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lokinet/vendor/abseil-cpp/absl/strings/charconv_test.cc
Michael 41f9f5fad6
Import abseil LTS 20181200
2019-02-03 01:56:38 +00:00

773 lines
33 KiB
C++
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// Copyright 2018 The Abseil Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
#include "absl/strings/charconv.h"
#include <cstdlib>
#include <string>
#include "gmock/gmock.h"
#include "gtest/gtest.h"
#include "absl/strings/internal/pow10_helper.h"
#include "absl/strings/str_cat.h"
#include "absl/strings/str_format.h"
#ifdef _MSC_FULL_VER
#define ABSL_COMPILER_DOES_EXACT_ROUNDING 0
#define ABSL_STRTOD_HANDLES_NAN_CORRECTLY 0
#else
#define ABSL_COMPILER_DOES_EXACT_ROUNDING 1
#define ABSL_STRTOD_HANDLES_NAN_CORRECTLY 1
#endif
namespace {
using absl::strings_internal::Pow10;
#if ABSL_COMPILER_DOES_EXACT_ROUNDING
// Tests that the given string is accepted by absl::from_chars, and that it
// converts exactly equal to the given number.
void TestDoubleParse(absl::string_view str, double expected_number) {
SCOPED_TRACE(str);
double actual_number = 0.0;
absl::from_chars_result result =
absl::from_chars(str.data(), str.data() + str.length(), actual_number);
EXPECT_EQ(result.ec, std::errc());
EXPECT_EQ(result.ptr, str.data() + str.length());
EXPECT_EQ(actual_number, expected_number);
}
void TestFloatParse(absl::string_view str, float expected_number) {
SCOPED_TRACE(str);
float actual_number = 0.0;
absl::from_chars_result result =
absl::from_chars(str.data(), str.data() + str.length(), actual_number);
EXPECT_EQ(result.ec, std::errc());
EXPECT_EQ(result.ptr, str.data() + str.length());
EXPECT_EQ(actual_number, expected_number);
}
// Tests that the given double or single precision floating point literal is
// parsed correctly by absl::from_chars.
//
// These convenience macros assume that the C++ compiler being used also does
// fully correct decimal-to-binary conversions.
#define FROM_CHARS_TEST_DOUBLE(number) \
{ \
TestDoubleParse(#number, number); \
TestDoubleParse("-" #number, -number); \
}
#define FROM_CHARS_TEST_FLOAT(number) \
{ \
TestFloatParse(#number, number##f); \
TestFloatParse("-" #number, -number##f); \
}
TEST(FromChars, NearRoundingCases) {
// Cases from "A Program for Testing IEEE Decimal-Binary Conversion"
// by Vern Paxson.
// Forms that should round towards zero. (These are the hardest cases for
// each decimal mantissa size.)
FROM_CHARS_TEST_DOUBLE(5.e125);
FROM_CHARS_TEST_DOUBLE(69.e267);
FROM_CHARS_TEST_DOUBLE(999.e-026);
FROM_CHARS_TEST_DOUBLE(7861.e-034);
FROM_CHARS_TEST_DOUBLE(75569.e-254);
FROM_CHARS_TEST_DOUBLE(928609.e-261);
FROM_CHARS_TEST_DOUBLE(9210917.e080);
FROM_CHARS_TEST_DOUBLE(84863171.e114);
FROM_CHARS_TEST_DOUBLE(653777767.e273);
FROM_CHARS_TEST_DOUBLE(5232604057.e-298);
FROM_CHARS_TEST_DOUBLE(27235667517.e-109);
FROM_CHARS_TEST_DOUBLE(653532977297.e-123);
FROM_CHARS_TEST_DOUBLE(3142213164987.e-294);
FROM_CHARS_TEST_DOUBLE(46202199371337.e-072);
FROM_CHARS_TEST_DOUBLE(231010996856685.e-073);
FROM_CHARS_TEST_DOUBLE(9324754620109615.e212);
FROM_CHARS_TEST_DOUBLE(78459735791271921.e049);
FROM_CHARS_TEST_DOUBLE(272104041512242479.e200);
FROM_CHARS_TEST_DOUBLE(6802601037806061975.e198);
FROM_CHARS_TEST_DOUBLE(20505426358836677347.e-221);
FROM_CHARS_TEST_DOUBLE(836168422905420598437.e-234);
FROM_CHARS_TEST_DOUBLE(4891559871276714924261.e222);
FROM_CHARS_TEST_FLOAT(5.e-20);
FROM_CHARS_TEST_FLOAT(67.e14);
FROM_CHARS_TEST_FLOAT(985.e15);
FROM_CHARS_TEST_FLOAT(7693.e-42);
FROM_CHARS_TEST_FLOAT(55895.e-16);
FROM_CHARS_TEST_FLOAT(996622.e-44);
FROM_CHARS_TEST_FLOAT(7038531.e-32);
FROM_CHARS_TEST_FLOAT(60419369.e-46);
FROM_CHARS_TEST_FLOAT(702990899.e-20);
FROM_CHARS_TEST_FLOAT(6930161142.e-48);
FROM_CHARS_TEST_FLOAT(25933168707.e-13);
FROM_CHARS_TEST_FLOAT(596428896559.e20);
// Similarly, forms that should round away from zero.
