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Changes imported from Abseil "staging" branch:

Browse source 
- 8320b38cd9f4f271fb6b278bd1e10d93f6ac3856 Use overloads for int32/int64/uint32/uint64 rather than i... by Jorg Brown <jorg@google.com>
  - f8b582b8deb3f78a3c6de2114b3ec4640f5427dd Internal change by Juemin Yang <jueminyang@google.com>
  - 240ff55ebf493ab1233ebe6976853a5fa2b3ec46 Remove the internal LowLevelAlloc's dependence on kLinker... by Greg Falcon <gfalcon@google.com>

GitOrigin-RevId: 8320b38cd9f4f271fb6b278bd1e10d93f6ac3856
Change-Id: If5004efa2b43856948390ab357b8e9403e4461b4
This commit is contained in:
Abseil Team 2017-12-14 12:36:12 -08:00 • committed by Titus Winters
parent 720c017e30
commit 6280bddf55
5 changed files with 233 additions and 181 deletions
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28
absl/strings/numbers.cc
View file

@ -135,16 +135,12 @@ bool SimpleAtob(absl::string_view str, bool* value) {
}
// ----------------------------------------------------------------------
// FastInt32ToBuffer()
// FastUInt32ToBuffer()
// FastInt64ToBuffer()
// FastUInt64ToBuffer()
// FastIntToBuffer() overloads
//
// Like the Fast*ToBuffer() functions above, these are intended for speed.
// Unlike the Fast*ToBuffer() functions, however, these functions write
// their output to the beginning of the buffer (hence the name, as the
// output is left-aligned). The caller is responsible for ensuring that
// the buffer has enough space to hold the output.
// their output to the beginning of the buffer. The caller is responsible
// for ensuring that the buffer has enough space to hold the output.
//
// Returns a pointer to the end of the std::string (i.e. the null character
// terminating the std::string).
@ -160,7 +156,7 @@ const char one_ASCII_final_digits[10][2] {
} // namespace
char* numbers_internal::FastUInt32ToBuffer(uint32_t i, char* buffer) {
char* numbers_internal::FastIntToBuffer(uint32_t i, char* buffer) {
uint32_t digits;
// The idea of this implementation is to trim the number of divides to as few
// as possible, and also reducing memory stores and branches, by going in
@ -230,7 +226,7 @@ char* numbers_internal::FastUInt32ToBuffer(uint32_t i, char* buffer) {
goto lt100_000_000;
}
char* numbers_internal::FastInt32ToBuffer(int32_t i, char* buffer) {
char* numbers_internal::FastIntToBuffer(int32_t i, char* buffer) {
uint32_t u = i;
if (i < 0) {
*buffer++ = '-';
@ -239,12 +235,12 @@ char* numbers_internal::FastInt32ToBuffer(int32_t i, char* buffer) {
// we write the equivalent expression "0 - u" instead.
u = 0 - u;
}
return numbers_internal::FastUInt32ToBuffer(u, buffer);
return numbers_internal::FastIntToBuffer(u, buffer);
}
char* numbers_internal::FastUInt64ToBuffer(uint64_t i, char* buffer) {
char* numbers_internal::FastIntToBuffer(uint64_t i, char* buffer) {
uint32_t u32 = static_cast<uint32_t>(i);
if (u32 == i) return numbers_internal::FastUInt32ToBuffer(u32, buffer);
if (u32 == i) return numbers_internal::FastIntToBuffer(u32, buffer);
// Here we know i has at least 10 decimal digits.
uint64_t top_1to11 = i / 1000000000;
@ -252,12 +248,12 @@ char* numbers_internal::FastUInt64ToBuffer(uint64_t i, char* buffer) {
uint32_t top_1to11_32 = static_cast<uint32_t>(top_1to11);
if (top_1to11_32 == top_1to11) {
buffer = numbers_internal::FastUInt32ToBuffer(top_1to11_32, buffer);
buffer = numbers_internal::FastIntToBuffer(top_1to11_32, buffer);
} else {
// top_1to11 has more than 32 bits too; print it in two steps.
uint32_t top_8to9 = static_cast<uint32_t>(top_1to11 / 100);
uint32_t mid_2 = static_cast<uint32_t>(top_1to11 - top_8to9 * 100);
buffer = numbers_internal::FastUInt32ToBuffer(top_8to9, buffer);
buffer = numbers_internal::FastIntToBuffer(top_8to9, buffer);
PutTwoDigits(mid_2, buffer);
buffer += 2;
}
@ -283,13 +279,13 @@ char* numbers_internal::FastUInt64ToBuffer(uint64_t i, char* buffer) {
return buffer + 1;
}
char* numbers_internal::FastInt64ToBuffer(int64_t i, char* buffer) {
char* numbers_internal::FastIntToBuffer(int64_t i, char* buffer) {
uint64_t u = i;
if (i < 0) {
*buffer++ = '-';
u = 0 - u;
}
return numbers_internal::FastUInt64ToBuffer(u, buffer);
return numbers_internal::FastIntToBuffer(u, buffer);
}
// Returns the number of leading 0 bits in a 64-bit value.

