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Diffstat (limited to 'absl/strings/internal/str_format/arg.cc')
| -rw-r--r-- | absl/strings/internal/str_format/arg.cc | 379 |
1 files changed, 379 insertions, 0 deletions
diff --git a/absl/strings/internal/str_format/arg.cc b/absl/strings/internal/str_format/arg.cc new file mode 100644 index 00000000..e5e1eee5 --- /dev/null +++ b/absl/strings/internal/str_format/arg.cc @@ -0,0 +1,379 @@ +// +// 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" + +namespace absl { +inline namespace lts_2018_12_18 { +namespace str_format_internal { +namespace { + +const char kDigit[2][32] = { "0123456789abcdef", "0123456789ABCDEF" }; + +// 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::uint128> { + using type = absl::uint128; +}; + +template <typename T> +struct IsSigned : std::is_signed<T> {}; +template <> +struct IsSigned<absl::uint128> : std::false_type {}; + +class ConvertedIntInfo { + public: + template <typename T> + ConvertedIntInfo(T v, ConversionChar conv) { + using Unsigned = typename MakeUnsigned<T>::type; + auto u = static_cast<Unsigned>(v); + if (IsNeg(v)) { + is_neg_ = true; + u = Unsigned{} - u; + } else { + is_neg_ = false; + } + UnsignedToStringRight(u, conv); + } + + string_view digits() const { + return {end() - size_, static_cast<size_t>(size_)}; + } + bool is_neg() const { return is_neg_; } + + private: + template <typename T, bool IsSigned> + struct IsNegImpl { + static bool Eval(T v) { return v < 0; } + }; + template <typename T> + struct IsNegImpl<T, false> { + static bool Eval(T) { + return false; + } + }; + + template <typename T> + bool IsNeg(T v) { + return IsNegImpl<T, IsSigned<T>::value>::Eval(v); + } + + template <typename T> + void UnsignedToStringRight(T u, ConversionChar conv) { + char *p = end(); + switch (conv.radix()) { + default: + case 10: + for (; u; u /= 10) + *--p = static_cast<char>('0' + static_cast<size_t>(u % 10)); + break; + case 8: + for (; u; u /= 8) + *--p = static_cast<char>('0' + static_cast<size_t>(u % 8)); + break; + case 16: { + const char *digits = kDigit[conv.upper() ? 1 : 0]; + for (; u; u /= 16) *--p = digits[static_cast<size_t>(u % 16)]; + break; + } + } + size_ = static_cast<int>(end() - p); + } + + const char *end() const { return storage_ + sizeof(storage_); } + char *end() { return storage_ + sizeof(storage_); } + + bool is_neg_; + int size_; + // Max size: 128 bit value as octal -> 43 digits + char storage_[128 / 3 + 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 ConvertedIntInfo &info, + const ConversionSpec conv) { + bool alt = conv.flags().alt; + int radix = conv.conv().radix(); + if (conv.conv().id() == ConversionChar::p) + alt = true; // always show 0x for %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 && radix == 16 && !info.digits().empty()) { + if (conv.conv().upper()) return "0X"; + return "0x"; + } + return {}; +} + +string_view SignColumn(bool neg, const ConversionSpec conv) { + if (conv.conv().is_signed()) { + if (neg) return "-"; + if (conv.flags().show_pos) return "+"; + if (conv.flags().sign_col) return " "; + } + return {}; +} + +bool ConvertCharImpl(unsigned char v, const ConversionSpec conv, + FormatSinkImpl *sink) { + size_t fill = 0; + if (conv.width() >= 0) fill = conv.width(); + ReducePadding(1, &fill); + if (!conv.flags().left) sink->Append(fill, ' '); + sink->Append(1, v); + if (conv.flags().left) sink->Append(fill, ' '); + return true; +} + +bool ConvertIntImplInner(const ConvertedIntInfo &info, + const ConversionSpec 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 = info.digits(); + ReducePadding(formatted, &fill); + + string_view sign = SignColumn(info.is_neg(), conv); + ReducePadding(sign, &fill); + + string_view base_indicator = BaseIndicator(info, conv); + ReducePadding(base_indicator, &fill); + + int precision = conv.precision(); + bool precision_specified = precision >= 0; + if (!precision_specified) + precision = 1; + + if (conv.flags().alt && conv.conv().id() == ConversionChar::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.flags().left ? fill : 0; + size_t num_right_spaces = conv.flags().left ? 