FROM_CHARS_TEST_DOUBLE(9.e-265);
FROM_CHARS_TEST_DOUBLE(85.e-037);
FROM_CHARS_TEST_DOUBLE(623.e100);
FROM_CHARS_TEST_DOUBLE(3571.e263);
FROM_CHARS_TEST_DOUBLE(81661.e153);
FROM_CHARS_TEST_DOUBLE(920657.e-023);
FROM_CHARS_TEST_DOUBLE(4603285.e-024);
FROM_CHARS_TEST_DOUBLE(87575437.e-309);
FROM_CHARS_TEST_DOUBLE(245540327.e122);
FROM_CHARS_TEST_DOUBLE(6138508175.e120);
FROM_CHARS_TEST_DOUBLE(83356057653.e193);
FROM_CHARS_TEST_DOUBLE(619534293513.e124);
FROM_CHARS_TEST_DOUBLE(2335141086879.e218);
FROM_CHARS_TEST_DOUBLE(36167929443327.e-159);
FROM_CHARS_TEST_DOUBLE(609610927149051.e-255);
FROM_CHARS_TEST_DOUBLE(3743626360493413.e-165);
FROM_CHARS_TEST_DOUBLE(94080055902682397.e-242);
FROM_CHARS_TEST_DOUBLE(899810892172646163.e283);
FROM_CHARS_TEST_DOUBLE(7120190517612959703.e120);
FROM_CHARS_TEST_DOUBLE(25188282901709339043.e-252);
FROM_CHARS_TEST_DOUBLE(308984926168550152811.e-052);
FROM_CHARS_TEST_DOUBLE(6372891218502368041059.e064);
FROM_CHARS_TEST_FLOAT(3.e-23);
FROM_CHARS_TEST_FLOAT(57.e18);
FROM_CHARS_TEST_FLOAT(789.e-35);
FROM_CHARS_TEST_FLOAT(2539.e-18);
FROM_CHARS_TEST_FLOAT(76173.e28);
FROM_CHARS_TEST_FLOAT(887745.e-11);
FROM_CHARS_TEST_FLOAT(5382571.e-37);
FROM_CHARS_TEST_FLOAT(82381273.e-35);
FROM_CHARS_TEST_FLOAT(750486563.e-38);
FROM_CHARS_TEST_FLOAT(3752432815.e-39);
FROM_CHARS_TEST_FLOAT(75224575729.e-45);
FROM_CHARS_TEST_FLOAT(459926601011.e15);
}
#undef FROM_CHARS_TEST_DOUBLE
#undef FROM_CHARS_TEST_FLOAT
#endif
float ToFloat(absl::string_view s) {
float f;
absl::from_chars(s.data(), s.data() + s.size(), f);
return f;
}
double ToDouble(absl::string_view s) {
double d;
absl::from_chars(s.data(), s.data() + s.size(), d);
return d;
}
// A duplication of the test cases in "NearRoundingCases" above, but with
// expected values expressed with integers, using ldexp/ldexpf. These test
// cases will work even on compilers that do not accurately round floating point
// literals.
