Class: Ruleby::Core::Engine

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

Overview

This is the core class of the library. A new rule engine is created by instantiating it. Each rule engine has one inference engine, one rule set and one working memory.

Instance Method Summary collapse

Constructor Details

#initialize(wm = WorkingMemory.new, cr = RulebyConflictResolver.new) ⇒ Engine

Returns a new instance of Engine.



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# File 'lib/core/engine.rb', line 205

def initialize(wm=WorkingMemory.new,cr=RulebyConflictResolver.new)
  @root = nil
  @working_memory = wm
  @conflict_resolver = cr
  @wm_altered = false
  assert InitialFact.new
end

Instance Method Details

#assert(object, &block) ⇒ Object

This method id called to add a new fact to working memory



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# File 'lib/core/engine.rb', line 218

def assert(object,&block)
  @wm_altered = true
  fact_helper(object,:plus,&block)
end

#assert_rule(rule) ⇒ Object

This method adds a new rule to the system.



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# File 'lib/core/engine.rb', line 242

def assert_rule(rule)         
  if @root == nil
    @root = RootNode.new(@working_memory) 
    @root.reset_counter
  end
  @root.assert_rule rule
end

#clear_errors ⇒ Object 



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# File 'lib/core/engine.rb', line 274

def clear_errors
  @root.clear_errors if @root
end

#errors ⇒ Object 



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# File 'lib/core/engine.rb', line 270

def errors
  @root.nil? ? [] : @root.errors
end

#facts ⇒ Object 



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# File 'lib/core/engine.rb', line 213

def facts
  @working_memory.facts.collect{|f| f.object}.select{|f| !f.is_a?(InitialFact)}
end

#match(agenda = nil, used_agenda = []) ⇒ Object

This method executes the activations that were generated by the rules that match facts in working memory.



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# File 'lib/core/engine.rb', line 252

def match(agenda=nil, used_agenda=[])      
  if @root
    @root.reset_counter
    agenda = @root.matches unless agenda 
    while (agenda.length > 0)
      agenda = @conflict_resolver.resolve agenda            
      activation = agenda.pop   
      used_agenda.push activation     
      activation.fire self   
      if @wm_altered          
        agenda = @root.matches(false)    
        @root.increment_counter
        @wm_altered = false
      end
    end
  end
end

#modify(object, &block) ⇒ Object

This method is called to alter an existing fact. It is essentially a retract followed by an assert.



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# File 'lib/core/engine.rb', line 232

def modify(object,&block)
  retract(object,&block)
  assert(object,&block)
end

#print ⇒ Object 



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# File 'lib/core/engine.rb', line 278

def print
  @working_memory.print
  @root.print
end

#retract(object, &block) ⇒ Object

This method is called to remove an existing fact from working memory



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# File 'lib/core/engine.rb', line 224

def retract(object,&block)
  @wm_altered = true
  fact_helper(object,:minus,&block)
  object
end

#retrieve(c) ⇒ Object 



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# File 'lib/core/engine.rb', line 237

def retrieve(c)
  facts.select {|f| f.kind_of?(c)}
end