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[wpiutil] StringExtras: Add substr() (#3742)

Browse Source 
Unlike std::string and std::string_view, this substr() allows a start
greater than the length of the string, in which case an empty string
is returned.  This matches llvm::StringRef behavior.
This commit is contained in:
Peter Johnson
2021-11-27 21:31:40 -08:00
committed by GitHub
parent 6f51cb3b98
commit ae208d2b17
18 changed files with 118 additions and 77 deletions
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4
cameraserver/src/main/native/cpp/cameraserver/CameraServer.cpp
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@@ -450,9 +450,9 @@ Instance::Instance() {
entry.SetString(VideoModeToString(sourceIt->second.GetVideoMode()));
return;
} else if (wpi::starts_with(relativeKey, "Property/")) {
propName = relativeKey.substr(9);
propName = wpi::substr(relativeKey, 9);
} else if (wpi::starts_with(relativeKey, "RawProperty/")) {
propName = relativeKey.substr(12);
propName = wpi::substr(relativeKey, 12);
} else {
return; // ignore
}

2
cscore/src/main/native/cpp/HttpCameraImpl.cpp
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@@ -208,7 +208,7 @@ wpi::HttpConnection* HttpCameraImpl::DeviceStreamConnect(
if (wpi::trim(key) == "boundary") {
value = wpi::trim(wpi::trim(value), '"'); // value may be quoted
if (wpi::starts_with(value, "--")) {
value = value.substr(2);
value = wpi::substr(value, 2);
}
boundary.append(value.begin(), value.end());
}

9
cscore/src/main/native/cpp/JpegUtil.cpp
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@@ -4,6 +4,7 @@
#include "JpegUtil.h"
#include <wpi/StringExtras.h>
#include <wpi/raw_istream.h>
namespace cs {
@@ -64,7 +65,7 @@ bool GetJpegSize(std::string_view data, int* width, int* height) {
return false;
}
data = data.substr(2); // Get to the first block
data = wpi::substr(data, 2); // Get to the first block
for (;;) {
if (data.size() < 4) {
return false; // EOF
@@ -89,7 +90,7 @@ bool GetJpegSize(std::string_view data, int* width, int* height) {
return true;
}
// Go to the next block
data = data.substr(bytes[2] * 256 + bytes[3] + 2);
data = wpi::substr(data, bytes[2] * 256 + bytes[3] + 2);
}
}
@@ -102,7 +103,7 @@ bool JpegNeedsDHT(const char* data, size_t* size, size_t* locSOF) {
*locSOF = *size;
// Search until SOS for DHT tag
sdata = sdata.substr(2); // Get to the first block
sdata = wpi::substr(sdata, 2); // Get to the first block
for (;;) {
if (sdata.size() < 4) {
return false; // EOF
@@ -121,7 +122,7 @@ bool JpegNeedsDHT(const char* data, size_t* size, size_t* locSOF) {
*locSOF = sdata.data() - data; // SOF
}
// Go to the next block
sdata = sdata.substr(bytes[2] * 256 + bytes[3] + 2);
sdata = wpi::substr(sdata, bytes[2] * 256 + bytes[3] + 2);
}
// Only add DHT if we also found SOF (insertion point)