TEST(FromChars, NearRoundingCasesExplicit) {
EXPECT_EQ(ToDouble("5.e125"), ldexp(6653062250012735, 365));
EXPECT_EQ(ToDouble("69.e267"), ldexp(4705683757438170, 841));
EXPECT_EQ(ToDouble("999.e-026"), ldexp(6798841691080350, -129));
EXPECT_EQ(ToDouble("7861.e-034"), ldexp(8975675289889240, -153));
EXPECT_EQ(ToDouble("75569.e-254"), ldexp(6091718967192243, -880));
EXPECT_EQ(ToDouble("928609.e-261"), ldexp(7849264900213743, -900));
EXPECT_EQ(ToDouble("9210917.e080"), ldexp(8341110837370930, 236));
EXPECT_EQ(ToDouble("84863171.e114"), ldexp(4625202867375927, 353));
EXPECT_EQ(ToDouble("653777767.e273"), ldexp(5068902999763073, 884));
EXPECT_EQ(ToDouble("5232604057.e-298"), ldexp(5741343011915040, -1010));
EXPECT_EQ(ToDouble("27235667517.e-109"), ldexp(6707124626673586, -380));
EXPECT_EQ(ToDouble("653532977297.e-123"), ldexp(7078246407265384, -422));
EXPECT_EQ(ToDouble("3142213164987.e-294"), ldexp(8219991337640559, -988));
EXPECT_EQ(ToDouble("46202199371337.e-072"), ldexp(5224462102115359, -246));
EXPECT_EQ(ToDouble("231010996856685.e-073"), ldexp(5224462102115359, -247));
EXPECT_EQ(ToDouble("9324754620109615.e212"), ldexp(5539753864394442, 705));
EXPECT_EQ(ToDouble("78459735791271921.e049"), ldexp(8388176519442766, 166));
EXPECT_EQ(ToDouble("272104041512242479.e200"), ldexp(5554409530847367, 670));
EXPECT_EQ(ToDouble("6802601037806061975.e198"), ldexp(5554409530847367, 668));
EXPECT_EQ(ToDouble("20505426358836677347.e-221"),
ldexp(4524032052079546, -722));
EXPECT_EQ(ToDouble("836168422905420598437.e-234"),
ldexp(5070963299887562, -760));
EXPECT_EQ(ToDouble("4891559871276714924261.e222"),
ldexp(6452687840519111, 757));
EXPECT_EQ(ToFloat("5.e-20"), ldexpf(15474250, -88));
EXPECT_EQ(ToFloat("67.e14"), ldexpf(12479722, 29));
EXPECT_EQ(ToFloat("985.e15"), ldexpf(14333636, 36));
EXPECT_EQ(ToFloat("7693.e-42"), ldexpf(10979816, -150));
EXPECT_EQ(ToFloat("55895.e-16"), ldexpf(12888509, -61));
EXPECT_EQ(ToFloat("996622.e-44"), ldexpf(14224264, -150));
EXPECT_EQ(ToFloat("7038531.e-32"), ldexpf(11420669, -107));
EXPECT_EQ(ToFloat("60419369.e-46"), ldexpf(8623340, -150));
EXPECT_EQ(ToFloat("702990899.e-20"), ldexpf(16209866, -61));
EXPECT_EQ(ToFloat("6930161142.e-48"), ldexpf(9891056, -150));
EXPECT_EQ(ToFloat("25933168707.e-13"), ldexpf(11138211, -32));
EXPECT_EQ(ToFloat("596428896559.e20"), ldexpf(12333860, 82));
EXPECT_EQ(ToDouble("9.e-265"), ldexp(8168427841980010, -930));
EXPECT_EQ(ToDouble("85.e-037"), ldexp(6360455125664090, -169));
EXPECT_EQ(ToDouble("623.e100"), ldexp(6263531988747231, 289));
EXPECT_EQ(ToDouble("3571.e263"), ldexp(6234526311072170, 833));
EXPECT_EQ(ToDouble("81661.e153"), ldexp(6696636728760206, 472));
EXPECT_EQ(ToDouble("920657.e-023"), ldexp(5975405561110124, -109));
EXPECT_EQ(ToDouble("4603285.e-024"), ldexp(5975405561110124, -110));
EXPECT_EQ(ToDouble("87575437.e-309"), ldexp(8452160731874668, -1053));
EXPECT_EQ(ToDouble("245540327.e122"), ldexp(4985336549131723, 381));
EXPECT_EQ(ToDouble("6138508175.e120"), ldexp(4985336549131723, 379));
EXPECT_EQ(ToDouble("83356057653.e193"), ldexp(5986732817132056, 625));
EXPECT_EQ(ToDouble("619534293513.e124"), ldexp(4798406992060657, 399));
EXPECT_EQ(ToDouble("2335141086879.e218"), ldexp(5419088166961646, 713));
EXPECT_EQ(ToDouble("36167929443327.e-159"), ldexp(8135819834632444, -536));
EXPECT_EQ(ToDouble("609610927149051.e-255"), ldexp(4576664294594737, -850));
EXPECT_EQ(ToDouble("3743626360493413.e-165"), ldexp(6898586531774201, -549));
EXPECT_EQ(ToDouble("94080055902682397.e-242"), ldexp(6273271706052298, -800));
EXPECT_EQ(ToDouble("899810892172646163.e283"), ldexp(7563892574477827, 947));
EXPECT_EQ(ToDouble("7120190517612959703.e120"), ldexp(5385467232557565, 409));
EXPECT_EQ(ToDouble("25188282901709339043.e-252"),
ldexp(5635662608542340, -825));
EXPECT_EQ(ToDouble("308984926168550152811.e-052"),
ldexp(5644774693823803, -157));
EXPECT_EQ(ToDouble("6372891218502368041059.e064"),
ldexp(4616868614322430, 233));
EXPECT_EQ(ToFloat("3.e-23"), ldexpf(9507380, -98));
EXPECT_EQ(ToFloat("57.e18"), ldexpf(12960300, 42));
EXPECT_EQ(ToFloat("789.e-35"), ldexpf(10739312, -130));
EXPECT_EQ(ToFloat("2539.e-18"), ldexpf(11990089, -72));
EXPECT_EQ(ToFloat("76173.e28"), ldexpf(9845130, 86));
EXPECT_EQ(ToFloat("887745.e-11"), ldexpf(9760860, -40));
EXPECT_EQ(ToFloat("5382571.e-37"), ldexpf(11447463, -124));
EXPECT_EQ(ToFloat("82381273.e-35"), ldexpf(8554961, -113));
EXPECT_EQ(ToFloat("750486563.e-38"), ldexpf(9975678, -120));
EXPECT_EQ(ToFloat("3752432815.e-39"), ldexpf(9975678, -121));
EXPECT_EQ(ToFloat("75224575729.e-45"), ldexpf(13105970, -137));
EXPECT_EQ(ToFloat("459926601011.e15"), ldexpf(12466336, 65));
}
// Common test logic for converting a string which lies exactly halfway between
// two target floats.
