From 5a0b3927a33807cca4c77c40eb873f8a3b51b0b0 Mon Sep 17 00:00:00 2001
From: Dan Goodliffe <dan@randomdan.homeip.net>
Date: Sat, 29 Apr 2023 19:07:11 +0100
Subject: Drop .hpp for header only things

Half of them acquired a .cpp part anyway
---
 lib/enumDetails.h | 143 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 143 insertions(+)
 create mode 100644 lib/enumDetails.h

(limited to 'lib/enumDetails.h')

diff --git a/lib/enumDetails.h b/lib/enumDetails.h
new file mode 100644
index 0000000..5966be2
--- /dev/null
+++ b/lib/enumDetails.h
@@ -0,0 +1,143 @@
+#pragma once
+
+#include <algorithm>
+#include <array>
+#include <limits>
+#include <optional>
+#include <string_view>
+
+/// EnumDetailsBase
+// Shared helpers
+struct EnumDetailsBase {
+	template<size_t len>
+	constexpr static auto
+	strArr(auto input, auto start, auto end)
+	{
+		std::array<char, len> out;
+		input.copy(out.begin(), end - start, start);
+		return out;
+	}
+};
+
+/// EnumTypeDetails
+// Extracts the fully qualified name of the enumeration
+template<typename E> struct EnumTypeDetails : EnumDetailsBase {
+#ifndef ENUM_PROBE
+protected:
+#endif
+	constexpr static std::string_view SEARCH_TYPE {"E = "};
+	constexpr static auto
+	typeraw()
+	{
+		return std::string_view {__PRETTY_FUNCTION__};
+	};
+	constexpr static auto typeNameStart {typeraw().find(SEARCH_TYPE) + SEARCH_TYPE.length()};
+	constexpr static auto typeNameEnd {typeraw().find_first_of("];", typeNameStart)};
+	constexpr static auto typeNameLen {typeNameEnd - typeNameStart};
+	constexpr static auto typeNameArr {strArr<typeNameLen>(typeraw(), typeNameStart, typeNameEnd)};
+
+public:
+	constexpr static std::string_view typeName {typeNameArr.data(), typeNameArr.size()};
+};
+
+/// EnumValueDetails
+// Extracts the value name and constructs string_views of the parts
+template<auto value> struct EnumValueDetails : public EnumTypeDetails<decltype(value)> {
+#ifndef ENUM_PROBE
+private:
+#endif
+	using T = EnumTypeDetails<decltype(value)>;
+	constexpr static auto
+	raw()
+	{
+		return std::string_view {__PRETTY_FUNCTION__};
+	};
+	constexpr static auto nameStart {raw().find_last_of(": ") + 1};
+	constexpr static auto nameEnd {raw().find_first_of("];", nameStart)};
+	constexpr static auto nameLen {nameEnd - nameStart};
+	constexpr static auto nameArr {EnumValueDetails::template strArr<nameLen>(raw(), nameStart, nameEnd)};
+
+public:
+	constexpr static std::string_view valueName {nameArr.data(), nameArr.size()};
+	constexpr static auto valid {valueName.back() < '0' || valueName.back() > '9'};
+	constexpr static auto raw_value {value};
+};
+
+/// EnumValueCollection
+// Customisation point for specifying the range of underlying values your enum can have
+template<typename E> struct EnumValueCollection {
+	using Vs = std::make_integer_sequence<int, 256>;
+};
+
+/// EnumDetails
+// Interface for lookups/checks/etc at runtime
+template<typename E> struct EnumDetails {
+#ifndef ENUM_PROBE
+private:
+#endif
+	template<auto... n>
+	constexpr static auto
+	get_valids(std::integer_sequence<int, n...>)
+	{
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wconversion"
+		return std::array {EnumValueDetails<static_cast<E>(n)>::valid...};
+#pragma GCC diagnostic pop
+	}
+	template<auto... n>
+	constexpr static auto
+	get_values(std::integer_sequence<int, n...>)
+	{
+		return std::array {EnumValueDetails<static_cast<E>(n)>::raw_value...};
+	}
+	template<auto... n>
+	constexpr static auto
+	get_valueNames(std::integer_sequence<int, n...>)
+	{
+		return std::array {EnumValueDetails<values[n]>::valueName...};
+	}
+
+	using EVC = EnumValueCollection<E>;
+	constexpr static auto valid_flags {get_valids(typename EVC::Vs {})};
+	constexpr static auto valid_count {std::count_if(valid_flags.begin(), valid_flags.end(), std::identity {})};
+
+	constexpr static auto
+	lookup(const auto key, const auto & search, const auto & out)
+			-> std::optional<typename std::decay_t<decltype(out)>::value_type>
+	{
+		if (const auto itr = std::find(search.begin(), search.end(), key); itr != search.end()) {
+			return out[static_cast<std::size_t>(std::distance(search.begin(), itr))];
+		}
+		return std::nullopt;
+	}
+
+public:
+	constexpr static auto values {[]() {
+		constexpr auto values {get_values(typename EVC::Vs {})};
+		static_assert(std::is_sorted(values.begin(), values.end()), "Candidate values must be sorted");
+		std::array<E, valid_count> out;
+		std::copy_if(values.begin(), values.end(), out.begin(), [valid = valid_flags.begin()](auto) mutable {
+			return *valid++;
+		});
+		return out;
+	}()};
+	constexpr static auto names {get_valueNames(std::make_integer_sequence<int, valid_count> {})};
+
+	constexpr static bool
+	is_valid(E value) noexcept
+	{
+		return std::binary_search(values.begin(), values.end(), value);
+	}
+
+	constexpr static std::optional<E>
+	parse(std::string_view name) noexcept
+	{
+		return lookup(name, names, values);
+	}
+
+	constexpr static std::optional<std::string_view>
+	to_string(E value) noexcept
+	{
+		return lookup(value, values, names);
+	}
+};
-- 
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