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Diffstat (limited to 'absl/strings/internal/str_format/arg.h')
| -rw-r--r-- | absl/strings/internal/str_format/arg.h | 434 |
1 files changed, 434 insertions, 0 deletions
diff --git a/absl/strings/internal/str_format/arg.h b/absl/strings/internal/str_format/arg.h new file mode 100644 index 000000000000..a9562188ea91 --- /dev/null +++ b/absl/strings/internal/str_format/arg.h @@ -0,0 +1,434 @@ +#ifndef ABSL_STRINGS_INTERNAL_STR_FORMAT_ARG_H_ +#define ABSL_STRINGS_INTERNAL_STR_FORMAT_ARG_H_ + +#include <string.h> +#include <wchar.h> + +#include <cstdio> +#include <iomanip> +#include <limits> +#include <sstream> +#include <string> +#include <type_traits> + +#include "absl/base/port.h" +#include "absl/meta/type_traits.h" +#include "absl/numeric/int128.h" +#include "absl/strings/internal/str_format/extension.h" +#include "absl/strings/string_view.h" + +class Cord; +class CordReader; + +namespace absl { + +class FormatCountCapture; +class FormatSink; + +namespace str_format_internal { + +template <typename T, typename = void> +struct HasUserDefinedConvert : std::false_type {}; + +template <typename T> +struct HasUserDefinedConvert< + T, void_t<decltype(AbslFormatConvert( + std::declval<const T&>(), std::declval<const ConversionSpec&>(), + std::declval<FormatSink*>()))>> : std::true_type {}; +template <typename T> +class StreamedWrapper; + +// If 'v' can be converted (in the printf sense) according to 'conv', +// then convert it, appending to `sink` and return `true`. +// Otherwise fail and return `false`. +// Raw pointers. +struct VoidPtr { + VoidPtr() = default; + template <typename T, + decltype(reinterpret_cast<uintptr_t>(std::declval<T*>())) = 0> + VoidPtr(T* ptr) // NOLINT + : value(ptr ? reinterpret_cast<uintptr_t>(ptr) : 0) {} + uintptr_t value; +}; +ConvertResult<Conv::p> FormatConvertImpl(VoidPtr v, const ConversionSpec& conv, + FormatSinkImpl* sink); + +// Strings. +ConvertResult<Conv::s> FormatConvertImpl(const std::string& v, + const ConversionSpec& conv, + FormatSinkImpl* sink); +ConvertResult<Conv::s> FormatConvertImpl(string_view v, + const ConversionSpec& conv, + FormatSinkImpl* sink); +ConvertResult<Conv::s | Conv::p> FormatConvertImpl(const char* v, + const ConversionSpec& conv, + FormatSinkImpl* sink); +template <class AbslCord, + typename std::enable_if< + std::is_same<AbslCord, ::Cord>::value>::type* = nullptr, + class AbslCordReader = ::CordReader> +ConvertResult<Conv::s> FormatConvertImpl(const AbslCord& value, + const ConversionSpec& conv, + FormatSinkImpl* sink) { + if (conv.conv().id() != ConversionChar::s) return {false}; + + bool is_left = conv.flags().left; + size_t space_remaining = 0; + + int width = conv.width(); + if (width >= 0) space_remaining = width; + + size_t to_write = value.size(); + + int precision = conv.precision(); + if (precision >= 0) + to_write = std::min(to_write, static_cast<size_t>(precision)); + + space_remaining = Excess(to_write, space_remaining); + + if (space_remaining > 0 && !is_left) sink->Append(space_remaining, ' '); + + string_view piece; + for (AbslCordReader reader(value); + to_write > 0 && reader.ReadFragment(&piece); to_write -= piece.size()) { + if (piece.size() > to_write) piece.remove_suffix(piece.size() - to_write); + sink->Append(piece); + } + + if (space_remaining > 0 && is_left) sink->Append(space_remaining, ' '); + return {true}; +} + +using IntegralConvertResult = + ConvertResult<Conv::c | Conv::numeric | Conv::star>; +using FloatingConvertResult = ConvertResult<Conv::floating>; + +// Floats. +FloatingConvertResult FormatConvertImpl(float v, const ConversionSpec& conv, + FormatSinkImpl* sink); +FloatingConvertResult FormatConvertImpl(double v, const ConversionSpec& conv, + FormatSinkImpl* sink); +FloatingConvertResult FormatConvertImpl(long double v, + const ConversionSpec& conv, + FormatSinkImpl* sink); + +// Chars. +IntegralConvertResult FormatConvertImpl(char v, const ConversionSpec& conv, + FormatSinkImpl* sink); +IntegralConvertResult FormatConvertImpl(signed char v, + const ConversionSpec& conv, + FormatSinkImpl* sink); +IntegralConvertResult FormatConvertImpl(unsigned char v, + const ConversionSpec& conv, + FormatSinkImpl* sink); + +// Ints. +IntegralConvertResult FormatConvertImpl(short v, // NOLINT + const ConversionSpec& conv, + FormatSinkImpl* sink); +IntegralConvertResult FormatConvertImpl(unsigned short v, // NOLINT + const ConversionSpec& conv, + FormatSinkImpl* sink); +IntegralConvertResult FormatConvertImpl(int v, const ConversionSpec& conv, + FormatSinkImpl* sink); +IntegralConvertResult FormatConvertImpl(unsigned v, const ConversionSpec& conv, + FormatSinkImpl* sink); +IntegralConvertResult FormatConvertImpl(long v, // NOLINT + const ConversionSpec& conv, + FormatSinkImpl* sink); +IntegralConvertResult FormatConvertImpl(unsigned long v, // NOLINT + const ConversionSpec& conv, + FormatSinkImpl* sink); +IntegralConvertResult FormatConvertImpl(long long v, // NOLINT + const ConversionSpec& conv, + FormatSinkImpl* sink); +IntegralConvertResult FormatConvertImpl(unsigned long long v, // NOLINT + const ConversionSpec& conv, + FormatSinkImpl* sink); +IntegralConvertResult FormatConvertImpl(uint128 v, const ConversionSpec& conv, + FormatSinkImpl* sink); +template <typename T, enable_if_t<std::is_same<T, bool>::value, int> = 0> +IntegralConvertResult FormatConvertImpl(T v, const ConversionSpec& conv, + FormatSinkImpl* sink) { + return FormatConvertImpl(static_cast<int>(v), conv, sink); +} + +// We provide this function to help the checker, but it is never defined. +// FormatArgImpl will use the underlying Convert functions instead. +template <typename T> +typename std::enable_if<std::is_enum<T>::value && + !HasUserDefinedConvert<T>::value, + IntegralConvertResult>::type +FormatConvertImpl(T v, const ConversionSpec& conv, FormatSinkImpl* sink); + +template <typename T> +ConvertResult<Conv::s> FormatConvertImpl(const StreamedWrapper<T>& v, + const ConversionSpec& conv, + FormatSinkImpl* out) { + std::ostringstream oss; + oss << v.v_; + if (!oss) return {false}; + return str_format_internal::FormatConvertImpl(oss.str(), conv, out); +} + +// Use templates and dependent types to delay evaluation of the function +// until after FormatCountCapture is fully defined. +struct FormatCountCaptureHelper { + template <class T = int> + static ConvertResult<Conv::n> ConvertHelper(const FormatCountCapture& v, + const ConversionSpec& conv, + FormatSinkImpl* sink) { + const absl::enable_if_t<sizeof(T) != 0, FormatCountCapture>& v2 = v; + + if (conv.conv().id() != str_format_internal::ConversionChar::n) + return {false}; + *v2.p_ = static_cast<int>(sink->size()); + return {true}; + } +}; + +template <class T = int> +ConvertResult<Conv::n> FormatConvertImpl(const FormatCountCapture& v, + const ConversionSpec& conv, + FormatSinkImpl* sink) { + return FormatCountCaptureHelper::ConvertHelper(v, conv, sink); +} + +// Helper friend struct to hide implementation details from the public API of +// FormatArgImpl. +struct FormatArgImplFriend { + template <typename Arg> + static bool ToInt(Arg arg, int* out) { + if (!arg.vtbl_->to_int) return false; + *out = arg.vtbl_->to_int(arg.data_); + return true; + } + + template <typename Arg> + static bool Convert(Arg arg, const str_format_internal::ConversionSpec& conv, + FormatSinkImpl* out) { + return arg.vtbl_->convert(arg.data_, conv, out); + } + + template <typename Arg> + static const void* GetVTablePtrForTest(Arg arg) { + return arg.vtbl_; + } +}; + +// A type-erased handle to a format argument. +class FormatArgImpl { + private: + enum { kInlinedSpace = 8 }; + + using VoidPtr = str_format_internal::VoidPtr; + + union Data { + const void* ptr; + const volatile void* volatile_ptr; + char buf[kInlinedSpace]; + }; + + struct VTable { + bool (*convert)(Data, const str_format_internal::ConversionSpec& conv, + FormatSinkImpl* out); + int (*to_int)(Data); + }; + + template <typename T> + struct store_by_value + : std::integral_constant<bool, (sizeof(T) <= kInlinedSpace) && + (std::is_integral<T>::value || + std::is_floating_point<T>::value || + std::is_pointer<T>::value || + std::is_same<VoidPtr, T>::value)> {}; + + enum StoragePolicy { ByPointer, ByVolatilePointer, ByValue }; + template <typename T> + struct storage_policy + : std::integral_constant<StoragePolicy, + (std::is_volatile<T>::value + ? ByVolatilePointer + : (store_by_value<T>::value ? ByValue + : ByPointer))> { + }; + + // An instance of an FormatArgImpl::VTable suitable for 'T'. + template <typename T> + struct TypedVTable; + + // To reduce the number of vtables we will decay values before hand. + // Anything with a user-defined Convert will get its own vtable. + // For everything else: + // - Decay char* and char arrays into `const char*` + // - Decay any other pointer to `const void*` + // - Decay all enums to their underlying type. + // - Decay function pointers to void*. + template <typename T, typename = void> + struct DecayType { + static constexpr bool kHasUserDefined = + str_format_internal::HasUserDefinedConvert<T>::value; + using type = typename std::conditional< + !kHasUserDefined && std::is_convertible<T, const char*>::value, + const char*, + typename std::conditional<!kHasUserDefined && + std::is_convertible<T, VoidPtr>::value, + VoidPtr, const T&>::type>::type; + }; + template <typename T> + struct DecayType<T, + typename std::enable_if< + !str_format_internal::HasUserDefinedConvert<T>::value && + std::is_enum<T>::value>::type> { + using type = typename std::underlying_type<T>::type; + }; + + public: + template <typename T> + explicit FormatArgImpl(const T& value) { + using D = typename DecayType<T>::type; + static_assert( + std::is_same<D, const T&>::value || storage_policy<D>::value == ByValue, + "Decayed types must be stored by value"); + Init(static_cast<D>(value)); + } + + private: + friend struct str_format_internal::FormatArgImplFriend; + template <typename T, StoragePolicy = storage_policy<T>::value> + struct Manager; + + template <typename T> + struct Manager<T, ByPointer> { + static Data SetValue(const T& value) { + Data data; + data.ptr = &value; + return data; + } + + static const T& Value(Data arg) { return *static_cast<const T*>(arg.ptr); } + }; + + template <typename T> + struct Manager<T, ByVolatilePointer> { + static Data SetValue(const T& value) { + Data data; + data.volatile_ptr = &value; + return data; + } + + static const T& Value(Data arg) { + return *static_cast<const T*>(arg.volatile_ptr); + } + }; + + template <typename T> + struct Manager<T, ByValue> { + static Data SetValue(const