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.flags().zero) { + 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 ConvertIntImplInner(T v, const ConversionSpec conv, FormatSinkImpl *sink) { + ConvertedIntInfo info(v, conv.conv()); + if (conv.flags().basic && conv.conv().id() != ConversionChar::p) { + if (info.is_neg()) sink->Append(1, '-'); + if (info.digits().empty()) { + sink->Append(1, '0'); + } else { + sink->Append(info.digits()); + } + return true; + } + return ConvertIntImplInner(info, conv, sink); +} + +template <typename T> +bool ConvertIntArg(T v, const ConversionSpec conv, FormatSinkImpl *sink) { + if (conv.conv().is_float()) { + return FormatConvertImpl(static_cast<double>(v), conv, sink).value; + } + if (conv.conv().id() == ConversionChar::c) + return ConvertCharImpl(static_cast<unsigned char>(v), conv, sink); + if (!conv.conv().is_integral()) + return false; + if (!conv.conv().is_signed() && IsSigned<T>::value) { + using U = typename MakeUnsigned<T>::type; + return FormatConvertImpl(static_cast<U>(v), conv, sink).value; + } + return ConvertIntImplInner(v, conv, sink); +} + +template <typename T> +bool ConvertFloatArg(T v, const ConversionSpec conv, FormatSinkImpl *sink) { + return conv.conv().is_float() && ConvertFloatImpl(v, conv, sink); +} + +inline bool ConvertStringArg(string_view v, const ConversionSpec conv, + FormatSinkImpl *sink) { + if (conv.conv().id() != ConversionChar::s) + return false; + if (conv.flags().basic) { + sink->Append(v); + return true; + } + return sink->PutPaddedString(v, conv.width(), conv.precision(), + conv.flags().left); +} + +} // namespace + +// ==================== Strings ==================== +ConvertResult<Conv::s> FormatConvertImpl(const std::string &v, + const ConversionSpec conv, + FormatSinkImpl *sink) { + return {ConvertStringArg(v, conv, sink)}; +} + +ConvertResult<Conv::s> FormatConvertImpl(string_view v, + const ConversionSpec conv, + FormatSinkImpl *sink) { + return {ConvertStringArg(v, conv, sink)}; +} + +ConvertResult<Conv::s | Conv::p> FormatConvertImpl(const char *v, + const ConversionSpec conv, + FormatSinkImpl *sink) { + if (conv.conv().id() == ConversionChar::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 null terminator on the valid range. + len = std::find(v, v + conv.precision(), '\0') - v; + } + return {ConvertStringArg(string_view(v, len), conv, sink)}; +} + +// ==================== Raw pointers ==================== +ConvertResult<Conv::p> FormatConvertImpl(VoidPtr v, const ConversionSpec conv, + FormatSinkImpl *sink) { + if (conv.conv().id() != ConversionChar::p) + return {false}; + if (!v.value) { + sink->Append("(nil)"); + return {true}; + } + return {ConvertIntImplInner(v.value, conv, sink)}; +} + +// ==================== Floats ==================== +FloatingConvertResult FormatConvertImpl(float v, const ConversionSpec conv, + FormatSinkImpl *sink) { + return {ConvertFloatArg(v, conv, sink)}; +} +FloatingConvertResult FormatConvertImpl(double v, const ConversionSpec conv, + FormatSinkImpl *sink) { + return {ConvertFloatArg(v, conv, sink)}; +} +FloatingConvertResult FormatConvertImpl(long double v, + const ConversionSpec conv, + FormatSinkImpl *sink) { + return {ConvertFloatArg(v, conv, sink)}; +} + +// ==================== Chars ==================== +IntegralConvertResult FormatConvertImpl(char v, const ConversionSpec conv, + FormatSinkImpl *sink) { + return {ConvertIntArg(v, conv, sink)}; +} +IntegralConvertResult FormatConvertImpl(signed char v, + const ConversionSpec conv, + FormatSinkImpl *sink) { + return {ConvertIntArg(v, conv, sink)}; +} +IntegralConvertResult FormatConvertImpl(unsigned char v, + const ConversionSpec conv, + FormatSinkImpl *sink) { + return {ConvertIntArg(v, conv, sink)}; +} + +// ==================== Ints ==================== +IntegralConvertResult FormatConvertImpl(short v, // NOLINT + const ConversionSpec conv, + FormatSinkImpl *sink) { + return {ConvertIntArg(v, conv, sink)}; +} +IntegralConvertResult FormatConvertImpl(unsigned short v, // NOLINT + const ConversionSpec conv, + FormatSinkImpl *sink) { + return {ConvertIntArg(v, conv, sink)}; +} +IntegralConvertResult FormatConvertImpl(int v, const ConversionSpec conv, + FormatSinkImpl *sink) { + return {ConvertIntArg(v, conv, sink)}; +} +IntegralConvertResult FormatConvertImpl(unsigned v, const ConversionSpec conv, + FormatSinkImpl *sink) { + return {ConvertIntArg(v, conv, sink)}; +} +IntegralConvertResult FormatConvertImpl(long v, // NOLINT + const ConversionSpec conv, + FormatSinkImpl *sink) { + return {ConvertIntArg(v, conv, sink)}; +} +IntegralConvertResult FormatConvertImpl(unsigned long v, // NOLINT + const ConversionSpec conv, + FormatSinkImpl *sink) { + return {ConvertIntArg(v, conv, sink)}; +} +IntegralConvertResult FormatConvertImpl(long long v, // NOLINT + const ConversionSpec conv, + FormatSinkImpl *sink) { + return {ConvertIntArg(v, conv, sink)}; +} +IntegralConvertResult FormatConvertImpl(unsigned long long v, // NOLINT + const ConversionSpec conv, + FormatSinkImpl *sink) { + return {ConvertIntArg(v, conv, sink)}; +} +IntegralConvertResult FormatConvertImpl(absl::uint128 v, + const ConversionSpec conv, + FormatSinkImpl *sink) { + return {ConvertIntArg(v, conv, sink)}; +} + +ABSL_INTERNAL_FORMAT_DISPATCH_OVERLOADS_EXPAND_(); + + +} // namespace str_format_internal + +} // inline namespace lts_2018_12_18 +} // namespace absl |