tvl-depot/absl/strings/internal/str_format/arg.cc
Abseil Team d85783fd0b Export of internal Abseil changes
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f34cd235a12ad0ee1fea3a1ee5a427272dc2b285 by Abseil Team <absl-team@google.com>:

Migrates uses of deprecated map types to recommended types.

PiperOrigin-RevId: 309945156

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e3410a47ad32c0775b6911610bc47b22938decad by Matthew Brown <matthewbr@google.com>:

Internal Change

PiperOrigin-RevId: 309856021

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a58cfa25e0bb59e7fa9647ac1aae65eaccff0086 by Greg Falcon <gfalcon@google.com>:

Internal change.

PiperOrigin-RevId: 309804612

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cdc5ec310035fbe25f496bda283fe655d94d7769 by Mark Barolak <mbar@google.com>:

Standardize the header comments for friend functions in cord.h

PiperOrigin-RevId: 309779073

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fe61602701be795e54477b0fdbf5ffc1df12a6b7 by Samuel Benzaquen <sbenza@google.com>:

Implement %f natively for any input.
It evaluates the input at runtime and allocates stack space accordingly.

This removes a potential fallback into snprintf, improves performance, and removes all memory allocations in this formatting path.

PiperOrigin-RevId: 309752501

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79e2a24f3f959e8b06ddf1d440bbabbd5f89b5b7 by Greg Falcon <gfalcon@google.com>:

Add a Cord::swap() method.  Many other Abseil types already provide this, but it was missing here.

We already provided a two-argument free function form of `swap()`, but that API is better suited for generic code.  The swap member function is a better API when the types are known.

PiperOrigin-RevId: 309751740

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85cdf60024f153fb4fcb7fe68ed2b14b9faf119d by Derek Mauro <dmauro@google.com>:

Cleanup uses of "linker initialized" SpinLocks

PiperOrigin-RevId: 309581867

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9e5443bfcec4b94056b13c75326576e987ab88fb by Matt Kulukundis <kfm@google.com>:

Clarify intended mixing properties of `absl::Hash`

PiperOrigin-RevId: 309520174

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a0630f0827b67f217aaeae68a448fe4c1101e17d by Greg Falcon <gfalcon@google.com>:

Comment out a test in Emscripten to sidestep `long double` issues.

PiperOrigin-RevId: 309482953
GitOrigin-RevId: f34cd235a12ad0ee1fea3a1ee5a427272dc2b285
Change-Id: Icce0c9d547117374d596b9d684e4054ddd118669
2020-05-05 13:52:13 -04:00

