Support chaining multiple result sets.

src/kuzu/queries.nim

@@ -147,14 +147,14 @@ func hasNext*( query: KuzuQueryResult ): bool =
 
 
 func getNext*( query: KuzuQueryResult ): KuzuFlatTuple =
-    ## Consume and return the next tuple result, or raise a KuzuIndexError
-    ## if at the end of the result set.
+    ## Consume and return the next tuple result, or raise a KuzuIterationError
+    ## if at the end of the result tuples.
     result = new KuzuFlatTuple
     if kuzu_query_result_get_next( addr query.handle, addr result.handle ) == KuzuSuccess:
         result.valid = true
         result.num_columns = query.num_columns
     else:
-        raise newException( KuzuIndexError, &"Query iteration past end." )
+        raise newException( KuzuIterationError, &"Query iteration past end of tuples." )
 
 
 func rewind*( query: KuzuQueryResult ) =
@@ -162,6 +162,32 @@ func rewind*( query: KuzuQueryResult ) =
     kuzu_query_result_reset_iterator( addr query.handle )
 
 
+func hasNextSet*( query: KuzuQueryResult ): bool =
+    ## Returns +true+ if there are more result sets to be consumed.
+    result = kuzu_query_result_has_next_query_result( addr query.handle )
+
+
+# Keeping this private, because it's only safe to call from within
+# an iterator -- overwriting a query variable with the next result
+# goes boom.
+func getNextSet( query: KuzuQueryResult ): KuzuQueryResult =
+    ## Consume and return the next query set result, or raise a KuzuIterationError
+    ## if at the end of sets.
+    result = new KuzuQueryResult
+    if kuzu_query_result_get_next_query_result( addr query.handle, addr result.handle ) == KuzuSuccess:
+        result.valid = true
+        result.getQueryMetadata()
+    else:
+        raise newException( KuzuIterationError, &"Query iteration past end of set." )
+
+
+iterator sets*( query: KuzuQueryResult ): KuzuQueryResult =
+    ## Iterate available query result sets, yielding to the block.
+    while query.hasNextSet:
+        yield query.getNextSet
+    # NOTE: There is no 'rewind' mechanism for result sets.
+
+
 iterator items*( query: KuzuQueryResult ): KuzuFlatTuple =
     ## Iterate available tuples, yielding to the block.
     while query.hasNext:

src/kuzu/types.nim

@@ -51,5 +51,6 @@ type
     KuzuException*      = object of CatchableError
     KuzuQueryError*     = object of KuzuException
     KuzuIndexError*     = object of KuzuException
+    KuzuIterationError* = object of KuzuException
     KuzuTypeError*      = object of KuzuException
 

tests/queries/t_can_contain_multiple_result_sets.nim

@@ -0,0 +1,42 @@
+# vim: set et sta sw=4 ts=4 :
+
+discard """
+output: "Jenny|Lenny\nLenny\nJenny\n"
+"""
+
+import kuzu
+
+let db = newKuzuDatabase()
+let conn = db.connect
+
+var q = conn.query """
+CREATE NODE TABLE User(
+    id SERIAL PRIMARY KEY,
+    name STRING
+);
+
+CREATE REL TABLE FOLLOWS(
+   From User To User
+);
+
+MERGE (a:User {name: "Lenny"})-[f:Follows]->(b:User {name: "Jenny"});
+"""
+
+q = conn.query( "MATCH (u:User) RETURN *" )
+
+assert typeOf( q ) is KuzuQueryResult
+assert q.hasNextSet == false
+
+q = conn.query """
+    MATCH (a:User)<-[f:Follows]-(b:User) RETURN a.name, b.name;
+    MATCH (u:User) RETURN u.name;
+"""
+
+assert typeOf( q ) is KuzuQueryResult
+assert q.hasNextSet == true
+
+echo q.getNext
+for query_result in q.sets:
+    for row in query_result.items:
+        echo row
+