8 files changed, 53 insertions, 25 deletions

diff --git a/src/cargotype.cpp b/src/cargotype.cpp
index 81818d5f9..bf9561dda 100644
--- a/src/cargotype.cpp
+++ b/src/cargotype.cpp
@@ -84,8 +84,7 @@ void SetupCargoForClimate(LandscapeID l)
  */
 CargoID GetCargoIDByLabel(CargoLabel cl)
 {
-	const CargoSpec *cs;
-	FOR_ALL_CARGOSPECS(cs) {
+	for (const CargoSpec *cs : CargoSpec::Iterate()) {
 		if (cs->label == cl) return cs->Index();
 	}
 
@@ -103,8 +102,7 @@ CargoID GetCargoIDByBitnum(uint8 bitnum)
 {
 	if (bitnum == INVALID_CARGO) return CT_INVALID;
 
-	const CargoSpec *cs;
-	FOR_ALL_CARGOSPECS(cs) {
+	for (const CargoSpec *cs : CargoSpec::Iterate()) {
 		if (cs->bitnum == bitnum) return cs->Index();
 	}
 
@@ -132,7 +130,6 @@ SpriteID CargoSpec::GetCargoIcon() const
 std::vector<const CargoSpec *> _sorted_cargo_specs; ///< Cargo specifications sorted alphabetically by name.
 uint8 _sorted_standard_cargo_specs_size;            ///< Number of standard cargo specifications stored in the _sorted_cargo_specs array.
 
-
 /** Sort cargo specifications by their name. */
 static bool CargoSpecNameSorter(const CargoSpec * const &a, const CargoSpec * const &b)
 {
@@ -169,9 +166,8 @@ static bool CargoSpecClassSorter(const CargoSpec * const &a, const CargoSpec * c
 void InitializeSortedCargoSpecs()
 {
 	_sorted_cargo_specs.clear();
-	const CargoSpec *cargo;
 	/* Add each cargo spec to the list. */
-	FOR_ALL_CARGOSPECS(cargo) {
+	for (const CargoSpec *cargo : CargoSpec::Iterate()) {
 		_sorted_cargo_specs.push_back(cargo);
 	}
 
diff --git a/src/cargotype.h b/src/cargotype.h
index afc501a2f..4a295f1ae 100644
--- a/src/cargotype.h
+++ b/src/cargotype.h
@@ -122,6 +122,49 @@ struct CargoSpec {
 
 	SpriteID GetCargoIcon() const;
 
+	/**
+	 * Iterator to iterate all valid CargoSpec
+	 */
+	struct Iterator {
+		typedef CargoSpec value_type;
+		typedef CargoSpec *pointer;
+		typedef CargoSpec &reference;
+		typedef size_t difference_type;
+		typedef std::forward_iterator_tag iterator_category;
+
+		explicit Iterator(size_t index) : index(index)
+		{
+			this->ValidateIndex();
+		};
+
+		bool operator==(const Iterator &other) const { return this->index == other.index; }
+		bool operator!=(const Iterator &other) const { return !(*this == other); }
+		CargoSpec * operator*() const { return CargoSpec::Get(this->index); }
+		Iterator & operator++() { this->index++; this->ValidateIndex(); return *this; }
+
+	private:
+		size_t index;
+		void ValidateIndex() { while (this->index < CargoSpec::GetArraySize() && !(CargoSpec::Get(this->index)->IsValid())) this->index++; }
+	};
+
+	/*
+	 * Iterable ensemble of all valid CargoSpec
+	 */
+	struct IterateWrapper {
+		size_t from;
+		IterateWrapper(size_t from = 0) : from(from) {}
+		Iterator begin() { return Iterator(this->from); }
+		Iterator end() { return Iterator(CargoSpec::GetArraySize()); }
+		bool empty() { return this->begin() == this->end(); }
+	};
+
+	/**
+	 * Returns an iterable ensemble of all valid CargoSpec
+	 * @param from index of the first CargoSpec to consider
+	 * @return an iterable ensemble of all valid CargoSpec
+	 */
+	static IterateWrapper Iterate(size_t from = 0) { return IterateWrapper(from); }
+
 private:
 	static CargoSpec array[NUM_CARGO]; ///< Array holding all CargoSpecs
 
@@ -150,10 +193,6 @@ static inline bool IsCargoInClass(CargoID c, CargoClass cc)
 	return (CargoSpec::Get(c)->classes & cc) != 0;
 }
 
-#define FOR_ALL_CARGOSPECS_FROM(var, start) for (size_t cargospec_index = start; var = nullptr, cargospec_index < CargoSpec::GetArraySize(); cargospec_index++) \
-		if ((var = CargoSpec::Get(cargospec_index))->IsValid())
-#define FOR_ALL_CARGOSPECS(var) FOR_ALL_CARGOSPECS_FROM(var, 0)
-
 #define FOR_EACH_SET_CARGO_ID(var, cargo_bits) FOR_EACH_SET_BIT_EX(CargoID, var, CargoTypes, cargo_bits)
 
