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@@ -0,0 +1,273 @@
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using System.Globalization;
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using System.Numerics;
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using Shouldly;
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using Xunit;
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namespace Just.PreciseMath.Tests;
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public class DoubleDoubleParsingTests
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{
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[Theory]
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[InlineData("9007199254740993", 9007199254740992.0, 1.0)]
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[InlineData("-9007199254740993", -9007199254740992.0, -1.0)]
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[InlineData("9.007199254740993e15", 9007199254740992.0, 1.0)]
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[InlineData(" +900719925474099300E-2\t", 9007199254740992.0, 1.0)]
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[InlineData("1.000000000000000055511151231257827021181583404541015625", 1.0, 5.551115123125783e-17)]
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public void ParsingRetainsDecimalInformationBeyondBinary64(string text, double high, double low)
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{
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// Exact binary cases: 2^53 + 1 and 1 + 2^-54. Neither may be rounded
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// through double or decimal before extracting the low component.
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AssertParsed(text, CultureInfo.InvariantCulture, high, low);
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}
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[Theory]
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[InlineData("0.1", 0.1, -5.551115123125783e-18)]
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[InlineData("-0.1", -0.1, 5.551115123125783e-18)]
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[InlineData("1.23456789012345678901234567890123456789", 1.2345678901234567, 9.858021020478981e-17)]
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[InlineData("1e-300", 1e-300, -2.5059094e-317)]
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[InlineData("2.4703282292062328e-324", double.Epsilon, 0.0)]
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public void NonDyadicDecimalInputsRetainTheRoundedResidual(string text, double high, double low)
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{
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// Reproduce independently with Python fractions: v = Fraction(text),
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// h = float(v), l = float(v - Fraction(h)); canonicalize a zero low to +0.
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AssertParsed(text, CultureInfo.InvariantCulture, high, low);
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}
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[Theory]
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[InlineData("G99")]
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[InlineData("E99")]
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[InlineData("F99")]
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public void SupportedFormatterOutputCanPreserveAnExactlyRepresentablePair(string format)
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{
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double low = Math.ScaleB(1.0, -80);
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DoubleDouble value = DoubleDouble.FromComponents(1.0, low);
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CultureInfo culture = CultureInfo.GetCultureInfo("fr-FR");
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// This dyadic has a terminating decimal expansion within the chosen
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// precision. No general G32 round-trip guarantee follows from this test.
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AssertParsed(value.ToString(format, culture), culture, 1.0, low);
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}
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[Theory]
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[InlineData(".125", 0.125)]
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[InlineData("125.e-3", 0.125)]
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[InlineData("00000125E-3", 0.125)]
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[InlineData("\r\n 1.25 \t", 1.25)]
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[InlineData("0", 0.0)]
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[InlineData("-0.000e999999999999999999999", -0.0)]
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[InlineData("1e999999999999999999999", double.PositiveInfinity)]
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[InlineData("-1e999999999999999999999", double.NegativeInfinity)]
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[InlineData("1e-999999999999999999999", 0.0)]
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[InlineData("-1e-999999999999999999999", -0.0)]
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[InlineData("NaN", double.NaN)]
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[InlineData("-nan", double.NaN)]
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[InlineData("Infinity", double.PositiveInfinity)]
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[InlineData("+infinity", double.PositiveInfinity)]
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[InlineData("-Infinity", double.NegativeInfinity)]
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public void ParsingHandlesGrammarAndSpecialValues(string text, double high)
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{
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AssertParsed(text, CultureInfo.InvariantCulture, high, 0.0);
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}
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[Theory]
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[InlineData("")]
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[InlineData(" \t\r\n")]
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[InlineData("+")]
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[InlineData(".")]
