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author | Konstantin Käfer <mail@kkaefer.com> | 2016-05-17 18:34:13 +0200 |
---|---|---|
committer | Konstantin Käfer <mail@kkaefer.com> | 2016-05-18 12:26:51 +0200 |
commit | c5fc7f1980814a1063773e6c876dad66b7909adf (patch) | |
tree | ccfb86db993eca6b0ebc0b4df6f58ae80327e38f | |
parent | 002393bdead2f036982ea3adb8a13a3d58f3428a (diff) | |
download | qtlocation-mapboxgl-c5fc7f1980814a1063773e6c876dad66b7909adf.tar.gz |
[core] use rapidjson's dtoa implementation to stringify floating point numbers
-rw-r--r-- | include/mbgl/util/string.hpp | 14 | ||||
-rw-r--r-- | src/mbgl/util/dtoa.cpp | 97 | ||||
-rw-r--r-- | src/mbgl/util/dtoa.hpp | 22 | ||||
-rw-r--r-- | test/test.gypi | 1 | ||||
-rw-r--r-- | test/util/number_conversions.cpp | 55 |
5 files changed, 189 insertions, 0 deletions
diff --git a/include/mbgl/util/string.hpp b/include/mbgl/util/string.hpp index d422a9d8f7..5d3631e190 100644 --- a/include/mbgl/util/string.hpp +++ b/include/mbgl/util/string.hpp @@ -5,6 +5,8 @@ #include <cassert> #include <exception> +#include <mbgl/util/dtoa.hpp> + namespace mbgl { namespace util { @@ -21,6 +23,18 @@ inline std::string toString(uint8_t num) { return std::to_string(unsigned(num)); } +inline std::string toString(float num) { + return dtoa(num); +} + +inline std::string toString(double num) { + return dtoa(num); +} + +inline std::string toString(long double num) { + return dtoa(num); +} + inline std::string toString(std::exception_ptr error) { assert(error); diff --git a/src/mbgl/util/dtoa.cpp b/src/mbgl/util/dtoa.cpp new file mode 100644 index 0000000000..7ccee345f6 --- /dev/null +++ b/src/mbgl/util/dtoa.cpp @@ -0,0 +1,97 @@ +#include "dtoa.hpp" + +#include <rapidjson/internal/dtoa.h> + +namespace mbgl { +namespace util { + +namespace { + +// From https://github.com/miloyip/rapidjson/blob/master/include/rapidjson/internal/dtoa.h + +inline char* Prettify(char* buffer, int length, int k) { + constexpr int maxDecimalPlaces = 324; + const int kk = length + k; // 10^(kk-1) <= v < 10^kk + + if (0 <= k && kk <= 21) { + // 1234e7 -> 12340000000 + for (int i = length; i < kk; i++) + buffer[i] = '0'; + return &buffer[kk]; + } + else if (0 < kk && kk <= 21) { + // 1234e-2 -> 12.34 + std::memmove(&buffer[kk + 1], &buffer[kk], static_cast<size_t>(length - kk)); + buffer[kk] = '.'; + if (0 > k + maxDecimalPlaces) { + // When maxDecimalPlaces = 2, 1.2345 -> 1.23, 1.102 -> 1.1 + // Remove extra trailing zeros (at least one) after truncation. + for (int i = kk + maxDecimalPlaces; i > kk + 1; i--) + if (buffer[i] != '0') + return &buffer[i + 1]; + return &buffer[kk + 2]; // Reserve one zero + } + else + return &buffer[length + 1]; + } + else if (-6 < kk && kk <= 0) { + // 1234e-6 -> 0.001234 + const int offset = 2 - kk; + std::memmove(&buffer[offset], &buffer[0], static_cast<size_t>(length)); + buffer[0] = '0'; + buffer[1] = '.'; + for (int i = 2; i < offset; i++) + buffer[i] = '0'; + if (length - kk > maxDecimalPlaces) { + // When maxDecimalPlaces = 2, 0.123 -> 0.12, 0.102 -> 0.1 + // Remove extra trailing zeros (at least one) after truncation. + for (int i = maxDecimalPlaces + 1; i > 2; i--) + if (buffer[i] != '0') + return &buffer[i + 1]; + return &buffer[3]; // Reserve one zero + } + else + return &buffer[length + offset]; + } + else if (kk < -maxDecimalPlaces) { + // Truncate to zero + buffer[0] = '0'; + return &buffer[1]; + } + else if (length == 1) { + // 1e30 + buffer[1] = 'e'; + return rapidjson::internal::WriteExponent(kk - 1, &buffer[2]); + } + else { + // 1234e30 -> 1.234e33 + std::memmove(&buffer[2], &buffer[1], static_cast<size_t>(length - 1)); + buffer[1] = '.'; + buffer[length + 1] = 'e'; + return