//
// mantissa and exponent represent the precise value between two floating point
// numbers, `expected_low` and `expected_high`. The floating point
// representation to parse in `StrCat(mantissa, "e", exponent)`.
//
// This function checks that an input just slightly less than the exact value
// is rounded down to `expected_low`, and an input just slightly greater than
// the exact value is rounded up to `expected_high`.
//
// The exact value should round to `expected_half`, which must be either
// `expected_low` or `expected_high`.
template <typename FloatType>
void TestHalfwayValue(const std::string& mantissa, int exponent,
FloatType expected_low, FloatType expected_high,
FloatType expected_half) {
std::string low_rep = mantissa;
low_rep[low_rep.size() - 1] -= 1;
absl::StrAppend(&low_rep, std::string(1000, '9'), "e", exponent);
FloatType actual_low = 0;
absl::from_chars(low_rep.data(), low_rep.data() + low_rep.size(), actual_low);
EXPECT_EQ(expected_low, actual_low);
std::string high_rep = absl::StrCat(mantissa, std::string(1000, '0'), "1e", exponent);
FloatType actual_high = 0;
absl::from_chars(high_rep.data(), high_rep.data() + high_rep.size(),
actual_high);
EXPECT_EQ(expected_high, actual_high);
std::string halfway_rep = absl::StrCat(mantissa, "e", exponent);
FloatType actual_half = 0;
absl::from_chars(halfway_rep.data(), halfway_rep.data() + halfway_rep.size(),
actual_half);
EXPECT_EQ(expected_half, actual_half);
}
TEST(FromChars, DoubleRounding) {
const double zero = 0.0;
const double first_subnormal = nextafter(zero, 1.0);
const double second_subnormal = nextafter(first_subnormal, 1.0);
const double first_normal = DBL_MIN;
const double last_subnormal = nextafter(first_normal, 0.0);
const double second_normal = nextafter(first_normal, 1.0);
const double last_normal = DBL_MAX;
const double penultimate_normal = nextafter(last_normal, 0.0);
// Various test cases for numbers between two representable floats. Each
// call to TestHalfwayValue tests a number just below and just above the
// halfway point, as well as the number exactly between them.
// Test between zero and first_subnormal. Round-to-even tie rounds down.
TestHalfwayValue(
"2."
"470328229206232720882843964341106861825299013071623822127928412503377536"
"351043759326499181808179961898982823477228588654633283551779698981993873"
"980053909390631503565951557022639229085839244910518443593180284993653615"
"250031937045767824921936562366986365848075700158576926990370631192827955"
"855133292783433840935197801553124659726357957462276646527282722005637400"
"648549997709659947045402082816622623785739345073633900796776193057750674"
"017632467360096895134053553745851666113422376667860416215968046191446729"
"184030053005753084904876539171138659164623952491262365388187963623937328"
"042389101867234849766823508986338858792562830275599565752445550725518931"
"369083625477918694866799496832404970582102851318545139621383772282614543"
"7693412532098591327667236328125",
-324, zero, first_subnormal, zero);
// first_subnormal and second_subnormal. Round-to-even tie rounds up.
TestHalfwayValue(
"7."
"410984687618698162648531893023320585475897039214871466383785237510132609"
"053131277979497545424539885696948470431685765963899850655339096945981621"
"940161728171894510697854671067917687257517734731555330779540854980960845"
"750095811137303474765809687100959097544227100475730780971111893578483867"
"565399878350301522805593404659373979179073872386829939581848166016912201"
"945649993128979841136206248449867871357218035220901702390328579173252022"
"052897402080290685402160661237554998340267130003581248647904138574340187"
"552090159017259254714629617513415977493871857473787096164563890871811984"
"127167305601704549300470526959016576377688490826798697257336652176556794"
"107250876433756084600398490497214911746308553955635418864151316847843631"
"3080237596295773983001708984375",
-324, first_subnormal, second_subnormal, second_subnormal);
// last_subnormal and first_normal. Round-to-even tie rounds up.