10
cscore/src/main/native/cpp/MjpegServerImpl.cpp
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@@ -797,14 +797,14 @@ void MjpegServerImpl::ConnThread::ProcessRequest() {
// compatibility, others are for Axis camera compatibility.
if ((pos = req.find("POST /stream")) != std::string_view::npos) {
kind = kStream;
parameters = req.substr(req.find('?', pos + 12)).substr(1);
parameters = wpi::substr(wpi::substr(req, req.find('?', pos + 12)), 1);
} else if ((pos = req.find("GET /?action=stream")) !=
std::string_view::npos) {
kind = kStream;
parameters = req.substr(req.find('&', pos + 19)).substr(1);
parameters = wpi::substr(wpi::substr(req, req.find('&', pos + 19)), 1);
} else if ((pos = req.find("GET /stream.mjpg")) != std::string_view::npos) {
kind = kStream;
parameters = req.substr(req.find('?', pos + 16)).substr(1);
parameters = wpi::substr(wpi::substr(req, req.find('?', pos + 16)), 1);
} else if (req.find("GET /settings") != std::string_view::npos &&
req.find(".json") != std::string_view::npos) {
kind = kGetSettings;
@@ -820,7 +820,7 @@ void MjpegServerImpl::ConnThread::ProcessRequest() {
} else if ((pos = req.find("GET /?action=command")) !=
std::string_view::npos) {
kind = kCommand;
parameters = req.substr(req.find('&', pos + 20)).substr(1);
parameters = wpi::substr(wpi::substr(req, req.find('&', pos + 20)), 1);
} else if (req.find("GET / ") != std::string_view::npos || req == "GET /\n") {
kind = kRootPage;
} else {
@@ -833,7 +833,7 @@ void MjpegServerImpl::ConnThread::ProcessRequest() {
pos = parameters.find_first_not_of(
"abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ_"
"-=&1234567890%./");
parameters = parameters.substr(0, pos);
parameters = wpi::substr(parameters, 0, pos);
SDEBUG("command parameters: \"{}\"", parameters);
// Read the rest of the HTTP request.

18
cscore/src/main/native/linux/UsbCameraImpl.cpp
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@@ -107,7 +107,7 @@ static __u32 FromPixelFormat(VideoMode::PixelFormat pixelFormat) {
static bool IsPercentageProperty(std::string_view name) {
if (wpi::starts_with(name, "raw_")) {
name = name.substr(4);
name = wpi::substr(name, 4);
}
return name == "brightness" || name == "contrast" || name == "saturation" ||
name == "hue" || name == "sharpness" || name == "gain" ||
@@ -181,13 +181,13 @@ static bool GetVendorProduct(int dev, int* vendor, int* product) {
}
std::string_view readStr{readBuf};
if (auto v = wpi::parse_integer<int>(
readStr.substr(readStr.find('v')).substr(1, 4), 16)) {
wpi::substr(wpi::substr(readStr, readStr.find('v')), 1, 4), 16)) {
*vendor = v.value();
} else {
return false;
}
if (auto v = wpi::parse_integer<int>(
readStr.substr(readStr.find('p')).substr(1, 4), 16)) {
wpi::substr(wpi::substr(readStr, readStr.find('p')), 1, 4), 16)) {
*product = v.value();
} else {
return false;
@@ -236,8 +236,8 @@ static bool GetDescriptionIoctl(const char* cpath, std::string* desc) {
std::optional<int> vendor;
std::optional<int> product;
if (wpi::starts_with(card, "UVC Camera (") &&
(vendor = wpi::parse_integer<int>(card.substr(12, 4), 16)) &&
(product = wpi::parse_integer<int>(card.substr(17, 4), 16))) {
(vendor = wpi::parse_integer<int>(wpi::substr(card, 12, 4), 16)) &&
(product = wpi::parse_integer<int>(wpi::substr(card, 17, 4), 16))) {
std::string card2 = GetUsbNameFromId(vendor.value(), product.value());
if (!card2.empty()) {
*desc = std::move(card2);
@@ -283,7 +283,7 @@ static int GetDeviceNum(const char* cpath) {
if (!wpi::starts_with(fn, "video")) {
return -1;
}
if (auto dev = wpi::parse_integer<int>(fn.substr(5), 10)) {
if (auto dev = wpi::parse_integer<int>(wpi::substr(fn, 5), 10)) {
return dev.value();
}
return -1;
@@ -1635,7 +1635,8 @@ std::vector<UsbCameraInfo> EnumerateUsbCameras(CS_Status* status) {
}
unsigned int dev = 0;
if (auto v = wpi::parse_integer<unsigned int>(fname.substr(5), 10)) {
if (auto v =
wpi::parse_integer<unsigned int>(wpi::substr(fname, 5), 10)) {
dev = v.value();
} else {
continue;
@@ -1686,7 +1687,8 @@ std::vector<UsbCameraInfo> EnumerateUsbCameras(CS_Status* status) {
std::string fname = fs::path{target}.filename();
std::optional<unsigned int> dev;
if (wpi::starts_with(fname, "video") &&
(dev = wpi::parse_integer<unsigned int>(fname.substr(5), 10)) &&
(dev = wpi::parse_integer<unsigned int>(wpi::substr(fname, 5),
10)) &&
dev.value() < retval.size()) {
retval[dev.value()].otherPaths.emplace_back(path.str());
}

