Replaced conversion with as_vector function for Vector and HalfVector

Author: ankane

CHANGELOG.md

@@ -2,6 +2,7 @@
 
 - Added support for libpqxx 8
 - Changed `HalfVector` to use `std::float16_t` or `_Float16` when available
+- Replaced conversion with `as_vector` function for `Vector` and `HalfVector`
 - Dropped support for libpqxx 7
 - Dropped support for C++17
 

include/pgvector/halfvec.hpp

@@ -47,12 +47,7 @@ class HalfVector {
     }
 
     /// Returns the half vector as a `std::vector<pgvector::Half>`.
-    operator const std::vector<Half>() const {
-        return value_;
-    }
-
-    /// Returns the half vector as a `std::span<const pgvector::Half>`.
-    operator const std::span<const Half>() const {
+    const std::vector<Half>& as_vector() const {
         return value_;
     }
 

include/pgvector/pqxx.hpp

@@ -45,7 +45,7 @@ template <> struct string_traits<pgvector::Vector> {
     }
 
     static std::string_view to_buf(std::span<char> buf, const pgvector::Vector& value, ctx c = {}) {
-        std::span<const float> values{value};
+        auto& values = value.as_vector();
 
         // important! size_buffer cannot throw an exception on overflow
         // so perform this check before writing any data
@@ -69,7 +69,7 @@ template <> struct string_traits<pgvector::Vector> {
     }
 
     static size_t size_buffer(const pgvector::Vector& value) noexcept {
-        std::span<const float> values{value};
+        auto& values = value.as_vector();
 
         // cannot throw an exception here on overflow
         // so throw in into_buf
@@ -109,7 +109,7 @@ template <> struct string_traits<pgvector::HalfVector> {
     }
 
     static std::string_view to_buf(std::span<char> buf, const pgvector::HalfVector& value, ctx c = {}) {
-        std::span<const pgvector::Half> values{value};
+        auto& values = value.as_vector();
 
         // important! size_buffer cannot throw an exception on overflow
         // so perform this check before writing any data
@@ -133,7 +133,7 @@ template <> struct string_traits<pgvector::HalfVector> {
     }
 
     static size_t size_buffer(const pgvector::HalfVector& value) noexcept {
-        std::span<const pgvector::Half> values{value};
+        auto& values = value.as_vector();
 
         // cannot throw an exception here on overflow
         // so throw in into_buf

include/pgvector/vector.hpp

@@ -31,12 +31,7 @@ class Vector {
     }
 
     /// Returns the vector as a `std::vector<float>`.
-    operator const std::vector<float>() const {
-        return value_;
-    }
-
-    /// Returns the vector as a `std::span<const float>`.
-    operator const std::span<const float>() const {
+    const std::vector<float>& as_vector() const {
         return value_;
     }
 

test/halfvec_test.cpp

@@ -16,14 +16,14 @@ static void test_constructor_span() {
     assert_equal(vec.dimensions(), 3u);
 }
 
-static void test_conversion() {
+static void test_as_vector() {
     auto vec = HalfVector({1, 2, 3});
-    auto half_vec = static_cast<std::vector<pgvector::Half>>(vec);
+    auto& half_vec = vec.as_vector();
     assert_equal(half_vec == std::vector<pgvector::Half>{1, 2, 3}, true);
 }
 
 void test_halfvec() {
     test_constructor_vector();
     test_constructor_span();
-    test_conversion();
+    test_as_vector();
 }

test/vector_test.cpp

@@ -16,14 +16,14 @@ static void test_constructor_span() {
     assert_equal(vec.dimensions(), 3u);
 }
 
-static void test_conversion() {
+static void test_as_vector() {
     auto vec = Vector({1, 2, 3});
-    auto float_vec = static_cast<std::vector<float>>(vec);
+    auto& float_vec = vec.as_vector();
     assert_equal(float_vec == std::vector<float>{1, 2, 3}, true);
 }
 
 void test_vector() {
     test_constructor_vector();
     test_constructor_span();
-    test_conversion();
+    test_as_vector();
 }