TestHalfwayValue(
"2."
"225073858507201136057409796709131975934819546351645648023426109724822222"
"021076945516529523908135087914149158913039621106870086438694594645527657"
"207407820621743379988141063267329253552286881372149012981122451451889849"
"057222307285255133155755015914397476397983411801999323962548289017107081"
"850690630666655994938275772572015763062690663332647565300009245888316433"
"037779791869612049497390377829704905051080609940730262937128958950003583"
"799967207254304360284078895771796150945516748243471030702609144621572289"
"880258182545180325707018860872113128079512233426288368622321503775666622"
"503982534335974568884423900265498198385487948292206894721689831099698365"
"846814022854243330660339850886445804001034933970427567186443383770486037"
"86162277173854562306587467901408672332763671875",
-308, last_subnormal, first_normal, first_normal);
// first_normal and second_normal. Round-to-even tie rounds down.
TestHalfwayValue(
"2."
"225073858507201630123055637955676152503612414573018013083228724049586647"
"606759446192036794116886953213985520549032000903434781884412325572184367"
"563347617020518175998922941393629966742598285899994830148971433555578567"
"693279306015978183162142425067962460785295885199272493577688320732492479"
"924816869232247165964934329258783950102250973957579510571600738343645738"
"494324192997092179207389919761694314131497173265255020084997973676783743"
"155205818804439163810572367791175177756227497413804253387084478193655533"
"073867420834526162513029462022730109054820067654020201547112002028139700"
"141575259123440177362244273712468151750189745559978653234255886219611516"
"335924167958029604477064946470184777360934300451421683607013647479513962"
"13837722826145437693412532098591327667236328125",
-308, first_normal, second_normal, first_normal);
// penultimate_normal and last_normal. Round-to-even rounds down.
TestHalfwayValue(
"1."
"797693134862315608353258760581052985162070023416521662616611746258695532"
"672923265745300992879465492467506314903358770175220871059269879629062776"
"047355692132901909191523941804762171253349609463563872612866401980290377"
"995141836029815117562837277714038305214839639239356331336428021390916694"
"57927874464075218944",
308, penultimate_normal, last_normal, penultimate_normal);
}
// Same test cases as DoubleRounding, now with new and improved Much Smaller
// Precision!
TEST(FromChars, FloatRounding) {
const float zero = 0.0;
const float first_subnormal = nextafterf(zero, 1.0);
const float second_subnormal = nextafterf(first_subnormal, 1.0);
const float first_normal = FLT_MIN;
const float last_subnormal = nextafterf(first_normal, 0.0);
const float second_normal = nextafterf(first_normal, 1.0);
const float last_normal = FLT_MAX;
const float penultimate_normal = nextafterf(last_normal, 0.0);
// Test between zero and first_subnormal. Round-to-even tie rounds down.
TestHalfwayValue(
"7."
"006492321624085354618647916449580656401309709382578858785341419448955413"
"42930300743319094181060791015625",
-46, zero, first_subnormal, zero);
// first_subnormal and second_subnormal. Round-to-even tie rounds up.
TestHalfwayValue(
"2."
"101947696487225606385594374934874196920392912814773657635602425834686624"
"028790902229957282543182373046875",
-45, first_subnormal, second_subnormal, second_subnormal);
// last_subnormal and first_normal. Round-to-even tie rounds up.
TestHalfwayValue(
"1."
"175494280757364291727882991035766513322858992758990427682963118425003064"
"9651730385585324256680905818939208984375",
-38, last_subnormal, first_normal, first_normal);
// first_normal and second_normal. Round-to-even tie rounds down.
TestHalfwayValue(
"1."
"175494420887210724209590083408724842314472120785184615334540294131831453"
"9442813071445925743319094181060791015625",
-38, first_normal, second_normal, first_normal);
// penultimate_normal and last_normal. Round-to-even rounds down.
