YT-CPPHGL-30: Implement a flat matrix data structure

include/gl/types/flat_jagged_vector.hpp

@@ -228,7 +228,7 @@ class flat_jagged_vector {
     /// @brief Reverse const iterator
     using const_reverse_iterator = std::reverse_iterator<const_iterator>;
 
-    // --- constructors ---
+    // --- constructors and assignment ---
 
     /// @brief Default constructor creates an empty `flat_jagged_vector`.
     /// @post `empty() == true`, `size() == 0`, `data_size() == 0`
@@ -330,7 +330,7 @@ class flat_jagged_vector {
     /// @return `true` if both vectors have the same structure and elements
     friend bool operator==(const flat_jagged_vector&, const flat_jagged_vector&) = default;
 
-    // --- capacity ---
+    // --- size and capacity ---
 
     /// @brief Returns the number of segments in this container.
     /// @return The count of segments
@@ -846,8 +846,6 @@ class flat_jagged_vector {
     requires std::convertible_to<std::ranges::range_reference_t<R>, value_type>
     void push_back(R&& r) {
         this->_ensure_offset_capacity();
-        if constexpr (std::ranges::sized_range<R>)
-            this->_data.reserve(this->_data.size() + std::ranges::size(r));
 
         if constexpr (std::ranges::contiguous_range<R>) {
             auto* ptr = std::ranges::data(r);
@@ -908,8 +906,6 @@ class flat_jagged_vector {
         const auto old_size = this->_data.size();
 
         this->_ensure_offset_capacity();
-        if constexpr (std::ranges::sized_range<R>)
-            this->_data.reserve(this->_data.size() + std::ranges::size(r));
 
         if constexpr (std::ranges::contiguous_range<R>) {
             auto* ptr = std::ranges::data(r);