Add a delete() method to the objects in the lua wrapper.

library/DataDefs.cpp

@@ -51,6 +51,11 @@ void type_identity::do_copy_pod(void *tgt, const void *src) {
     memmove(tgt, src, size);
 };
 
+bool type_identity::do_destroy_pod(void *obj) {
+    free(obj);
+    return true;
+}
+
 void *type_identity::allocate() {
     if (can_allocate())
         return do_allocate();
@@ -65,6 +70,13 @@ bool type_identity::copy(void *tgt, const void *src) {
         return false;
 }
 
+bool type_identity::destroy(void *obj) {
+    if (can_allocate() && obj)
+        return do_destroy(obj);
+    else
+        return false;
+}
+
 void *enum_identity::do_allocate() {
     void *p = malloc(byte_size());
     memcpy(p, &first_item_value, std::min(byte_size(), sizeof(int64_t)));

library/LuaWrapper.cpp

@@ -593,10 +593,7 @@ static int meta_new(lua_State *state)
 
     void *ptr = id->allocate();
     if (!ptr)
-    {
-        lua_pushnil(state);
-        return 1;
-    }
+        luaL_error(state, "Cannot allocate %s", id->getFullName().c_str());
 
     if (lua_isuserdata(state, 1))
     {
@@ -630,6 +627,30 @@ static int meta_assign(lua_State *state)
     return 0;
 }
 
+/**
+ * Method: deallocation for DF object references.
+ */
+static int meta_delete(lua_State *state)
+{
+    int argc = lua_gettop(state);
+
+    if (argc != 1)
+        luaL_error(state, "Usage: object:delete() or df.delete(object)");
+
+    if (lua_isnil(state, 1))
+    {
+        lua_pushboolean(state, true);
+        return 1;
+    }
+
+    type_identity *id = get_object_identity(state, 1, "df.delete()", false);
+
+    bool ok = id->destroy(get_object_ref(state, 1));
+
+    lua_pushboolean(state, ok);
+    return 1;
+}
+
 /**
  * Verify that the object is a DF ref with UPVAL_METATABLE.
  * If everything ok, extract the address.
@@ -741,6 +762,10 @@ void LuaWrapper::SetPtrMethods(lua_State *state, int meta_idx, int read_idx)
     lua_setfield(state, meta_idx, "new");
     EnableMetaField(state, read_idx, "new");
 
+    lua_getfield(state, LUA_REGISTRYINDEX, DFHACK_DELETE_NAME);
+    lua_setfield(state, meta_idx, "delete");
+    EnableMetaField(state, read_idx, "delete");
+
     lua_getfield(state, LUA_REGISTRYINDEX, DFHACK_ASSIGN_NAME);
     lua_setfield(state, meta_idx, "assign");
     EnableMetaField(state, read_idx, "assign");
@@ -1022,6 +1047,10 @@ static void DoAttach(lua_State *state)
     lua_pushcclosure(state, meta_assign, 1);
     lua_setfield(state, LUA_REGISTRYINDEX, DFHACK_ASSIGN_NAME);
 
+    lua_getfield(state, LUA_REGISTRYINDEX, DFHACK_TYPETABLE_NAME);
+    lua_pushcclosure(state, meta_delete, 1);
+    lua_setfield(state, LUA_REGISTRYINDEX, DFHACK_DELETE_NAME);
+
     luaL_register(state, "df", no_functions);
 
     {
@@ -1035,6 +1064,8 @@ static void DoAttach(lua_State *state)
         lua_setfield(state, -2, "sizeof");
         lua_getfield(state, LUA_REGISTRYINDEX, DFHACK_NEW_NAME);
         lua_setfield(state, -2, "new");
+        lua_getfield(state, LUA_REGISTRYINDEX, DFHACK_DELETE_NAME);
+        lua_setfield(state, -2, "delete");
         lua_getfield(state, LUA_REGISTRYINDEX, DFHACK_DISPLACE_NAME);
         lua_setfield(state, -2, "_displace");
         lua_getfield(state, LUA_REGISTRYINDEX, DFHACK_ASSIGN_NAME);

library/include/DataDefs.h

@@ -73,10 +73,12 @@ namespace DFHack
 
         void *do_allocate_pod();
         void do_copy_pod(void *tgt, const void *src);
+        bool do_destroy_pod(void *obj);
 
         virtual bool can_allocate() { return true; }
         virtual void *do_allocate() { return do_allocate_pod(); }
         virtual void do_copy(void *tgt, const void *src) { do_copy_pod(tgt, src); }
+        virtual bool do_destroy(void *obj) { return do_destroy_pod(obj); }
 
     public:
         virtual ~type_identity() {}
@@ -101,6 +103,7 @@ namespace DFHack
 
         void *allocate();
         bool copy(void *tgt, const void *src);
+        bool destroy(void *obj);
     };
 
     class DFHACK_EXPORT constructed_identity : public type_identity {
@@ -113,6 +116,7 @@ namespace DFHack
         virtual bool can_allocate() { return (allocator != NULL); }
         virtual void *do_allocate() { return allocator(NULL,NULL); }
         virtual void do_copy(void *tgt, const void *src) { allocator(tgt,src); }
+        virtual bool do_destroy(void *obj) { return allocator(NULL,obj) == obj; }
     public:
         virtual bool isPrimitive() { return false; }
         virtual bool isConstructed() { return true; }
@@ -162,6 +166,7 @@ namespace DFHack
         virtual bool can_allocate() { return true; }
         virtual void *do_allocate() { return do_allocate_pod(); }
         virtual void do_copy(void *tgt, const void *src) { do_copy_pod(tgt, src); }
+        virtual bool do_destroy(void *obj) { return do_destroy_pod(obj); }
 
     public:
         bitfield_identity(size_t size,
@@ -189,6 +194,7 @@ namespace DFHack
         virtual bool can_allocate() { return true; }
         virtual void *do_allocate();
         virtual void do_copy(void *tgt, const void *src) { do_copy_pod(tgt, src); }
+        virtual bool do_destroy(void *obj) { return do_destroy_pod(obj); }
 
     public:
         enum_identity(size_t size,

library/include/LuaWrapper.h

@@ -68,6 +68,7 @@ namespace DFHack { namespace LuaWrapper {
 #define DFHACK_DISPLACE_NAME "DFHack::Displace"
 #define DFHACK_NEW_NAME "DFHack::New"
 #define DFHACK_ASSIGN_NAME "DFHack::Assign"
+#define DFHACK_DELETE_NAME "DFHack::Delete"
 
 /*
  * Upvalue: contents of DFHACK_TYPETABLE_NAME