472 lines
16 KiB
C++

//
// POSIX spec:
// http://pubs.opengroup.org/onlinepubs/009695399/functions/fprintf.html
//
#include "absl/strings/internal/str_format/arg.h"
#include <cassert>
#include <cerrno>
#include <cstdlib>
#include <string>
#include <type_traits>
#include "absl/base/port.h"
#include "absl/strings/internal/str_format/float_conversion.h"
#include "absl/strings/numbers.h"
namespace absl {
ABSL_NAMESPACE_BEGIN
namespace str_format_internal {
namespace {
// Reduce *capacity by s.size(), clipped to a 0 minimum.
void ReducePadding(string_view s, size_t *capacity) {
*capacity = Excess(s.size(), *capacity);
}
// Reduce *capacity by n, clipped to a 0 minimum.
void ReducePadding(size_t n, size_t *capacity) {
*capacity = Excess(n, *capacity);
}
template <typename T>
struct MakeUnsigned : std::make_unsigned<T> {};
template <>
struct MakeUnsigned<absl::int128> {
using type = absl::uint128;
};
template <>
struct MakeUnsigned<absl::uint128> {
using type = absl::uint128;
};
template <typename T>
struct IsSigned : std::is_signed<T> {};
template <>
struct IsSigned<absl::int128> : std::true_type {};
template <>
struct IsSigned<absl::uint128> : std::false_type {};
// Integral digit printer.
// Call one of the PrintAs* routines after construction once.
// Use with_neg_and_zero/without_neg_or_zero/is_negative to access the results.
class IntDigits {
public:
// Print the unsigned integer as octal.
// Supports unsigned integral types and uint128.
template <typename T>
void PrintAsOct(T v) {
static_assert(!IsSigned<T>::value, "");
char *p = storage_ + sizeof(storage_);
do {
*--p = static_cast<char>('0' + (static_cast<size_t>(v) & 7));
v >>= 3;
} while (v);
start_ = p;
size_ = storage_ + sizeof(storage_) - p;
}
// Print the signed or unsigned integer as decimal.
// Supports all integral types.
template <typename T>
void PrintAsDec(T v) {
static_assert(std::is_integral<T>::value, "");
start_ = storage_;
size_ = numbers_internal::FastIntToBuffer(v, storage_) - storage_;
}
void PrintAsDec(int128 v) {
auto u = static_cast<uint128>(v);
bool add_neg = false;
if (v < 0) {
add_neg = true;
u = uint128{} - u;
}
PrintAsDec(u, add_neg);
}
void PrintAsDec(uint128 v, bool add_neg = false) {
// This function can be sped up if needed. We can call FastIntToBuffer
// twice, or fix FastIntToBuffer to support uint128.
char *p = storage_ + sizeof(storage_);
do {
p -= 2;
numbers_internal::PutTwoDigits(static_cast<size_t>(v % 100), p);
v /= 100;
} while (v);
if (p[0] == '0') {
// We printed one too many hexits.
++p;
}
if (add_neg) {
*--p = '-';
}
size_ = storage_ + sizeof(storage_) - p;
start_ = p;
}
// Print the unsigned integer as hex using lowercase.
// Supports unsigned integral types and uint128.
template <typename T>
void PrintAsHexLower(T v) {
static_assert(!IsSigned<T>::value, "");
char *p = storage_ + sizeof(storage_);
do {
p -= 2;
constexpr const char* table = numbers_internal::kHexTable;
std::memcpy(p, table + 2 * (static_cast<size_t>(v) & 0xFF), 2);
if (sizeof(T) == 1) break;
v >>= 8;
} while (v);
if (p[0] == '0') {
// We printed one too many digits.
++p;
}
start_ = p;
size_ = storage_ + sizeof(storage_) - p;
}
// Print the unsigned integer as hex using uppercase.
// Supports unsigned integral types and uint128.
template <typename T>
void PrintAsHexUpper(T v) {
static_assert(!IsSigned<T>::value, "");
char *p = storage_ + sizeof(storage_);
// kHexTable is only lowercase, so do it manually for uppercase.
do {
*--p = "0123456789ABCDEF"[static_cast<size_t>(v) & 15];
v >>= 4;
} while (v);
start_ = p;
size_ = storage_ + sizeof(storage_) - p;
}
// The printed value including the '-' sign if available.
// For inputs of value `0`, this will return "0"
string_view with_neg_and_zero() const { return {start_, size_}; }
// The printed value not including the '-' sign.
// For inputs of value `0`, this will return "".
string_view without_neg_or_zero() const {
static_assert('-' < '0', "The check below verifies both.");
size_t advance = start_[0] <= '0' ? 1 : 0;
return {start_ + advance, size_ - advance};
}
bool is_negative() const { return start_[0] == '-'; }
private:
const char *start_;
size_t size_;
// Max size: 128 bit value as octal -> 43 digits, plus sign char
char storage_[128 / 3 + 1 + 1];
};
// Note: 'o' conversions do not have a base indicator, it's just that
// the '#' flag is specified to modify the precision for 'o' conversions.
string_view BaseIndicator(const IntDigits &as_digits,
const FormatConversionSpecImpl conv) {
// always show 0x for %p.
bool alt = conv.has_alt_flag() ||
