#include <folly/Range.h>
#include <boost/implicit_cast.hpp>
+#include <algorithm>
#include <type_traits>
#include <limits>
#include <string>
// V8 JavaScript implementation
#include <double-conversion/double-conversion.h>
-#define FOLLY_RANGE_CHECK(condition, message) \
- ((condition) ? (void)0 : throw std::range_error( \
- (__FILE__ "(" + std::to_string((long long int) __LINE__) + "): " \
+#define FOLLY_RANGE_CHECK_STRINGIZE(x) #x
+#define FOLLY_RANGE_CHECK_STRINGIZE2(x) FOLLY_RANGE_CHECK_STRINGIZE(x)
+
+#define FOLLY_RANGE_CHECK(condition, message) \
+ ((condition) ? (void)0 : throw std::range_error( \
+ (std::string(__FILE__ "(" FOLLY_RANGE_CHECK_STRINGIZE2(__LINE__) "): ") \
+ (message)).c_str()))
namespace folly {
+/**
+ * The identity conversion function.
+ * to<T>(T) returns itself for all types T.
+ */
+template <class Tgt, class Src>
+typename std::enable_if<std::is_same<Tgt, Src>::value, Tgt>::type
+to(const Src & value) {
+ return value;
+}
+
+template <class Tgt, class Src>
+typename std::enable_if<std::is_same<Tgt, Src>::value, Tgt>::type
+to(Src && value) {
+ return std::move(value);
+}
+
/*******************************************************************************
* Integral to integral
******************************************************************************/
*/
template <class Tgt, class Src>
typename std::enable_if<
- std::is_integral<Src>::value && std::is_integral<Tgt>::value,
+ std::is_integral<Src>::value
+ && std::is_integral<Tgt>::value
+ && !std::is_same<Tgt, Src>::value,
Tgt>::type
to(const Src & value) {
/* static */ if (std::numeric_limits<Tgt>::max()
template <class Tgt, class Src>
typename std::enable_if<
- std::is_floating_point<Tgt>::value && std::is_floating_point<Src>::value,
+ std::is_floating_point<Tgt>::value
+ && std::is_floating_point<Src>::value
+ && !std::is_same<Tgt, Src>::value,
Tgt>::type
to(const Src & value) {
/* static */ if (std::numeric_limits<Tgt>::max() <
return ceil((double(sizeof(IntegerType) * CHAR_BIT) * M_LN2) / M_LN10);
}
-inline unsigned int
-unsafeTelescope128(char * buffer, unsigned int room, unsigned __int128 x) {
+inline size_t
+unsafeTelescope128(char * buffer, size_t room, unsigned __int128 x) {
typedef unsigned __int128 Usrc;
- unsigned int p = room - 1;
+ size_t p = room - 1;
while (x >= (Usrc(1) << 64)) { // Using 128-bit division while needed
const auto y = x / 10;
toAppend(__int128 value, Tgt * result) {
typedef unsigned __int128 Usrc;
char buffer[detail::digitsEnough<unsigned __int128>() + 1];
- unsigned int p;
+ size_t p;
if (value < 0) {
p = detail::unsafeTelescope128(buffer, sizeof(buffer), Usrc(-value));
void
toAppend(unsigned __int128 value, Tgt * result) {
char buffer[detail::digitsEnough<unsigned __int128>()];
- unsigned int p;
+ size_t p;
p = detail::unsafeTelescope128(buffer, sizeof(buffer), value);
* Conversions from floating-point types to string types.
******************************************************************************/
+namespace detail {
+constexpr int kConvMaxDecimalInShortestLow = -6;
+constexpr int kConvMaxDecimalInShortestHigh = 21;
+} // folly::detail
+
/** Wrapper around DoubleToStringConverter **/
template <class Tgt, class Src>
typename std::enable_if<
DoubleToStringConverter
conv(DoubleToStringConverter::NO_FLAGS,
"infinity", "NaN", 'E',
- -6, // decimal in shortest low
- 21, // decimal in shortest high
+ detail::kConvMaxDecimalInShortestLow,
+ detail::kConvMaxDecimalInShortestHigh,
6, // max leading padding zeros
1); // max trailing padding zeros
char buffer[256];
}
/**
- * Very primitive, lets say its our best effort
+ * Upper bound of the length of the output from
+ * DoubleToStringConverter::ToShortest(double, StringBuilder*),
+ * as used in toAppend(double, string*).