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[InlineData("e1")]
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[InlineData("1e")]
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[InlineData("1e+")]
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[InlineData("1e--1")]
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[InlineData("1e999999999999999999x")]
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[InlineData("0e999999999999999999x")]
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[InlineData("--1")]
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[InlineData("+ 1")]
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[InlineData("1 2")]
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[InlineData("1.2.3")]
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[InlineData("1e2e3")]
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[InlineData("1,000")]
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[InlineData("$1")]
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[InlineData("(1)")]
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[InlineData("0x10")]
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[InlineData("1_000")]
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[InlineData("１２３")]
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[InlineData("1\0")]
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[InlineData("NaNx")]
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public void InvalidInputFailsWithoutLeavingAPartialResult(string text)
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{
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DoubleDouble.TryParse(text, CultureInfo.InvariantCulture, out DoubleDouble fromString).ShouldBeFalse();
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DoubleDouble.TryParse(text.AsSpan(), CultureInfo.InvariantCulture, out DoubleDouble fromSpan).ShouldBeFalse();
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AssertPositiveZero(fromString);
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AssertPositiveZero(fromSpan);
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Should.Throw<FormatException>(() => DoubleDouble.Parse(text, CultureInfo.InvariantCulture));
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Should.Throw<FormatException>(() => DoubleDouble.Parse(text.AsSpan(), CultureInfo.InvariantCulture));
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}
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[Fact]
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public void NullStringFailsTryParseAndThrowsArgumentNullFromParse()
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{
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DoubleDouble.TryParse((string?)null, out DoubleDouble result).ShouldBeFalse();
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AssertPositiveZero(result);
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DoubleDouble.TryParse((string?)null, CultureInfo.InvariantCulture, out result).ShouldBeFalse();
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AssertPositiveZero(result);
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Should.Throw<ArgumentNullException>(() => DoubleDouble.Parse((string)null!, CultureInfo.InvariantCulture));
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}
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[Fact]
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public void CultureSuppliesDecimalSeparatorAndBothExponentSigns()
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{
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NumberFormatInfo info = (NumberFormatInfo)CultureInfo.InvariantCulture.NumberFormat.Clone();
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info.NumberDecimalSeparator = "::";
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info.PositiveSign = "plus";
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info.NegativeSign = "minus";
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AssertParsed("minus1::25eplus2", info, -125.0, 0.0);
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AssertParsed("plus125eminus2", info, 1.25, 0.0);
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AssertParsed("12,5", CultureInfo.GetCultureInfo("fr-FR"), 12.5, 0.0);
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DoubleDouble.TryParse("1.25", info, out DoubleDouble result).ShouldBeFalse();
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AssertPositiveZero(result);
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}
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[Fact]
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public void CultureSpecialSymbolsAreRecognizedBeforeConsumingTheirSigns()
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{
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NumberFormatInfo info = (NumberFormatInfo)CultureInfo.InvariantCulture.NumberFormat.Clone();
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info.NaNSymbol = "+missing";
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info.PositiveInfinitySymbol = "-unbounded";
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info.NegativeInfinitySymbol = "negative-limit";
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AssertParsed("+MISSING", info, double.NaN, 0.0);
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AssertParsed("-UNBOUNDED", info, double.PositiveInfinity, 0.0);
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AssertParsed("NEGATIVE-LIMIT", info, double.NegativeInfinity, 0.0);
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}
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[Fact]
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public void DefaultTryParseAndNullProvidersUseCurrentCulture()
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{
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CultureInfo previous = CultureInfo.CurrentCulture;
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try
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{
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CultureInfo.CurrentCulture = CultureInfo.GetCultureInfo("fr-FR");
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const string Text = "1,25";
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DoubleDouble.Parse(Text, null).High.ShouldBe(1.25);
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DoubleDouble.Parse(Text.AsSpan(), null).High.ShouldBe(1.25);
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DoubleDouble.TryParse(Text, out DoubleDouble fromString).ShouldBeTrue();
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DoubleDouble.TryParse(Text.AsSpan(), out DoubleDouble fromSpan).ShouldBeTrue();
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fromString.High.ShouldBe(1.25);
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fromSpan.High.ShouldBe(1.25);
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AssertParsed(Text, null, 1.25, 0.0);
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}
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finally
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{
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CultureInfo.CurrentCulture = previous;
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}
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}
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[Fact]
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public void GenericStringAndSpanParsingInterfacesAreImplemented()
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{
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ParseString<DoubleDouble>("9007199254740993").Low.ShouldBe(1.0);
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ParseSpan<DoubleDouble>("9007199254740993").Low.ShouldBe(1.0);
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}
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[Fact]
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public void InputLengthIsBoundedBeforeIgnoringWhitespaceOrLeadingZeros()
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{
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AssertParsed(new string('0', 4095) + "1", CultureInfo.InvariantCulture, 1.0, 0.0);
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AssertParsed("1" + new string('0', 4095), CultureInfo.InvariantCulture, double.PositiveInfinity, 0.0);
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InvalidInputFailsWithoutLeavingAPartialResult(new string('0', 4096) + "1");
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InvalidInputFailsWithoutLeavingAPartialResult(new string(' ', 4096) + "1");
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}
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[Fact]
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public void LongMantissasCanCancelLargeExponentsWithoutOverflowOrUnderflow()
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{
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AssertParsed("1" + new string('0', 4000) + "e-4000", CultureInfo.InvariantCulture, 1.0, 0.0);
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AssertParsed("0." + new string('0', 4000) + "1e4001", CultureInfo.InvariantCulture, 1.0, 0.0);
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}
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[Fact]
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public void ExactDyadicsCoverSubnormalAndOverflowRoundingBoundaries()
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{
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foreach (int sign in new[] { -1, 1 })
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{
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// Integer coefficients and powers of two define independent exact inputs.
