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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.
This commit is contained in:
Morph 2021-08-04 03:55:48 -04:00
parent 2868d4ba84
commit 705f111058
2 changed files with 73 additions and 0 deletions

View file

@ -6,10 +6,64 @@
#include <fmt/format.h>
#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<u8>(c - '0');
}
if (c >= 'a' && c <= 'f') {
return static_cast<u8>(c - 'a' + 10);
}
if (c >= 'A' && c <= 'F') {
return static_cast<u8>(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());

View file

@ -5,6 +5,7 @@
#pragma once
#include <string>
#include <string_view>
#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;