Class: Philiprehberger::RuleEngine::Rule

Inherits:
Object
  • Object
show all
Includes:
Helpers
Defined in:
lib/philiprehberger/rule_engine/rule.rb

Overview

A single rule with a name, condition, action, and priority.

Instance Attribute Summary collapse

Instance Method Summary collapse

Methods included from Helpers

#all?, #any?, #none?

Constructor Details

#initialize(name, tags: []) ⇒ Rule

Returns a new instance of Rule.

Parameters:

  • name (String) —

    the rule name

  • tags (Array<Symbol>) (defaults to: []) —

    optional tags for grouping



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# File 'lib/philiprehberger/rule_engine/rule.rb', line 20

def initialize(name, tags: [])
  @name = name
  @tags = tags.map(&:to_sym)
  @priority = 0
  @condition = nil
  @action = nil
  @enabled = true
end

Instance Attribute Details

#enabled ⇒ Boolean

Returns whether the rule is enabled.

Returns:

  • (Boolean) —

    whether the rule is enabled



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# File 'lib/philiprehberger/rule_engine/rule.rb', line 16

def enabled
  @enabled
end

#name ⇒ String (readonly)

Returns the rule name.

Returns:

  • (String) —

    the rule name



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# File 'lib/philiprehberger/rule_engine/rule.rb', line 10

def name
  @name
end

#tags ⇒ Array<Symbol> (readonly)

Returns the rule tags.

Returns:

  • (Array<Symbol>) —

    the rule tags



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# File 'lib/philiprehberger/rule_engine/rule.rb', line 13

def tags
  @tags
end

Instance Method Details

#action {|facts| ... } ⇒ void

This method returns an undefined value.

Set the action for this rule.

Yields:

  • (facts) —

    block that receives facts and performs the action



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# File 'lib/philiprehberger/rule_engine/rule.rb', line 41

def action(&block)
  @action = block
end

#condition {|facts| ... } ⇒ void

This method returns an undefined value.

Set the condition for this rule.

Yields:

  • (facts) —

    block that receives facts and returns truthy/falsy



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# File 'lib/philiprehberger/rule_engine/rule.rb', line 33

def condition(&block)
  @condition = block
end

#execute(facts) ⇒ Object

Execute the action with the given facts.

Parameters:

  • facts (Object) —

    the facts to act on

Returns:

  • (Object) —

    the action result



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# File 'lib/philiprehberger/rule_engine/rule.rb', line 71

def execute(facts)
  return nil unless @action

  instance_exec(facts, &@action)
end

#matches?(facts) ⇒ Boolean

Check if the condition matches the given facts.

Parameters:

  • facts (Object) —

    the facts to evaluate

Returns:

  • (Boolean) 


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# File 'lib/philiprehberger/rule_engine/rule.rb', line 61

def matches?(facts)
  return false unless @condition

  !!instance_exec(facts, &@condition)
end

#priority(value = nil) ⇒ Integer

Get or set the priority for this rule.

Parameters:

  • value (Integer, nil) (defaults to: nil) —

    priority value (lower runs first); omit to get current value

Returns:

  • (Integer) —

    the current priority



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# File 'lib/philiprehberger/rule_engine/rule.rb', line 49

def priority(value = nil)
  if value.nil?
    @priority
  else
    @priority = value
  end
end

#to_h ⇒ Hash

Serialize rule metadata to a hash.

Returns:

  • (Hash) —

    rule metadata (name, priority, enabled)



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# File 'lib/philiprehberger/rule_engine/rule.rb', line 80

def to_h
  {
    name: @name,
    priority: @priority,
    enabled: @enabled,
    tags: @tags
  }
end