 /**
diff --git a/src/economy.cpp b/src/economy.cpp
index 716446ba9..9982e79e0 100644
--- a/src/economy.cpp
+++ b/src/economy.cpp
@@ -798,8 +798,7 @@ void RecomputePrices()
 	}
 
 	/* Setup cargo payment */
-	CargoSpec *cs;
-	FOR_ALL_CARGOSPECS(cs) {
+	for (CargoSpec *cs : CargoSpec::Iterate()) {
 		cs->current_payment = ((int64)cs->initial_payment * _economy.inflation_payment) >> 16;
 	}
 
diff --git a/src/newgrf.cpp b/src/newgrf.cpp
index 46bd5a655..19cc436dd 100644
--- a/src/newgrf.cpp
+++ b/src/newgrf.cpp
@@ -5332,8 +5332,7 @@ static CargoID TranslateCargo(uint8 feature, uint8 ctype)
 			return CT_INVALID;
 		}
 
-		const CargoSpec *cs;
-		FOR_ALL_CARGOSPECS(cs) {
+		for (const CargoSpec *cs : CargoSpec::Iterate()) {
 			if (cs->bitnum == ctype) {
 				grfmsg(6, "TranslateCargo: Cargo bitnum %d mapped to cargo type %d.", ctype, cs->Index());
 				return cs->Index();
@@ -8811,8 +8810,7 @@ static void CalculateRefitMasks()
 
 			if (_gted[engine].cargo_allowed != 0) {
 				/* Build up the list of cargo types from the set cargo classes. */
-				const CargoSpec *cs;
-				FOR_ALL_CARGOSPECS(cs) {
+				for (const CargoSpec *cs : CargoSpec::Iterate()) {
 					if (_gted[engine].cargo_allowed    & cs->classes) SetBit(mask,     cs->Index());
 					if (_gted[engine].cargo_disallowed & cs->classes) SetBit(not_mask, cs->Index());
 				}
diff --git a/src/newgrf_station.cpp b/src/newgrf_station.cpp
index a127d54c9..fa3f831aa 100644
--- a/src/newgrf_station.cpp
+++ b/src/newgrf_station.cpp
@@ -572,8 +572,7 @@ StationResolverObject::StationResolverObject(const StationSpec *statspec, BaseSt
 	} else if (Station::IsExpected(this->station_scope.st)) {
 		const Station *st = Station::From(this->station_scope.st);
 		/* Pick the first cargo that we have waiting */
-		const CargoSpec *cs;
-		FOR_ALL_CARGOSPECS(cs) {
+		for (const CargoSpec *cs : CargoSpec::Iterate()) {
 			if (this->station_scope.statspec->grf_prop.spritegroup[cs->Index()] != nullptr &&
 					st->goods[cs->Index()].cargo.TotalCount() > 0) {
 				ctype = cs->Index();
diff --git a/src/script/api/script_cargolist.cpp b/src/script/api/script_cargolist.cpp
index fbd150c6c..0019dc5e9 100644
--- a/src/script/api/script_cargolist.cpp
+++ b/src/script/api/script_cargolist.cpp
@@ -19,8 +19,7 @@
 
 ScriptCargoList::ScriptCargoList()
 {
-	const CargoSpec *cs;
-	FOR_ALL_CARGOSPECS(cs) {
+	for (const CargoSpec *cs : CargoSpec::Iterate()) {
 		this->AddItem(cs->Index());
 	}
 }
diff --git a/src/station_cmd.cpp b/src/station_cmd.cpp
index 7266ad618..482b95462 100644
--- a/src/station_cmd.cpp
+++ b/src/station_cmd.cpp
@@ -3467,8 +3467,7 @@ static void UpdateStationRating(Station *st)
 	byte_inc_sat(&st->time_since_load);
 	byte_inc_sat(&st->time_since_unload);
 
-	const CargoSpec *cs;
-	FOR_ALL_CARGOSPECS(cs) {
+	for (const CargoSpec *cs : CargoSpec::Iterate()) {
 		GoodsEntry *ge = &st->goods[cs->Index()];
 		/* Slowly increase the rating back to his original level in the case we
 		 *  didn't deliver cargo yet to this station. This happens when a bribe
diff --git a/src/town_cmd.cpp b/src/town_cmd.cpp
index 43f3523f8..a0f5df23e 100644
--- a/src/town_cmd.cpp
+++ b/src/town_cmd.cpp
@@ -2779,8 +2779,7 @@ CommandCost CmdRenameTown(TileIndex tile, DoCommandFlag flags, uint32 p1, uint32
  */
 const CargoSpec *FindFirstCargoWithTownEffect(TownEffect effect)
 {
-	const CargoSpec *cs;
-	FOR_ALL_CARGOSPECS(cs) {
+	for (const CargoSpec *cs : CargoSpec::Iterate()) {
 		if (cs->town_effect == effect) return cs;
 	}
 	return nullptr;