Make sure that sqlgen::Range is an input_range

include/sqlgen/Iterator.hpp

@@ -1,6 +1,7 @@
 #ifndef SQLGEN_ITERATOR_HPP_
 #define SQLGEN_ITERATOR_HPP_
 
+#include <iterator>
 #include <memory>
 #include <ranges>
 
@@ -19,7 +20,15 @@ class Iterator {
   using difference_type = std::ptrdiff_t;
   using value_type = Result<T>;
 
-  struct End {};
+  struct End {
+    bool operator==(const Iterator<T>& _it) const noexcept {
+      return _it == *this;
+    }
+
+    bool operator!=(const Iterator<T>& _it) const noexcept {
+      return _it != *this;
+    }
+  };
 
   Iterator(const Ref<IteratorBase>& _it)
       : current_batch_(get_next_batch(_it)), it_(_it), ix_(0) {}
@@ -30,11 +39,11 @@ class Iterator {
 
   Result<T>* operator->() const noexcept { return &(*current_batch_)[ix_]; }
 
-  bool operator==(const End&) noexcept {
+  bool operator==(const End&) const noexcept {
     return ix_ >= current_batch_->size() && it_->end();
   }
 
-  bool operator!=(const End& _end) noexcept { return !(*this == _end); }
+  bool operator!=(const End& _end) const noexcept { return !(*this == _end); }
 
   Iterator<T>& operator++() noexcept {
     if (ix_ >= current_batch_->size() && !it_->end()) {

include/sqlgen/Range.hpp

@@ -5,6 +5,7 @@
 #include <ranges>
 
 #include "Iterator.hpp"
+#include "Result.hpp"
 
 namespace sqlgen {
 
@@ -13,7 +14,10 @@ namespace sqlgen {
 template <class T>
 class Range {
  public:
-  using value_type = T;
+  using value_type = Result<T>;
+
+  static_assert(std::input_iterator<Iterator<T>>,
+                "This must be an input iterator.");
 
   struct End {};
 

include/sqlgen/read.hpp

@@ -12,9 +12,8 @@ namespace sqlgen {
 
 template <class ContainerType>
 Result<ContainerType> read(const Ref<Connection>& _conn) noexcept {
-  using ValueType = typename ContainerType::value_type;
-
   if constexpr (internal::is_range_v<ContainerType>) {
+    using ValueType = typename ContainerType::value_type::value_type;
     const auto query = transpilation::to_select_from<ValueType>();
     return _conn->read(query).transform(
         [](auto&& _it) { return ContainerType(_it); });
@@ -32,6 +31,7 @@ Result<ContainerType> read(const Ref<Connection>& _conn) noexcept {
       return container;
     };
 
+    using ValueType = typename ContainerType::value_type;
     return read<Range<ValueType>>(_conn).and_then(to_container);
   }
 }

tests/CMakeLists.txt

@@ -11,7 +11,7 @@ target_precompile_headers(sqlgen-tests PRIVATE [["sqlgen.hpp"]] <iostream> <stri
 if (MSVC)
     set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std:c++20")
 else()
-    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -O3 -Wall -Werror -ggdb")
+    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -O3 -Wall -Werror -ggdb -fconcepts-diagnostics-depth=5")
 endif()
 
 target_link_libraries(

tests/sqlite/test_range.cpp

@@ -0,0 +1,50 @@
+#include <gtest/gtest.h>
+
+#include <ranges>
+#include <rfl.hpp>
+#include <rfl/json.hpp>
+#include <sqlgen.hpp>
+#include <sqlgen/sqlite.hpp>
+#include <vector>
+
+namespace test_range {
+
+struct Person {
+  sqlgen::PrimaryKey<uint32_t> id;
+  std::string first_name;
+  std::string last_name;
+  int age;
+};
+
+TEST(sqlite, test_range) {
+  static_assert(std::ranges::input_range<sqlgen::Range<Person>>,
+                "Must be an input range.");
+
+  using namespace std::ranges::views;
+
+  const auto people1 = std::vector<Person>(
+      {Person{
+           .id = 0, .first_name = "Homer", .last_name = "Simpson", .age = 45},
+       Person{.id = 1, .first_name = "Bart", .last_name = "Simpson", .age = 10},
+       Person{.id = 2, .first_name = "Lisa", .last_name = "Simpson", .age = 8},
+       Person{
+           .id = 3, .first_name = "Maggie", .last_name = "Simpson", .age = 0}});
+
+  const auto conn = sqlgen::sqlite::connect();
+
+  sqlgen::write(conn, people1);
+
+  const auto people2 = sqlgen::read<sqlgen::Range<Person>>(conn).value();
+
+  const auto first_names =
+      sqlgen::internal::collect::vector(people2 | transform([](const auto& _r) {
+                                          return _r.value().first_name;
+                                        }));
+
+  EXPECT_EQ(first_names.at(0), "Homer");
+  EXPECT_EQ(first_names.at(1), "Bart");
+  EXPECT_EQ(first_names.at(2), "Lisa");
+  EXPECT_EQ(first_names.at(3), "Maggie");
+}
+
+}  // namespace test_range