TestHalfwayValue("3.40282336497324057985868971510891282432", 38,
penultimate_normal, last_normal, penultimate_normal);
}
TEST(FromChars, Underflow) {
// Check that underflow is handled correctly, according to the specification
// in DR 3081.
double d;
float f;
absl::from_chars_result result;
std::string negative_underflow = "-1e-1000";
const char* begin = negative_underflow.data();
const char* end = begin + negative_underflow.size();
d = 100.0;
result = absl::from_chars(begin, end, d);
EXPECT_EQ(result.ptr, end);
EXPECT_EQ(result.ec, std::errc::result_out_of_range);
EXPECT_TRUE(std::signbit(d)); // negative
EXPECT_GE(d, -std::numeric_limits<double>::min());
f = 100.0;
result = absl::from_chars(begin, end, f);
EXPECT_EQ(result.ptr, end);
EXPECT_EQ(result.ec, std::errc::result_out_of_range);
EXPECT_TRUE(std::signbit(f)); // negative
EXPECT_GE(f, -std::numeric_limits<float>::min());
std::string positive_underflow = "1e-1000";
begin = positive_underflow.data();
end = begin + positive_underflow.size();
d = -100.0;
result = absl::from_chars(begin, end, d);
EXPECT_EQ(result.ptr, end);
EXPECT_EQ(result.ec, std::errc::result_out_of_range);
EXPECT_FALSE(std::signbit(d)); // positive
EXPECT_LE(d, std::numeric_limits<double>::min());
f = -100.0;
result = absl::from_chars(begin, end, f);
EXPECT_EQ(result.ptr, end);
EXPECT_EQ(result.ec, std::errc::result_out_of_range);
EXPECT_FALSE(std::signbit(f)); // positive
EXPECT_LE(f, std::numeric_limits<float>::min());
}
TEST(FromChars, Overflow) {
// Check that overflow is handled correctly, according to the specification
// in DR 3081.
double d;
float f;
absl::from_chars_result result;
std::string negative_overflow = "-1e1000";
const char* begin = negative_overflow.data();
const char* end = begin + negative_overflow.size();
d = 100.0;
result = absl::from_chars(begin, end, d);
EXPECT_EQ(result.ptr, end);
EXPECT_EQ(result.ec, std::errc::result_out_of_range);
EXPECT_TRUE(std::signbit(d)); // negative
EXPECT_EQ(d, -std::numeric_limits<double>::max());
f = 100.0;
result = absl::from_chars(begin, end, f);
EXPECT_EQ(result.ptr, end);
EXPECT_EQ(result.ec, std::errc::result_out_of_range);
EXPECT_TRUE(std::signbit(f)); // negative
EXPECT_EQ(f, -std::numeric_limits<float>::max());
std::string positive_overflow = "1e1000";
begin = positive_overflow.data();
end = begin + positive_overflow.size();
d = -100.0;
result = absl::from_chars(begin, end, d);
EXPECT_EQ(result.ptr, end);
EXPECT_EQ(result.ec, std::errc::result_out_of_range);
EXPECT_FALSE(std::signbit(d)); // positive
EXPECT_EQ(d, std::numeric_limits<double>::max());
f = -100.0;
result = absl::from_chars(begin, end, f);
EXPECT_EQ(result.ptr, end);
EXPECT_EQ(result.ec, std::errc::result_out_of_range);
EXPECT_FALSE(std::signbit(f)); // positive
EXPECT_EQ(f, std::numeric_limits<float>::max());
}
TEST(FromChars, ReturnValuePtr) {
// Check that `ptr` points one past the number scanned, even if that number
// is not representable.
double d;
absl::from_chars_result result;
std::string normal = "3.14@#$%@#$%";
result = absl::from_chars(normal.data(), normal.data() + normal.size(), d);
EXPECT_EQ(result.ec, std::errc());
EXPECT_EQ(result.ptr - normal.data(), 4);
std::string overflow = "1e1000@#$%@#$%";
result = absl::from_chars(overflow.data(),
overflow.data() + overflow.size(), d);
EXPECT_EQ(result.ec, std::errc::result_out_of_range);
EXPECT_EQ(result.ptr - overflow.data(), 6);
std::string garbage = "#$%@#$%";
result = absl::from_chars(garbage.data(),
garbage.data() + garbage.size(), d);
EXPECT_EQ(result.ec, std::errc::invalid_argument);
EXPECT_EQ(result.ptr - garbage.data(), 0);
}
// Check for a wide range of inputs that strtod() and absl::from_chars() exactly
// agree on the conversion amount.
//
// This test assumes the platform's strtod() uses perfect round_to_nearest
// rounding.
TEST(FromChars, TestVersusStrtod) {
for (int mantissa = 1000000; mantissa <= 9999999; mantissa += 501) {
for (int exponent = -300; exponent < 300; ++exponent) {
std::string candidate = absl::StrCat(mantissa, "e", exponent);
double strtod_value = strtod(candidate.c_str(), nullptr);
double absl_value = 0;
absl::from_chars(candidate.data(), candidate.data() + candidate.size(),
absl_value);
ASSERT_EQ(strtod_value, absl_value) << candidate;
}
}
}
// Check for a wide range of inputs that strtof() and absl::from_chars() exactly
// agree on the conversion amount.
