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Use Schubfach algorithm for float repr #2128

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Merged
slozier merged 3 commits into from
Nov 2, 2026
+563 −54
Merged

Use Schubfach algorithm for float repr #2128

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17a4a0c
Use Schubfach algorithm for float repr
slozier Nov 1, 2026
69c4c4a
Update float_repr_style and fix tests
slozier Nov 1, 2026
c783470
Add test_float_repr
slozier Nov 2, 2026
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1 change: 1 addition & 0 deletions IronPython.slnx
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Original file line number Diff line number Diff line change
Expand Up @@ -65,5 +65,6 @@
<Project Path="src/extensions/IronPython.SQLite/IronPython.SQLite.csproj" />
<Project Path="src/extensions/IronPython.Wpf/IronPython.Wpf.csproj" />
<Project Path="src/roslyn/IronPython.Analyzer/IronPython.Analyzer.csproj" />
<Project Path="src/roslyn/IronPython.SourceGenerator/IronPython.SourceGenerator.csproj" />
<Project Path="tests/IronPython.Tests/IronPython.Tests.csproj" />
</Solution>
2 changes: 1 addition & 1 deletion src/core/IronPython.StdLib
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Submodule IronPython.StdLib updated 4 files
+1 −1 lib/difflib.py
+7 −9 lib/mimetypes.py
+3 −4 lib/test/test_fstring.py
+0 −1 lib/test/test_optparse.py
7 changes: 7 additions & 0 deletions src/core/IronPython/IronPython.csproj
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Expand Up @@ -83,6 +83,13 @@
</ProjectReference>
</ItemGroup>

<ItemGroup>
<ProjectReference Include="..\..\roslyn\IronPython.SourceGenerator\IronPython.SourceGenerator.csproj">
<ReferenceOutputAssembly>false</ReferenceOutputAssembly>
<OutputItemType>Analyzer</OutputItemType>
</ProjectReference>
</ItemGroup>

<ItemGroup Condition=" '$(TargetFramework)' == 'netstandard2.0' ">
<PackageReference Include="System.Text.Encoding.CodePages" Version="4.7.0" />
</ItemGroup>
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10 changes: 3 additions & 7 deletions src/core/IronPython/Modules/sys.cs
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Expand Up @@ -119,7 +119,7 @@ public static void setcheckinterval(int value) {
throw PythonOps.NotImplementedError("IronPython does not support sys.setcheckinterval");
}

// warnoptions is set by PythonContext and updated on each reload
// warnoptions is set by PythonContext and updated on each reload

public static PythonTuple exc_info(CodeContext/*!*/ context) {
return PythonOps.GetExceptionInfo(context);
Expand Down Expand Up @@ -294,7 +294,7 @@ public override string __repr__(CodeContext context) {

#if PROFILE_SUPPORT
// not enabled because we don't yet support tracing built-in functions. Doing so is a little
// difficult because it's hard to flip tracing on/off for them w/o a perf overhead in the
// difficult because it's hard to flip tracing on/off for them w/o a perf overhead in the
// non-profiling case.
public static void setprofile(CodeContext/*!*/ context, TracebackDelegate o) {
PythonContext pyContext = context.LanguageContext;
Expand Down Expand Up @@ -489,11 +489,7 @@ public override string __repr__(CodeContext context) {
}
}

#if NETCOREAPP3_1_OR_GREATER
public static string float_repr_style = "short";
#else
public static string float_repr_style = "legacy";
#endif

public static floatinfo float_info = new floatinfo(
Double.MaxValue, // DBL_MAX
Expand Down Expand Up @@ -603,7 +599,7 @@ public static void PerformModuleReload(PythonContext/*!*/ context, PythonDiction

dict["platform"] = PythonContext.GetPlatform();

// !!! These fields do need to be reset on "reload(sys)". However, the initial value is specified by the
// !!! These fields do need to be reset on "reload(sys)". However, the initial value is specified by the
// engine elsewhere. For now, we initialize them just once to some default value
dict["warnoptions"] = new PythonList(0);

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23 changes: 2 additions & 21 deletions src/core/IronPython/Runtime/Operations/FloatOps.cs
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Expand Up @@ -733,27 +733,8 @@ public static bool NotEquals(Double x, int y) {
return x != y;
}

internal static string Repr(CodeContext/*!*/ context, double self, bool trailingZeroAfterWholeFloat) {
if (double.IsNaN(self)) {
return "nan";
}

// first format using Python's specific formatting rules...
string res = StringFormatter.Format(context, "%.17g", self, trailingZeroAfterWholeFloat: trailingZeroAfterWholeFloat);
if (LiteralParser.ParseFloat(res) == self) {
return res;
}
#if NETCOREAPP3_1_OR_GREATER
Debug.Assert(false);
#endif

// if it's not round trippable though use .NET's round-trip format
res = self.ToString("R", CultureInfo.InvariantCulture);
if (trailingZeroAfterWholeFloat && !res.Contains('.')) {
res += ".0";
}
return res;
}
internal static string Repr(CodeContext/*!*/ context, double self, bool trailingZeroAfterWholeFloat)
=> Schubfach.dtoa(self, trailingZeroAfterWholeFloat);

public static string __repr__(CodeContext/*!*/ context, double self)
=> Repr(context, self, trailingZeroAfterWholeFloat: true);
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