3
cscore/src/main/native/linux/UsbCameraProperty.cpp
View File

@@ -6,6 +6,7 @@
#include <fmt/format.h>
#include <wpi/SmallString.h>
#include <wpi/StringExtras.h>
#include "UsbUtil.h"
@@ -93,7 +94,7 @@ static int GetStringCtrlIoctl(int fd, int id, int maximum, std::string* value) {
static int SetStringCtrlIoctl(int fd, int id, int maximum,
std::string_view value) {
wpi::SmallString<64> str{value.substr(0, maximum)};
wpi::SmallString<64> str{wpi::substr(value, 0, maximum)};
struct v4l2_ext_control ctrl;
struct v4l2_ext_controls ctrls;

6
cscore/src/main/native/linux/UsbUtil.cpp
View File

@@ -49,7 +49,7 @@ static std::string GetUsbNameFromFile(int vendor, int product) {
// look for vendor at start of line
if (wpi::starts_with(line, vendorStr)) {
foundVendor = true;
buf += wpi::trim(line.substr(5));
buf += wpi::trim(wpi::substr(line, 5));
buf += ' ';
continue;
}
@@ -62,8 +62,8 @@ static std::string GetUsbNameFromFile(int vendor, int product) {
}
// look for product
if (wpi::starts_with(line.substr(1), productStr)) {
buf += wpi::trim(line.substr(6));
if (wpi::starts_with(wpi::substr(line, 1), productStr)) {
buf += wpi::trim(wpi::substr(line, 6));
return buf;
}
}

2
cscore/src/main/native/windows/UsbCameraImpl.cpp
View File

@@ -269,7 +269,7 @@ void UsbCameraImpl::DeviceDisconnect() {
static bool IsPercentageProperty(std::string_view name) {
if (wpi::starts_with(name, "raw_"))
name = name.substr(4);
name = wpi::substr(name, 4);
return name == "Brightness" || name == "Contrast" || name == "Saturation" ||
name == "Hue" || name == "Sharpness" || name == "Gain" ||
name == "Exposure";

2
ntcore/src/main/native/cpp/Storage_load.cpp
View File

@@ -87,7 +87,7 @@ static std::pair<std::string_view, std::string_view> ReadStringToken(
break;
}
}
return {wpi::slice(source, 0, pos), source.substr(pos)};
return {wpi::slice(source, 0, pos), wpi::substr(source, pos)};
}
static int fromxdigit(char ch) {