*/
template <class Src>
typename std::enable_if<
std::is_floating_point<Src>::value, size_t>::type
estimateSpaceNeeded(Src value) {
- size_t sofar = 0;
- if (value < 0) {
- ++sofar;
- value = -value;
- }
-
- if (value < 1) {
- return sofar + 10; // lets assume 0 + '.' + 8 precision digits
- }
-
- if (value < static_cast<double>(std::numeric_limits<uint64_t>::max())) {
- sofar += digits10(static_cast<uint64_t>(value));
- } else {
- return 64; // give up, it will be more than 23 anyway
- }
-
- return sofar + 10; // integral part + '.' + 8 precision digits
+ // kBase10MaximalLength is 17. We add 1 for decimal point,
+ // e.g. 10.0/9 is 17 digits and 18 characters, including the decimal point.
+ constexpr int kMaxMantissaSpace =
+ double_conversion::DoubleToStringConverter::kBase10MaximalLength + 1;
+ // strlen("E-") + digits10(numeric_limits<double>::max_exponent10)
+ constexpr int kMaxExponentSpace = 2 + 3;
+ static const int kMaxPositiveSpace = std::max({
+ // E.g. 1.1111111111111111E-100.
+ kMaxMantissaSpace + kMaxExponentSpace,
+ // E.g. 0.000001.1111111111111111, if kConvMaxDecimalInShortestLow is -6.
+ kMaxMantissaSpace - detail::kConvMaxDecimalInShortestLow,
+ // If kConvMaxDecimalInShortestHigh is 21, then 1e21 is the smallest
+ // number > 1 which ToShortest outputs in exponential notation,
+ // so 21 is the longest non-exponential number > 1.
+ detail::kConvMaxDecimalInShortestHigh
+ });
+ return kMaxPositiveSpace + (value < 0); // +1 for minus sign, if negative
}
/**
template <class Src>
constexpr typename std::enable_if<
!std::is_fundamental<Src>::value
+#ifdef FOLLY_HAVE_INT128_T
+ // On OSX 10.10, is_fundamental<__int128> is false :-O
+ && !std::is_same<__int128, Src>::value
+ && !std::is_same<unsigned __int128, Src>::value
+#endif
&& !IsSomeString<Src>::value
&& !std::is_convertible<Src, const char*>::value
&& !std::is_convertible<Src, StringPiece>::value
/**
* Variadic conversion to string. Appends each element in turn.
- * If we have two or more things to append, we will reserve
- * the space for them (at least we will try).
+ * If we have two or more things to append, we it will not reserve
+ * the space for them and will depend on strings exponential growth.
+ * If you just append once consider using toAppendFit which reserves
+ * the space needed (but does not have exponential as a result).
*/
template <class... Ts>
typename std::enable_if<sizeof...(Ts) >= 3
typename detail::last_element<Ts...>::type
>::type>::value>::type
toAppend(const Ts&... vs) {
- detail::reserveInTarget(vs...);
detail::toAppendStrImpl(vs...);
}
+/**
+ * Special version of the call that preallocates exaclty as much memory
+ * as need for arguments to be stored in target. This means we are
+ * not doing exponential growth when we append. If you are using it
+ * in a loop you are aiming at your foot with a big perf-destroying
+ * bazooka.
+ * On the other hand if you are appending to a string once, this
+ * will probably save a few calls to malloc.
+ */
+template <class... Ts>
+typename std::enable_if<
+ IsSomeString<
+ typename std::remove_pointer<
+ typename detail::last_element<Ts...>::type
+ >::type>::value>::type
+toAppendFit(const Ts&... vs) {
+ detail::reserveInTarget(vs...);
+ toAppend(vs...);
+}
+
+template <class Ts>
+void toAppendFit(const Ts&) {}
+
/**
* Variadic base case: do nothing.
*/
}
/**
- * Append to string with a delimiter in between elements.
+ * Append to string with a delimiter in between elements. Check out
+ * comments for toAppend for details about memory allocation.