conv.conversion_char() == FormatConversionCharInternal::p;
bool hex = (conv.conversion_char() == FormatConversionCharInternal::x ||
conv.conversion_char() == FormatConversionCharInternal::X ||
conv.conversion_char() == FormatConversionCharInternal::p);
// From the POSIX description of '#' flag:
// "For x or X conversion specifiers, a non-zero result shall have
// 0x (or 0X) prefixed to it."
if (alt && hex && !as_digits.without_neg_or_zero().empty()) {
return conv.conversion_char() == FormatConversionCharInternal::X ? "0X"
: "0x";
}
return {};
}
string_view SignColumn(bool neg, const FormatConversionSpecImpl conv) {
if (conv.conversion_char() == FormatConversionCharInternal::d ||
conv.conversion_char() == FormatConversionCharInternal::i) {
if (neg) return "-";
if (conv.has_show_pos_flag()) return "+";
if (conv.has_sign_col_flag()) return " ";
}
return {};
}
bool ConvertCharImpl(unsigned char v, const FormatConversionSpecImpl conv,
FormatSinkImpl *sink) {
size_t fill = 0;
if (conv.width() >= 0) fill = conv.width();
ReducePadding(1, &fill);
if (!conv.has_left_flag()) sink->Append(fill, ' ');
sink->Append(1, v);
if (conv.has_left_flag()) sink->Append(fill, ' ');
return true;
}
bool ConvertIntImplInnerSlow(const IntDigits &as_digits,
const FormatConversionSpecImpl conv,
FormatSinkImpl *sink) {
// Print as a sequence of Substrings:
// [left_spaces][sign][base_indicator][zeroes][formatted][right_spaces]
size_t fill = 0;
if (conv.width() >= 0) fill = conv.width();
string_view formatted = as_digits.without_neg_or_zero();
ReducePadding(formatted, &fill);
string_view sign = SignColumn(as_digits.is_negative(), conv);
ReducePadding(sign, &fill);
string_view base_indicator = BaseIndicator(as_digits, conv);
ReducePadding(base_indicator, &fill);
int precision = conv.precision();
bool precision_specified = precision >= 0;
if (!precision_specified)
precision = 1;
if (conv.has_alt_flag() &&
conv.conversion_char() == FormatConversionCharInternal::o) {
// From POSIX description of the '#' (alt) flag:
// "For o conversion, it increases the precision (if necessary) to
// force the first digit of the result to be zero."
if (formatted.empty() || *formatted.begin() != '0') {
int needed = static_cast<int>(formatted.size()) + 1;
precision = std::max(precision, needed);
}
}
size_t num_zeroes = Excess(formatted.size(), precision);
ReducePadding(num_zeroes, &fill);
size_t num_left_spaces = !conv.has_left_flag() ? fill : 0;
size_t num_right_spaces = conv.has_left_flag() ? fill : 0;
// From POSIX description of the '0' (zero) flag:
// "For d, i, o, u, x, and X conversion specifiers, if a precision
// is specified, the '0' flag is ignored."
if (!precision_specified && conv.has_zero_flag()) {
num_zeroes += num_left_spaces;
num_left_spaces = 0;
}
sink->Append(num_left_spaces, ' ');
sink->Append(sign);
sink->Append(base_indicator);
sink->Append(num_zeroes, '0');
sink->Append(formatted);
sink->Append(num_right_spaces, ' ');
return true;
}
template <typename T>
bool ConvertIntArg(T v, const FormatConversionSpecImpl conv,
FormatSinkImpl *sink) {
using U = typename MakeUnsigned<T>::type;
IntDigits as_digits;
switch (conv.conversion_char()) {
case FormatConversionCharInternal::c:
return ConvertCharImpl(static_cast<unsigned char>(v), conv, sink);
case FormatConversionCharInternal::o:
as_digits.PrintAsOct(static_cast<U>(v));
break;
case FormatConversionCharInternal::x:
as_digits.PrintAsHexLower(static_cast<U>(v));
break;
case FormatConversionCharInternal::X:
as_digits.PrintAsHexUpper(static_cast<U>(v));
break;
case FormatConversionCharInternal::u:
as_digits.PrintAsDec(static_cast<U>(v));
break;
case FormatConversionCharInternal::d:
case FormatConversionCharInternal::i:
as_digits.PrintAsDec(v);
break;
case FormatConversionCharInternal::a:
case FormatConversionCharInternal::e:
case FormatConversionCharInternal::f:
case FormatConversionCharInternal::g:
case FormatConversionCharInternal::A:
case FormatConversionCharInternal::E:
case FormatConversionCharInternal::F:
case FormatConversionCharInternal::G:
return ConvertFloatImpl(static_cast<double>(v), conv, sink);
default:
return false;
}
if (conv.is_basic()) {
sink->Append(as_digits.with_neg_and_zero());
return true;
}
return ConvertIntImplInnerSlow(as_digits, conv, sink);
}
template <typename T>
bool ConvertFloatArg(T v, const FormatConversionSpecImpl conv,
FormatSinkImpl *sink) {
return FormatConversionCharIsFloat(conv.conversion_char()) &&
ConvertFloatImpl(v, conv, sink);
}
inline bool ConvertStringArg(string_view v, const FormatConversionSpecImpl conv,
