Class: ApacheCrunch::DerivedValueFetcher

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

Overview

Returns the value of an element derived from one captured directly from the log.

Instance Method Summary collapse

Constructor Details

#initialize ⇒ DerivedValueFetcher

Returns a new instance of DerivedValueFetcher.



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# File 'lib/element_value_fetcher.rb', line 46

def initialize
    @_DerivationRuleFinder = DerivationRuleFinder
end

Instance Method Details

#dep_inject!(derivation_rule_finder_cls) ⇒ Object

Handles dependency injection



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# File 'lib/element_value_fetcher.rb', line 51

def dep_inject!(derivation_rule_finder_cls)
    @_DerivationRuleFinder = derivation_rule_finder_cls
end

#fetch(entry, element_name) ⇒ Object

Returns the value for the given name by deriving from an Element in the Entry.

Returns nil if no such value can be derived.



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# File 'lib/element_value_fetcher.rb', line 58

def fetch(entry, element_name)
    # Find the derivation rule that will get us the element we want
    rule = @_DerivationRuleFinder.find(element_name)
    return nil if rule.nil?
    
    # Get the value of the element from which we're deriving
    source_element_name = rule.source_name
    source_element = entry.captured_elements[source_element_name]
    return nil if source_element.nil?

    # Do the derivation
    rule.derive(element_name, source_element.value)
end