26
absl/strings/numbers.h
View file

@ -81,14 +81,6 @@ bool safe_strto64_base(absl::string_view text, int64_t* value, int base);
bool safe_strtou32_base(absl::string_view text, uint32_t* value, int base);
bool safe_strtou64_base(absl::string_view text, uint64_t* value, int base);
// These functions are intended for speed. All functions take an output buffer
// as an argument and return a pointer to the last byte they wrote, which is the
// terminating '\0'. At most `kFastToBufferSize` bytes are written.
char* FastInt32ToBuffer(int32_t i, char* buffer);
char* FastUInt32ToBuffer(uint32_t i, char* buffer);
char* FastInt64ToBuffer(int64_t i, char* buffer);
char* FastUInt64ToBuffer(uint64_t i, char* buffer);
static const int kFastToBufferSize = 32;
static const int kSixDigitsToBufferSize = 16;
@ -100,6 +92,16 @@ static const int kSixDigitsToBufferSize = 16;
// Required buffer size is `kSixDigitsToBufferSize`.
size_t SixDigitsToBuffer(double d, char* buffer);
// These functions are intended for speed. All functions take an output buffer
// as an argument and return a pointer to the last byte they wrote, which is the
// terminating '\0'. At most `kFastToBufferSize` bytes are written.
char* FastIntToBuffer(int32_t, char*);
char* FastIntToBuffer(uint32_t, char*);
char* FastIntToBuffer(int64_t, char*);
char* FastIntToBuffer(uint64_t, char*);
// For enums and integer types that are not an exact match for the types above,
// use templates to call the appropriate one of the four overloads above.
template <typename int_type>
char* FastIntToBuffer(int_type i, char* buffer) {
static_assert(sizeof(i) <= 64 / 8,
@ -109,15 +111,15 @@ char* FastIntToBuffer(int_type i, char* buffer) {
// If one day something like std::is_signed<enum E> works, switch to it.
if (static_cast<int_type>(1) - 2 < 0) { // Signed
if (sizeof(i) > 32 / 8) { // 33-bit to 64-bit
return numbers_internal::FastInt64ToBuffer(i, buffer);
return FastIntToBuffer(static_cast<int64_t>(i), buffer);
} else { // 32-bit or less
return numbers_internal::FastInt32ToBuffer(i, buffer);
return FastIntToBuffer(static_cast<int32_t>(i), buffer);
}
} else { // Unsigned
if (sizeof(i) > 32 / 8) { // 33-bit to 64-bit
return numbers_internal::FastUInt64ToBuffer(i, buffer);
return FastIntToBuffer(static_cast<uint64_t>(i), buffer);
} else { // 32-bit or less
return numbers_internal::FastUInt32ToBuffer(i, buffer);
return FastIntToBuffer(static_cast<uint32_t>(i), buffer);
}
}
}

