Add reset() method to small_shared_two_way_ptrt

This adds a reset() method which clears the contents of the shared pointer.
Furthermore, the code to remove a reference to the pointed-to object is factored
out into a method destruct(). The method is used both by the destructor and by
reset().

Author: danpoe

src/util/small_shared_two_way_ptr.h

@@ -101,30 +101,13 @@ class small_shared_two_way_ptrt final
 
   ~small_shared_two_way_ptrt()
   {
-    if(!p)
-    {
-      return;
-    }
-
-    auto use_count = p->use_count();
+    destruct();
+  }
 
-    if(use_count == 1)
-    {
-      if(p->is_derived_u())
-      {
-        U *u = static_cast<U *>(p);
-        delete u;
-      }
-      else
-      {
-        V *v = static_cast<V *>(p);
-        delete v;
-      }
-    }
-    else
-    {
-      p->decrement_use_count();
-    }
+  void reset()
+  {
+    destruct();
+    p = nullptr;
   }
 
   void swap(small_shared_two_way_ptrt &rhs)
@@ -186,6 +169,34 @@ class small_shared_two_way_ptrt final
   }
 
 private:
+  void destruct()
+  {
+    if(!p)
+    {
+      return;
+    }
+
+    auto use_count = p->use_count();
+
+    if(use_count == 1)
+    {
+      if(p->is_derived_u())
+      {
+        U *u = static_cast<U *>(p);
+        delete u;
+      }
+      else
+      {
+        V *v = static_cast<V *>(p);
+        delete v;
+      }
+    }
+    else
+    {
+      p->decrement_use_count();
+    }
+  }
+
   pointeet *p = nullptr;
 };
 

unit/util/small_shared_two_way_ptr.cpp

@@ -61,6 +61,7 @@ TEST_CASE("Small shared two-way pointer")
   SECTION("Basic")
   {
     spt sp1;
+    REQUIRE(!sp1);
     REQUIRE(sp1.use_count() == 0);
 
     const d1t *p;
@@ -86,6 +87,10 @@ TEST_CASE("Small shared two-way pointer")
     REQUIRE(sp1.use_count() == 3);
     REQUIRE(sp2.use_count() == 3);
     REQUIRE(sp3.use_count() == 3);
+
+    sp1.reset();
+    REQUIRE(!sp1);
+    REQUIRE(sp1.use_count() == 0);
   }
 
   SECTION("Creation")