18
ntcore/src/main/native/cpp/networktables/NetworkTable.cpp
View File

@@ -22,7 +22,7 @@ std::string_view NetworkTable::BasenameKey(std::string_view key) {
if (slash == std::string_view::npos) {
return key;
}
return key.substr(slash + 1);
return wpi::substr(key, slash + 1);
}
std::string NetworkTable::NormalizeKey(std::string_view key,
@@ -105,7 +105,7 @@ NT_EntryListener NetworkTable::AddEntryListener(TableEntryListener listener,
return nt::AddEntryListener(
m_inst, fmt::format("{}/", m_path),
[=](const EntryNotification& event) {
auto relative_key = std::string_view{event.name}.substr(prefix_len);
auto relative_key = wpi::substr(event.name, prefix_len);
if (relative_key.find(PATH_SEPARATOR_CHAR) != std::string_view::npos) {
return;
}
@@ -124,8 +124,8 @@ NT_EntryListener NetworkTable::AddEntryListener(std::string_view key,
entry.GetHandle(),
[=](const EntryNotification& event) {
listener(const_cast<NetworkTable*>(this),
std::string_view{event.name}.substr(prefix_len), entry,
event.value, event.flags);
wpi::substr(event.name, prefix_len), entry, event.value,
event.flags);
},
flags);
}
@@ -149,12 +149,12 @@ NT_EntryListener NetworkTable::AddSubTableListener(TableListener listener,
NT_EntryListener id = nt::AddEntryListener(
m_inst, fmt::format("{}/", m_path),
[=](const EntryNotification& event) {
auto relative_key = std::string_view{event.name}.substr(prefix_len);
auto relative_key = wpi::substr(event.name, prefix_len);
auto end_sub_table = relative_key.find(PATH_SEPARATOR_CHAR);
if (end_sub_table == std::string_view::npos) {
return;
}
auto sub_table_key = relative_key.substr(0, end_sub_table);
auto sub_table_key = wpi::substr(relative_key, 0, end_sub_table);
if (notified_tables->find(sub_table_key) == notified_tables->end()) {
return;
}
@@ -196,7 +196,7 @@ std::vector<std::string> NetworkTable::GetKeys(int types) const {
auto infos = GetEntryInfo(m_inst, fmt::format("{}/", m_path), types);
std::scoped_lock lock(m_mutex);
for (auto& info : infos) {
auto relative_key = std::string_view{info.name}.substr(prefix_len);
auto relative_key = wpi::substr(info.name, prefix_len);
if (relative_key.find(PATH_SEPARATOR_CHAR) != std::string_view::npos) {
continue;
}
@@ -210,12 +210,12 @@ std::vector<std::string> NetworkTable::GetSubTables() const {
std::vector<std::string> keys;
size_t prefix_len = m_path.size() + 1;
for (auto& entry : GetEntryInfo(m_inst, fmt::format("{}/", m_path), 0)) {
auto relative_key = std::string_view{entry.name}.substr(prefix_len);
auto relative_key = wpi::substr(entry.name, prefix_len);
size_t end_subtable = relative_key.find(PATH_SEPARATOR_CHAR);
if (end_subtable == std::string_view::npos) {
continue;
}
keys.emplace_back(relative_key.substr(0, end_subtable));
keys.emplace_back(wpi::substr(relative_key, 0, end_subtable));
}
return keys;
}

15
ntcore/src/test/native/cpp/WireEncoderTest.cpp
View File

@@ -7,6 +7,8 @@
#include <string>
#include <string_view>
#include <wpi/StringExtras.h>
#include "TestPrinters.h"
#include "WireEncoder.h"
#include "gtest/gtest.h"
@@ -84,7 +86,7 @@ TEST_F(WireEncoderTest, Write8) {
e.Write8(0x101u); // should be truncated
e.Write8(0u);
ASSERT_EQ(3u, e.size() - off);
ASSERT_EQ("\x05\x01\x00"sv, std::string_view(e.data(), e.size()).substr(off));
ASSERT_EQ("\x05\x01\x00"sv, wpi::substr({e.data(), e.size()}, off));
}
TEST_F(WireEncoderTest, Write16) {
@@ -99,7 +101,7 @@ TEST_F(WireEncoderTest, Write16) {
e.Write16(0u);
ASSERT_EQ(8u, e.size() - off);
ASSERT_EQ("\x00\x05\x00\x01\x45\x67\x00\x00"sv,
std::string_view(e.data(), e.size()).substr(off));
wpi::substr({e.data(), e.size()}, off));
}
TEST_F(WireEncoderTest, Write32) {
@@ -117,7 +119,7 @@ TEST_F(WireEncoderTest, Write32) {
ASSERT_EQ(std::string_view("\x00\x00\x00\x05\x00\x00\x00\x01\x00\x00\xab\xcd"
"\x12\x34\x56\x78\x00\x00\x00\x00",
20),
std::string_view(e.data(), e.size()).substr(off));
wpi::substr({e.data(), e.size()}, off));
}
TEST_F(WireEncoderTest, WriteDouble) {
@@ -140,7 +142,7 @@ TEST_F(WireEncoderTest, WriteDouble) {
"\x00\x10\x00\x00\x00\x00\x00\x00"
"\x7f\xef\xff\xff\xff\xff\xff\xff",
40),
std::string_view(e.data(), e.size()).substr(off));
wpi::substr({e.data(), e.size()}, off));
}
TEST_F(WireEncoderTest, WriteUleb128) {
@@ -153,8 +155,7 @@ TEST_F(WireEncoderTest, WriteUleb128) {
e.WriteUleb128(0x7ful);
e.WriteUleb128(0x80ul);
ASSERT_EQ(4u, e.size() - off);
ASSERT_EQ("\x00\x7f\x80\x01"sv,
std::string_view(e.data(), e.size()).substr(off));
ASSERT_EQ("\x00\x7f\x80\x01"sv, wpi::substr({e.data(), e.size()}, off));
}
TEST_F(WireEncoderTest, WriteType) {
@@ -174,7 +175,7 @@ TEST_F(WireEncoderTest, WriteType) {
ASSERT_EQ(nullptr, e.error());
ASSERT_EQ(8u, e.size() - off);
ASSERT_EQ("\x00\x01\x02\x03\x10\x11\x12\x20"sv,
std::string_view(e.data(), e.size()).substr(off));
wpi::substr({e.data(), e.size()}, off));
}
TEST_F(WireEncoderTest, WriteTypeError) {