//
// This test assumes the platform's strtof() uses perfect round_to_nearest
// rounding.
TEST(FromChars, TestVersusStrtof) {
for (int mantissa = 1000000; mantissa <= 9999999; mantissa += 501) {
for (int exponent = -43; exponent < 32; ++exponent) {
std::string candidate = absl::StrCat(mantissa, "e", exponent);
float strtod_value = strtof(candidate.c_str(), nullptr);
float absl_value = 0;
absl::from_chars(candidate.data(), candidate.data() + candidate.size(),
absl_value);
ASSERT_EQ(strtod_value, absl_value) << candidate;
}
}
}
// Tests if two floating point values have identical bit layouts. (EXPECT_EQ
// is not suitable for NaN testing, since NaNs are never equal.)
template <typename Float>
bool Identical(Float a, Float b) {
return 0 == memcmp(&a, &b, sizeof(Float));
}
// Check that NaNs are parsed correctly. The spec requires that
// std::from_chars on "NaN(123abc)" return the same value as std::nan("123abc").
// How such an n-char-sequence affects the generated NaN is unspecified, so we
// just test for symmetry with std::nan and strtod here.
//
// (In Linux, this parses the value as a number and stuffs that number into the
// free bits of a quiet NaN.)
TEST(FromChars, NaNDoubles) {
for (std::string n_char_sequence :
{"", "1", "2", "3", "fff", "FFF", "200000", "400000", "4000000000000",
"8000000000000", "abc123", "legal_but_unexpected",
"99999999999999999999999", "_"}) {
std::string input = absl::StrCat("nan(", n_char_sequence, ")");
SCOPED_TRACE(input);
double from_chars_double;
absl::from_chars(input.data(), input.data() + input.size(),
from_chars_double);
double std_nan_double = std::nan(n_char_sequence.c_str());
EXPECT_TRUE(Identical(from_chars_double, std_nan_double));
// Also check that we match strtod()'s behavior. This test assumes that the
// platform has a compliant strtod().
#if ABSL_STRTOD_HANDLES_NAN_CORRECTLY
double strtod_double = strtod(input.c_str(), nullptr);
EXPECT_TRUE(Identical(from_chars_double, strtod_double));
#endif // ABSL_STRTOD_HANDLES_NAN_CORRECTLY
// Check that we can parse a negative NaN
std::string negative_input = "-" + input;
double negative_from_chars_double;
absl::from_chars(negative_input.data(),
negative_input.data() + negative_input.size(),
negative_from_chars_double);
EXPECT_TRUE(std::signbit(negative_from_chars_double));
EXPECT_FALSE(Identical(negative_from_chars_double, from_chars_double));
from_chars_double = std::copysign(from_chars_double, -1.0);
EXPECT_TRUE(Identical(negative_from_chars_double, from_chars_double));
}
}
TEST(FromChars, NaNFloats) {
for (std::string n_char_sequence :
{"", "1", "2", "3", "fff", "FFF", "200000", "400000", "4000000000000",
"8000000000000", "abc123", "legal_but_unexpected",
"99999999999999999999999", "_"}) {
std::string input = absl::StrCat("nan(", n_char_sequence, ")");
SCOPED_TRACE(input);
float from_chars_float;
absl::from_chars(input.data(), input.data() + input.size(),
from_chars_float);
float std_nan_float = std::nanf(n_char_sequence.c_str());
EXPECT_TRUE(Identical(from_chars_float, std_nan_float));
// Also check that we match strtof()'s behavior. This test assumes that the
// platform has a compliant strtof().
#if ABSL_STRTOD_HANDLES_NAN_CORRECTLY
float strtof_float = strtof(input.c_str(), nullptr);
EXPECT_TRUE(Identical(from_chars_float, strtof_float));
#endif // ABSL_STRTOD_HANDLES_NAN_CORRECTLY
// Check that we can parse a negative NaN
std::string negative_input = "-" + input;
float negative_from_chars_float;
absl::from_chars(negative_input.data(),
negative_input.data() + negative_input.size(),
negative_from_chars_float);
EXPECT_TRUE(std::signbit(negative_from_chars_float));
EXPECT_FALSE(Identical(negative_from_chars_float, from_chars_float));
from_chars_float = std::copysign(from_chars_float, -1.0);
EXPECT_TRUE(Identical(negative_from_chars_float, from_chars_float));
}
}
// Returns an integer larger than step. The values grow exponentially.
int NextStep(int step) {
return step + (step >> 2) + 1;
}
// Test a conversion on a family of input strings, checking that the calculation
// is correct for in-bounds values, and that overflow and underflow are done
// correctly for out-of-bounds values.
//
// input_generator maps from an integer index to a string to test.
