third-party/benchmark/src/string_util.cc

   1 #include "string_util.h"
   2
   3 #include <array>
   4 #ifdef BENCHMARK_STL_ANDROID_GNUSTL
   5 #include <cerrno>
   6 #endif
   7 #include <cmath>
   8 #include <cstdarg>
   9 #include <cstdio>
  10 #include <memory>
  11 #include <sstream>
  12
  13 #include "arraysize.h"
  14
  15 namespace benchmark {
  16 namespace {
  17
  18 // kilo, Mega, Giga, Tera, Peta, Exa, Zetta, Yotta.
  19 const char kBigSIUnits[] = "kMGTPEZY";
  20 // Kibi, Mebi, Gibi, Tebi, Pebi, Exbi, Zebi, Yobi.
  21 const char kBigIECUnits[] = "KMGTPEZY";
  22 // milli, micro, nano, pico, femto, atto, zepto, yocto.
  23 const char kSmallSIUnits[] = "munpfazy";
  24
  25 // We require that all three arrays have the same size.
  26 static_assert(arraysize(kBigSIUnits) == arraysize(kBigIECUnits),
  27               "SI and IEC unit arrays must be the same size");
  28 static_assert(arraysize(kSmallSIUnits) == arraysize(kBigSIUnits),
  29               "Small SI and Big SI unit arrays must be the same size");
  30
  31 static const int64_t kUnitsSize = arraysize(kBigSIUnits);
  32
  33 void ToExponentAndMantissa(double val, double thresh, int precision,
  34                            double one_k, std::string* mantissa,
  35                            int64_t* exponent) {
  36   std::stringstream mantissa_stream;
  37
  38   if (val < 0) {
  39     mantissa_stream << "-";
  40     val = -val;
  41   }
  42
  43   // Adjust threshold so that it never excludes things which can't be rendered
  44   // in 'precision' digits.
  45   const double adjusted_threshold =
  46       std::max(thresh, 1.0 / std::pow(10.0, precision));
  47   const double big_threshold = adjusted_threshold * one_k;
  48   const double small_threshold = adjusted_threshold;
  49   // Values in ]simple_threshold,small_threshold[ will be printed as-is
  50   const double simple_threshold = 0.01;
  51
  52   if (val > big_threshold) {
  53     // Positive powers
  54     double scaled = val;
  55     for (size_t i = 0; i < arraysize(kBigSIUnits); ++i) {
  56       scaled /= one_k;
  57       if (scaled <= big_threshold) {
  58         mantissa_stream << scaled;
  59         *exponent = i + 1;
  60         *mantissa = mantissa_stream.str();
  61         return;
  62       }
  63     }
  64     mantissa_stream << val;
  65     *exponent = 0;
  66   } else if (val < small_threshold) {
  67     // Negative powers
  68     if (val < simple_threshold) {
  69       double scaled = val;
  70       for (size_t i = 0; i < arraysize(kSmallSIUnits); ++i) {
  71         scaled *= one_k;
  72         if (scaled >= small_threshold) {
  73           mantissa_stream << scaled;
  74           *exponent = -static_cast<int64_t>(i + 1);
  75           *mantissa = mantissa_stream.str();
  76           return;
  77         }
  78       }
  79     }
  80     mantissa_stream << val;
  81     *exponent = 0;
  82   } else {
  83     mantissa_stream << val;
  84     *exponent = 0;
  85   }
  86   *mantissa = mantissa_stream.str();
  87 }
  88
  89 std::string ExponentToPrefix(int64_t exponent, bool iec) {
  90   if (exponent == 0) return "";
  91
  92   const int64_t index = (exponent > 0 ? exponent - 1 : -exponent - 1);
  93   if (index >= kUnitsSize) return "";
  94
  95   const char* array =
  96       (exponent > 0 ? (iec ? kBigIECUnits : kBigSIUnits) : kSmallSIUnits);
  97   if (iec)
  98     return array[index] + std::string("i");
  99   else
 100     return std::string(1, array[index]);
 101 }
 102
 103 std::string ToBinaryStringFullySpecified(double value, double threshold,
 104                                          int precision, double one_k = 1024.0) {
 105   std::string mantissa;
 106   int64_t exponent;
 107   ToExponentAndMantissa(value, threshold, precision, one_k, &mantissa,
 108                         &exponent);
 109   return mantissa + ExponentToPrefix(exponent, false);
 110 }
 111
 112 }  // end namespace
 113
 114 void AppendHumanReadable(int n, std::string* str) {
 115   std::stringstream ss;
 116   // Round down to the nearest SI prefix.
 117   ss << ToBinaryStringFullySpecified(n, 1.0, 0);
 118   *str += ss.str();
 119 }
 120
 121 std::string HumanReadableNumber(double n, double one_k) {
 122   // 1.1 means that figures up to 1.1k should be shown with the next unit down;
 123   // this softens edge effects.
 124   // 1 means that we should show one decimal place of precision.
