Transform regex X| into X?
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Transform regex X| into X?
#118087
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@MihuBot regexdiff |
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Tagging subscribers to this area: @dotnet/area-system-text-regularexpressions |
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471 out of 18857 patterns have generated source code changes. Examples of GeneratedRegex source diffs"\\r\\n|\\r" (823 uses)[GeneratedRegex("\\r\\n|\\r")] /// Explanation:<br/>
/// <code>
/// ○ Match '\r'.<br/>
- /// ○ Match with 2 alternative expressions, atomically.<br/>
- /// ○ Match '\n'.<br/>
- /// ○ Match an empty string.<br/>
+ /// ○ Match '\n' atomically, optionally.<br/>
/// </code>
/// </remarks>
[global::System.CodeDom.Compiler.GeneratedCodeAttribute("System.Text.RegularExpressions.Generator", "42.42.42.42")]
return false; // The input didn't match.
}
- // Match with 2 alternative expressions, atomically.
+ // Match '\n' atomically, optionally.
{
- int alternation_starting_pos = pos;
-
- // Branch 0
+ if ((uint)slice.Length > (uint)1 && slice[1] == '\n')
{
- // Match '\n'.
- if ((uint)slice.Length < 2 || slice[1] != '\n')
- {
- goto AlternationBranch;
- }
-
- pos += 2;
- slice = inputSpan.Slice(pos);
- goto AlternationMatch;
-
- AlternationBranch:
- pos = alternation_starting_pos;
- slice = inputSpan.Slice(pos);
- }
-
- // Branch 1
- {
-
+ slice = slice.Slice(1);
pos++;
- slice = inputSpan.Slice(pos);
}
-
- AlternationMatch:;
}
// The input matched.
+ pos++;
base.runtextpos = pos;
base.Capture(0, matchStart, pos);
return true;"(\\b\\d+([\\.,]\\d*)?|\\b)(?<unit>or[ae]|hrs ..." (330 uses)[GeneratedRegex("(\\b\\d+([\\.,]\\d*)?|\\b)(?<unit>or[ae]|hrs|hr|h|minut[oi]|mins|min|second[oi]|secs|sec)\\b", RegexOptions.ExplicitCapture | RegexOptions.Singleline)] /// ○ Match a character in the set [ae].<br/>
/// ○ Match a sequence of expressions.<br/>
/// ○ Match 'h'.<br/>
- /// ○ Match with 2 alternative expressions.<br/>
- /// ○ Match a sequence of expressions.<br/>
- /// ○ Match 'r'.<br/>
- /// ○ Match with 2 alternative expressions.<br/>
- /// ○ Match 's'.<br/>
- /// ○ Match an empty string.<br/>
- /// ○ Match an empty string.<br/>
+ /// ○ Optional (greedy).<br/>
+ /// ○ Match 'r'.<br/>
+ /// ○ Match 's' greedily, optionally.<br/>
/// ○ Match a sequence of expressions.<br/>
/// ○ Match the string "min".<br/>
/// ○ Match with 3 alternative expressions.<br/>
int alternation_branch1 = 0;
int alternation_branch2 = 0;
int alternation_branch3 = 0;
- int alternation_branch4 = 0;
- int alternation_branch5 = 0;
int alternation_starting_capturepos = 0;
int alternation_starting_capturepos1 = 0;
int alternation_starting_capturepos2 = 0;
int alternation_starting_capturepos3 = 0;
- int alternation_starting_capturepos4 = 0;
- int alternation_starting_capturepos5 = 0;
int alternation_starting_pos = 0;
int alternation_starting_pos1 = 0;
int alternation_starting_pos2 = 0;
int alternation_starting_pos3 = 0;
- int alternation_starting_pos4 = 0;
- int alternation_starting_pos5 = 0;
int capture_starting_pos = 0;
int charloop_capture_pos = 0;
int charloop_starting_pos = 0, charloop_ending_pos = 0;
+ int charloop_starting_pos1 = 0, charloop_ending_pos1 = 0;
int loop_iteration = 0;
+ int loop_iteration1 = 0;
int stackpos = 0;
ReadOnlySpan<char> slice = inputSpan.Slice(pos);
goto AlternationBranch2;
}
- // Match with 2 alternative expressions.
+ // Optional (greedy).
//{
- alternation_starting_pos2 = pos;
- alternation_starting_capturepos2 = base.Crawlpos();
+ pos++;
+ slice = inputSpan.Slice(pos);
+ loop_iteration1 = 0;
- // Branch 0
- //{
- // Match 'r'.
- if ((uint)slice.Length < 2 || slice[1] != 'r')
- {
- goto AlternationBranch3;
- }
-
- // Match with 2 alternative expressions.
- //{
- alternation_starting_pos3 = pos;
- alternation_starting_capturepos3 = base.Crawlpos();
-
- // Branch 0
- //{
- // Match 's'.
- if ((uint)slice.Length < 3 || slice[2] != 's')
- {
- goto AlternationBranch4;
- }
-
- alternation_branch3 = 0;
- pos += 3;
- slice = inputSpan.Slice(pos);
- goto AlternationMatch3;
-
- AlternationBranch4:
- pos = alternation_starting_pos3;
- slice = inputSpan.Slice(pos);
- UncaptureUntil(alternation_starting_capturepos3);
- //}
-
- // Branch 1
- //{
-
- alternation_branch3 = 1;
- pos += 2;
- slice = inputSpan.Slice(pos);
- goto AlternationMatch3;
- //}
-
- AlternationBacktrack3:
- if (Utilities.s_hasTimeout)
- {
- base.CheckTimeout();
- }
-
- switch (alternation_branch3)
- {
- case 0:
- goto AlternationBranch4;
- case 1:
- goto AlternationBranch3;
- }
-
- AlternationMatch3:;
- //}
-
- alternation_branch2 = 0;
- goto AlternationMatch2;
-
- AlternationBranch3:
- pos = alternation_starting_pos2;
- slice = inputSpan.Slice(pos);
- UncaptureUntil(alternation_starting_capturepos2);
- //}
+ LoopBody1:
+ Utilities.StackPush(ref base.runstack!, ref stackpos, base.Crawlpos(), pos);
- // Branch 1
+ loop_iteration1++;
+
+ // Match 'r'.
+ if (slice.IsEmpty || slice[0] != 'r')
+ {
+ goto LoopIterationNoMatch1;
+ }
+
+ // Match 's' greedily, optionally.
//{
-
- alternation_branch2 = 1;
pos++;
slice = inputSpan.Slice(pos);
- goto AlternationMatch2;
+ charloop_starting_pos1 = pos;
+
+ if (!slice.IsEmpty && slice[0] == 's')
+ {
+ slice = slice.Slice(1);
+ pos++;
+ }
+
+ charloop_ending_pos1 = pos;
+ goto CharLoopEnd1;
+
+ CharLoopBacktrack1:
+ UncaptureUntil(base.runstack![--stackpos]);
+ Utilities.StackPop(base.runstack!, ref stackpos, out charloop_ending_pos1, out charloop_starting_pos1);
+
+ if (Utilities.s_hasTimeout)
+ {
+ base.CheckTimeout();
+ }
+
+ if (charloop_starting_pos1 >= charloop_ending_pos1)
+ {
+ goto LoopIterationNoMatch1;
+ }
+ pos = --charloop_ending_pos1;
+ slice = inputSpan.Slice(pos);
+
+ CharLoopEnd1:
+ Utilities.StackPush(ref base.runstack!, ref stackpos, charloop_starting_pos1, charloop_ending_pos1, base.Crawlpos());
//}
- AlternationBacktrack2:
+
+ // The loop has an upper bound of 1. Continue iterating greedily if it hasn't yet been reached.
