From 915b78b5e1bf836834e3ef5adcd5e3be166fab0c Mon Sep 17 00:00:00 2001
From: Kp <kp@valhallalegends.com>
Date: Wed, 13 Aug 2014 02:44:59 +0000
Subject: [PATCH] Add vvalptridx_t for always-valid valptridx values

---
 common/include/valptridx.h | 78 ++++++++++++++++++++++++++++++++++++--
 common/main/object.h       |  8 ++--
 similar/main/gamesave.cpp  |  2 +-
 similar/main/object.cpp    | 24 +++---------
 4 files changed, 85 insertions(+), 27 deletions(-)

diff --git a/common/include/valptridx.h b/common/include/valptridx.h
index 7a49b2d56..c36a0ec37 100644
--- a/common/include/valptridx.h
+++ b/common/include/valptridx.h
@@ -103,7 +103,7 @@ protected:
 		static index_type check_index_range(const A &a, index_type s) __attribute_warn_unused_result;
 	pointer_type p;
 	index_type i;
-	static decltype(get_global_array(pointer_type())) get_array()
+	static constexpr decltype(get_global_array(pointer_type())) get_array()
 	{
 		return get_global_array(pointer_type());
 	}
@@ -124,19 +124,85 @@ typename valptridx_t<T, I, magic_constant>::index_type valptridx_t<T, I, magic_c
 	return DXX_VALPTRIDX_CHECK(static_cast<std::size_t>(s) < a.size(), "invalid index used in array subscript", s, index_range_exception);
 }
 
+template <typename T, typename I, template <I> class magic_constant>
+class vvalptridx_t : public valptridx_t<T, I, magic_constant>
+{
+	typedef valptridx_t<T, I, magic_constant> base_t;
+protected:
+	using base_t::get_array;
+	using base_t::check_index_range;
+	using base_t::index_range_exception;
+public:
+	typedef typename base_t::pointer_type pointer_type;
+	typedef typename base_t::index_type index_type;
+	template <index_type v>
+		static constexpr const magic_constant<v> &check_constant_index(const magic_constant<v> &m)
+		{
+			return DXX_VALPTRIDX_CHECK(static_cast<std::size_t>(v) < get_array().size(), "invalid index used", m, index_range_exception);
+		}
+	vvalptridx_t() = delete;
+	template <typename A>
+	vvalptridx_t(A &a, pointer_type t, index_type s) :
+		base_t(a, t, s)
+	{
+	}
+	template <index_type v>
+		vvalptridx_t(const magic_constant<v> &m) :
+			base_t(check_constant_index(m))
+	{
+	}
+	vvalptridx_t(const vvalptridx_t<typename tt::remove_const<T>::type, I, magic_constant> &t) :
+		base_t(t)
+	{
+	}
+	vvalptridx_t(pointer_type p) :
+		base_t(p)
+	{
+	}
+	vvalptridx_t(const base_t &t) :
+		base_t(get_array(), t, t)
+	{
+	}
+	template <typename A>
+	vvalptridx_t(A &a, index_type s) :
+		base_t(check_index_range(a, s))
+	{
+	}
+	vvalptridx_t(index_type s) :
+		base_t(check_index_range(get_array(), s))
+	{
+	}
+	using base_t::operator==;
+	template <index_type v>
+		bool operator==(const magic_constant<v> &m) const
+		{
+			return base_t::operator==(check_constant_index(m));
+		}
+	template <typename R>
+		bool operator!=(const R &rhs) const
+		{
+			return !(*this == rhs);
+		}
+};
+
 #define _DEFINE_VALPTRIDX_SUBTYPE_USERTYPE(N,P,I,A,name,Pconst)	\
-	static inline decltype(A) Pconst &get_global_array(P Pconst*) { return A; }	\
+	static inline constexpr decltype(A) Pconst &get_global_array(P Pconst*) { return A; }	\
 	\
 	struct name : valptridx_t<P Pconst, I, P##_magic_constant_t> {	\
 		name() = delete;	\
 		DXX_INHERIT_CONSTRUCTORS(name, valptridx_t<P Pconst, I, P##_magic_constant_t>);	\
 	};	\
 	\
-	static inline name N(name::pointer_type o, name::index_type i) {	\
+	struct v##name : vvalptridx_t<P Pconst, I, P##_magic_constant_t> {	\
+		v##name() = delete;	\
+		DXX_INHERIT_CONSTRUCTORS(v##name, vvalptridx_t<P Pconst, I, P##_magic_constant_t>);	\
+	};	\
+	\
+	static inline v##name N(name::pointer_type o, name::index_type i) {	\
 		return {A, o, i};	\
 	}	\
 	\
-	static inline name operator-(P Pconst *o, decltype(A) &O)	\
+	static inline v##name operator-(P Pconst *o, decltype(A) &O)	\
 	{	\
 		return N(o, const_cast<const P *>(o) - &(const_cast<const decltype(A) &>(O).front()));	\
 	}	\
@@ -146,4 +212,8 @@ typename valptridx_t<T, I, magic_constant>::index_type valptridx_t<T, I, magic_c
 #define DEFINE_VALPTRIDX_SUBTYPE(N,P,I,A)	\
 	_DEFINE_VALPTRIDX_SUBTYPE_USERTYPE(N,P,I,A,N##_t,);	\
 	_DEFINE_VALPTRIDX_SUBTYPE_USERTYPE(N,P,I,A,c##N##_t,const);	\
+	\
+	static inline v##N##_t N(N##_t::index_type i) {	\
+		return {A, i};	\
+	}	\
 
diff --git a/common/main/object.h b/common/main/object.h
index 642f04512..a95995942 100644
--- a/common/main/object.h
+++ b/common/main/object.h
@@ -653,17 +653,17 @@ int obj_get_new_seg(object *obj);
 
