meet difficult problem on COUNT node

src/Nitload.RegularAnalysis/Text/TextRegexSourceGen.GenClass.cs

@@ -220,8 +220,11 @@ namespace Nitload.RegularAnalysis.Text
                             int max,
                             bool is_greedy,
                             [NotNull] in SequenceEmitter<string> sc,
+                            in List<SequenceEmitter<string>> func_list,
                             in SourceGenContext context,
-                            in ExitLabel exit
+                            in ExitLabel exit,
+                            IReadOnlyList<RegexAstNode>? continuation = null,
+                            int next = 0
         )
         {
             if (min < 0 || (max >= 0 && max < min)) {
@@ -300,22 +303,60 @@ namespace Nitload.RegularAnalysis.Text
             }
 
             int additional_limit = max < 0 ? -1 : max - min;
+            bool has_continuation = continuation is not null && next < continuation.Count;
+            bool can_retry = has_continuation && additional_limit != 0;
+            string additional_entry = $"__additional_entry_{scratch_scope_index}";
+            if (can_retry) {
+                _ = sc.AppendLine($"{ROS_char} {additional_entry} = {remain_span};");
+            }
+            if (can_retry || (is_greedy && additional_limit > 0)) {
+                _ = sc.AppendLine($"int {additional_count} = 0;");
+            }
             if (is_greedy && additional_limit != 0)
             {
-                _ = additional_limit < 0 ?
+                string limit = additional_limit < 0 ? string.Empty :
-                    sc.AppendLine($"while (!{remain_span}.IsEmpty && {remain_span}[0] == {expected_literal})")
+                    $"{additional_count} < {additional_limit} && ";
+                _ = sc.AppendLine($"while ({limit}!{remain_span}.IsEmpty && {remain_span}[0] == {expected_literal})")
                       .AppendLine("{")
-                      .AppendLine($"{remain_span} = {remain_span}.Slice(1);")
+                      .AppendLine($"{remain_span} = {remain_span}.Slice(1);");
-                      .AppendLine("}") :
+                if (can_retry || additional_limit > 0) {
-                    sc.AppendLine($"for (int {additional_count} = 0; {additional_count} < {additional_limit} && !{remain_span}.IsEmpty && {remain_span}[0] == {expected_literal}; {additional_count}++)")
+                    _ = sc.AppendLine($"{additional_count}++;");
-                      .AppendLine("{")
+                }
-                      .AppendLine($"{remain_span} = {remain_span}.Slice(1);")
+                _ = sc.AppendLine("}");
-                      .AppendLine("}");
+            }
-            } else if (!is_greedy && additional_limit != 0)
+            if (can_retry)
             {
-                // Lazy COUNT deliberately stops at Min. Its optional tail is consumed only when
+                // The same optional count drives scanning and retries. Required units stay consumed.
-                // a future continuation attempt fails and requests another repetition.
+                ExitLabel retry = context.RequestExitLabel(ExitMode.Goto);
-                _ = sc.AppendLine("// TODO(NGRA): Retry the lazy COUNT tail from its continuation.");
+                _ = sc.AppendLine("while (true)")
+                      .AppendLine("{")
+                      .AppendLine($"{remain_span} = {additional_entry}.Slice({additional_count});");
+                GenerateConcatTail(continuation!, next, sc, func_list, context, retry);
+                _ = sc.AppendLine("break;")
+                      .AppendLine($"{retry.GetLabelName()}: {{}}");
+                if (is_greedy)
+                {
+                    _ = sc.AppendLine($"if ({additional_count} == 0)")
+                          .AppendLine("{")
+                          .AppendLine($"{remain_span} = {additional_entry};")
+                          .AppendLine($"goto {exit_label_node};")
+                          .AppendLine("}")
+                          .AppendLine($"{additional_count}--;");
+                } else
+                {
+                    string limit = additional_limit < 0 ? string.Empty :
+                        $"{additional_count} == {additional_limit} || ";
+                    _ = sc.AppendLine($"{remain_span} = {additional_entry}.Slice({additional_count});")
+                          .AppendLine($"if ({limit}{remain_span}.IsEmpty || {remain_span}[0] != {expected_literal})")
+                          .AppendLine("{")
+                          .AppendLine($"{remain_span} = {additional_entry};")
+                          .AppendLine($"goto {exit_label_node};")
+                          .AppendLine("}")
+                          .AppendLine($"{additional_count}++;");
+                }
+                _ = sc.AppendLine("}");
+            } else if (has_continuation) {
+                GenerateConcatTail(continuation!, next, sc, func_list, context, exit);
             }
         }
 
