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Improve map performance #1990

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Merged
slozier merged 1 commit into from
Feb 12, 2026
Merged

Improve map performance #1990

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15 changes: 13 additions & 2 deletions src/core/IronPython/Runtime/Map.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -23,6 +23,7 @@ namespace IronPython.Runtime {
public class Map : IEnumerator {
private readonly CodeContext _context;
private readonly object? _func;
private readonly IEnumerator? _enumerator;
private readonly IEnumerator[] _enumerators;

public Map(CodeContext context, object? func, [NotNone] params object[] iterables) {
Expand All @@ -39,6 +40,11 @@ public Map(CodeContext context, object? func, [NotNone] params object[] iterable
_enumerators[i] = enumerator;
}

// fast path for single iterable
if (_enumerators.Length == 1) {
_enumerator = _enumerators[0];
}

_context = context;
_func = func;
}
Expand All @@ -48,8 +54,13 @@ public Map(CodeContext context, object? func, [NotNone] params object[] iterable

[PythonHidden]
public bool MoveNext() {
if (_enumerators.Length > 0 && _enumerators.All(x => x.MoveNext())) {
Current = PythonOps.CallWithContext(_context, _func, _enumerators.Select(x => x.Current).ToArray());
if (_enumerator is null) {
if (_enumerators.All(x => x.MoveNext())) {
Current = PythonOps.CallWithContext(_context, _func, _enumerators.Select(x => x.Current).ToArray());
return true;
}
} else if (_enumerator.MoveNext()) {
Current = PythonCalls.Call(_context, _func, _enumerator.Current);
return true;
}
Current = default;
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