rapidjson::internal::WriteExponent(kk - 1, &buffer[0 + length + 2]); + } +} + +} // namespace + +char* dtoa(double value, char* buffer) { + rapidjson::internal::Double d(value); + if (d.IsZero()) { + if (d.Sign()) + *buffer++ = '-'; // -0.0, Issue #289 + buffer[0] = '0'; + return &buffer[1]; + } + else { + if (value < 0) { + *buffer++ = '-'; + value = -value; + } + int length, K; + rapidjson::internal::Grisu2(value, buffer, &length, &K); + return Prettify(buffer, length, K); + } +} + +} // namespace util +} // namespace mbgl diff --git a/src/mbgl/util/dtoa.hpp b/src/mbgl/util/dtoa.hpp new file mode 100644 index 0000000000..00c2c25ce2 --- /dev/null +++ b/src/mbgl/util/dtoa.hpp @@ -0,0 +1,22 @@ +#ifndef MBGL_UTIL_DTOA +#define MBGL_UTIL_DTOA + +#include <string> + +namespace mbgl { +namespace util { + +char* dtoa(double value, char* buffer); + +inline std::string dtoa(double value) { + std::string data; + data.resize(25); + auto end = dtoa(value, const_cast<char*>(data.data())); + data.resize(end - data.data()); + return data; +} + +} // end namespace util +} // end namespace mbgl + +#endif diff --git a/test/test.gypi b/test/test.gypi index 5c04262644..51e4a2e621 100644 --- a/test/test.gypi +++ b/test/test.gypi @@ -25,6 +25,7 @@ 'util/mapbox.cpp', 'util/merge_lines.cpp', 'util/run_loop.cpp', + 'util/number_conversions.cpp', 'util/text_conversions.cpp', 'util/thread.cpp', 'util/thread_local.cpp', diff --git a/test/util/number_conversions.cpp b/test/util/number_conversions.cpp new file mode 100644 index 0000000000..cfeda3eec7 --- /dev/null +++ b/test/util/number_conversions.cpp @@ -0,0 +1,55 @@ +#include <iostream> +#include <mbgl/test/util.hpp> + +#include <mbgl/util/string.hpp> + +using namespace mbgl; + +TEST(NumberConversions, number_to_string) { + EXPECT_EQ("0", util::toString(0)); + EXPECT_EQ("10", util::toString(10)); + EXPECT_EQ("-10", util::toString(-10)); + EXPECT_EQ("10", util::toString(10.0)); + EXPECT_EQ("-10", util::toString(-10.0)); + + EXPECT_EQ("1", util::toString(1)); + EXPECT_EQ("-1", util::toString(-1)); + EXPECT_EQ("32768", util::toString(32768)); + EXPECT_EQ("-32768", util::toString(-32768)); + + EXPECT_EQ("1", util::toString(1.000000)); + EXPECT_EQ("-1", util::toString(-1.000000)); + EXPECT_EQ("32768", util::toString(32768.000000)); + EXPECT_EQ("-32768", util::toString(-32768.000000)); + + EXPECT_EQ("1.01", util::toString(1.01)); + EXPECT_EQ("-1.01", util::toString(-1.01)); + EXPECT_EQ("32768.01", util::toString(32768.01)); + EXPECT_EQ("-32768.01", util::toString(-32768.01)); + + EXPECT_EQ("1.01", util::toString(1.0100)); + EXPECT_EQ("-1.01", util::toString(-1.0100)); + EXPECT_EQ("32768.01", util::toString(32768.0100)); + EXPECT_EQ("-32768.01", util::toString(-32768.0100)); + + EXPECT_EQ("1.123456", util::toString(1.123456)); + EXPECT_EQ("-1.123456", util::toString(-1.123456)); + EXPECT_EQ("32768.123456", util::toString(32768.123456)); + EXPECT_EQ("-32768.123456", util::toString(-32768.123456)); + + EXPECT_EQ("1.123456789", util::toString(1.123456789)); + EXPECT_EQ("-1.123456789", util::toString(-1.123456789)); + EXPECT_EQ("32768.123456789", util::toString(32768.123456789)); + EXPECT_EQ("-32768.123456789", util::toString(-32768.123456789)); + + EXPECT_EQ("3.141592653589793", util::toString(3.1415926535897932385128089594061862044327426701784)); + EXPECT_EQ("-3.141592653589793", util::toString(-3.1415926535897932385128089594061862044327426701784)); + + EXPECT_EQ("123456789", util::toString(123456789)); + + EXPECT_EQ("0.0000532", util::toString((long double)5.32e-5)); + EXPECT_EQ("5.32e-40", util::toString((long double)5.32e-40)); + + EXPECT_EQ("10", util::toString(unsigned(10))); + EXPECT_EQ("10", util::toString(unsigned(10.0))); +} |