+ if (loop_iteration1 == 0)
+ {
+ goto LoopBody1;
+ }
+ goto LoopEnd1;
+
+ // The loop iteration failed. Put state back to the way it was before the iteration.
+ LoopIterationNoMatch1:
+ if (--loop_iteration1 < 0)
+ {
+ // Unable to match the remainder of the expression after exhausting the loop.
+ goto AlternationBranch2;
+ }
+ pos = base.runstack![--stackpos];
+ UncaptureUntil(base.runstack![--stackpos]);
+ slice = inputSpan.Slice(pos);
+ goto LoopEnd1;
+
+ LoopBacktrack:
if (Utilities.s_hasTimeout)
{
base.CheckTimeout();
}
- switch (alternation_branch2)
+ if (loop_iteration1 == 0)
{
- case 0:
- goto AlternationBacktrack3;
- case 1:
- goto AlternationBranch2;
+ // No iterations of the loop remain to backtrack into. Fail the loop.
+ goto AlternationBranch2;
}
-
- AlternationMatch2:;
+ goto CharLoopBacktrack1;
+ LoopEnd1:;
//}
alternation_branch1 = 1;
// Match the string "min".
if (!slice.StartsWith("min"))
{
- goto AlternationBranch5;
+ goto AlternationBranch3;
}
// Match with 3 alternative expressions.
//{
- alternation_starting_pos4 = pos;
- alternation_starting_capturepos4 = base.Crawlpos();
+ alternation_starting_pos2 = pos;
+ alternation_starting_capturepos2 = base.Crawlpos();
// Branch 0
//{
!slice.Slice(3).StartsWith("ut") || // Match the string "ut".
(((ch = slice[5]) != 'i') & (ch != 'o'))) // Match a character in the set [io].
{
- goto AlternationBranch6;
+ goto AlternationBranch4;
}
- alternation_branch4 = 0;
+ alternation_branch2 = 0;
pos += 6;
slice = inputSpan.Slice(pos);
- goto AlternationMatch4;
+ goto AlternationMatch2;
- AlternationBranch6:
- pos = alternation_starting_pos4;
+ AlternationBranch4:
+ pos = alternation_starting_pos2;
slice = inputSpan.Slice(pos);
- UncaptureUntil(alternation_starting_capturepos4);
+ UncaptureUntil(alternation_starting_capturepos2);
//}
// Branch 1
// Match 's'.
if ((uint)slice.Length < 4 || slice[3] != 's')
{
- goto AlternationBranch7;
+ goto AlternationBranch5;
}
- alternation_branch4 = 1;
+ alternation_branch2 = 1;
pos += 4;
slice = inputSpan.Slice(pos);
- goto AlternationMatch4;
+ goto AlternationMatch2;
- AlternationBranch7:
- pos = alternation_starting_pos4;
+ AlternationBranch5:
+ pos = alternation_starting_pos2;
slice = inputSpan.Slice(pos);
- UncaptureUntil(alternation_starting_capturepos4);
+ UncaptureUntil(alternation_starting_capturepos2);
//}
// Branch 2
//{
- alternation_branch4 = 2;
+ alternation_branch2 = 2;
pos += 3;
slice = inputSpan.Slice(pos);
- goto AlternationMatch4;
+ goto AlternationMatch2;
//}
- AlternationBacktrack4:
+ AlternationBacktrack2:
if (Utilities.s_hasTimeout)
{
base.CheckTimeout();
}
- switch (alternation_branch4)
+ switch (alternation_branch2)
{
case 0:
- goto AlternationBranch6;
+ goto AlternationBranch4;
case 1:
- goto AlternationBranch7;
- case 2:
goto AlternationBranch5;
+ case 2:
+ goto AlternationBranch3;
}
- AlternationMatch4:;
+ AlternationMatch2:;
//}
alternation_branch1 = 2;
goto AlternationMatch1;
- AlternationBranch5:
+ AlternationBranch3:
pos = alternation_starting_pos1;
slice = inputSpan.Slice(pos);
UncaptureUntil(alternation_starting_capturepos1);
// Match with 3 alternative expressions.
//{
- alternation_starting_pos5 = pos;
- alternation_starting_capturepos5 = base.Crawlpos();
+ alternation_starting_pos3 = pos;
+ alternation_starting_capturepos3 = base.Crawlpos();
// Branch 0
//{
!slice.Slice(3).StartsWith("ond") || // Match the string "ond".
(((ch = slice[6]) != 'i') & (ch != 'o'))) // Match a character in the set [io].
{
- goto AlternationBranch8;
+ goto AlternationBranch6;
}
- alternation_branch5 = 0;
+ alternation_branch3 = 0;
pos += 7;
slice = inputSpan.Slice(pos);
- goto AlternationMatch5;
+ goto AlternationMatch3;
- AlternationBranch8:
- pos = alternation_starting_pos5;
+ AlternationBranch6:
+ pos = alternation_starting_pos3;
slice = inputSpan.Slice(pos);
- UncaptureUntil(alternation_starting_capturepos5);
+ UncaptureUntil(alternation_starting_capturepos3);
//}
// Branch 1
// Match 's'.
if ((uint)slice.Length < 4 || slice[3] != 's')
{
- goto AlternationBranch9;
+ goto AlternationBranch7;
}
- alternation_branch5 = 1;
+ alternation_branch3 = 1;
pos += 4;
slice = inputSpan.Slice(pos);
- goto AlternationMatch5;
+ goto AlternationMatch3;
- AlternationBranch9:
- pos = alternation_starting_pos5;
+ AlternationBranch7:
+ pos = alternation_starting_pos3;
slice = inputSpan.Slice(pos);
- UncaptureUntil(alternation_starting_capturepos5);
+ UncaptureUntil(alternation_starting_capturepos3);
//}
// Branch 2
//{
- alternation_branch5 = 2;
+ alternation_branch3 = 2;
pos += 3;
slice = inputSpan.Slice(pos);
- goto AlternationMatch5;
+ goto AlternationMatch3;
//}
- AlternationBacktrack5:
+ AlternationBacktrack3:
if (Utilities.s_hasTimeout)
{
base.CheckTimeout();
}
- switch (alternation_branch5)
+ switch (alternation_branch3)
{
case 0:
- goto AlternationBranch8;
+ goto AlternationBranch6;
case 1:
- goto AlternationBranch9;
+ goto AlternationBranch7;
case 2:
goto AlternationBacktrack;
}
- AlternationMatch5:;
+ AlternationMatch3:;
//}
alternation_branch1 = 3;
case 0:
goto AlternationBranch1;
case 1:
- goto AlternationBacktrack2;
+ goto LoopBacktrack;
case 2:
- goto AlternationBacktrack4;
+ goto AlternationBacktrack2;
case 3:
- goto AlternationBacktrack5;
+ goto AlternationBacktrack3;
}
AlternationMatch1:;
(WordCategoriesMask & (1 << (int)CharUnicodeInfo.GetUnicodeCategory(ch))) != 0;
}
+ /// <summary>Pops 2 values from the backtracking stack.</summary>
+ [MethodImpl(MethodImplOptions.AggressiveInlining)]
+ internal static void StackPop(int[] stack, ref int pos, out int arg0, out int arg1)
+ {
+ arg0 = stack[--pos];
+ arg1 = stack[--pos];
+ }
+
/// <summary>Pushes 2 values onto the backtracking stack.</summary>
[MethodImpl(MethodImplOptions.AggressiveInlining)]
internal static void StackPush(ref int[] stack, ref int pos, int arg0, int arg1)
}
}
+ /// <summary>Pushes 3 values onto the backtracking stack.</summary>
+ [MethodImpl(MethodImplOptions.AggressiveInlining)]
+ internal static void StackPush(ref int[] stack, ref int pos, int arg0, int arg1, int arg2)
+ {
+ // If there's space available for all 3 values, store them.
