From e1eea9d98a8d53d56ce17cb67b320c34b4a8bfc8 Mon Sep 17 00:00:00 2001
From: Max Kellermann <max.kellermann@gmail.com>
Date: Thu, 4 Jan 2024 21:03:25 +0100
Subject: [PATCH] util/NumberParser: new library based on std::from_chars()

---
 src/util/NumberParser.hxx | 30 ++++++++++++++++++++++++++++++
 1 file changed, 30 insertions(+)
 create mode 100644 src/util/NumberParser.hxx

diff --git a/src/util/NumberParser.hxx b/src/util/NumberParser.hxx
new file mode 100644
index 000000000..101225eba
--- /dev/null
+++ b/src/util/NumberParser.hxx
@@ -0,0 +1,30 @@
+// SPDX-License-Identifier: BSD-2-Clause
+// author: Max Kellermann <max.kellermann@gmail.com>
+
+#pragma once
+
+#include <charconv>
+#include <concepts>
+#include <optional>
+#include <string_view>
+
+template<std::integral T>
+[[gnu::pure]]
+std::optional<T>
+ParseInteger(const char *first, const char *last, int base=10) noexcept
+{
+	T value;
+	auto [ptr, ec] = std::from_chars(first, last, value, base);
+	if (ptr == last && ec == std::errc{})
+		return value;
+	else
+		return std::nullopt;
+}
+
+template<std::integral T>
+[[gnu::pure]]
+std::optional<T>
+ParseInteger(std::string_view src, int base=10) noexcept
+{
+	return ParseInteger<T>(src.data(), src.data() + src.size(), base);
+}