Make CoordsSet a forward range (#8776)

src/main/cpp/net/eagle0/common/IterableBitset.hpp

@@ -105,6 +105,7 @@ public:
 
     class Iter {
     public:
+        using iterator_concept = std::forward_iterator_tag;
         using iterator_category = std::forward_iterator_tag;
         using difference_type = std::ptrdiff_t;
         using value_type = size_t;
@@ -112,14 +113,14 @@ public:
         using reference = size_t;
 
     private:
-        size_t storeIndex;
-        size_t bitIndex;
+        size_t storeIndex = STORE_COUNT;
+        size_t bitIndex = 0;
 
-        const IterableBitset& bs;
+        const IterableBitset* bs = nullptr;
 
         void ToNext() {
             do {
-                const STORE_TYPE current = bs.store[storeIndex] >> bitIndex;
+                const STORE_TYPE current = bs->store[storeIndex] >> bitIndex;
                 if (current != 0) {
                     // Skip ahead by the number of trailing zeroes
                     const auto ctz = std::countr_zero(current);
@@ -132,10 +133,12 @@ public:
         }
 
     public:
+        Iter() = default;
+
         Iter(const IterableBitset& bs, const int startStore, const int startBit)
             : storeIndex(startStore),
               bitIndex(startBit),
-              bs(bs) {
+              bs(&bs) {
             ToNext();
         }
 

src/main/cpp/net/eagle0/shardok/library/map/CoordsSet.hpp

@@ -190,6 +190,7 @@ public:
 
     class Iter {
     public:
+        using iterator_concept = std::forward_iterator_tag;
         using iterator_category = std::forward_iterator_tag;
         using value_type = Coords;
         using difference_type = std::ptrdiff_t;
@@ -197,12 +198,14 @@ public:
         using reference = Coords;
 
     private:
-        BackingBitset::Iter iterator;
+        BackingBitset::Iter iterator{};
 
-        const CoordsSet& cs;
+        const CoordsSet* cs = nullptr;
 
     public:
-        Iter(const CoordsSet& cs, BackingBitset::Iter iter) : iterator(iter), cs(cs) {}
+        Iter() = default;
+
+        Iter(const CoordsSet& cs, BackingBitset::Iter iter) : iterator(iter), cs(&cs) {}
 
         [[nodiscard]] auto operator==(const Iter& rhs) const -> bool {
             return iterator == rhs.iterator;
@@ -224,8 +227,8 @@ public:
         [[nodiscard]] auto operator*() const -> Coords {
             const size_t index = *iterator;
 
-            const int row = static_cast<int>(index / static_cast<size_t>(cs.columnCount));
-            const int column = static_cast<int>(index % static_cast<size_t>(cs.columnCount));
+            const int row = static_cast<int>(index / static_cast<size_t>(cs->columnCount));
+            const int column = static_cast<int>(index % static_cast<size_t>(cs->columnCount));
             return Coords(row, column);
         }
     };

src/test/cpp/net/eagle0/shardok/library/map/CoordsSet_test.cpp

@@ -9,6 +9,7 @@
 #include <cstddef>
 #include <exception>
 #include <iterator>
+#include <ranges>
 #include <type_traits>
 #include <vector>
 
@@ -24,6 +25,9 @@ static_assert(std::is_same_v<
 static_assert(
         std::is_same_v<std::iterator_traits<CoordsSet::Iter>::difference_type, std::ptrdiff_t>);
 static_assert(std::is_same_v<std::iterator_traits<CoordsSet::Iter>::value_type, Coords>);
+static_assert(std::forward_iterator<CoordsSet::Iter>);
+static_assert(std::ranges::forward_range<const CoordsSet>);
+static_assert(std::ranges::sized_range<const CoordsSet>);
 
 class CoordsSetTest : public ::testing::Test {
     void SetUp() override {}