+ int[] s = stack;
+ int p = pos;
+ if ((uint)(p + 2) < (uint)s.Length)
+ {
+ s[p] = arg0;
+ s[p + 1] = arg1;
+ s[p + 2] = arg2;
+ pos += 3;
+ return;
+ }
+
+ // Otherwise, resize the stack to make room and try again.
+ WithResize(ref stack, ref pos, arg0, arg1, arg2);
+
+ // <summary>Resize the backtracking stack array and push 3 values onto the stack.</summary>
+ [MethodImpl(MethodImplOptions.NoInlining)]
+ static void WithResize(ref int[] stack, ref int pos, int arg0, int arg1, int arg2)
+ {
+ Array.Resize(ref stack, (pos + 2) * 2);
+ StackPush(ref stack, ref pos, arg0, arg1, arg2);
+ }
+ }
+
/// <summary>Supports searching for characters in or not in "\0\u0001\u0002\u0003\u0004\u0005\u0006\a\b\t\n\v\f\r\u000e\u000f\u0010\u0011\u0012\u0013\u0014\u0015\u0016\u0017\u0018\u0019\u001a\u001b\u001c\u001d\u001e\u001f !\"#$%&'()*+,-./:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\\]^_`abcdefgijklnpqrtuvwxyz{|}~\u007f".</summary>
internal static readonly SearchValues<char> s_ascii_FFFFFFFFFFFF00FCFFFFFFFFFF5EF7FF = SearchValues.Create("\0\u0001\u0002\u0003\u0004\u0005\u0006\a\b\t\n\v\f\r\u000e\u000f\u0010\u0011\u0012\u0013\u0014\u0015\u0016\u0017\u0018\u0019\u001a\u001b\u001c\u001d\u001e\u001f !\"#$%&'()*+,-./:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\\]^_`abcdefgijklnpqrtuvwxyz{|}~\u007f");
}For more diff examples, see https://gist.github.com/MihuBot/a495e0c60796a8d6786b3298c93aa46a JIT assembly changesFor a list of JIT diff regressions, see Regressions.md Sample source code for further analysisconst string JsonPath = "RegexResults-1300.json";
if (!File.Exists(JsonPath))
{
await using var archiveStream = await new HttpClient().GetStreamAsync("https://mihubot.xyz/r/E2loz5g");
using var archive = new ZipArchive(archiveStream, ZipArchiveMode.Read);
archive.Entries.First(e => e.Name == "Results.json").ExtractToFile(JsonPath);
}
using FileStream jsonFileStream = File.OpenRead(JsonPath);
RegexEntry[] entries = JsonSerializer.Deserialize<RegexEntry[]>(jsonFileStream, new JsonSerializerOptions { IncludeFields = true })!;
Console.WriteLine($"Working with {entries.Length} patterns");
record KnownPattern(string Pattern, RegexOptions Options, int Count);
sealed class RegexEntry
{
public required KnownPattern Regex { get; set; }
public required string MainSource { get; set; }
public required string PrSource { get; set; }
public string? FullDiff { get; set; }
public string? ShortDiff { get; set; }
public (string Name, string Values)[]? SearchValuesOfChar { get; set; }
public (string[] Values, StringComparison ComparisonType)[]? SearchValuesOfString { get; set; }
} |
jeffhandley
approved these changes
Jul 26, 2025
This was referenced Jul 26, 2025
9454bdd to
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@MihuBot regexdiff |
3 tasks
|
@MihuBot regexdiff |
|
659 out of 18857 patterns have generated source code changes. Examples of GeneratedRegex source diffs"\\r\\n|\\r" (823 uses)[GeneratedRegex("\\r\\n|\\r")] /// Explanation:<br/>
/// <code>
/// ○ Match '\r'.<br/>
- /// ○ Match with 2 alternative expressions, atomically.<br/>
- /// ○ Match '\n'.<br/>
- /// ○ Match an empty string.<br/>
+ /// ○ Match '\n' atomically, optionally.<br/>
/// </code>
/// </remarks>
[global::System.CodeDom.Compiler.GeneratedCodeAttribute("System.Text.RegularExpressions.Generator", "42.42.42.42")]
return false; // The input didn't match.
}
- // Match with 2 alternative expressions, atomically.
+ // Match '\n' atomically, optionally.
{
- int alternation_starting_pos = pos;
-
- // Branch 0
+ if ((uint)slice.Length > (uint)1 && slice[1] == '\n')
{
- // Match '\n'.
- if ((uint)slice.Length < 2 || slice[1] != '\n')
- {
- goto AlternationBranch;
- }
-
- pos += 2;
- slice = inputSpan.Slice(pos);
- goto AlternationMatch;
-
- AlternationBranch:
- pos = alternation_starting_pos;
- slice = inputSpan.Slice(pos);
- }
-
- // Branch 1
- {
-
+ slice = slice.Slice(1);
pos++;
- slice = inputSpan.Slice(pos);
}
-
- AlternationMatch:;
}
// The input matched.
+ pos++;
base.runtextpos = pos;
base.Capture(0, matchStart, pos);
return true;"(http|https):\\/\\/[\\w\\-_]+(\\.[\\w\\-_]+)+" (479 uses)[GeneratedRegex("(http|https):\\/\\/[\\w\\-_]+(\\.[\\w\\-_]+)+")] /// <code>
/// ○ 1st capture group.<br/>
/// ○ Match the string "http".<br/>
- /// ○ Match with 2 alternative expressions.<br/>
- /// ○ Match an empty string.<br/>
- /// ○ Match 's'.<br/>
+ /// ○ Match 's' atomically, optionally.<br/>
/// ○ Match the string "://".<br/>
/// ○ Match a character in the set [\-_\w] atomically at least once.<br/>
/// ○ Loop greedily and atomically at least once.<br/>
int pos = base.runtextpos;
int matchStart = pos;
char ch;
- int alternation_branch = 0;
- int alternation_starting_capturepos = 0;
- int alternation_starting_pos = 0;
int capture_starting_pos = 0;
int loop_iteration = 0;
int stackpos = 0;
ReadOnlySpan<char> slice = inputSpan.Slice(pos);
// 1st capture group.
- //{
+ {
capture_starting_pos = pos;
// Match the string "http".
return false; // The input didn't match.
}
- // Match with 2 alternative expressions.
- //{
- alternation_starting_pos = pos;
- alternation_starting_capturepos = base.Crawlpos();
-
- // Branch 0
- //{
-
- alternation_branch = 0;
- pos += 4;
- slice = inputSpan.Slice(pos);
- goto AlternationMatch;
-
- AlternationBranch:
- pos = alternation_starting_pos;
- slice = inputSpan.Slice(pos);
- UncaptureUntil(alternation_starting_capturepos);
- //}
-
- // Branch 1
- //{
- // Match 's'.
- if ((uint)slice.Length < 5 || slice[4] != 's')
- {
- UncaptureUntil(0);
- return false; // The input didn't match.
- }
-
- alternation_branch = 1;
- pos += 5;
- slice = inputSpan.Slice(pos);
- goto AlternationMatch;
- //}
-
- AlternationBacktrack:
- if (Utilities.s_hasTimeout)
+ // Match 's' atomically, optionally.