74
absl/strings/numbers_test.cc
View file

@ -110,13 +110,38 @@ TEST(ToString, PerfectDtoa) {
}
}
template <typename integer>
struct MyInteger {
integer i;
explicit constexpr MyInteger(integer i) : i(i) {}
constexpr operator integer() const { return i; }
constexpr MyInteger operator+(MyInteger other) const { return i + other.i; }
constexpr MyInteger operator-(MyInteger other) const { return i - other.i; }
constexpr MyInteger operator*(MyInteger other) const { return i * other.i; }
constexpr MyInteger operator/(MyInteger other) const { return i / other.i; }
constexpr bool operator<(MyInteger other) const { return i < other.i; }
constexpr bool operator<=(MyInteger other) const { return i <= other.i; }
constexpr bool operator==(MyInteger other) const { return i == other.i; }
constexpr bool operator>=(MyInteger other) const { return i >= other.i; }
constexpr bool operator>(MyInteger other) const { return i > other.i; }
constexpr bool operator!=(MyInteger other) const { return i != other.i; }
integer as_integer() const { return i; }
};
typedef MyInteger<int64_t> MyInt64;
typedef MyInteger<uint64_t> MyUInt64;
void CheckInt32(int32_t x) {
char buffer[absl::numbers_internal::kFastToBufferSize];
char* actual = absl::numbers_internal::FastInt32ToBuffer(x, buffer);
char* actual = absl::numbers_internal::FastIntToBuffer(x, buffer);
std::string expected = std::to_string(x);
ASSERT_TRUE(expected == std::string(buffer, actual))
<< "Expected \"" << expected << "\", Actual \"" << actual << "\", Input "
<< x;
EXPECT_EQ(expected, std::string(buffer, actual)) << " Input " << x;
char* generic_actual = absl::numbers_internal::FastIntToBuffer(x, buffer);
EXPECT_EQ(expected, std::string(buffer, generic_actual)) << " Input " << x;
}
void CheckInt64(int64_t x) {
@ -124,40 +149,47 @@ void CheckInt64(int64_t x) {
buffer[0] = '*';
buffer[23] = '*';
buffer[24] = '*';
char* actual = absl::numbers_internal::FastInt64ToBuffer(x, &buffer[1]);
char* actual = absl::numbers_internal::FastIntToBuffer(x, &buffer[1]);
std::string expected = std::to_string(x);
ASSERT_TRUE(expected == std::string(&buffer[1], actual))
<< "Expected \"" << expected << "\", Actual \"" << actual << "\", Input "
<< x;
ASSERT_EQ(buffer[0], '*');
ASSERT_EQ(buffer[23], '*');
ASSERT_EQ(buffer[24], '*');
EXPECT_EQ(expected, std::string(&buffer[1], actual)) << " Input " << x;
EXPECT_EQ(buffer[0], '*');
EXPECT_EQ(buffer[23], '*');
EXPECT_EQ(buffer[24], '*');
char* my_actual =
absl::numbers_internal::FastIntToBuffer(MyInt64(x), &buffer[1]);
EXPECT_EQ(expected, std::string(&buffer[1], my_actual)) << " Input " << x;
}
void CheckUInt32(uint32_t x) {
char buffer[absl::numbers_internal::kFastToBufferSize];
char* actual = absl::numbers_internal::FastUInt32ToBuffer(x, buffer);
char* actual = absl::numbers_internal::FastIntToBuffer(x, buffer);
std::string expected = std::to_string(x);
ASSERT_TRUE(expected == std::string(buffer, actual))
<< "Expected \"" << expected << "\", Actual \"" << actual << "\", Input "
<< x;
EXPECT_EQ(expected, std::string(buffer, actual)) << " Input " << x;
char* generic_actual = absl::numbers_internal::FastIntToBuffer(x, buffer);
EXPECT_EQ(expected, std::string(buffer, generic_actual)) << " Input " << x;
}
void CheckUInt64(uint64_t x) {
char buffer[absl::numbers_internal::kFastToBufferSize + 1];
char* actual = absl::numbers_internal::FastUInt64ToBuffer(x, &buffer[1]);
char* actual = absl::numbers_internal::FastIntToBuffer(x, &buffer[1]);
std::string expected = std::to_string(x);
ASSERT_TRUE(expected == std::string(&buffer[1], actual))
<< "Expected \"" << expected << "\", Actual \"" << actual << "\", Input "
<< x;
EXPECT_EQ(expected, std::string(&buffer[1], actual)) << " Input " << x;
char* generic_actual = absl::numbers_internal::FastIntToBuffer(x, &buffer[1]);
EXPECT_EQ(expected, std::string(&buffer[1], generic_actual)) << " Input " << x;
char* my_actual =
absl::numbers_internal::FastIntToBuffer(MyUInt64(x), &buffer[1]);
EXPECT_EQ(expected, std::string(&buffer[1], my_actual)) << " Input " << x;
}
void CheckHex64(uint64_t v) {
char expected[16 + 1];
std::string actual = absl::StrCat(absl::Hex(v, absl::kZeroPad16));
snprintf(expected, sizeof(expected), "%016" PRIx64, static_cast<uint64_t>(v));
ASSERT_TRUE(expected == actual)
<< "Expected \"" << expected << "\", Actual \"" << actual << "\"";
EXPECT_EQ(expected, actual) << " Input " << v;
}
TEST(Numbers, TestFastPrints) {