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Diffstat (limited to 'absl/strings/charconv_test.cc')
| -rw-r--r-- | absl/strings/charconv_test.cc | 766 |
1 files changed, 766 insertions, 0 deletions
diff --git a/absl/strings/charconv_test.cc b/absl/strings/charconv_test.cc new file mode 100644 index 000000000000..f8d71cc6c448 --- /dev/null +++ b/absl/strings/charconv_test.cc @@ -0,0 +1,766 @@ +// 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/str_cat.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 { + +#if ABSL_COMPILER_DOES_EXACT_ROUNDING + +// Tests that the given std::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 std::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 std::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); + } + // 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); + } + // 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 std::pow(10.0, 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 std::pow(10.0, index); }; + TestOverflowAndUnderflow<float>(input_gen, expected_gen, -45, 38); +} + +} // namespace |