From cd8581574be22f33944446f54c86ad66cba6697d Mon Sep 17 00:00:00 2001
From: Jonathan Sieber <jonathan.sieber@hicknhack-software.com>
Date: Thu, 30 Jan 2020 14:19:52 +0100
Subject: [PATCH] forEachIndex as "constexpr for": Iterate over a sequence with
 compile-time available indices

---
 src/meta17.lib/meta17/IndexPack.iterate.h | 13 +++++++++++++
 src/meta17.lib/meta17/meta17.qbs          |  1 +
 2 files changed, 14 insertions(+)
 create mode 100644 src/meta17.lib/meta17/IndexPack.iterate.h

diff --git a/src/meta17.lib/meta17/IndexPack.iterate.h b/src/meta17.lib/meta17/IndexPack.iterate.h
new file mode 100644
index 0000000..32816a0
--- /dev/null
+++ b/src/meta17.lib/meta17/IndexPack.iterate.h
@@ -0,0 +1,13 @@
+#pragma once
+#include "Index.h"
+#include "IndexPack.h"
+
+namespace meta17 {
+
+/// "constexpr for": Iterate over a sequence with compile-time available indices
+template <class Callable, size_t... Is>
+constexpr auto forEachIndex(IndexPack<Is...>, Callable &&callable) {
+  return (..., callable(Index<Is>{}));
+}
+
+} // namespace meta17
diff --git a/src/meta17.lib/meta17/meta17.qbs b/src/meta17.lib/meta17/meta17.qbs
index 68193d9..f27bcc2 100644
--- a/src/meta17.lib/meta17/meta17.qbs
+++ b/src/meta17.lib/meta17/meta17.qbs
@@ -50,6 +50,7 @@ Product {
             "IndexPack.extract.h",
             "IndexPack.for.h",
             "IndexPack.h",
+            "IndexPack.iterate.h",
             "IndexPack.make.h",
             "IndexPack.ops.h",
             "IndexPack.trait.h",