+ {
+ if ((uint)slice.Length > (uint)4 && slice[4] == 's')
{
- base.CheckTimeout();
+ slice = slice.Slice(1);
+ pos++;
}
-
- switch (alternation_branch)
- {
- case 0:
- goto AlternationBranch;
- case 1:
- UncaptureUntil(0);
- return false; // The input didn't match.
- }
-
- AlternationMatch:;
- //}
+ }
+ pos += 4;
+ slice = inputSpan.Slice(pos);
base.Capture(1, capture_starting_pos, pos);
-
- goto CaptureSkipBacktrack;
-
- CaptureBacktrack:
- goto AlternationBacktrack;
-
- CaptureSkipBacktrack:;
- //}
+ }
// Match the string "://".
if (!slice.StartsWith("://"))
{
- goto CaptureBacktrack;
+ UncaptureUntil(0);
+ return false; // The input didn't match.
}
// Match a character in the set [\-_\w] atomically at least once.
if (iteration == 0)
{
- goto CaptureBacktrack;
+ UncaptureUntil(0);
+ return false; // The input didn't match.
}
slice = slice.Slice(iteration);
if (--loop_iteration < 0)
{
// Unable to match the remainder of the expression after exhausting the loop.
- goto CaptureBacktrack;
+ UncaptureUntil(0);
+ return false; // The input didn't match.
}
pos = base.runstack![--stackpos];
UncaptureUntil(base.runstack![--stackpos]);
if (loop_iteration == 0)
{
// All possible iterations have matched, but it's below the required minimum of 1. Fail the loop.
- goto CaptureBacktrack;
+ UncaptureUntil(0);
+ return false; // The input didn't match.
}
LoopEnd:"(http|https):\\/\\/[\\w\\-_]+(\\.[\\w\\-_]+) ..." (479 uses)[GeneratedRegex("(http|https):\\/\\/[\\w\\-_]+(\\.[\\w\\-_]+)+([\\w\\-\\.,/~\\+#]*)?")] /// <code>
/// ○ 1st capture group.<br/>
/// ○ Match the string "http".<br/>
- /// ○ Match with 2 alternative expressions.<br/>
- /// ○ Match an empty string.<br/>
- /// ○ Match 's'.<br/>
+ /// ○ Match 's' atomically, optionally.<br/>
/// ○ Match the string "://".<br/>
/// ○ Match a character in the set [\-_\w] atomically at least once.<br/>
/// ○ Loop greedily at least once.<br/>
int pos = base.runtextpos;
int matchStart = pos;
char ch;
- int alternation_branch = 0;
- int alternation_starting_capturepos = 0;
- int alternation_starting_pos = 0;
int capture_starting_pos = 0;
int charloop_starting_pos = 0, charloop_ending_pos = 0;
int loop_iteration = 0;
ReadOnlySpan<char> slice = inputSpan.Slice(pos);
// 1st capture group.
- //{
+ {
capture_starting_pos = pos;
// Match the string "http".
return false; // The input didn't match.
}
- // Match with 2 alternative expressions.
- //{
- alternation_starting_pos = pos;
- alternation_starting_capturepos = base.Crawlpos();
-
- // Branch 0
- //{
-
- alternation_branch = 0;
- pos += 4;
- slice = inputSpan.Slice(pos);
- goto AlternationMatch;
-
- AlternationBranch:
- pos = alternation_starting_pos;
- slice = inputSpan.Slice(pos);
- UncaptureUntil(alternation_starting_capturepos);
- //}
-
- // Branch 1
- //{
- // Match 's'.
- if ((uint)slice.Length < 5 || slice[4] != 's')
- {
- UncaptureUntil(0);
- return false; // The input didn't match.
- }
-
- alternation_branch = 1;
- pos += 5;
- slice = inputSpan.Slice(pos);
- goto AlternationMatch;
- //}
-
- AlternationBacktrack:
- if (Utilities.s_hasTimeout)
+ // Match 's' atomically, optionally.
+ {
+ if ((uint)slice.Length > (uint)4 && slice[4] == 's')
{
- base.CheckTimeout();
+ slice = slice.Slice(1);
+ pos++;
}
-
- switch (alternation_branch)
- {
- case 0:
- goto AlternationBranch;
- case 1:
- UncaptureUntil(0);
- return false; // The input didn't match.
- }
-
- AlternationMatch:;
- //}
+ }
+ pos += 4;
+ slice = inputSpan.Slice(pos);
base.Capture(1, capture_starting_pos, pos);
-
- goto CaptureSkipBacktrack;
-
- CaptureBacktrack:
- goto AlternationBacktrack;
-
- CaptureSkipBacktrack:;
- //}
+ }
// Match the string "://".
if (!slice.StartsWith("://"))
{
- goto CaptureBacktrack;
+ UncaptureUntil(0);
+ return false; // The input didn't match.
}
// Match a character in the set [\-_\w] atomically at least once.
if (iteration == 0)
{
- goto CaptureBacktrack;
+ UncaptureUntil(0);
+ return false; // The input didn't match.
}
slice = slice.Slice(iteration);
base.Capture(2, capture_starting_pos1, pos);
Utilities.StackPush(ref base.runstack!, ref stackpos, capture_starting_pos1);
- goto CaptureSkipBacktrack1;
+ goto CaptureSkipBacktrack;
- CaptureBacktrack1:
+ CaptureBacktrack:
capture_starting_pos1 = base.runstack![--stackpos];
goto CharLoopBacktrack;
- CaptureSkipBacktrack1:;
+ CaptureSkipBacktrack:;
//}
if (--loop_iteration < 0)
{
// Unable to match the remainder of the expression after exhausting the loop.
- goto CaptureBacktrack;
+ UncaptureUntil(0);
+ return false; // The input didn't match.
}
pos = base.runstack![--stackpos];
UncaptureUntil(base.runstack![--stackpos]);
if (loop_iteration == 0)
{
// No iterations have been matched to backtrack into. Fail the loop.
- goto CaptureBacktrack;
+ UncaptureUntil(0);
+ return false; // The input didn't match.
}
goto LoopEnd;
if (loop_iteration == 0)
{
// No iterations of the loop remain to backtrack into. Fail the loop.
- goto CaptureBacktrack;
+ UncaptureUntil(0);
+ return false; // The input didn't match.
}
- goto CaptureBacktrack1;
+ goto CaptureBacktrack;
LoopEnd:;
//}"(http|https):\\/\\/[\\w\\-_]+(\\.[\\w\\-_]+) ..." (479 uses)[GeneratedRegex("(http|https):\\/\\/[\\w\\-_]+(\\.[\\w\\-_]+)+([\\w\\-\\.,/~\\+#]*)?/")] /// <code>
/// ○ 1st capture group.<br/>
/// ○ Match the string "http".<br/>
- /// ○ Match with 2 alternative expressions.<br/>
- /// ○ Match an empty string.<br/>
- /// ○ Match 's'.<br/>
+ /// ○ Match 's' atomically, optionally.<br/>
/// ○ Match the string "://".<br/>
/// ○ Match a character in the set [\-_\w] atomically at least once.<br/>
/// ○ Loop greedily at least once.<br/>
int pos = base.runtextpos;
int matchStart = pos;
char ch;
- int alternation_branch = 0;
- int alternation_starting_capturepos = 0;
- int alternation_starting_pos = 0;
int capture_starting_pos = 0;
int charloop_starting_pos = 0, charloop_ending_pos = 0;
int charloop_starting_pos1 = 0, charloop_ending_pos1 = 0;
ReadOnlySpan<char> slice = inputSpan.Slice(pos);
// 1st capture group.
