From 705f1110587502a49dda51790fa14ac9843e135e Mon Sep 17 00:00:00 2001 From: Morph <39850852+Morph1984@users.noreply.github.com> Date: Wed, 4 Aug 2021 03:55:48 -0400 Subject: [PATCH] common: uuid: Add hex string to UUID constructor This allows for easily converting a hex string into a Common::UUID, which is backed by a 128 bit unsigned integer. --- src/common/uuid.cpp | 54 +++++++++++++++++++++++++++++++++++++++++++++ src/common/uuid.h | 19 ++++++++++++++++ 2 files changed, 73 insertions(+) diff --git a/src/common/uuid.cpp b/src/common/uuid.cpp index 18303a1e3..d7435a6e9 100644 --- a/src/common/uuid.cpp +++ b/src/common/uuid.cpp @@ -6,10 +6,64 @@ #include +#include "common/assert.h" #include "common/uuid.h" namespace Common { +namespace { + +bool IsHexDigit(char c) { + return (c >= '0' && c <= '9') || (c >= 'a' && c <= 'f') || (c >= 'A' && c <= 'F'); +} + +u8 HexCharToByte(char c) { + if (c >= '0' && c <= '9') { + return static_cast(c - '0'); + } + if (c >= 'a' && c <= 'f') { + return static_cast(c - 'a' + 10); + } + if (c >= 'A' && c <= 'F') { + return static_cast(c - 'A' + 10); + } + ASSERT_MSG(false, "{} is not a hexadecimal digit!", c); + return u8{0}; +} + +} // Anonymous namespace + +u128 HexStringToU128(std::string_view hex_string) { + const size_t length = hex_string.length(); + + // Detect "0x" prefix. + const bool has_0x_prefix = length > 2 && hex_string[0] == '0' && hex_string[1] == 'x'; + const size_t offset = has_0x_prefix ? 2 : 0; + + // Check length. + if (length > 32 + offset) { + ASSERT_MSG(false, "hex_string has more than 32 hexadecimal characters!"); + return INVALID_UUID; + } + + u64 lo = 0; + u64 hi = 0; + for (size_t i = 0; i < length - offset; ++i) { + const char c = hex_string[length - 1 - i]; + if (!IsHexDigit(c)) { + ASSERT_MSG(false, "{} is not a hexadecimal digit!", c); + return INVALID_UUID; + } + if (i < 16) { + lo |= u64{HexCharToByte(c)} << (i * 4); + } + if (i >= 16) { + hi |= u64{HexCharToByte(c)} << ((i - 16) * 4); + } + } + return u128{lo, hi}; +} + UUID UUID::Generate() { std::random_device device; std::mt19937 gen(device()); diff --git a/src/common/uuid.h b/src/common/uuid.h index 0ffa37e7c..aeb36939a 100644 --- a/src/common/uuid.h +++ b/src/common/uuid.h @@ -5,6 +5,7 @@ #pragma once #include +#include #include "common/common_types.h" @@ -12,12 +13,30 @@ namespace Common { constexpr u128 INVALID_UUID{{0, 0}}; +/** + * Converts a hex string to a 128-bit unsigned integer. + * + * The hex string can be formatted in lowercase or uppercase, with or without the "0x" prefix. + * + * This function will assert and return INVALID_UUID under the following conditions: + * - If the hex string is more than 32 characters long + * - If the hex string contains non-hexadecimal characters + * + * @param hex_string Hexadecimal string + * + * @returns A 128-bit unsigned integer if successfully converted, INVALID_UUID otherwise. + */ +[[nodiscard]] u128 HexStringToU128(std::string_view hex_string); + struct UUID { // UUIDs which are 0 are considered invalid! u128 uuid; UUID() = default; constexpr explicit UUID(const u128& id) : uuid{id} {} constexpr explicit UUID(const u64 lo, const u64 hi) : uuid{{lo, hi}} {} + explicit UUID(std::string_view hex_string) { + uuid = HexStringToU128(hex_string); + } [[nodiscard]] constexpr explicit operator bool() const { return uuid != INVALID_UUID;