Add Lua support for std::unique_ptr and std::auto_ptr

Equivalent to Python/Ruby implementations.

Author: wsfulton

CHANGES.current

@@ -7,6 +7,10 @@ the issue number to the end of the URL: https://github.com/swig/swig/issues/
 Version 4.1.0 (in progress)
 ===========================
 
+2022-08-11: wsfulton
+            [Lua] Add support for std::unique_ptr in std_unique_ptr.i.
+            Add support for std::auto_ptr in std_auto_ptr.i.
+
 2022-08-05: wsfulton
             [D] Fix occasional undefined behaviour with inheritance hierarchies, particularly
             when using virtual inheritance as the pointers weren't correctly upcast from derived

Examples/test-suite/cpp11_std_unique_ptr.i

@@ -1,6 +1,6 @@
 %module cpp11_std_unique_ptr
 
-#if defined(SWIGCSHARP) || defined(SWIGJAVA) || defined(SWIGPYTHON) || defined(SWIGRUBY) || defined(SWIGPERL) || defined(SWIGTCL) || defined(SWIGOCTAVE) || defined(SWIGJAVASCRIPT) || defined(SWIGD) || defined(SWIGPHP)
+#if !(defined(SWIGGO) || defined(SWIGOCAML) || defined(SWIGMZSCHEME) || defined(SWIGR) || defined(SWIGSCILAB))
 
 %include "std_string.i"
 %include "std_unique_ptr.i"

Examples/test-suite/li_std_auto_ptr.i

@@ -12,7 +12,7 @@
 #endif
 %}
 
-#if defined(SWIGCSHARP) || defined(SWIGJAVA) || defined(SWIGPYTHON) || defined(SWIGRUBY) || defined(SWIGPERL) || defined(SWIGTCL) || defined(SWIGOCTAVE) || defined(SWIGJAVASCRIPT) || defined(SWIGD) || (SWIGPHP)
+#if !(defined(SWIGGO) || defined(SWIGOCAML) || defined(SWIGMZSCHEME) || defined(SWIGR) || defined(SWIGSCILAB))
 