- //{
+ {
capture_starting_pos = pos;
// Match the string "http".
return false; // The input didn't match.
}
- // Match with 2 alternative expressions.
- //{
- alternation_starting_pos = pos;
- alternation_starting_capturepos = base.Crawlpos();
-
- // Branch 0
- //{
-
- alternation_branch = 0;
- pos += 4;
- slice = inputSpan.Slice(pos);
- goto AlternationMatch;
-
- AlternationBranch:
- pos = alternation_starting_pos;
- slice = inputSpan.Slice(pos);
- UncaptureUntil(alternation_starting_capturepos);
- //}
-
- // Branch 1
- //{
- // Match 's'.
- if ((uint)slice.Length < 5 || slice[4] != 's')
- {
- UncaptureUntil(0);
- return false; // The input didn't match.
- }
-
- alternation_branch = 1;
- pos += 5;
- slice = inputSpan.Slice(pos);
- goto AlternationMatch;
- //}
-
- AlternationBacktrack:
- if (Utilities.s_hasTimeout)
+ // Match 's' atomically, optionally.
+ {
+ if ((uint)slice.Length > (uint)4 && slice[4] == 's')
{
- base.CheckTimeout();
+ slice = slice.Slice(1);
+ pos++;
}
-
- switch (alternation_branch)
- {
- case 0:
- goto AlternationBranch;
- case 1:
- UncaptureUntil(0);
- return false; // The input didn't match.
- }
-
- AlternationMatch:;
- //}
+ }
+ pos += 4;
+ slice = inputSpan.Slice(pos);
base.Capture(1, capture_starting_pos, pos);
-
- goto CaptureSkipBacktrack;
-
- CaptureBacktrack:
- goto AlternationBacktrack;
-
- CaptureSkipBacktrack:;
- //}
+ }
// Match the string "://".
if (!slice.StartsWith("://"))
{
- goto CaptureBacktrack;
+ UncaptureUntil(0);
+ return false; // The input didn't match.
}
// Match a character in the set [\-_\w] atomically at least once.
if (iteration == 0)
{
- goto CaptureBacktrack;
+ UncaptureUntil(0);
+ return false; // The input didn't match.
}
slice = slice.Slice(iteration);
base.Capture(2, capture_starting_pos1, pos);
Utilities.StackPush(ref base.runstack!, ref stackpos, capture_starting_pos1);
- goto CaptureSkipBacktrack1;
+ goto CaptureSkipBacktrack;
- CaptureBacktrack1:
+ CaptureBacktrack:
capture_starting_pos1 = base.runstack![--stackpos];
goto CharLoopBacktrack;
- CaptureSkipBacktrack1:;
+ CaptureSkipBacktrack:;
//}
if (--loop_iteration < 0)
{
// Unable to match the remainder of the expression after exhausting the loop.
- goto CaptureBacktrack;
+ UncaptureUntil(0);
+ return false; // The input didn't match.
}
pos = base.runstack![--stackpos];
UncaptureUntil(base.runstack![--stackpos]);
if (loop_iteration == 0)
{
// No iterations have been matched to backtrack into. Fail the loop.
- goto CaptureBacktrack;
+ UncaptureUntil(0);
+ return false; // The input didn't match.
}
goto LoopEnd;
if (loop_iteration == 0)
{
// No iterations of the loop remain to backtrack into. Fail the loop.
- goto CaptureBacktrack;
+ UncaptureUntil(0);
+ return false; // The input didn't match.
}
- goto CaptureBacktrack1;
+ goto CaptureBacktrack;
LoopEnd:;
//}
base.Capture(3, capture_starting_pos2, pos);
Utilities.StackPush(ref base.runstack!, ref stackpos, capture_starting_pos2);
- goto CaptureSkipBacktrack2;
+ goto CaptureSkipBacktrack1;
- CaptureBacktrack2:
+ CaptureBacktrack1:
capture_starting_pos2 = base.runstack![--stackpos];
goto CharLoopBacktrack1;
- CaptureSkipBacktrack2:;
+ CaptureSkipBacktrack1:;
//}
// No iterations of the loop remain to backtrack into. Fail the loop.
goto LoopBacktrack;
}
- goto CaptureBacktrack2;
+ goto CaptureBacktrack1;
LoopEnd1:;
//}"^ps_(?<major>1|2|3|4|5)_(?<minor>0|1|)$" (308 uses)[GeneratedRegex("^ps_(?<major>1|2|3|4|5)_(?<minor>0|1|)$")] /// ○ Match a character in the set [1-5].<br/>
/// ○ Match '_'.<br/>
/// ○ "minor" capture group.<br/>
- /// ○ Match with 2 alternative expressions.<br/>
- /// ○ Match a character in the set [01].<br/>
- /// ○ Match an empty string.<br/>
+ /// ○ Match a character in the set [01] atomically, optionally.<br/>
/// ○ Match if at the end of the string or if before an ending newline.<br/>
/// </code>
/// </remarks>
{
int pos = base.runtextpos;
int matchStart = pos;
- int alternation_branch = 0;
- int alternation_starting_capturepos = 0;
- int alternation_starting_pos = 0;
int capture_starting_pos = 0;
int capture_starting_pos1 = 0;
ReadOnlySpan<char> slice = inputSpan.Slice(pos);
}
// "minor" capture group.
- //{
+ {
pos++;
slice = inputSpan.Slice(pos);
capture_starting_pos1 = pos;
- // Match with 2 alternative expressions.
- //{
- alternation_starting_pos = pos;
- alternation_starting_capturepos = base.Crawlpos();
-
- // Branch 0
- //{
- // Match a character in the set [01].
- if (slice.IsEmpty || !char.IsBetween(slice[0], '0', '1'))
- {
- goto AlternationBranch;
- }
-
- alternation_branch = 0;
+ // Match a character in the set [01] atomically, optionally.
+ {
+ if (!slice.IsEmpty && char.IsBetween(slice[0], '0', '1'))
+ {
+ slice = slice.Slice(1);
pos++;
- slice = inputSpan.Slice(pos);
- goto AlternationMatch;
-
- AlternationBranch:
- pos = alternation_starting_pos;
- slice = inputSpan.Slice(pos);
- UncaptureUntil(alternation_starting_capturepos);
- //}
-
- // Branch 1
- //{
-
- alternation_branch = 1;
- goto AlternationMatch;
- //}
-
- AlternationBacktrack:
- if (Utilities.s_hasTimeout)
- {
- base.CheckTimeout();
}
-
- switch (alternation_branch)
- {
- case 0:
- goto AlternationBranch;
- case 1:
- UncaptureUntil(0);
- return false; // The input didn't match.
- }
-
- AlternationMatch:;
- //}
+ }
base.Capture(2, capture_starting_pos1, pos);
-
- goto CaptureSkipBacktrack;
-
- CaptureBacktrack:
- goto AlternationBacktrack;
-
- CaptureSkipBacktrack:;
- //}
+ }
// Match if at the end of the string or if before an ending newline.
if (pos < inputSpan.Length - 1 || ((uint)pos < (uint)inputSpan.Length && inputSpan[pos] != '\n'))
{
- goto CaptureBacktrack;
+ UncaptureUntil(0);
+ return false; // The input didn't match.