@@ -399,8 +440,11 @@ namespace Nitload.RegularAnalysis.Text
                             int max,
                             bool is_greedy,
                             [NotNull] in SequenceEmitter<string> sc,
+                            in List<SequenceEmitter<string>> func_list,
                             in SourceGenContext context,
-                            in ExitLabel exit
+                            in ExitLabel exit,
+                            IReadOnlyList<RegexAstNode>? continuation = null,
+                            int next = 0
         )
         {
             if (min < 0 || (max >= 0 && max < min)) {
@@ -510,26 +554,60 @@ namespace Nitload.RegularAnalysis.Text
             }
 
             int additional_limit = max < 0 ? -1 : max - min;
+            bool has_continuation = continuation is not null && next < continuation.Count;
+            bool can_retry = has_continuation && additional_limit != 0;
+            string additional_entry = $"__additional_entry_{scratch_scope_index}";
+            if (can_retry) {
+                _ = sc.AppendLine($"{ROS_char} {additional_entry} = {remain_span};");
+            }
+            if (can_retry || (is_greedy && additional_limit > 0)) {
+                _ = sc.AppendLine($"int {additional_count} = 0;");
+            }
             if (is_greedy && additional_limit != 0)
             {
-                if (additional_limit < 0)
+                string limit = additional_limit < 0 ? string.Empty :
-                {
+                    $"{additional_count} < {additional_limit} && ";
-                    _ = sc.AppendLine($"while ({remain_span}.{starts_with}({expected_literal}))")
+                _ = sc.AppendLine($"while ({limit}{remain_span}.{starts_with}({expected_literal}))")
                       .AppendLine("{")
-                          .AppendLine($"{remain_span} = {remain_span}.Slice({literal.Length});")
+                      .AppendLine($"{remain_span} = {remain_span}.Slice({literal.Length});");
-                          .AppendLine("}");
+                if (can_retry || additional_limit > 0) {
+                    _ = sc.AppendLine($"{additional_count}++;");
+                }
+                _ = sc.AppendLine("}");
+            }
+            if (can_retry)
+            {
+                // Each retry moves by a complete literal using the scan's own optional counter.
+                ExitLabel retry = context.RequestExitLabel(ExitMode.Goto);
+                _ = sc.AppendLine("while (true)")
+                      .AppendLine("{")
+                      .AppendLine($"{remain_span} = {additional_entry}.Slice({additional_count} * {literal.Length});");
+                GenerateConcatTail(continuation!, next, sc, func_list, context, retry);
+                _ = sc.AppendLine("break;")
+                      .AppendLine($"{retry.GetLabelName()}: {{}}");
+                if (is_greedy)
+                {
+                    _ = sc.AppendLine($"if ({additional_count} == 0)")
+                          .AppendLine("{")
+                          .AppendLine($"{remain_span} = {additional_entry};")
+                          .AppendLine($"goto {exit_label_node};")
+                          .AppendLine("}")
+                          .AppendLine($"{additional_count}--;");
                 } else
                 {
-                    _ = sc.AppendLine($"for (int {additional_count} = 0; {additional_count} < {additional_limit} && {remain_span}.{starts_with}({expected_literal}); {additional_count}++)")
+                    string limit = additional_limit < 0 ? string.Empty :
+                        $"{additional_count} == {additional_limit} || ";
+                    _ = sc.AppendLine($"{remain_span} = {additional_entry}.Slice({additional_count} * {literal.Length});")
+                          .AppendLine($"if ({limit}!{remain_span}.{starts_with}({expected_literal}))")
                           .AppendLine("{")
-                          .AppendLine($"{remain_span} = {remain_span}.Slice({literal.Length});")
+                          .AppendLine($"{remain_span} = {additional_entry};")
-                          .AppendLine("}");
+                          .AppendLine($"goto {exit_label_node};")
+                          .AppendLine("}")
+                          .AppendLine($"{additional_count}++;");
                 }
-            } else if (!is_greedy && additional_limit != 0)
+                _ = sc.AppendLine("}");
-            {
+            } else if (has_continuation) {
-                // Lazy COUNT deliberately stops at Min. Its optional tail is consumed only when
+                GenerateConcatTail(continuation!, next, sc, func_list, context, exit);
-                // a future continuation attempt fails and requests another repetition.
-                _ = sc.AppendLine("// TODO(NGRA): Retry the lazy COUNT tail from its continuation.");
             }
         }
 
@@ -604,12 +682,10 @@ namespace Nitload.RegularAnalysis.Text
                             in ExitLabel exit_label = default
         )
         {
-            if (!RegexAstNode.IsNullOrEmpty(node.Left)) {
+            // Keep the complete suffix visible even when CONCAT is left-associated.
-                GenerateMethodSource(node.Left, sc, func_list, context, exit_label);
+            List<RegexAstNode> sequence = [];
-            }
+            AppendConcatNodes(node, sequence);
-            if (!RegexAstNode.IsNullOrEmpty(node.Right)) {
+            GenerateConcatTail(sequence, 0, sc, func_list, context, exit_label);
-                GenerateMethodSource(node.Right, sc, func_list, context, exit_label);
-            }
         }
 