2
wpiutil/src/main/native/cpp/HttpUtil.cpp
View File

@@ -232,7 +232,7 @@ bool FindMultipartBoundary(raw_istream& is, std::string_view boundary,
// Did we find the boundary?
if (searchBuf[0] == '-' && searchBuf[1] == '-' &&
searchBuf.substr(2) == boundary) {
wpi::substr(searchBuf, 2) == boundary) {
return true;
}

5
wpiutil/src/main/native/cpp/MimeTypes.cpp
View File

@@ -4,6 +4,7 @@
#include "wpi/MimeTypes.h"
#include "wpi/StringExtras.h"
#include "wpi/StringMap.h"
namespace wpi {
@@ -53,11 +54,11 @@ std::string_view MimeTypeFromPath(std::string_view path) {
auto pos = path.find_last_of("/");
if (pos != std::string_view::npos) {
path = path.substr(pos + 1);
path = wpi::substr(path, pos + 1);
}
auto dot_pos = path.find_last_of(".");
if (dot_pos > 0 && dot_pos != std::string_view::npos) {
auto type = mimeTypes.find(path.substr(dot_pos + 1));
auto type = mimeTypes.find(wpi::substr(path, dot_pos + 1));
if (type != mimeTypes.end()) {
return type->getValue();
}

4
wpiutil/src/main/native/cpp/StringExtras.cpp
View File

@@ -65,7 +65,7 @@ std::string_view::size_type wpi::find_lower(
std::string_view::size_type wpi::find_lower(
std::string_view str, std::string_view other,
std::string_view::size_type from) noexcept {
auto s = str.substr(from);
auto s = substr(str, from);
while (s.size() >= other.size()) {
if (starts_with_lower(s, other)) {
return from;
@@ -98,7 +98,7 @@ std::string_view::size_type wpi::rfind_lower(std::string_view str,
}
for (size_t i = str.size() - n + 1, e = 0; i != e;) {
--i;
if (equals_lower(str.substr(i, n), other)) {
if (equals_lower(substr(str, i, n), other)) {
return i;
}
}

15
wpiutil/src/main/native/include/wpi/SmallString.h
View File

@@ -181,21 +181,6 @@ public:
}
/// @}
/// @name Substring Operations
/// @{
/// Return a reference to the substring from [Start, Start + N).
///
/// \param Start The index of the starting character in the substring; if
/// the index is npos or greater than the length of the string then the
/// empty substring will be returned.
///
/// \param N The number of characters to included in the substring. If \p N
/// exceeds the number of characters remaining in the string, the string
/// suffix (starting with \p Start) will be returned.
std::string_view substr(size_t Start, size_t N = std::string_view::npos) const {
return str().substr(Start, N);
}
// Extra methods.