}
// The input matched.For more diff examples, see https://gist.github.com/MihuBot/9cd26902240a71cfb7e4de17b43e6f9c JIT assembly changesFor a list of JIT diff regressions, see Regressions.md Sample source code for further analysisconst string JsonPath = "RegexResults-1313.json";
if (!File.Exists(JsonPath))
{
await using var archiveStream = await new HttpClient().GetStreamAsync("https://mihubot.xyz/r/E2v-Wpg");
using var archive = new ZipArchive(archiveStream, ZipArchiveMode.Read);
archive.Entries.First(e => e.Name == "Results.json").ExtractToFile(JsonPath);
}
using FileStream jsonFileStream = File.OpenRead(JsonPath);
RegexEntry[] entries = JsonSerializer.Deserialize<RegexEntry[]>(jsonFileStream, new JsonSerializerOptions { IncludeFields = true })!;
Console.WriteLine($"Working with {entries.Length} patterns");
record KnownPattern(string Pattern, RegexOptions Options, int Count);
sealed class RegexEntry
{
public required KnownPattern Regex { get; set; }
public required string MainSource { get; set; }
public required string PrSource { get; set; }
public string? FullDiff { get; set; }
public string? ShortDiff { get; set; }
public (string Name, string Values)[]? SearchValuesOfChar { get; set; }
public (string[] Values, StringComparison ComparisonType)[]? SearchValuesOfString { get; set; }
} |
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Pull Request Overview
This PR implements an optimization for regular expressions that transforms alternations with empty branches (like X|) into optional quantifiers (like X?). This transformation enables better downstream optimizations, particularly loop coalescing.
Key changes:
- Transforms
X|patterns intoX?and|Xpatterns intoX??(lazy optional) - Ensures re-reduction when new optimization opportunities are exposed
- Adds comprehensive test coverage for various alternation-to-quantifier transformations
Reviewed Changes
Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.
| File | Description |
|---|---|
| RegexNode.cs | Implements the core transformation logic in ReduceAlternation() and forces re-reduction when opportunities are detected |
| RegexReductionTests.cs | Adds test cases validating the transformation of alternations with empty branches to optional quantifiers |
src/libraries/System.Text.RegularExpressions/src/System/Text/RegularExpressions/RegexNode.cs
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An alternation with two branches where the second is empty is the same as the first branch just being an optional loop; similarly, when the first branch is empty, it's a lazy optional loop of the second branch. Expressing as an optional is better optimized elsewhere in the regex transforms, e.g. with loop coalescing, so we're better off with the optional representation.
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a5b020e
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|
@MihuBot regexdiff |
|
659 out of 18857 patterns have generated source code changes. Examples of GeneratedRegex source diffs"\\r\\n|\\r" (823 uses)[GeneratedRegex("\\r\\n|\\r")] /// Explanation:<br/>
/// <code>
/// ○ Match '\r'.<br/>
- /// ○ Match with 2 alternative expressions, atomically.<br/>
- /// ○ Match '\n'.<br/>
- /// ○ Match an empty string.<br/>
+ /// ○ Match '\n' atomically, optionally.<br/>
/// </code>
/// </remarks>
[global::System.CodeDom.Compiler.GeneratedCodeAttribute("System.Text.RegularExpressions.Generator", "42.42.42.42")]
return false; // The input didn't match.
}
- // Match with 2 alternative expressions, atomically.
+ // Match '\n' atomically, optionally.
{
- int alternation_starting_pos = pos;
-
- // Branch 0
+ if ((uint)slice.Length > (uint)1 && slice[1] == '\n')
{
- // Match '\n'.
- if ((uint)slice.Length < 2 || slice[1] != '\n')
- {
- goto AlternationBranch;
- }
-
- pos += 2;
- slice = inputSpan.Slice(pos);
- goto AlternationMatch;
-
- AlternationBranch:
- pos = alternation_starting_pos;
- slice = inputSpan.Slice(pos);
- }
-
- // Branch 1
- {
-
+ slice = slice.Slice(1);
pos++;
- slice = inputSpan.Slice(pos);
}
-
- AlternationMatch:;
}
// The input matched.
+ pos++;
base.runtextpos = pos;
base.Capture(0, matchStart, pos);
return true;"(http|https):\\/\\/[\\w\\-_]+(\\.[\\w\\-_]+)+" (479 uses)[GeneratedRegex("(http|https):\\/\\/[\\w\\-_]+(\\.[\\w\\-_]+)+")] /// <code>
/// ○ 1st capture group.<br/>
/// ○ Match the string "http".<br/>
- /// ○ Match with 2 alternative expressions.<br/>
- /// ○ Match an empty string.<br/>
- /// ○ Match 's'.<br/>
+ /// ○ Match 's' atomically, optionally.<br/>
/// ○ Match the string "://".<br/>
/// ○ Match a character in the set [\-_\w] atomically at least once.<br/>
/// ○ Loop greedily and atomically at least once.<br/>
int pos = base.runtextpos;
int matchStart = pos;
char ch;
- int alternation_branch = 0;
- int alternation_starting_capturepos = 0;
- int alternation_starting_pos = 0;
int capture_starting_pos = 0;
int loop_iteration = 0;
int stackpos = 0;
ReadOnlySpan<char> slice = inputSpan.Slice(pos);
// 1st capture group.
- //{
+ {
capture_starting_pos = pos;
// Match the string "http".
return false; // The input didn't match.
}
- // Match with 2 alternative expressions.
- //{
- alternation_starting_pos = pos;
- alternation_starting_capturepos = base.Crawlpos();
-
- // Branch 0
- //{
-
- alternation_branch = 0;
- pos += 4;
- slice = inputSpan.Slice(pos);
- goto AlternationMatch;
-
- AlternationBranch:
- pos = alternation_starting_pos;
- slice = inputSpan.Slice(pos);
- UncaptureUntil(alternation_starting_capturepos);
- //}
-
- // Branch 1
- //{
- // Match 's'.
- if ((uint)slice.Length < 5 || slice[4] != 's')
- {
- UncaptureUntil(0);
- return false; // The input didn't match.
- }
-
- alternation_branch = 1;
- pos += 5;
- slice = inputSpan.Slice(pos);
- goto AlternationMatch;
- //}
-
- AlternationBacktrack:
- if (Utilities.s_hasTimeout)
+ // Match 's' atomically, optionally.
+ {
+ if ((uint)slice.Length > (uint)4 && slice[4] == 's')
{
- base.CheckTimeout();
+ slice = slice.Slice(1);
+ pos++;
}
-
- switch (alternation_branch)
- {
- case 0:
- goto AlternationBranch;
- case 1:
- UncaptureUntil(0);
- return false; // The input didn't match.
- }
-
- AlternationMatch:;
- //}
+ }
+ pos += 4;
+ slice = inputSpan.Slice(pos);
base.Capture(1, capture_starting_pos, pos);
-
- goto CaptureSkipBacktrack;
-
- CaptureBacktrack:
- goto AlternationBacktrack;
-
- CaptureSkipBacktrack:;
- //}
+ }
// Match the string "://".
if (!slice.StartsWith("://"))
{
- goto CaptureBacktrack;
+ UncaptureUntil(0);
+ return false; // The input didn't match.
}
// Match a character in the set [\-_\w] atomically at least once.
if (iteration == 0)
{
- goto CaptureBacktrack;
+ UncaptureUntil(0);
+ return false; // The input didn't match.
}
slice = slice.Slice(iteration);
if (--loop_iteration < 0)
{
// Unable to match the remainder of the expression after exhausting the loop.
- goto CaptureBacktrack;
+ UncaptureUntil(0);
+ return false; // The input didn't match.
