precondition.rb in health-data-standards-3.7.0

- old
+ new
@@ -1,47 +1,73 @@
 module HQMF2
-  
+  # Represents the logic that defines grouping of criteria and actions done on it.
   class Precondition
-  
     include HQMF2::Utilities
-    
-    attr_reader :preconditions, :reference
-  
-    def initialize(entry, doc)
-      @doc = doc
-      @entry = entry
-      @preconditions = @entry.xpath('./*/cda:precondition', HQMF2::Document::NAMESPACES).collect do |precondition|
-        Precondition.new(precondition, @doc)
+
+    attr_reader :preconditions, :reference, :conjunction, :id
+
+    def self.parse(entry, doc, id_generator)
+      doc = doc
+      entry = entry
+      aggregation = entry.at_xpath('./cda:allTrue | ./cda:atLeastOneTrue | ./cda:allFalse | ./cda:atLeastOneFalse',
+                                   HQMF2::Document::NAMESPACES)
+
+      # Sets the reference criteria for the precondition (if it exists)
+      reference_def = entry.at_xpath('./*/cda:id', HQMF2::Document::NAMESPACES)
+      reference_def ||= entry.at_xpath('./cda:join/cda:templateId/cda:item', HQMF2::Document::NAMESPACES)
+      reference = Reference.new(reference_def) if reference_def
+
+      # Unless there is an aggregator, no further actions are necessary.
+      return new(id_generator.next_id, nil, [], false, reference) unless aggregation
+
+      precondition_entries = entry.xpath('./*/cda:precondition', HQMF2::Document::NAMESPACES)
+      preconditions = precondition_entries.collect do |precondition|
+        precondition = Precondition.parse(precondition, doc, id_generator)
+        # There are cases where a precondition may contain no references or preconditions, and should be ignored.
+        precondition.reference.nil? && precondition.preconditions.empty? ? nil : precondition
       end
-      reference_def = @entry.at_xpath('./*/cda:id', HQMF2::Document::NAMESPACES)
-      if !reference_def
-        reference_def = @entry.at_xpath('./cda:join/cda:templateId/cda:item', HQMF2::Document::NAMESPACES)
-      end
-      if reference_def
-        @reference = Reference.new(reference_def)
-      end
+      preconditions.compact!
+      handle_aggregation(id_generator, reference, preconditions, aggregation)
     end
-    
-    # Return true of this precondition represents a conjunction with nested preconditions
-    # or false of this precondition is a reference to a data criteria
-    def conjunction?
-      @preconditions.length>0
-    end
-    
-    # Get the conjunction code, e.g. allTrue, allFalse
-    # @return [String] conjunction code
-    def conjunction_code
-      if conjunction?
-        @entry.at_xpath('./*[1]', HQMF2::Document::NAMESPACES).name
+
+    # "False" aggregators exist, and require special handling, so this manages that and returns the
+    #   proper precondition.
+    def self.handle_aggregation(id_generator, reference, preconditions, aggregation, conjunction = nil)
+      negation = false
+      conjunction = aggregation.name
+      case conjunction
+      # DeMorgan's law is used to handle negated caes: e.g. to find if all are false, negate the "at least one true"
+      # check.
+      when 'allFalse'
+        negation = true
+        conjunction = 'atLeastOneTrue'
+      when 'atLeastOneFalse'
+        negation = true
+        conjunction = 'allTrue'
+      end
+      # Return the proper precondition given if a negation exists
+      if negation
+        # Wrap the negation in a seperate precondition which this will reference
+        precondition_wrapper = new(id_generator.next_id, conjunction, preconditions, true, reference)
+        new(id_generator.next_id, conjunction, [precondition_wrapper])
       else
-        nil
+        new(id_generator.next_id, conjunction, preconditions, false, reference)
       end
     end
-    
+
+    def initialize(id, conjunction, preconditions = [], negation = false, reference = nil)
+      @preconditions = preconditions || []
+      @conjunction = conjunction
+      @reference = reference
+      @negation = negation
+      @id = id
+    end
+
+    # Generates this classes hqmf-model equivalent
     def to_model
-      pcs = preconditions.collect {|p| p.to_model}
-      mr = reference ? reference.to_model : nil
-      HQMF::Precondition.new(nil, pcs, mr, conjunction_code, false)
+      pcs = @preconditions.collect(&:to_model)
+      mr = @reference ? @reference.to_model : nil
+      cc = @conjunction
+      HQMF::Precondition.new(@id, pcs, mr, cc, @negation)
     end
   end
-    
 end