*/
template <class Delimiter, class... Ts>
typename std::enable_if<sizeof...(Ts) >= 3
typename detail::last_element<Ts...>::type
>::type>::value>::type
toAppendDelim(const Delimiter& delim, const Ts&... vs) {
- detail::reserveInTargetDelim(delim, vs...);
detail::toAppendDelimStrImpl(delim, vs...);
}
/**
- * to<SomeString>(SomeString str) returns itself. As both std::string and
- * folly::fbstring use Copy-on-Write, it's much more efficient by
- * avoiding copying the underlying char array.
+ * Detail in comment for toAppendFit
*/
-template <class Tgt, class Src>
+template <class Delimiter, class... Ts>
typename std::enable_if<
- IsSomeString<Tgt>::value && std::is_same<Tgt, Src>::value,
- Tgt>::type
-to(const Src & value) {
- return value;
+ IsSomeString<
+ typename std::remove_pointer<
+ typename detail::last_element<Ts...>::type
+ >::type>::value>::type
+toAppendDelimFit(const Delimiter& delim, const Ts&... vs) {
+ detail::reserveInTargetDelim(delim, vs...);
+ toAppendDelim(delim, vs...);
}
+template <class De, class Ts>
+void toAppendDelimFit(const De&, const Ts&) {}
+
/**
* to<SomeString>(v1, v2, ...) uses toAppend() (see below) as back-end
* for all types.
Tgt>::type
to(const Ts&... vs) {
Tgt result;
- toAppend(vs..., &result);
+ toAppendFit(vs..., &result);
return result;
}
Tgt>::type
toDelim(const Delim& delim, const Ts&... vs) {
Tgt result;
- toAppendDelim(delim, vs..., &result);
+ toAppendDelimFit(delim, vs..., &result);
return result;
}
FOLLY_RANGE_CHECK(!src->empty(), "No digits found in input string");
int length;
- auto result = conv.StringToDouble(src->data(), src->size(),
- &length); // processed char count
+ auto result = conv.StringToDouble(src->data(),
+ static_cast<int>(src->size()),
+ &length); // processed char count
if (!std::isnan(result)) {
src->advance(length);
// std::underlying_type became available by gcc 4.7.0
template <class Tgt, class Src>
-typename std::enable_if<std::is_enum<Src>::value, Tgt>::type
+typename std::enable_if<
+ std::is_enum<Src>::value && !std::is_same<Src, Tgt>::value, Tgt>::type
to(const Src & value) {
return to<Tgt>(static_cast<typename std::underlying_type<Src>::type>(value));
}
template <class Tgt, class Src>
-typename std::enable_if<std::is_enum<Tgt>::value, Tgt>::type
+typename std::enable_if<
+ std::is_enum<Tgt>::value && !std::is_same<Src, Tgt>::value, Tgt>::type
to(const Src & value) {
return static_cast<Tgt>(to<typename std::underlying_type<Tgt>::type>(value));
}
#else
template <class Tgt, class Src>
-typename std::enable_if<std::is_enum<Src>::value, Tgt>::type
+typename std::enable_if<
+ std::is_enum<Src>::value && !std::is_same<Src, Tgt>::value, Tgt>::type
to(const Src & value) {
/* static */ if (Src(-1) < 0) {
/* static */ if (sizeof(Src) <= sizeof(int)) {
}
template <class Tgt, class Src>
-typename std::enable_if<std::is_enum<Tgt>::value, Tgt>::type
+typename std::enable_if<
+ std::is_enum<Tgt>::value && !std::is_same<Src, Tgt>::value, Tgt>::type
to(const Src & value) {
/* static */ if (Tgt(-1) < 0) {
/* static */ if (sizeof(Tgt) <= sizeof(int)) {
// to avoid defining this global macro name in other files that include Conv.h.
#ifndef FOLLY_CONV_INTERNAL
#undef FOLLY_RANGE_CHECK
+#undef FOLLY_RANGE_CHECK_STRINGIZE2
+#undef FOLLY_RANGE_CHECK_STRINGIZE
#endif
#endif /* FOLLY_BASE_CONV_H_ */
projects / folly.git / blobdiff