From 4688fc7d0dcd182e74ea102bfcd80d6b69516e4d Mon Sep 17 00:00:00 2001
From: Dan Goodliffe <dan@randomdan.homeip.net>
Date: Wed, 28 Dec 2022 14:17:36 +0000
Subject: Add two new array helpers

* create a new array from an old one and a mutation
* mutate all the members of an existing array
---
 lib/collections.hpp | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/lib/collections.hpp b/lib/collections.hpp
index ad4d947..5f4be68 100644
--- a/lib/collections.hpp
+++ b/lib/collections.hpp
@@ -12,3 +12,24 @@ operator+(const std::array<T, first> & a, const std::array<T, second> & b)
 	std::copy(b.begin(), b.end(), out);
 	return r;
 }
+
+template<typename T, std::size_t N>
+auto
+operator*(const std::array<T, N> & in, auto && f)
+{
+	std::array<decltype(f(in[0])), N> out;
+
+	for (auto outitr = out.begin(); const auto & v : in) {
+		*outitr++ = f(v);
+	}
+	return out;
+}
+
+template<typename T, std::size_t N>
+auto &
+operator*=(std::array<T, N> & in, auto && f)
+{
+	for (const auto & v : in) {
+		f(v);
+	}
+}
-- 
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