// expected_generator maps from an integer index to an expected Float value.
// from_chars conversion of input_generator(i) should result in
// expected_generator(i).
//
// lower_bound and upper_bound denote the smallest and largest values for which
// the conversion is expected to succeed.
template <typename Float>
void TestOverflowAndUnderflow(
const std::function<std::string(int)>& input_generator,
const std::function<Float(int)>& expected_generator, int lower_bound,
int upper_bound) {
// test legal values near lower_bound
int index, step;
for (index = lower_bound, step = 1; index < upper_bound;
index += step, step = NextStep(step)) {
std::string input = input_generator(index);
SCOPED_TRACE(input);
Float expected = expected_generator(index);
Float actual;
auto result =
absl::from_chars(input.data(), input.data() + input.size(), actual);
EXPECT_EQ(result.ec, std::errc());
EXPECT_EQ(expected, actual)
<< absl::StrFormat("%a vs %a", expected, actual);
}
// test legal values near upper_bound
for (index = upper_bound, step = 1; index > lower_bound;
index -= step, step = NextStep(step)) {
std::string input = input_generator(index);
SCOPED_TRACE(input);
Float expected = expected_generator(index);
Float actual;
auto result =
absl::from_chars(input.data(), input.data() + input.size(), actual);
EXPECT_EQ(result.ec, std::errc());
EXPECT_EQ(expected, actual)
<< absl::StrFormat("%a vs %a", expected, actual);
}
// Test underflow values below lower_bound
for (index = lower_bound - 1, step = 1; index > -1000000;
index -= step, step = NextStep(step)) {
std::string input = input_generator(index);
SCOPED_TRACE(input);
Float actual;
auto result =
absl::from_chars(input.data(), input.data() + input.size(), actual);
EXPECT_EQ(result.ec, std::errc::result_out_of_range);
EXPECT_LT(actual, 1.0); // check for underflow
}
// Test overflow values above upper_bound
for (index = upper_bound + 1, step = 1; index < 1000000;
index += step, step = NextStep(step)) {
std::string input = input_generator(index);
SCOPED_TRACE(input);
Float actual;
auto result =
absl::from_chars(input.data(), input.data() + input.size(), actual);
EXPECT_EQ(result.ec, std::errc::result_out_of_range);
EXPECT_GT(actual, 1.0); // check for overflow
}
}
// Check that overflow and underflow are caught correctly for hex doubles.
//
// The largest representable double is 0x1.fffffffffffffp+1023, and the
// smallest representable subnormal is 0x0.0000000000001p-1022, which equals
// 0x1p-1074. Therefore 1023 and -1074 are the limits of acceptable exponents
// in this test.
TEST(FromChars, HexdecimalDoubleLimits) {
auto input_gen = [](int index) { return absl::StrCat("0x1.0p", index); };
auto expected_gen = [](int index) { return std::ldexp(1.0, index); };
TestOverflowAndUnderflow<double>(input_gen, expected_gen, -1074, 1023);
}
// Check that overflow and underflow are caught correctly for hex floats.
//
// The largest representable float is 0x1.fffffep+127, and the smallest
// representable subnormal is 0x0.000002p-126, which equals 0x1p-149.
// Therefore 127 and -149 are the limits of acceptable exponents in this test.
TEST(FromChars, HexdecimalFloatLimits) {
auto input_gen = [](int index) { return absl::StrCat("0x1.0p", index); };
auto expected_gen = [](int index) { return std::ldexp(1.0f, index); };
TestOverflowAndUnderflow<float>(input_gen, expected_gen, -149, 127);
}
// Check that overflow and underflow are caught correctly for decimal doubles.
//
// The largest representable double is about 1.8e308, and the smallest
// representable subnormal is about 5e-324. '1e-324' therefore rounds away from
// the smallest representable positive value. -323 and 308 are the limits of
// acceptable exponents in this test.
TEST(FromChars, DecimalDoubleLimits) {
auto input_gen = [](int index) { return absl::StrCat("1.0e", index); };
auto expected_gen = [](int index) { return Pow10(index); };
TestOverflowAndUnderflow<double>(input_gen, expected_gen, -323, 308);
}
// Check that overflow and underflow are caught correctly for decimal floats.
//
// The largest representable float is about 3.4e38, and the smallest
// representable subnormal is about 1.45e-45. '1e-45' therefore rounds towards
// the smallest representable positive value. -45 and 38 are the limits of
// acceptable exponents in this test.
TEST(FromChars, DecimalFloatLimits) {
auto input_gen = [](int index) { return absl::StrCat("1.0e", index); };
auto expected_gen = [](int index) { return Pow10(index); };
TestOverflowAndUnderflow<float>(input_gen, expected_gen, -45, 38);
}
} // namespace
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