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Fix duplicate parser lookups #302

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Merged
sebastienros merged 1 commit into from
Dec 31, 2025
Merged

Fix duplicate parser lookups #302

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46 changes: 41 additions & 5 deletions src/Parlot/Fluent/OneOf.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -28,6 +28,42 @@ public OneOf(Parser<T>[] parsers)
Parsers = parsers ?? throw new ArgumentNullException(nameof(parsers));
OriginalParsers = parsers;

static void AddUniqueRange(List<Parser<T>> target, IReadOnlyList<Parser<T>> items)
{
for (var i = 0; i < items.Count; i++)
{
var item = items[i];

var exists = false;
for (var j = 0; j < target.Count; j++)
{
if (ReferenceEquals(target[j], item))
{
exists = true;
break;
}
}

if (!exists)
{
target.Add(item);
}
}
}

static void AddUniqueSingle(List<Parser<T>> target, Parser<T> item)
{
for (var j = 0; j < target.Count; j++)
{
if (ReferenceEquals(target[j], item))
{
return;
}
}

target.Add(item);
}

// We can't build a lookup table if there is only one parser
if (Parsers.Count <= 1)
{
Expand Down Expand Up @@ -63,28 +99,28 @@ public OneOf(Parser<T>[] parsers)

if (c != OtherSeekableChar)
{
lookupTable[c].AddRange(subParsers);
AddUniqueRange(lookupTable[c], subParsers);
}
else
{
_otherParsers ??= [];
_otherParsers.AddRange(subParsers!);
AddUniqueRange(_otherParsers, subParsers);

foreach (var entry in lookupTable)
{
entry.Value.AddRange(subParsers);
AddUniqueRange(entry.Value, subParsers);
}
}
}
}
else
{
_otherParsers ??= [];
_otherParsers.Add(parser);
AddUniqueSingle(_otherParsers, parser);

foreach (var entry in lookupTable)
{
entry.Value.Add(parser);
AddUniqueSingle(entry.Value, parser);
}
}
}
Expand Down