🚧 Add ESearchResult methods for handling UPDATE return data

lib/net/imap/esearch_result.rb

@@ -171,23 +171,63 @@ def initialize(position:, set:)
         # A SequenceSet of updates to the search context.
 
         ##
-        # method: set
+        # Returns #set
+        def to_sequence_set; set end
 
+        # Converts #set to an array of numbers (UIDs or sequence numbers).
+        def to_a; set.numbers end
+
+        # :call-seq: update(context) -> updated context
+        #
+        # Given a SequenceSet +context+, returns a new SequenceSet, updated by
+        # +self+.
+        def update(context) update! context.dup end
+
+        # :call-seq: update!(context) -> updated context
+        #
+        # Modifies a SequenceSet +context+ by the updates in +self+.
+        # Implemented by subclasses.
+        def update(context) raise "implemented by subclasses" end
       end
 
       # Returned by ESearchResult#addto and ESearchResult#updates.
       #
       # Requires <tt>CONTEXT=SEARCH</tt>/<tt>CONTEXT=SORT</tt>
       # {[RFC5267]}[https://www.rfc-editor.org/rfc/rfc5267.html]
       class AddToContext < ContextUpdate
+        alias additions set
+
+        # Updates context by adding #additions.
+        #
+        # *NOTE:* positions other than zero are not currently supported.
+        def update!(context)
+          if position.zero?
+            context.merge additions
+          else
+            raise "Positions other than zero are not currently supported."
+            # TODO: context.insert additions
+          end
+        end
       end
 
       # Returned by ESearchResult#removefrom and ESearchResult#updates.
       #
       # Requires <tt>CONTEXT=SEARCH</tt>/<tt>CONTEXT=SORT</tt>
       # {[RFC5267]}[https://www.rfc-editor.org/rfc/rfc5267.html]
       class RemoveFromContext < ContextUpdate
+        alias removals set
 
+        # Updates context by subtracting #additions.
+        #
+        # *NOTE:* positions other than zero are not currently supported.
+        def update!(context)
+          if position.zero?
+            context.subtract removals
+          else
+            raise "Positions other than zero are not currently supported."
+            # TODO: context.remove removals
+          end
+        end
       end
 
       # :call-seq: updates -> array of context updates, or nil