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fix(string): revert errno in TryParseImpl and use std::from_chars instead of strtoxxx (#128)

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This commit is contained in:
kang jinci
2023-08-26 16:28:11 +08:00
committed by GitHub
parent a8ad093ed7
commit b4912f947c
2 changed files with 22 additions and 33 deletions
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flare/base/string.cc
+12 -27
View File
@@ -15,6 +15,7 @@
#include "flare/base/string.h"
#include <array>
#include <charconv>
#include <climits>
#include <cstdlib>
#include <optional>
@@ -55,6 +56,13 @@ std::optional<T> TryParseImpl(F fptr, const char* s,
if (FLARE_UNLIKELY(s[0] == 0)) {
return std::nullopt;
}
struct LastErrorStasher {
LastErrorStasher() : last_errno(errno) { errno = 0; }
~LastErrorStasher() { errno = last_errno; }
int last_errno;
} _;
char* end;
auto result = fptr(s, &end, args...);
if (end != s + strlen(s)) { // Return value `0` is also handled by this test.
@@ -241,9 +249,6 @@ bool IEquals(std::string_view first, std::string_view second) {
return true;
}
// TODO(luobogao): Once we have `from_chars` at hand, use it instead (so as to
// support `std::string_view` efficiently).
std::optional<bool> TryParseTraits<bool>::TryParse(
std::string_view s, bool recognizes_alphabet_symbol, bool ignore_case) {
if (auto num_opt = flare::TryParse<int>(s); num_opt) {
@@ -266,32 +271,12 @@ template <class T>
std::optional<T>
TryParseTraits<T, std::enable_if_t<std::is_integral_v<T>>>::TryParse(
std::string_view s, int base) {
// `strtoll` expects a terminating null, therefore we copy `s` into this
// temporary buffer before calling that method.
//
// Comparing to constructing a `std::string` here, this saves us a memory
// allocation.
char temp_buffer[129];
if (FLARE_UNLIKELY(s.size() > 128)) { // Out-of-range anyway.
T value;
auto [ptr, ec] = std::from_chars(s.begin(), s.end(), value, base);
if (ec != std::errc() || ptr != s.end()) {
return {};
}
memcpy(temp_buffer, s.data(), s.size());
temp_buffer[s.size()] = 0;
// Here we always use the largest type to hold the result, and check if the
// result is actually larger than what `T` can hold.
//
// It's not very efficient, though.
if constexpr (std::is_signed_v<T>) {
auto opt = TryParseImpl<std::int64_t>(&strtoll, temp_buffer,
{LLONG_MIN, LLONG_MAX}, base);
return TryNarrowCast<T>(opt);
} else {
auto opt =
TryParseImpl<std::uint64_t>(&strtoull, temp_buffer, {ULLONG_MAX}, base);
return TryNarrowCast<T>(opt);
}
return value;
}
template <class T>
flare/base/string_test.cc
+10 -6
View File
@@ -28,6 +28,7 @@ TEST(String, TryParseIntegral) {
ASSERT_FALSE(TryParse<int>(std::string(123456, 'a')));
ASSERT_FALSE(TryParse<int>(""));
ASSERT_FALSE(TryParse<int>("a"));
ASSERT_FALSE(TryParse<int>("1-2"));
ASSERT_FALSE(TryParse<std::int8_t>(std::to_string(INT8_MAX + 1LL)));
ASSERT_FALSE(TryParse<std::int8_t>(std::to_string(INT8_MIN - 1LL)));
ASSERT_FALSE(TryParse<std::uint8_t>(std::to_string(UINT8_MAX + 1LL)));
@@ -44,7 +45,9 @@ TEST(String, TryParseIntegral) {
ASSERT_FALSE(TryParse<std::int64_t>(std::to_string(INT64_MIN) + "0"));
ASSERT_FALSE(TryParse<std::uint64_t>(std::to_string(UINT64_MAX) + "0"));
ASSERT_FALSE(TryParse<std::uint64_t>("-1"));
ASSERT_TRUE(TryParse<int>("0"));
ASSERT_TRUE(TryParse<std::int64_t>(std::to_string(INT64_MAX)));
ASSERT_TRUE(TryParse<std::int8_t>("0"));
ASSERT_TRUE(TryParse<std::uint8_t>("0"));
ASSERT_TRUE(TryParse<std::int16_t>("0"));
@@ -79,12 +82,13 @@ TEST(String, TryParseFloatingPoint) {
ASSERT_FALSE(TryParse<long double>(""));
ASSERT_FALSE(TryParse<double>("a"));
ASSERT_FALSE(TryParse<long double>("a"));
ASSERT_FALSE(TryParse<float>(std::to_string(HUGE_VALF * 10)));
ASSERT_FALSE(TryParse<float>(std::to_string(-HUGE_VALF * 10)));
ASSERT_FALSE(TryParse<double>(std::to_string(HUGE_VAL * 10)));
ASSERT_FALSE(TryParse<double>(std::to_string(-HUGE_VAL * 10)));
ASSERT_FALSE(TryParse<long double>(std::to_string(HUGE_VALL * 10)));
ASSERT_FALSE(TryParse<long double>(std::to_string(-HUGE_VALL * 10)));
ASSERT_TRUE(TryParse<float>(std::to_string(HUGE_VALF)));
ASSERT_TRUE(TryParse<float>(std::to_string(-HUGE_VALF)));
ASSERT_TRUE(TryParse<double>(std::to_string(HUGE_VAL)));
ASSERT_TRUE(TryParse<double>(std::to_string(-HUGE_VAL)));
ASSERT_TRUE(TryParse<long double>(std::to_string(HUGE_VALL)));
ASSERT_TRUE(TryParse<long double>(std::to_string(-HUGE_VALL)));
for (int i = 0; i != 100000; ++i) {
auto x = 1.0 * Random() * Random();