day.rb in sparql-3.2.0

- old
+ new

@@ -1,16 +1,25 @@
 module SPARQL; module Algebra
   class Operator
     ##
     # The SPARQL logical `day` operator.
     #
-    # @example
-    #     (prefix ((: <http://example.org/>))
-    #       (project (?s ?x)
-    #         (extend ((?x (day ?date)))
-    #           (bgp (triple ?s :date ?date)))))
+    # [121] BuiltInCall ::= ... | 'DAY' '(' Expression ')' 
     #
+    # @example SPARQL Grammar
+    #   PREFIX : <http://example.org/>
+    #   SELECT ?s (DAY(?date) AS ?x) WHERE {
+    #     ?s :date ?date
+    #   }
+    #
+    # @example SSE
+    #   (prefix
+    #    ((: <http://example.org/>))
+    #    (project (?s ?x)
+    #     (extend ((?x (day ?date)))
+    #      (bgp (triple ?s :date ?date)))))
+    #
     # @see https://www.w3.org/TR/sparql11-query/#func-day
     class Day < Operator::Unary
       include Evaluatable
 
       NAME = :day
@@ -23,9 +32,18 @@
       # @return [RDF::Literal]
       # @raise  [TypeError] if the operand is not a simple literal
       def apply(operand, **options)
         raise TypeError, "expected an RDF::Literal::DateTime, but got #{operand.inspect}" unless operand.is_a?(RDF::Literal::DateTime)
         RDF::Literal(operand.object.day)
+      end
+
+      ##
+      #
+      # Returns a partial SPARQL grammar for this operator.
+      #
+      # @return [String]
+      def to_sparql(**options)
+        "DAY(#{operands.last.to_sparql(**options)})"
       end
     end # Day
   end # Operator
 end; end # SPARQL::Algebra