 %include "std_string.i"
 //#include <iostream>

Examples/test-suite/lua/li_std_auto_ptr_runme.lua

@@ -0,0 +1,93 @@
+require("import")	-- the import fn
+import("li_std_auto_ptr")	-- import code
+
+-- catch "undefined" global variables
+local env = _ENV -- Lua 5.2
+if not env then env = getfenv () end -- Lua 5.1
+setmetatable(env, {__index=function (t,i) error("undefined global variable `"..i.."'",2) end})
+
+
+function checkCount(expected_count)
+  -- call gc to make unused objects are collected
+  collectgarbage()
+  actual_count = li_std_auto_ptr.Klass.getTotal_count()
+  if not (actual_count == expected_count) then
+    error("Counts incorrect, expected:"..expected_count.." actual:"..actual_count)
+  end
+end
+
+--Test raw pointer handling involving virtual inheritance
+kini = li_std_auto_ptr.KlassInheritance("KlassInheritanceInput")
+checkCount(1)
+s = li_std_auto_ptr.useKlassRawPtr(kini)
+if not (s == "KlassInheritanceInput") then
+  error("Incorrect string: "..s)
+end
+kini = nil
+checkCount(0)
+
+-- auto_ptr as input
+kin = li_std_auto_ptr.Klass("KlassInput")
+checkCount(1)
+s = li_std_auto_ptr.takeKlassAutoPtr(kin)
+checkCount(0)
+if not (s == "KlassInput") then
+  error("Incorrect string: "..s)
+end
+if not (li_std_auto_ptr.is_nullptr(kin)) then
+  error("is_nullptr failed")
+end
+kin = nil -- Should not fail, even though already deleted
+checkCount(0)
+
+kin = li_std_auto_ptr.Klass("KlassInput")
+checkCount(1)
+s = li_std_auto_ptr.takeKlassAutoPtr(kin)
+checkCount(0)
+if not (s == "KlassInput") then
+  error("Incorrect string: "..s)
+end
+if not (li_std_auto_ptr.is_nullptr(kin)) then
+  error("is_nullptr failed")
+end
+s, msg = pcall(function() li_std_auto_ptr.takeKlassAutoPtr(kin) end)
+assert(s == false and msg == "Cannot release ownership as memory is not owned for argument 1 of type 'Klass *' in takeKlassAutoPtr")
+
+kin = nil -- Should not fail, even though already deleted
+checkCount(0)
+
+kin = li_std_auto_ptr.Klass("KlassInput")
+notowned = li_std_auto_ptr.get_not_owned_ptr(kin)
+s, msg = pcall(function() li_std_auto_ptr.takeKlassAutoPtr(notowned) end)
+assert(s == false and msg == "Cannot release ownership as memory is not owned for argument 1 of type 'Klass *' in takeKlassAutoPtr")
+checkCount(1)
+kin = nil
+checkCount(0)
+
+kini = li_std_auto_ptr.KlassInheritance("KlassInheritanceInput")
+checkCount(1)
+s = li_std_auto_ptr.takeKlassAutoPtr(kini)
+checkCount(0)
+if not (s == "KlassInheritanceInput") then
+  error("Incorrect string: "..s)
+end
+if not (li_std_auto_ptr.is_nullptr(kini)) then
+  error("is_nullptr failed")
+end
+kini = nil -- Should not fail, even though already deleted
+checkCount(0)
+
+-- auto_ptr as output
+k1 = li_std_auto_ptr.makeKlassAutoPtr("first")
+k2 = li_std_auto_ptr.makeKlassAutoPtr("second")
+checkCount(2)
+
+k1 = nil
+checkCount(1)
+
+if not (k2:getLabel() == "second") then
+  error("wrong object label")
+end
+
+k2 = nil
+checkCount(0)

Lib/lua/luarun.swg

@@ -1757,6 +1757,7 @@ SWIGRUNTIME void SWIG_Lua_NewPointerObj(lua_State *L,void *ptr,swig_type_info *t
  (if possible) */
 SWIGRUNTIME int  SWIG_Lua_ConvertPtr(lua_State *L,int index,void **ptr,swig_type_info *type,int flags)
 {
+  int ret = SWIG_ERROR;
   swig_lua_userdata *usr;
   swig_cast_info *cast;
   /* special case: lua nil => NULL pointer */
@@ -1773,25 +1774,36 @@ SWIGRUNTIME int  SWIG_Lua_ConvertPtr(lua_State *L,int index,void **ptr,swig_type
   usr=(swig_lua_userdata*)lua_touserdata(L,index);  /* get data */
   if (usr)
   {
+    if (((flags & SWIG_POINTER_RELEASE) == SWIG_POINTER_RELEASE) && !usr->own)
+    {
+      return SWIG_ERROR_RELEASE_NOT_OWNED;
+    }
     if (flags & SWIG_POINTER_DISOWN) /* must disown the object */
     {
-        usr->own=0;
+      usr->own = 0;
     }
     if (!type)            /* special cast void*, no casting fn */
     {
       *ptr=usr->ptr;
-      return SWIG_OK; /* ok */
+      ret = SWIG_OK;
     }
-    cast=SWIG_TypeCheckStruct(usr->type,type); /* performs normal type checking */
-    if (cast)
+    else
     {
-      int newmemory = 0;
-      *ptr=SWIG_TypeCast(cast,usr->ptr,&newmemory);
-      assert(!newmemory); /* newmemory handling not yet implemented */
-      return SWIG_OK;  /* ok */
+      cast=SWIG_TypeCheckStruct(usr->type,type); /* performs normal type checking */
+      if (cast)
+      {
+        int newmemory = 0;
+        *ptr=SWIG_TypeCast(cast,usr->ptr,&newmemory);
+        assert(!newmemory); /* newmemory handling not yet implemented */
+        ret = SWIG_OK;
+      }
+    }
+    if ((ret == SWIG_OK) && (flags & SWIG_POINTER_CLEAR))
+    {
+      usr->ptr = 0;
     }
   }
-  return SWIG_ERROR;  /* error */
+  return ret;
 }
 
