From 7bafc1dfc1cb5ca40fd92d2b2df99ea91c221bdc Mon Sep 17 00:00:00 2001
From: Lukas Thomann <lukas.thomann@outlook.com>
Date: Tue, 6 Oct 2026 11:46:11 +0200
Subject: [PATCH 1/2] refactor: use std range formatting instead of
 cth::str::to_string

C++23 formats ranges of any formattable type. The cth formatter took over
every range, split strings into characters, prefixed the output with
cth::str::printable_rng and rejected the std range format specs.
---
 cth/incl/cth/string.hpp       | 43 -----------------------------------
 cth/tests/src/string_test.cpp | 33 ---------------------------
 2 files changed, 76 deletions(-)

diff --git a/cth/incl/cth/string.hpp b/cth/incl/cth/string.hpp
index b280429..7ad76e2 100644
--- a/cth/incl/cth/string.hpp
+++ b/cth/incl/cth/string.hpp
@@ -66,39 +66,6 @@ template<cth::mta::arithmetic T>
 }
 
 
-/**
- * @brief formats ranges to string
- * @tparam Rng must satisfy rng::static_dim_rng<Rng>
- */
-template<rng::viewable_rng Rng> requires(rng::static_dim_rng<mta::rcvr_t<Rng>>)
-[[nodiscard]] constexpr std::string to_string(Rng&& range) {
-    static constexpr bool MD_RANGE = mta::md_range<Rng, 2>;
-
-    decltype(auto) rng = rng::to_viewable(range);
-    using rng_t = decltype(rng);
-
-    if(std::ranges::empty(rng))
-        return {};
-
-
-    std::string string = "[";
-    for(auto&& element : std::forward<rng_t>(rng)) {
-        using E = decltype(element);
-        if constexpr(MD_RANGE)
-            string.insert_range(
-                string.end(),
-                std::format("{}, ", cth::str::to_string(std::forward<E>(element)))
-            );
-        else {
-            static_assert(std::formattable<E, char>, "range value type is not formattable");
-            string.insert_range(string.end(), std::format("{}, ", std::forward<E>(element)));
-        }
-    }
-
-    string.pop_back();
-    string.back() = ']';
-    return string;
-}
 
 
 /**
@@ -130,16 +97,6 @@ template<
 } // namespace cth::str
 
 
-namespace cth::str {
-template<class T>
-concept printable_rng = rng::viewable_rng<T> && rng::static_dim_rng<mta::rcvr_t<T>> &&
-    !cth::mta::constructs_any_of<T, std::string_view, std::string>;
-}
-
-
-CTH_FORMAT_CPT(cth::str::printable_rng, cth::str::to_string);
-
-
 namespace cth::expr::str {
 
 template<mta::arithmetic T>
diff --git a/cth/tests/src/string_test.cpp b/cth/tests/src/string_test.cpp
index f4975c9..d932ead 100644
--- a/cth/tests/src/string_test.cpp
+++ b/cth/tests/src/string_test.cpp
@@ -18,39 +18,6 @@ STR_TEST(to_string, range_decline_nonstatic_dim) {
     EXPECT_FALSE(cth::rng::static_dim_rng<std::filesystem::path&>);
 }
 
-STR_TEST(to_string, value_only_rng) {
-    static constexpr size_t COUNT = 10;
-
-    std::map<size_t, size_t> map{};
-    for(size_t i = 0; i < COUNT; i++)
-        map[i] = i;
-
-    auto view = map | std::views::keys | std::views::filter([](auto const id) { return id % 2 == 0; });
-
-    auto const result = std::format("{}", view);
-    EXPECT_EQ("cth::str::printable_rng{[0, 2, 4, 6, 8]}", result);
-}
-
-STR_TEST(to_string, range) {
-    std::vector<int> const vec = {1, 2, 3, 4, 5};
-    std::string const str = cth::str::to_string(vec);
-    EXPECT_EQ(str, "[1, 2, 3, 4, 5]");
-}
-
-STR_TEST(to_string, 2drange) {
-    std::vector<std::vector<int>> const vec = {{1, 2, 3}, {4, 5, 6}, {7, 8, 9}};
-    std::string const str = cth::str::to_string(vec);
-    EXPECT_EQ(str, "[[1, 2, 3], [4, 5, 6], [7, 8, 9]]");
-}
-
-STR_TEST(to_string, view) {
-    std::vector<int> const vec = {1, 2, 3, 4, 5};
-
-    std::string const str = cth::str::to_string(std::views::all(vec));
-    EXPECT_EQ(str, "[1, 2, 3, 4, 5]");
-}
-
-
 STR_TEST(to_num, main) {
     EXPECT_EQ(cth::str::to_num<uint32_t>("1234"), 1234u);
     EXPECT_EQ(cth::str::to_num<float>("1234"), 1234.f);

From bf8b082fb9cd2db1973e11aba28baed613598a2d Mon Sep 17 00:00:00 2001
From: Lukas Thomann <lukas.thomann@outlook.com>
Date: Tue, 6 Oct 2026 11:53:18 +0200
Subject: [PATCH 2/2] test: format ranges of formattable types with all cth
 headers included

Guards against cth taking over std range formatting again.
---
 cth/tests/src/format_test.cpp | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/cth/tests/src/format_test.cpp b/cth/tests/src/format_test.cpp
index 10b36e6..121d02b 100644
--- a/cth/tests/src/format_test.cpp
+++ b/cth/tests/src/format_test.cpp
@@ -2,8 +2,12 @@
 
 #define FMT_TEST(suite, test_name) CTH_EX_TEST(format, suite, test_name)
 
+#include "cth/cth.hpp"
 #include "cth/string/format.hpp"
 
+#include <string>
+#include <vector>
+
 
 namespace test {
 
@@ -61,4 +65,15 @@ FMT_TEST(CTH_FORMAT_CPT, main) {
 
     ASSERT_EQ(str, expected);
 }
+
+FMT_TEST(range, main) {
+    std::vector<::test::Test1> const points{{1, 2}, {3, 4}};
+    std::vector<std::string> const words{"oaf", "farthest"};
+    std::vector<std::vector<int>> const nested{{1, 2}, {3}};
+
+    EXPECT_EQ(std::format("{}", points), "[test::Test1{x: 1, y: 2}, test::Test1{x: 3, y: 4}]");
+    EXPECT_EQ(std::format("{}", words), R"(["oaf", "farthest"])");
+    EXPECT_EQ(std::format("{::}", words), "[oaf, farthest]");
+    EXPECT_EQ(std::format("{}", nested), "[[1, 2], [3]]");
+}
 }