 125   return ToBinaryStringFullySpecified(n, 1.1, 1, one_k);
 126 }
 127
 128 std::string StrFormatImp(const char* msg, va_list args) {
 129   // we might need a second shot at this, so pre-emptivly make a copy
 130   va_list args_cp;
 131   va_copy(args_cp, args);
 132
 133   // TODO(ericwf): use std::array for first attempt to avoid one memory
 134   // allocation guess what the size might be
 135   std::array<char, 256> local_buff;
 136   std::size_t size = local_buff.size();
 137   // 2015-10-08: vsnprintf is used instead of snd::vsnprintf due to a limitation
 138   // in the android-ndk
 139   auto ret = vsnprintf(local_buff.data(), size, msg, args_cp);
 140
 141   va_end(args_cp);
 142
 143   // handle empty expansion
 144   if (ret == 0) return std::string{};
 145   if (static_cast<std::size_t>(ret) < size)
 146     return std::string(local_buff.data());
 147
 148   // we did not provide a long enough buffer on our first attempt.
 149   // add 1 to size to account for null-byte in size cast to prevent overflow
 150   size = static_cast<std::size_t>(ret) + 1;
 151   auto buff_ptr = std::unique_ptr<char[]>(new char[size]);
 152   // 2015-10-08: vsnprintf is used instead of snd::vsnprintf due to a limitation
 153   // in the android-ndk
 154   vsnprintf(buff_ptr.get(), size, msg, args);
 155   return std::string(buff_ptr.get());
 156 }
 157
 158 std::string StrFormat(const char* format, ...) {
 159   va_list args;
 160   va_start(args, format);
 161   std::string tmp = StrFormatImp(format, args);
 162   va_end(args);
 163   return tmp;
 164 }
 165
 166 std::vector<std::string> StrSplit(const std::string& str, char delim) {
 167   if (str.empty()) return {};
 168   std::vector<std::string> ret;
 169   size_t first = 0;
 170   size_t next = str.find(delim);
 171   for (; next != std::string::npos;
 172        first = next + 1, next = str.find(delim, first)) {
 173     ret.push_back(str.substr(first, next - first));
 174   }
 175   ret.push_back(str.substr(first));
 176   return ret;
 177 }
 178
 179 #ifdef BENCHMARK_STL_ANDROID_GNUSTL
 180 /*
 181  * GNU STL in Android NDK lacks support for some C++11 functions, including
 182  * stoul, stoi, stod. We reimplement them here using C functions strtoul,
 183  * strtol, strtod. Note that reimplemented functions are in benchmark::
 184  * namespace, not std:: namespace.
 185  */
 186 unsigned long stoul(const std::string& str, size_t* pos, int base) {
 187   /* Record previous errno */
 188   const int oldErrno = errno;
 189   errno = 0;
 190
 191   const char* strStart = str.c_str();
 192   char* strEnd = const_cast<char*>(strStart);
 193   const unsigned long result = strtoul(strStart, &strEnd, base);
 194
 195   const int strtoulErrno = errno;
 196   /* Restore previous errno */
 197   errno = oldErrno;
 198
 199   /* Check for errors and return */
 200   if (strtoulErrno == ERANGE) {
 201     throw std::out_of_range("stoul failed: " + str +
 202                             " is outside of range of unsigned long");
 203   } else if (strEnd == strStart || strtoulErrno != 0) {
 204     throw std::invalid_argument("stoul failed: " + str + " is not an integer");
 205   }
 206   if (pos != nullptr) {
 207     *pos = static_cast<size_t>(strEnd - strStart);
 208   }
 209   return result;
 210 }
 211
 212 int stoi(const std::string& str, size_t* pos, int base) {
 213   /* Record previous errno */
 214   const int oldErrno = errno;
 215   errno = 0;
 216
 217   const char* strStart = str.c_str();
 218   char* strEnd = const_cast<char*>(strStart);
 219   const long result = strtol(strStart, &strEnd, base);
 220
 221   const int strtolErrno = errno;
 222   /* Restore previous errno */
 223   errno = oldErrno;
 224
 225   /* Check for errors and return */
 226   if (strtolErrno == ERANGE || long(int(result)) != result) {
 227     throw std::out_of_range("stoul failed: " + str +
 228                             " is outside of range of int");
 229   } else if (strEnd == strStart || strtolErrno != 0) {
 230     throw std::invalid_argument("stoul failed: " + str + " is not an integer");
 231   }
 232   if (pos != nullptr) {
 233     *pos = static_cast<size_t>(strEnd - strStart);
 234   }
 235   return int(result);
 236 }
 237
 238 double stod(const std::string& str, size_t* pos) {
 239   /* Record previous errno */
 240   const int oldErrno = errno;
 241   errno = 0;
 242
 243   const char* strStart = str.c_str();
 244   char* strEnd = const_cast<char*>(strStart);
 245   const double result = strtod(strStart, &strEnd);
 246
 247   /* Restore previous errno */
 248   const int strtodErrno = errno;
 249   errno = oldErrno;
 250
 251   /* Check for errors and return */
 252   if (strtodErrno == ERANGE) {
 253     throw std::out_of_range("stoul failed: " + str +
 254                             " is outside of range of int");
 255   } else if (strEnd == strStart || strtodErrno != 0) {
 256     throw std::invalid_argument("stoul failed: " + str + " is not an integer");
 257   }
 258   if (pos != nullptr) {
 259     *pos = static_cast<size_t>(strEnd - strStart);
 260   }
 261   return result;
 262 }
 263 #endif
 264
 265 }  // end namespace benchmark