FormatSinkImpl *sink) {
if (conv.conversion_char() != FormatConversionCharInternal::s) return false;
if (conv.is_basic()) {
sink->Append(v);
return true;
}
return sink->PutPaddedString(v, conv.width(), conv.precision(),
conv.has_left_flag());
}
} // namespace
// ==================== Strings ====================
StringConvertResult FormatConvertImpl(const std::string &v,
const FormatConversionSpecImpl conv,
FormatSinkImpl *sink) {
return {ConvertStringArg(v, conv, sink)};
}
StringConvertResult FormatConvertImpl(string_view v,
const FormatConversionSpecImpl conv,
FormatSinkImpl *sink) {
return {ConvertStringArg(v, conv, sink)};
}
ArgConvertResult<FormatConversionCharSetUnion(
FormatConversionCharSetInternal::s, FormatConversionCharSetInternal::p)>
FormatConvertImpl(const char *v, const FormatConversionSpecImpl conv,
FormatSinkImpl *sink) {
if (conv.conversion_char() == FormatConversionCharInternal::p)
return {FormatConvertImpl(VoidPtr(v), conv, sink).value};
size_t len;
if (v == nullptr) {
len = 0;
} else if (conv.precision() < 0) {
len = std::strlen(v);
} else {
// If precision is set, we look for the NUL-terminator on the valid range.
len = std::find(v, v + conv.precision(), '\0') - v;
}
return {ConvertStringArg(string_view(v, len), conv, sink)};
}
// ==================== Raw pointers ====================
ArgConvertResult<FormatConversionCharSetInternal::p> FormatConvertImpl(
VoidPtr v, const FormatConversionSpecImpl conv, FormatSinkImpl *sink) {
if (conv.conversion_char() != FormatConversionCharInternal::p) return {false};
if (!v.value) {
sink->Append("(nil)");
return {true};
}
IntDigits as_digits;
as_digits.PrintAsHexLower(v.value);
return {ConvertIntImplInnerSlow(as_digits, conv, sink)};
}
// ==================== Floats ====================
FloatingConvertResult FormatConvertImpl(float v,
const FormatConversionSpecImpl conv,
FormatSinkImpl *sink) {
return {ConvertFloatArg(v, conv, sink)};
}
FloatingConvertResult FormatConvertImpl(double v,
const FormatConversionSpecImpl conv,
FormatSinkImpl *sink) {
return {ConvertFloatArg(v, conv, sink)};
}
FloatingConvertResult FormatConvertImpl(long double v,
const FormatConversionSpecImpl conv,
FormatSinkImpl *sink) {
return {ConvertFloatArg(v, conv, sink)};
}
// ==================== Chars ====================
IntegralConvertResult FormatConvertImpl(char v,
const FormatConversionSpecImpl conv,
FormatSinkImpl *sink) {
return {ConvertIntArg(v, conv, sink)};
}
IntegralConvertResult FormatConvertImpl(signed char v,
const FormatConversionSpecImpl conv,
FormatSinkImpl *sink) {
return {ConvertIntArg(v, conv, sink)};
}
IntegralConvertResult FormatConvertImpl(unsigned char v,
const FormatConversionSpecImpl conv,
FormatSinkImpl *sink) {
return {ConvertIntArg(v, conv, sink)};
}
// ==================== Ints ====================
IntegralConvertResult FormatConvertImpl(short v, // NOLINT
const FormatConversionSpecImpl conv,
FormatSinkImpl *sink) {
return {ConvertIntArg(v, conv, sink)};
}
IntegralConvertResult FormatConvertImpl(unsigned short v, // NOLINT
const FormatConversionSpecImpl conv,
FormatSinkImpl *sink) {
return {ConvertIntArg(v, conv, sink)};
}
IntegralConvertResult FormatConvertImpl(int v,
const FormatConversionSpecImpl conv,
FormatSinkImpl *sink) {
return {ConvertIntArg(v, conv, sink)};
}
IntegralConvertResult FormatConvertImpl(unsigned v,
const FormatConversionSpecImpl conv,
FormatSinkImpl *sink) {
return {ConvertIntArg(v, conv, sink)};
}
IntegralConvertResult FormatConvertImpl(long v, // NOLINT
const FormatConversionSpecImpl conv,
FormatSinkImpl *sink) {
return {ConvertIntArg(v, conv, sink)};
}
IntegralConvertResult FormatConvertImpl(unsigned long v, // NOLINT
const FormatConversionSpecImpl conv,
FormatSinkImpl *sink) {
return {ConvertIntArg(v, conv, sink)};
}
IntegralConvertResult FormatConvertImpl(long long v, // NOLINT
const FormatConversionSpecImpl conv,
FormatSinkImpl *sink) {
return {ConvertIntArg(v, conv, sink)};
}
IntegralConvertResult FormatConvertImpl(unsigned long long v, // NOLINT
const FormatConversionSpecImpl conv,
FormatSinkImpl *sink) {
return {ConvertIntArg(v, conv, sink)};
}
IntegralConvertResult FormatConvertImpl(absl::int128 v,
const FormatConversionSpecImpl conv,
FormatSinkImpl *sink) {
return {ConvertIntArg(v, conv, sink)};
}
IntegralConvertResult FormatConvertImpl(absl::uint128 v,
const FormatConversionSpecImpl conv,
FormatSinkImpl *sink) {
return {ConvertIntArg(v, conv, sink)};
}
ABSL_INTERNAL_FORMAT_DISPATCH_OVERLOADS_EXPAND_();
} // namespace str_format_internal
ABSL_NAMESPACE_END
} // namespace absl