}
pos = base.runstack![--stackpos];
UncaptureUntil(base.runstack![--stackpos]);
if (loop_iteration == 0)
{
// All possible iterations have matched, but it's below the required minimum of 1. Fail the loop.
- goto CaptureBacktrack;
+ UncaptureUntil(0);
+ return false; // The input didn't match.
}
LoopEnd:"(http|https):\\/\\/[\\w\\-_]+(\\.[\\w\\-_]+) ..." (479 uses)[GeneratedRegex("(http|https):\\/\\/[\\w\\-_]+(\\.[\\w\\-_]+)+([\\w\\-\\.,/~\\+#]*)?")] /// <code>
/// ○ 1st capture group.<br/>
/// ○ Match the string "http".<br/>
- /// ○ Match with 2 alternative expressions.<br/>
- /// ○ Match an empty string.<br/>
- /// ○ Match 's'.<br/>
+ /// ○ Match 's' atomically, optionally.<br/>
/// ○ Match the string "://".<br/>
/// ○ Match a character in the set [\-_\w] atomically at least once.<br/>
/// ○ Loop greedily at least once.<br/>
int pos = base.runtextpos;
int matchStart = pos;
char ch;
- int alternation_branch = 0;
- int alternation_starting_capturepos = 0;
- int alternation_starting_pos = 0;
int capture_starting_pos = 0;
int charloop_starting_pos = 0, charloop_ending_pos = 0;
int loop_iteration = 0;
ReadOnlySpan<char> slice = inputSpan.Slice(pos);
// 1st capture group.
- //{
+ {
capture_starting_pos = pos;
// Match the string "http".
return false; // The input didn't match.
}
- // Match with 2 alternative expressions.
- //{
- alternation_starting_pos = pos;
- alternation_starting_capturepos = base.Crawlpos();
-
- // Branch 0
- //{
-
- alternation_branch = 0;
- pos += 4;
- slice = inputSpan.Slice(pos);
- goto AlternationMatch;
-
- AlternationBranch:
- pos = alternation_starting_pos;
- slice = inputSpan.Slice(pos);
- UncaptureUntil(alternation_starting_capturepos);
- //}
-
- // Branch 1
- //{
- // Match 's'.
- if ((uint)slice.Length < 5 || slice[4] != 's')
- {
- UncaptureUntil(0);
- return false; // The input didn't match.
- }
-
- alternation_branch = 1;
- pos += 5;
- slice = inputSpan.Slice(pos);
- goto AlternationMatch;
- //}
-
- AlternationBacktrack:
- if (Utilities.s_hasTimeout)
+ // Match 's' atomically, optionally.
+ {
+ if ((uint)slice.Length > (uint)4 && slice[4] == 's')
{
- base.CheckTimeout();
+ slice = slice.Slice(1);
+ pos++;
}
-
- switch (alternation_branch)
- {
- case 0:
- goto AlternationBranch;
- case 1:
- UncaptureUntil(0);
- return false; // The input didn't match.
- }
-
- AlternationMatch:;
- //}
+ }
+ pos += 4;
+ slice = inputSpan.Slice(pos);
base.Capture(1, capture_starting_pos, pos);
-
- goto CaptureSkipBacktrack;
-
- CaptureBacktrack:
- goto AlternationBacktrack;
-
- CaptureSkipBacktrack:;
- //}
+ }
// Match the string "://".
if (!slice.StartsWith("://"))
{
- goto CaptureBacktrack;
+ UncaptureUntil(0);
+ return false; // The input didn't match.
}
// Match a character in the set [\-_\w] atomically at least once.
if (iteration == 0)
{
- goto CaptureBacktrack;
+ UncaptureUntil(0);
+ return false; // The input didn't match.
}
slice = slice.Slice(iteration);
base.Capture(2, capture_starting_pos1, pos);
Utilities.StackPush(ref base.runstack!, ref stackpos, capture_starting_pos1);
- goto CaptureSkipBacktrack1;
+ goto CaptureSkipBacktrack;
- CaptureBacktrack1:
+ CaptureBacktrack:
capture_starting_pos1 = base.runstack![--stackpos];
goto CharLoopBacktrack;
- CaptureSkipBacktrack1:;
+ CaptureSkipBacktrack:;
//}
if (--loop_iteration < 0)
{
// Unable to match the remainder of the expression after exhausting the loop.
- goto CaptureBacktrack;
+ UncaptureUntil(0);
+ return false; // The input didn't match.
}
pos = base.runstack![--stackpos];
UncaptureUntil(base.runstack![--stackpos]);
if (loop_iteration == 0)
{
// No iterations have been matched to backtrack into. Fail the loop.
- goto CaptureBacktrack;
+ UncaptureUntil(0);
+ return false; // The input didn't match.
}
goto LoopEnd;
if (loop_iteration == 0)
{
// No iterations of the loop remain to backtrack into. Fail the loop.
- goto CaptureBacktrack;
+ UncaptureUntil(0);
+ return false; // The input didn't match.
}
- goto CaptureBacktrack1;
+ goto CaptureBacktrack;
LoopEnd:;
//}"(http|https):\\/\\/[\\w\\-_]+(\\.[\\w\\-_]+) ..." (479 uses)[GeneratedRegex("(http|https):\\/\\/[\\w\\-_]+(\\.[\\w\\-_]+)+([\\w\\-\\.,/~\\+#]*)?/")] /// <code>
/// ○ 1st capture group.<br/>
/// ○ Match the string "http".<br/>
- /// ○ Match with 2 alternative expressions.<br/>
- /// ○ Match an empty string.<br/>
- /// ○ Match 's'.<br/>
+ /// ○ Match 's' atomically, optionally.<br/>
/// ○ Match the string "://".<br/>
/// ○ Match a character in the set [\-_\w] atomically at least once.<br/>
/// ○ Loop greedily at least once.<br/>
int pos = base.runtextpos;
int matchStart = pos;
char ch;
- int alternation_branch = 0;
- int alternation_starting_capturepos = 0;
- int alternation_starting_pos = 0;
int capture_starting_pos = 0;
int charloop_starting_pos = 0, charloop_ending_pos = 0;
int charloop_starting_pos1 = 0, charloop_ending_pos1 = 0;
ReadOnlySpan<char> slice = inputSpan.Slice(pos);
// 1st capture group.
- //{
+ {
capture_starting_pos = pos;
// Match the string "http".
return false; // The input didn't match.
}
- // Match with 2 alternative expressions.
- //{
- alternation_starting_pos = pos;
- alternation_starting_capturepos = base.Crawlpos();
-
- // Branch 0
- //{
-
- alternation_branch = 0;
- pos += 4;
- slice = inputSpan.Slice(pos);
- goto AlternationMatch;
-
- AlternationBranch:
- pos = alternation_starting_pos;
- slice = inputSpan.Slice(pos);
- UncaptureUntil(alternation_starting_capturepos);
- //}
-
- // Branch 1
- //{
- // Match 's'.
- if ((uint)slice.Length < 5 || slice[4] != 's')
- {
- UncaptureUntil(0);
- return false; // The input didn't match.
- }
-
- alternation_branch = 1;
- pos += 5;
- slice = inputSpan.Slice(pos);
- goto AlternationMatch;
- //}
-
- AlternationBacktrack:
- if (Utilities.s_hasTimeout)
+ // Match 's' atomically, optionally.
+ {
+ if ((uint)slice.Length > (uint)4 && slice[4] == 's')
{
- base.CheckTimeout();
+ slice = slice.Slice(1);
+ pos++;
}
-
- switch (alternation_branch)
- {
- case 0:
- goto AlternationBranch;
- case 1:
- UncaptureUntil(0);
- return false; // The input didn't match.
