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Avoid concatenating adjacent regex loops+strings under right-to-left #103591

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Merged
merged 1 commit into from
Jun 19, 2024
Merged

Avoid concatenating adjacent regex loops+strings under right-to-left #103591

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5 changes: 4 additions & 1 deletion src/libraries/System.Text.RegularExpressions/src/System/Text/RegularExpressions/RegexNode.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -1702,7 +1702,10 @@ static bool CanCombineCounts(int nodeMin, int nodeMax, int nextMin, int nextMax)
break;

// Coalescing a loop with a subsequent string
case RegexNodeKind.Oneloop or RegexNodeKind.Onelazy when nextNode.Kind == RegexNodeKind.Multi && currentNode.Ch == nextNode.Str![0]:
case RegexNodeKind.Oneloop or RegexNodeKind.Onelazy when
nextNode.Kind == RegexNodeKind.Multi &&
(nextNode.Options & RegexOptions.RightToLeft) == 0 && // RTL multi nodes don't have their text reversed, and it's not worth the code to optimize further
currentNode.Ch == nextNode.Str![0]:
{
// Determine how many of the multi's characters can be combined.
// We already checked for the first, so we know it's at least one.
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5 changes: 5 additions & 0 deletions src/libraries/System.Text.RegularExpressions/tests/FunctionalTests/Regex.Match.Tests.cs
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Expand Up @@ -870,6 +870,11 @@ public static IEnumerable<object[]> Match_MemberData()
yield return (@"\s+\d+", " asdf12 ", RegexOptions.RightToLeft, 0, 6, false, string.Empty);
yield return ("aaa", "aaabbb", RegexOptions.None, 3, 3, false, string.Empty);
yield return ("abc|def", "123def456", RegexOptions.RightToLeft | RegexOptions.IgnoreCase | RegexOptions.CultureInvariant, 0, 9, true, "def");
yield return (@"^says?$", "says", RegexOptions.RightToLeft, 0, 4, true, "says");
yield return (@"^says?$", "say", RegexOptions.RightToLeft, 0, 3, true, "say");
yield return (@"^say(s?)$", "says", RegexOptions.RightToLeft, 0, 4, true, "says");
yield return (@"^(say)s?$", "says", RegexOptions.RightToLeft, 0, 4, true, "says");
yield return (@"^(.+?) (says?),\s'(.+)'$", "User says, 'adventure'", RegexOptions.RightToLeft, 0, 22, true, "User says, 'adventure'");

// .* : RTL, Case-sensitive
yield return (@".*\nfoo", "This shouldn't match", RegexOptions.None | RegexOptions.RightToLeft, 0, 20, false, "");
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