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AssertParsed(DyadicText(sign, -1074), CultureInfo.InvariantCulture, sign * double.Epsilon, 0.0);
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AssertParsed(DyadicText(sign, -1075), CultureInfo.InvariantCulture, sign < 0 ? -0.0 : 0.0, 0.0);
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AssertParsed(DyadicText(3 * sign, -1076), CultureInfo.InvariantCulture, sign * double.Epsilon, 0.0);
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BigInteger maximum = (BigInteger.One << 1024) - (BigInteger.One << 971);
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AssertParsed(DyadicText(sign * maximum, 0), CultureInfo.InvariantCulture, sign * double.MaxValue, 0.0);
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BigInteger midpoint = maximum + (BigInteger.One << 970);
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AssertParsed(DyadicText(sign * midpoint, 0), CultureInfo.InvariantCulture,
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sign < 0 ? double.NegativeInfinity : double.PositiveInfinity, 0.0);
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// Residual rounding reaches the overflow midpoint although the exact
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// input is below it. The adjacent finite pair must be selected.
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AssertParsed(DyadicText(sign * (midpoint - (BigInteger.One << 916)), 0), CultureInfo.InvariantCulture,
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sign * double.MaxValue, sign * Math.BitDecrement(Math.ScaleB(1.0, 970)));
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}
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}
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[Theory]
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[InlineData(2, false)]
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[InlineData(3, true)]
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public void LowComponentRoundingUsesExactResidualAndTiesToEven(int tail, bool roundUp)
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{
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// 1 + 2^-54 + tail*2^-108. At tail=2 the low is at its midpoint;
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// at tail=3 it lies above the midpoint. The high remains exactly 1.
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BigInteger coefficient = (BigInteger.One << 108) + (BigInteger.One << 54) + tail;
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double low = Math.ScaleB(1.0, -54);
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AssertParsed(DyadicText(coefficient, -108), CultureInfo.InvariantCulture,
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1.0, roundUp ? Math.BitIncrement(low) : low);
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}
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private static T ParseString<T>(string text) where T : IParsable<T>
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{
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T.TryParse(text, CultureInfo.InvariantCulture, out T? result).ShouldBeTrue();
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result.ShouldBe(T.Parse(text, CultureInfo.InvariantCulture));
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return T.Parse(text, CultureInfo.InvariantCulture);
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}
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private static T ParseSpan<T>(ReadOnlySpan<char> text) where T : ISpanParsable<T>
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{
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T.TryParse(text, CultureInfo.InvariantCulture, out T? result).ShouldBeTrue();
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result.ShouldBe(T.Parse(text, CultureInfo.InvariantCulture));
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return T.Parse(text, CultureInfo.InvariantCulture);
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}
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private static string DyadicText(BigInteger coefficient, int exponent)
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{
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// c*2^-k = (c*5^k)*10^-k. No production conversion or formatting helpers.
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return exponent >= 0
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? (coefficient << exponent).ToString(CultureInfo.InvariantCulture)
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: (coefficient * BigInteger.Pow(5, -exponent)).ToString(CultureInfo.InvariantCulture)
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+ "e" + exponent.ToString(CultureInfo.InvariantCulture);
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}
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private static void AssertPositiveZero(DoubleDouble value)
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{
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BitConverter.DoubleToInt64Bits(value.High).ShouldBe(0L);
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BitConverter.DoubleToInt64Bits(value.Low).ShouldBe(0L);
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}
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private static void AssertParsed(string text, IFormatProvider? provider, double high, double low)
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{
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DoubleDouble.TryParse(text, provider, out DoubleDouble fromString).ShouldBeTrue();
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DoubleDouble.TryParse(text.AsSpan(), provider, out DoubleDouble fromSpan).ShouldBeTrue();
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DoubleDouble[] results = [DoubleDouble.Parse(text, provider), DoubleDouble.Parse(text.AsSpan(), provider),
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fromString, fromSpan];
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foreach (DoubleDouble result in results)
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{
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result.High.ShouldBe(high);
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result.Low.ShouldBe(low);
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if (double.IsFinite(high))
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{
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(result.High + result.Low).ShouldBe(result.High);
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}
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if (high == 0.0)
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{
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BitConverter.DoubleToInt64Bits(result.High).ShouldBe(BitConverter.DoubleToInt64Bits(high));
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}
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if (low == 0.0)
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{
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BitConverter.DoubleToInt64Bits(result.Low).ShouldBe(0L);
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}
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}
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}
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}
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