 // when an object has moved into a new segment, this function unlinks it
 // from its old segment, and links it into the new segment
-void obj_relink(objptridx_t objnum,segnum_t newsegnum);
+void obj_relink(vobjptridx_t objnum,segnum_t newsegnum);
 
 // for getting out of messed up linking situations (i.e. caused by demo playback)
 void obj_relink_all(void);
 
 // links an object into a segment's list of objects.
 // takes object number and segment number
-void obj_link(objptridx_t objnum,segnum_t segnum);
+void obj_link(vobjptridx_t objnum,segnum_t segnum);
 
 // unlinks an object from a segment's list of objects
-void obj_unlink(objptridx_t objnum);
+void obj_unlink(vobjptridx_t objnum);
 
 // initialize a new object.  adds to the list for the given segment
 // returns the object number
@@ -675,7 +675,7 @@ objptridx_t obj_create(enum object_type_t type, ubyte id, segnum_t segnum, const
 objptridx_t obj_create_copy(objnum_t objnum, vms_vector *new_pos, segnum_t newsegnum);
 
 // remove object from the world
-void obj_delete(objptridx_t objnum);
+void obj_delete(vobjptridx_t objnum);
 
 // called after load.  Takes number of objects, and objects should be
 // compressed
diff --git a/similar/main/gamesave.cpp b/similar/main/gamesave.cpp
index 9fd2303b2..76ff61757 100644
--- a/similar/main/gamesave.cpp
+++ b/similar/main/gamesave.cpp
@@ -1023,7 +1023,7 @@ static int load_game_data(PHYSFS_file *LoadFile)
 			}
 			else {
 				Objects[i].segnum = segment_none;			//avoid Assert()
-				obj_link(objptridx(&Objects[i],i),objsegnum);
+				obj_link(objptridx(i),objsegnum);
 			}
 		}
 	}
diff --git a/similar/main/object.cpp b/similar/main/object.cpp
index 41ec8d021..929fc2c48 100644
--- a/similar/main/object.cpp
+++ b/similar/main/object.cpp
@@ -86,7 +86,7 @@ using std::min;
 using std::max;
 
 static void obj_detach_all(object *parent);
-static void obj_detach_one(objptridx_t sub);
+static void obj_detach_one(vobjptridx_t sub);
 
 /*
  *  Global variables
@@ -890,14 +890,10 @@ void special_reset_objects(void)
 }
 
 //link the object into the list for its segment
-void obj_link(objptridx_t obj,segnum_t segnum)
+void obj_link(vobjptridx_t obj,segnum_t segnum)
 {
-	Assert(obj != object_none);
-
 	Assert(obj->segnum == segment_none);
-
 	Assert(segnum>=0 && segnum<=Highest_segment_index);
-
 	obj->segnum = segnum;
 	
 	obj->next = Segments[segnum].objects;
@@ -919,12 +915,9 @@ void obj_link(objptridx_t obj,segnum_t segnum)
 		Objects[0].prev = object_none;
 }
 
-void obj_unlink(objptridx_t obj)
+void obj_unlink(vobjptridx_t obj)
 {
 	segment *seg = &Segments[obj->segnum];
-
-	Assert(obj != object_none);
-
 	if (obj->prev == object_none)
 		seg->objects = obj->next;
 	else
@@ -1242,9 +1235,8 @@ objptridx_t obj_create_copy(objnum_t objnum, vms_vector *new_pos, segnum_t newse
 #endif
 
 //remove object from the world
-void obj_delete(objptridx_t obj)
+void obj_delete(vobjptridx_t obj)
 {
-	Assert(obj != object_none);
 	Assert(obj->type != OBJ_NONE);
 	Assert(obj != ConsoleObject);
 
@@ -1589,16 +1581,12 @@ void obj_delete_all_that_should_be_dead()
 
 //when an object has moved into a new segment, this function unlinks it
 //from its old segment, and links it into the new segment
-void obj_relink(objptridx_t objnum,segnum_t newsegnum)
+void obj_relink(vobjptridx_t objnum,segnum_t newsegnum)
 {
-
 	Assert((objnum >= 0) && (objnum <= Highest_object_index));
 	Assert((newsegnum <= Highest_segment_index) && (newsegnum >= 0));
-
 	obj_unlink(objnum);
-
 	obj_link(objnum,newsegnum);
-
 }
 
 // for getting out of messed up linking situations (i.e. caused by demo playback)
@@ -2095,7 +2083,7 @@ void obj_attach(objptridx_t parent,objptridx_t sub)
 }
 
 //dettaches one object
-void obj_detach_one(objptridx_t sub)
+void obj_detach_one(vobjptridx_t sub)
 {
 	Assert(sub->flags & OF_ATTACHED);
 	Assert(sub->ctype.expl_info.attach_parent != object_none);