- }
-
- AlternationMatch:;
- //}
+ }
+ pos += 4;
+ slice = inputSpan.Slice(pos);
base.Capture(1, capture_starting_pos, pos);
-
- goto CaptureSkipBacktrack;
-
- CaptureBacktrack:
- goto AlternationBacktrack;
-
- CaptureSkipBacktrack:;
- //}
+ }
// Match the string "://".
if (!slice.StartsWith("://"))
{
- goto CaptureBacktrack;
+ UncaptureUntil(0);
+ return false; // The input didn't match.
}
// Match a character in the set [\-_\w] atomically at least once.
if (iteration == 0)
{
- goto CaptureBacktrack;
+ UncaptureUntil(0);
+ return false; // The input didn't match.
}
slice = slice.Slice(iteration);
base.Capture(2, capture_starting_pos1, pos);
Utilities.StackPush(ref base.runstack!, ref stackpos, capture_starting_pos1);
- goto CaptureSkipBacktrack1;
+ goto CaptureSkipBacktrack;
- CaptureBacktrack1:
+ CaptureBacktrack:
capture_starting_pos1 = base.runstack![--stackpos];
goto CharLoopBacktrack;
- CaptureSkipBacktrack1:;
+ CaptureSkipBacktrack:;
//}
if (--loop_iteration < 0)
{
// Unable to match the remainder of the expression after exhausting the loop.
- goto CaptureBacktrack;
+ UncaptureUntil(0);
+ return false; // The input didn't match.
}
pos = base.runstack![--stackpos];
UncaptureUntil(base.runstack![--stackpos]);
if (loop_iteration == 0)
{
// No iterations have been matched to backtrack into. Fail the loop.
- goto CaptureBacktrack;
+ UncaptureUntil(0);
+ return false; // The input didn't match.
}
goto LoopEnd;
if (loop_iteration == 0)
{
// No iterations of the loop remain to backtrack into. Fail the loop.
- goto CaptureBacktrack;
+ UncaptureUntil(0);
+ return false; // The input didn't match.
}
- goto CaptureBacktrack1;
+ goto CaptureBacktrack;
LoopEnd:;
//}
base.Capture(3, capture_starting_pos2, pos);
Utilities.StackPush(ref base.runstack!, ref stackpos, capture_starting_pos2);
- goto CaptureSkipBacktrack2;
+ goto CaptureSkipBacktrack1;
- CaptureBacktrack2:
+ CaptureBacktrack1:
capture_starting_pos2 = base.runstack![--stackpos];
goto CharLoopBacktrack1;
- CaptureSkipBacktrack2:;
+ CaptureSkipBacktrack1:;
//}
// No iterations of the loop remain to backtrack into. Fail the loop.
goto LoopBacktrack;
}
- goto CaptureBacktrack2;
+ goto CaptureBacktrack1;
LoopEnd1:;
//}"^ps_(?<major>1|2|3|4|5)_(?<minor>0|1|)$" (308 uses)[GeneratedRegex("^ps_(?<major>1|2|3|4|5)_(?<minor>0|1|)$")] /// ○ Match a character in the set [1-5].<br/>
/// ○ Match '_'.<br/>
/// ○ "minor" capture group.<br/>
- /// ○ Match with 2 alternative expressions.<br/>
- /// ○ Match a character in the set [01].<br/>
- /// ○ Match an empty string.<br/>
+ /// ○ Match a character in the set [01] atomically, optionally.<br/>
/// ○ Match if at the end of the string or if before an ending newline.<br/>
/// </code>
/// </remarks>
{
int pos = base.runtextpos;
int matchStart = pos;
- int alternation_branch = 0;
- int alternation_starting_capturepos = 0;
- int alternation_starting_pos = 0;
int capture_starting_pos = 0;
int capture_starting_pos1 = 0;
ReadOnlySpan<char> slice = inputSpan.Slice(pos);
}
// "minor" capture group.
- //{
+ {
pos++;
slice = inputSpan.Slice(pos);
capture_starting_pos1 = pos;
- // Match with 2 alternative expressions.
- //{
- alternation_starting_pos = pos;
- alternation_starting_capturepos = base.Crawlpos();
-
- // Branch 0
- //{
- // Match a character in the set [01].
- if (slice.IsEmpty || !char.IsBetween(slice[0], '0', '1'))
- {
- goto AlternationBranch;
- }
-
- alternation_branch = 0;
+ // Match a character in the set [01] atomically, optionally.
+ {
+ if (!slice.IsEmpty && char.IsBetween(slice[0], '0', '1'))
+ {
+ slice = slice.Slice(1);
pos++;
- slice = inputSpan.Slice(pos);
- goto AlternationMatch;
-
- AlternationBranch:
- pos = alternation_starting_pos;
- slice = inputSpan.Slice(pos);
- UncaptureUntil(alternation_starting_capturepos);
- //}
-
- // Branch 1
- //{
-
- alternation_branch = 1;
- goto AlternationMatch;
- //}
-
- AlternationBacktrack:
- if (Utilities.s_hasTimeout)
- {
- base.CheckTimeout();
}
-
- switch (alternation_branch)
- {
- case 0:
- goto AlternationBranch;
- case 1:
- UncaptureUntil(0);
- return false; // The input didn't match.
- }
-
- AlternationMatch:;
- //}
+ }
base.Capture(2, capture_starting_pos1, pos);
-
- goto CaptureSkipBacktrack;
-
- CaptureBacktrack:
- goto AlternationBacktrack;
-
- CaptureSkipBacktrack:;
- //}
+ }
// Match if at the end of the string or if before an ending newline.
if (pos < inputSpan.Length - 1 || ((uint)pos < (uint)inputSpan.Length && inputSpan[pos] != '\n'))
{
- goto CaptureBacktrack;
+ UncaptureUntil(0);
+ return false; // The input didn't match.
}
// The input matched.For more diff examples, see https://gist.github.com/MihuBot/3bce07f425cf5dd2f9385e5952306c0c JIT assembly changesFor a list of JIT diff regressions, see Regressions.md Sample source code for further analysisconst string JsonPath = "RegexResults-1316.json";
if (!File.Exists(JsonPath))
{
await using var archiveStream = await new HttpClient().GetStreamAsync("https://mihubot.xyz/r/E2wTWV0");
using var archive = new ZipArchive(archiveStream, ZipArchiveMode.Read);
archive.Entries.First(e => e.Name == "Results.json").ExtractToFile(JsonPath);
}
using FileStream jsonFileStream = File.OpenRead(JsonPath);
RegexEntry[] entries = JsonSerializer.Deserialize<RegexEntry[]>(jsonFileStream, new JsonSerializerOptions { IncludeFields = true })!;
Console.WriteLine($"Working with {entries.Length} patterns");
record KnownPattern(string Pattern, RegexOptions Options, int Count);
sealed class RegexEntry
{
public required KnownPattern Regex { get; set; }
public required string MainSource { get; set; }
public required string PrSource { get; set; }
public string? FullDiff { get; set; }
public string? ShortDiff { get; set; }
public (string Name, string Values)[]? SearchValuesOfChar { get; set; }
public (string[] Values, StringComparison ComparisonType)[]? SearchValuesOfString { get; set; }
} |
MihaZupan
approved these changes
Jul 28, 2025
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An alternation with two branches where the second is empty is the same as the first branch just being an optional loop. The latter way of it being expressed is better optimized elsewhere in the regex transforms, e.g. with loop coalescing, so we're better off with the optional representation.