a few add to source gen

src/StgSharp.RegularAnalysis/Text/RegexAnalyzer.SourceGen.cs

@@ -20,9 +20,7 @@ namespace StgSharp.RegularAnalysis.Text
     public partial class RegexAnalyzer
     {
 
-        internal static SequenceEmitter<string> GenerateSource(
-                                                TextRegexSource source
-        )
+        internal static SequenceEmitter<string> GenerateSource(TextRegexSource source)
         {
             SequenceEmitter<string> se = new();
             List<SequenceEmitter<string>> sub_match_list = [];
@@ -33,6 +31,8 @@ namespace StgSharp.RegularAnalysis.Text
             RegexIR[] window = new RegexIR[8];
             Span<RegexIR> scan_win = window;
 
+            const string current_ptr = "current_ptr";
+
             _ = se.AppendLine(@"public override MatchResult Match(ReadOnlySpan<char> text)")//
                   .AppendLine(@"{");
 
@@ -44,6 +44,8 @@ namespace StgSharp.RegularAnalysis.Text
                       .AppendLine($@"bool region_{i}_success;");
             }
 
+            _ = se.AppendLine($@"int {current_ptr} = 0;");
+
             int index = 0;
             do
             {
@@ -61,15 +63,19 @@ namespace StgSharp.RegularAnalysis.Text
 
             return se;
             /**/
-            int TryGenerateMatch(
-                Span<RegexIR> scan_win,
-                SequenceEmitter<string> sb
-            )
+            int TryGenerateMatch(Span<RegexIR> scan_win, SequenceEmitter<string> sb)
             {
                 if (scan_win[0] is not RegexMatchSeqIR seq) {
                     return -1;
                 }
-                _ = sb.Append(string.Empty);
+                string pattern = seq.Pattern;
+                int length = pattern.Length;
+                _ = sb.Append(string.Empty)
+                      .AppendLine($@"if(text[{current_ptr}..({current_ptr} + {length})] == {pattern})")
+                      .AppendLine($@"{{")
+                      .AppendLine($@"{current_ptr} += {length};")
+                      .AppendLine($@"}}");
+
                 return 1;
             }
             /**/
@@ -77,3 +83,4 @@ namespace StgSharp.RegularAnalysis.Text
 
     }
 }
+