Formatting

include/vamp_zero/parse.hpp

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+#pragma once
+
+#include <charconv>
+#include <concepts>
+#include <expected>
+#include <string>
+#include <string_view>
+#include <system_error>
+#include <type_traits>
+
+#include <modulus/result.hpp>
+
+#include <vamp_zero/errors.hpp>
+
+
+namespace vamp_zero {
+
+template <std::integral VALUE>
+  requires(!std::is_same_v<VALUE, std::bool_t>)
+auto parse_integer(std::string_view text, std::string_view name) -> std::expected<VALUE, modulus::error> {
+  auto invalid = [&](std::string_view reason) {
+    return modulus::fail<VALUE>(
+      make_error(error_code::INVALID_ARGUMENT, std::string{name} + " " + std::string{reason}));
+  };
+  if (text.empty()) {
+    return invalid("must be an integer");
+  }
+  auto value = VALUE{};
+  auto end = text.data() + text.size();
+  auto parsed = std::from_chars(text.data(), end, value);
+  if (parsed.ec == std::errc::result_out_of_range) {
+    return invalid("is out of range");
+  }
+  if (parsed.ec != std::errc{} || parsed.ptr != end) {
+    return invalid("must be an integer");
+  }
+  return modulus::success(value);
+}
+
+}