delete(self)
  @activation_stamps.delete(context)
end

#resolution_policy=(policy) ⇒ Object 



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# File 'lib/context_manager.rb', line 48

def resolution_policy=(policy)
  @resolution_policy = policy
  @adaptations.each do |adaptation|
    self.deploy_best_adaptation_for(adaptation.adapted_class, adaptation.adapted_selector)
  end
end

#signal_activation_request(context) ⇒ Object 



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# File 'lib/context_manager.rb', line 65

def signal_activation_request(context)
  @total_activations += 1
  @activation_stamps[context] = @total_activations
end