query.rb in ruby-marc-spec-0.1.2

- old
+ new

@@ -1,5 +1,6 @@
+require 'marc/spec/parsing/parser'
 require 'marc/spec/queries/part'
 
 module MARC
   module Spec
     module Queries
@@ -31,22 +32,21 @@
           end.string
         end
 
         # TODO: don't support nested subqueries
         def execute(executor, context_fields, context_result = nil)
-          fields = tag ? executor.apply_tag(tag) : context_fields
+          fields = tag_or_context_fields(executor, context_fields)
           return [] if fields.empty?
 
-          field_results = root_results(fields, executor, context_result)
-          return field_results if subqueries.empty?
+          field_results(executor, fields, context_result)
+        end
 
-          fields.each_with_object([]) do |field, results|
-            subqueries.each do |subquery|
-              subquery_results = subquery.execute(executor, [field])
-              results.concat(subquery_results)
-            end
-          end
+        def any_results?(executor, context_fields, context_result = nil)
+          fields = tag_or_context_fields(executor, context_fields)
+          return false if fields.empty?
+
+          any_field_results?(executor, fields, context_result)
         end
 
         protected
 
         def equality_attrs
@@ -64,18 +64,41 @@
         end
         # rubocop:enable Metrics/AbcSize
 
         private
 
+        def tag_or_context_fields(executor, context_fields)
+          tag ? executor.apply_tag(tag) : context_fields
+        end
+
+        def field_results(executor, fields, context_result)
+          return root_results(fields, executor, context_result) if subqueries.empty?
+
+          subquery_results(executor, fields)
+        end
+
         def root_results(fields, executor, context_result)
           field_results = results_for_fields(executor, fields)
           # TODO: something less ridiculous
           return field_results unless field_results.empty? && select_from_context?(context_result)
 
           selector.apply(context_result)
         end
 
+        def subquery_results(executor, fields)
+          # NOTE: we do this one field at a time so that results are grouped
+          #       by field, rather than by subfield code. Which isn't part of
+          #       the MARCSpec spec, but it seems more in the spirit of MARC
+          #       to preserve order wherever possible.
+          fields.each_with_object([]) do |field, results|
+            subqueries.each do |subquery|
+              subquery_results = subquery.execute(executor, [field])
+              results.concat(subquery_results)
+            end
+          end
+        end
+
         def select_from_context?(context_result)
           tag.nil? && context_result && selector.can_apply?(context_result)
         end
 
         def results_for_fields(executor, fields)
@@ -90,9 +113,24 @@
           return results unless condition
 
           results.select { |result| executor.condition_met?(condition, field, result) }
         end
 
+        def any_field_results?(executor, fields, context_result)
+          return any_root_results?(executor, fields, context_result) if subqueries.empty?
+
+          any_subfield_results?(executor, fields)
+        end
+
+        def any_root_results?(executor, fields, context_result)
+          root_results(fields, executor, context_result).any?
+        end
+
+        def any_subfield_results?(executor, fields)
+          fields.any? do |field|
+            subqueries.any? { |sq| sq.any_results?(executor, [field]) }
+          end
+        end
       end
     end
   end
 end