From a5a0ad3634c512afb1686a2ec8940843e7f0eb63 Mon Sep 17 00:00:00 2001
From: Dan Goodliffe <dan@randomdan.homeip.net>
Date: Mon, 10 Apr 2023 13:20:49 +0100
Subject: operator* collection helper reserves target space when possible

---
 lib/collections.hpp | 3 +++
 1 file changed, 3 insertions(+)

(limited to 'lib')

diff --git a/lib/collections.hpp b/lib/collections.hpp
index 4df622e..b51d18e 100644
--- a/lib/collections.hpp
+++ b/lib/collections.hpp
@@ -70,6 +70,9 @@ template<template<typename...> typename C, typename... T>
 operator*(const C<T...> & in, auto && f)
 {
 	C<decltype(f(*in.begin()))> out;
+	if constexpr (requires { out.reserve(in.size()); }) {
+		out.reserve(in.size());
+	}
 
 	std::transform(in.begin(), in.end(), std::inserter(out, out.end()), f);
 	return out;
-- 
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