container/f_vec: added convenience interface to create vector

Added constructors and methods to create a fragmented vector from range and from single element. Signed-off-by: Michał Maślanka <[email protected]>
redpanda-data · Jan 3, 2025 · 6139187 · 6139187
1 parent f28f9fa
commit 6139187
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diff --git a/src/v/container/fragmented_vector.h b/src/v/container/fragmented_vector.h
@@ -22,6 +22,7 @@
 #include <cstddef>
 #include <initializer_list>
 #include <iterator>
+#include <ranges>
 #include <span>
 #include <stdexcept>
 #include <type_traits>
@@ -119,6 +120,16 @@ class fragmented_vector {
      */
     fragmented_vector(std::initializer_list<value_type> elems)
       : fragmented_vector(elems.begin(), elems.end()) {}
+    /**
+     * @brief Construct a new vector from a given range
+     */
+    template<typename Range>
+    requires std::ranges::sized_range<Range>
+    explicit fragmented_vector(Range range)
+      : fragmented_vector() {
+        reserve(std::ranges::size(range));
+        std::move(range.begin(), range.end(), std::back_inserter(*this));
+    }
 
     fragmented_vector& operator=(fragmented_vector&& other) noexcept {
         if (this != &other) {
@@ -480,6 +491,13 @@ class fragmented_vector {
      */
     void erase_to_end(const_iterator begin) { pop_back_n(cend() - begin); }
 
+    template<typename... Args>
+    static fragmented_vector single(Args&&... args) {
+        fragmented_vector v;
+        v.emplace_back(std::forward<Args>(args)...);
+        return v;
+    }
+
     friend std::ostream&
     operator<<(std::ostream& os, const fragmented_vector& v) {
         os << "[";

diff --git a/src/v/container/tests/fragmented_vector_test.cc b/src/v/container/tests/fragmented_vector_test.cc
@@ -553,4 +553,20 @@ TEST(ChunkedVector, ShrinkToFit) {
     EXPECT_EQ(vec.capacity(), 10);
 }
 
+TEST(ChunkedVector, FromRange) {
+    std::vector<int32_t> buffer;
+    buffer.reserve(10);
+    for (int i = 0; i < 10; ++i) {
+        buffer.push_back(i);
+    }
+
+    auto vec = chunked_vector<int32_t>(buffer);
+    EXPECT_THAT(vec, ElementsAreArray(buffer));
+}
+
+TEST(ChunkedVector, InPlaceSingleElement) {
+    auto v = chunked_vector<std::pair<ss::sstring, int32_t>>::single("a2", 3);
+    ASSERT_THAT(v, ElementsAre(std::make_pair("a2", 3)));
+}
+
 } // namespace