From ffa09a50a07e60e1a9d370993c0709ccb1a22b2d Mon Sep 17 00:00:00 2001
From: Danny Robson <danny@nerdcruft.net>
Date: Thu, 17 Oct 2024 09:08:19 +1000
Subject: [PATCH] ranges: add a simplistic implementation of enumerate

This is a temporary workaround because clang lacks it.
---
 cruft/util/CMakeLists.txt       |  1 +
 cruft/util/ranges/enumerate.hpp | 19 +++++++++++++++++++
 2 files changed, 20 insertions(+)
 create mode 100644 cruft/util/ranges/enumerate.hpp

diff --git a/cruft/util/CMakeLists.txt b/cruft/util/CMakeLists.txt
index 94c8d0a7..e799a912 100644
--- a/cruft/util/CMakeLists.txt
+++ b/cruft/util/CMakeLists.txt
@@ -545,6 +545,7 @@ list (
     range.cpp
     range.hpp
     ranges/chunk.hpp
+    ranges/enumerate.hpp
     rational.cpp
     rational.hpp
     region.cpp
diff --git a/cruft/util/ranges/enumerate.hpp b/cruft/util/ranges/enumerate.hpp
new file mode 100644
index 00000000..a1b6d58e
--- /dev/null
+++ b/cruft/util/ranges/enumerate.hpp
@@ -0,0 +1,19 @@
+#pragma once
+
+#include <ranges>
+
+namespace cruft::util::ranges {
+    /// A very simple implementation of std::views::enumerate provided because clang-19 lacks it
+    ///
+    /// clang#19: check me again in clang-20
+    template <typename Rng>
+    requires (std::ranges::input_range<Rng>)
+    auto
+    enumerate (Rng &&r)
+    {
+        return std::views::zip (
+            std::views::iota (0),
+            std::forward<Rng> (r)
+        );
+    }
+}