49
wpiutil/src/main/native/include/wpi/StringExtras.h
View File

@@ -207,12 +207,31 @@ inline std::string_view::size_type rfind_lower(std::string_view str,
return rfind_lower(str, std::string_view{other});
}
/**
* Returns the substring of @p str from [start, start + n).
*
* @param start The index of the starting character in the substring; if
* the index is npos or greater than the length of the string then the
* empty substring will be returned.
*
* @param n The number of characters to included in the substring. If n
* exceeds the number of characters remaining in the string, the string
* suffix (starting with @p start) will be returned.
*/
constexpr std::string_view substr(
std::string_view str, std::string_view::size_type start,
std::string_view::size_type n = std::string_view::npos) noexcept {
auto length = str.size();
start = (std::min)(start, length);
return {str.data() + start, (std::min)(n, length - start)};
}
/**
* Checks if @p str starts with the given @p prefix.
*/
constexpr bool starts_with(std::string_view str,
std::string_view prefix) noexcept {
return str.substr(0, prefix.size()) == prefix;
return substr(str, 0, prefix.size()) == prefix;
}
/**
@@ -354,6 +373,34 @@ constexpr std::string_view drop_back(
return str;
}
/**
* Returns a view equal to @p str but with only the first @p n
* elements remaining. If @p n is greater than the length of the
* string, the entire string is returned.
*/
constexpr std::string_view take_front(
std::string_view str, std::string_view::size_type n = 1) noexcept {
auto length = str.size();
if (n >= length) {
return str;
}
return drop_back(str, length - n);
}
/**
* Returns a view equal to @p str but with only the last @p n
* elements remaining. If @p n is greater than the length of the
* string, the entire string is returned.
*/
constexpr std::string_view take_back(
std::string_view str, std::string_view::size_type n = 1) noexcept {
auto length = str.size();
if (n >= length) {
return str;
}
return drop_front(str, length - n);
}
/**
* Returns a reference to the substring of @p str from [start, end).
*

25
wpiutil/src/main/native/include/wpi/UrlParser.h
View File

@@ -7,6 +7,7 @@
#include <string_view>
#include "wpi/StringExtras.h"
#include "wpi/http_parser.h"
namespace wpi {
@@ -52,35 +53,35 @@ class UrlParser {
}
std::string_view GetSchema() const {
return m_data.substr(m_url.field_data[UF_SCHEMA].off,
m_url.field_data[UF_SCHEMA].len);
return wpi::substr(m_data, m_url.field_data[UF_SCHEMA].off,
m_url.field_data[UF_SCHEMA].len);
}
std::string_view GetHost() const {
return m_data.substr(m_url.field_data[UF_HOST].off,
m_url.field_data[UF_HOST].len);
return wpi::substr(m_data, m_url.field_data[UF_HOST].off,
m_url.field_data[UF_HOST].len);
}
unsigned int GetPort() const { return m_url.port; }
std::string_view GetPath() const {
return m_data.substr(m_url.field_data[UF_PATH].off,
m_url.field_data[UF_PATH].len);
return wpi::substr(m_data, m_url.field_data[UF_PATH].off,
m_url.field_data[UF_PATH].len);
}
std::string_view GetQuery() const {
return m_data.substr(m_url.field_data[UF_QUERY].off,
m_url.field_data[UF_QUERY].len);
return wpi::substr(m_data, m_url.field_data[UF_QUERY].off,
m_url.field_data[UF_QUERY].len);
}
std::string_view GetFragment() const {
return m_data.substr(m_url.field_data[UF_FRAGMENT].off,
m_url.field_data[UF_FRAGMENT].len);
return wpi::substr(m_data, m_url.field_data[UF_FRAGMENT].off,
m_url.field_data[UF_FRAGMENT].len);
}
std::string_view GetUserInfo() const {
return m_data.substr(m_url.field_data[UF_USERINFO].off,
m_url.field_data[UF_USERINFO].len);
return wpi::substr(m_data, m_url.field_data[UF_USERINFO].off,
m_url.field_data[UF_USERINFO].len);
}
private:

6
wpiutil/src/main/native/linux/MulticastServiceResolver.cpp
View File

@@ -6,6 +6,7 @@
#include "AvahiClient.h"
#include "wpi/SmallString.h"
#include "wpi/StringExtras.h"
#include "wpi/mutex.h"
using namespace wpi;
@@ -61,8 +62,9 @@ static void ResolveCallback(AvahiServiceResolver* r, AvahiIfIndex interface,
// Todo make this just do key
continue;
}
std::string_view key = value.substr(0, splitIndex);
value = value.substr(splitIndex + 1, value.size() - splitIndex - 1);
std::string_view key = wpi::substr(value, 0, splitIndex);
value =
wpi::substr(value, splitIndex + 1, value.size() - splitIndex - 1);
data.txt.emplace_back(std::pair<std::string, std::string>{key, value});
}
wpi::SmallString<256> outputHostName;