T& value) { + Data data; + memcpy(data.buf, &value, sizeof(value)); + return data; + } + + static T Value(Data arg) { + T value; + memcpy(&value, arg.buf, sizeof(T)); + return value; + } + }; + + template <typename T> + void Init(const T& value); + + template <typename T> + static int ToIntVal(const T& val) { + using CommonType = typename std::conditional<std::is_signed<T>::value, + int64_t, uint64_t>::type; + if (static_cast<CommonType>(val) > + static_cast<CommonType>(std::numeric_limits<int>::max())) { + return std::numeric_limits<int>::max(); + } else if (std::is_signed<T>::value && + static_cast<CommonType>(val) < + static_cast<CommonType>(std::numeric_limits<int>::min())) { + return std::numeric_limits<int>::min(); + } + return static_cast<int>(val); + } + + Data data_; + const VTable* vtbl_; +}; + +template <typename T> +struct FormatArgImpl::TypedVTable { + private: + static bool ConvertImpl(Data arg, + const str_format_internal::ConversionSpec& conv, + FormatSinkImpl* out) { + return str_format_internal::FormatConvertImpl(Manager<T>::Value(arg), conv, + out) + .value; + } + + template <typename U = T, typename = void> + struct ToIntImpl { + static constexpr int (*value)(Data) = nullptr; + }; + + template <typename U> + struct ToIntImpl<U, + typename std::enable_if<std::is_integral<U>::value>::type> { + static int Invoke(Data arg) { return ToIntVal(Manager<T>::Value(arg)); } + static constexpr int (*value)(Data) = &Invoke; + }; + + template <typename U> + struct ToIntImpl<U, typename std::enable_if<std::is_enum<U>::value>::type> { + static int Invoke(Data arg) { + return ToIntVal(static_cast<typename std::underlying_type<T>::type>( + Manager<T>::Value(arg))); + } + static constexpr int (*value)(Data) = &Invoke; + }; + + public: + static constexpr VTable value{&ConvertImpl, ToIntImpl<>::value}; +}; + +template <typename T> +constexpr FormatArgImpl::VTable FormatArgImpl::TypedVTable<T>::value; + +template <typename T> +void FormatArgImpl::Init(const T& value) { + data_ = Manager<T>::SetValue(value); + vtbl_ = &TypedVTable<T>::value; +} + +extern template struct FormatArgImpl::TypedVTable<str_format_internal::VoidPtr>; + +extern template struct FormatArgImpl::TypedVTable<bool>; +extern template struct FormatArgImpl::TypedVTable<char>; +extern template struct FormatArgImpl::TypedVTable<signed char>; +extern template struct FormatArgImpl::TypedVTable<unsigned char>; +extern template struct FormatArgImpl::TypedVTable<short>; // NOLINT +extern template struct FormatArgImpl::TypedVTable<unsigned short>; // NOLINT +extern template struct FormatArgImpl::TypedVTable<int>; +extern template struct FormatArgImpl::TypedVTable<unsigned>; +extern template struct FormatArgImpl::TypedVTable<long>; // NOLINT +extern template struct FormatArgImpl::TypedVTable<unsigned long>; // NOLINT +extern template struct FormatArgImpl::TypedVTable<long long>; // NOLINT +extern template struct FormatArgImpl::TypedVTable< + unsigned long long>; // NOLINT +extern template struct FormatArgImpl::TypedVTable<uint128>; + +extern template struct FormatArgImpl::TypedVTable<float>; +extern template struct FormatArgImpl::TypedVTable<double>; +extern template struct FormatArgImpl::TypedVTable<long double>; + +extern template struct FormatArgImpl::TypedVTable<const char*>; +extern template struct FormatArgImpl::TypedVTable<std::string>; +extern template struct FormatArgImpl::TypedVTable<string_view>; +} // namespace str_format_internal +} // namespace absl + +#endif // ABSL_STRINGS_INTERNAL_STR_FORMAT_ARG_H_ |