Merge pull request #43 from OpenVicProject/add/vdf-search

1 files changed, 56 insertions, 0 deletions

diff --git a/src/openvic-simulation/utility/ConstexprIntToStr.hpp b/src/openvic-simulation/utility/ConstexprIntToStr.hpp
new file mode 100644
index 0000000..e383365
--- /dev/null
+++ b/src/openvic-simulation/utility/ConstexprIntToStr.hpp
@@ -0,0 +1,56 @@
+#pragma once
+
+#include <array>
+#include <cstddef>
+#include <string_view>
+#include <utility>
+
+namespace OpenVic::ConstexprIntToStr {
+	template<class T, T... values1, T... values2>
+	constexpr decltype(auto) append_sequence(std::integer_sequence<T, values1...>, std::integer_sequence<T, values2...>) {
+		return std::integer_sequence<T, values1..., values2...> {};
+	}
+
+	template<class sequence_t>
+	struct string_sequence_to_view;
+
+	template<char... chars>
+	struct string_sequence_to_view<std::integer_sequence<char, chars...>> {
+		static constexpr decltype(auto) get() {
+			return std::string_view { c_str };
+		}
+
+		static constexpr const char c_str[] { chars..., char {} };
+	};
+
+	template<std::size_t value>
+	constexpr decltype(auto) integer_to_string_sequence() {
+		constexpr auto digits = []() {
+			return "0123456789abcdefghijklmnopqrstuvwxyz";
+		};
+
+		constexpr std::size_t remainder = value % 10;
+		constexpr std::size_t next_value = value / 10;
+
+		if constexpr (next_value != 0) {
+			return append_sequence(integer_to_string_sequence<next_value>(), std::integer_sequence<char, digits()[remainder]> {});
+		} else {
+			return std::integer_sequence<char, digits()[remainder]> {};
+		}
+	}
+	template<std::size_t i>
+	constexpr std::string_view make_string() {
+		return string_sequence_to_view<decltype(integer_to_string_sequence<i>())> {}.c_str;
+	}
+
+	template<std::size_t... ManyIntegers>
+	constexpr auto generate_itosv_array(std::integer_sequence<std::size_t, ManyIntegers...>) {
+		return std::array<std::string_view, sizeof...(ManyIntegers)> { make_string<ManyIntegers>()... };
+	}
+
+	// Make array of N string views, countings up from 0 to N - 1
+	template<std::size_t N>
+	constexpr auto make_itosv_array() {
+		return generate_itosv_array(std::make_integer_sequence<std::size_t, N>());
+	}
+}
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