 SWIGRUNTIME void* SWIG_Lua_MustGetPtr(lua_State *L,int index,swig_type_info *type,int flags,

Lib/lua/std_auto_ptr.i

@@ -0,0 +1,33 @@
+/* -----------------------------------------------------------------------------
+ * std_auto_ptr.i
+ *
+ * SWIG library file for handling std::auto_ptr.
+ * Memory ownership is passed from the std::auto_ptr C++ layer to the proxy
+ * class when returning a std::auto_ptr from a function.
+ * Memory ownership is passed from the proxy class to the std::auto_ptr in the
+ * C++ layer when passed as a parameter to a wrapped function.
+ * ----------------------------------------------------------------------------- */
+
+%define %auto_ptr(TYPE)
+%typemap(in, checkfn="lua_isuserdata", noblock=1) std::auto_ptr< TYPE > (void *argp = 0, int res = 0) {
+  res = SWIG_ConvertPtr(L, $input, &argp, $descriptor(TYPE *), SWIG_POINTER_RELEASE);
+  if (!SWIG_IsOK(res)) {
+    if (res == SWIG_ERROR_RELEASE_NOT_OWNED) {
+      lua_pushfstring(L, "Cannot release ownership as memory is not owned for argument $argnum of type 'TYPE *' in $symname"); SWIG_fail;
+    } else {
+      SWIG_fail_ptr("$symname", $argnum, $descriptor(TYPE *));
+    }
+  }
+  $1.reset((TYPE *)argp);
+}
+
+%typemap (out) std::auto_ptr< TYPE > %{
+  SWIG_NewPointerObj(L, $1.release(), $descriptor(TYPE *), SWIG_POINTER_OWN); SWIG_arg++;
+%}
+
+%template() std::auto_ptr< TYPE >;
+%enddef
+
+namespace std {
+  template <class T> class auto_ptr {};
+}

Lib/lua/std_unique_ptr.i

@@ -0,0 +1,33 @@
+/* -----------------------------------------------------------------------------
+ * std_unique_ptr.i
+ *
+ * SWIG library file for handling std::unique_ptr.
+ * Memory ownership is passed from the std::unique_ptr C++ layer to the proxy
+ * class when returning a std::unique_ptr from a function.
+ * Memory ownership is passed from the proxy class to the std::unique_ptr in the
+ * C++ layer when passed as a parameter to a wrapped function.
+ * ----------------------------------------------------------------------------- */
+
+%define %unique_ptr(TYPE)
+%typemap(in, checkfn="lua_isuserdata", noblock=1) std::unique_ptr< TYPE > (void *argp = 0, int res = 0) {
+  res = SWIG_ConvertPtr(L, $input, &argp, $descriptor(TYPE *), SWIG_POINTER_RELEASE);
+  if (!SWIG_IsOK(res)) {
+    if (res == SWIG_ERROR_RELEASE_NOT_OWNED) {
+      lua_pushfstring(L, "Cannot release ownership as memory is not owned for argument $argnum of type 'TYPE *' in $symname"); SWIG_fail;
+    } else {
+      SWIG_fail_ptr("$symname", $argnum, $descriptor(TYPE *));
+    }
+  }
+  $1.reset((TYPE *)argp);
+}
+
+%typemap (out) std::unique_ptr< TYPE > %{
+  SWIG_NewPointerObj(L, $1.release(), $descriptor(TYPE *), SWIG_POINTER_OWN); SWIG_arg++;
+%}
+
+%template() std::unique_ptr< TYPE >;
+%enddef
+
+namespace std {
+  template <class T> class unique_ptr {};
+}