         private static void GenerateCount(
@@ -617,13 +693,25 @@ namespace Nitload.RegularAnalysis.Text
                             [NotNull] in SequenceEmitter<string> sc,
                             in List<SequenceEmitter<string>> func_list,
                             in SourceGenContext context,
-                            in ExitLabel exit_label
+                            in ExitLabel exit_label,
+                            IReadOnlyList<RegexAstNode>? continuation = null,
+                            int next = 0
         )
         {
             RegexAstNode value = RegexAstNode.IsNullOrEmpty(node.Left) ? node.Right : node.Left;
             if (RegexAstNode.IsNullOrEmpty(value)) {
                 throw new InvalidOperationException("COUNT requires an operand.");
             }
+            // Inspect transparent CONCAT wrappers without rewriting the repetition body.
+            while (value.Label == RegexElementLabel.CONCAT)
+            {
+                bool left_empty = RegexAstNode.IsNullOrEmpty(value.Left);
+                bool right_empty = RegexAstNode.IsNullOrEmpty(value.Right);
+                if (left_empty == right_empty) {
+                    break;
+                }
+                value = left_empty ? value.Right : value.Left;
+            }
             RegexCountPayload payload = node.PayloadAs<RegexCountPayload>();
             int min = payload.Min;
             int max = payload.Max;
@@ -641,14 +729,16 @@ namespace Nitload.RegularAnalysis.Text
                 switch (value.Label & RegexElementLabel.SEQUENCE)
                 {
                     case RegexElementLabel.UNIT:
-                        GenerateUnitCount(value, min, max, is_greedy, sc, context, exit_label);
+                        GenerateUnitCount(value, min, max, is_greedy, sc, func_list, context,
-                        break;
+                                          exit_label, continuation, next);
+                        return;
                     case RegexElementLabel.UNIT_SET:
                         GenerateUnitSetCount(value, min, max, is_greedy, sc, context, exit_label);
                         break;
                     case RegexElementLabel.UNIT_SPAN:
-                        GenerateUnitSpanCount(value, min, max, is_greedy, sc, context, exit_label);
+                        GenerateUnitSpanCount(value, min, max, is_greedy, sc, func_list, context,
-                        break;
+                                              exit_label, continuation, next);
+                        return;
                     default:
 
                         // TODO(NGRA): Diagnose malformed COUNT children instead of emitting an
@@ -656,7 +746,9 @@ namespace Nitload.RegularAnalysis.Text
                         break;
                 }
             }
-
+            if (continuation is not null) {
+                GenerateConcatTail(continuation, next, sc, func_list, context, exit_label);
+            }
         }
 
         #endregion

src/Nitload.RegularAnalysis/Text/TextRegexSourceGen.GenSpecial.cs

@@ -180,6 +180,50 @@ namespace Nitload.RegularAnalysis.Text
 
             #endregion
 
+        #region CONCAT continuation
+
+        private static void AppendConcatNodes(
+                            RegexAstNode node,
+                            List<RegexAstNode> sequence
+        )
+        {
+            if (RegexAstNode.IsNullOrEmpty(node)) {
+                return;
+            }
+            if (node.Label == RegexElementLabel.CONCAT &&
+                !RegexAstNode.IsDotStar(node.Left) && !IsNamedFind(node))
+            {
+                AppendConcatNodes(node.Left, sequence);
+                AppendConcatNodes(node.Right, sequence);
+            } else {
+                sequence.Add(node);
+            }
+        }
+
+        private static void GenerateConcatTail(
+                            IReadOnlyList<RegexAstNode> sequence,
+                            int start,
+                            in SequenceEmitter<string> sc,
+                            in List<SequenceEmitter<string>> func_list,
+                            in SourceGenContext context,
+                            in ExitLabel exit_label
+        )
+        {
+            for (int i = start; i < sequence.Count; i++)
+            {
+                RegexAstNode node = sequence[i];
+                if (node.Label == RegexElementLabel.COUNT)
+                {
+                    // COUNT owns both its repetition and the continuation that may retry it.
+                    GenerateCount(node, sc, func_list, context, exit_label, sequence, i + 1);
+                    return;
+                }
+                GenerateMethodSource(node, sc, func_list, context, exit_label);
+            }
+        }
+
+        #endregion
+
         #region FIND concatenation
 
         private static bool TryGenerateFindConcat(

test/StgSharpDebug/Program.cs

@@ -24,17 +24,8 @@ namespace Nitload
 
         private static string testExpPath = @"D:\Programmer\stepcode\data\ap203\ap203.exp";
 
-        internal static unsafe void Main(
+        internal static unsafe void Main()
-                                    string[] args
-        )
         {
-            // Select the managed-only emitter preview before initializing the normal runtime.
-            if (args.Length > 0 && args[0] == "--regex-preview")
-            {
-                Environment.ExitCode = TestRegexGenerate.Run(args[1..]);
-                return;
-            }
-
             try
             {
                 World.Initialize(new()
@@ -47,7 +38,7 @@ namespace Nitload
                      .InitializeModule();
 
                 // TestRegexAnalyse.Run();
-                _ = TestRegexGenerate.Run("abc|123");
+                _ = TestRegexGenerate.Run("abc1{1,2}23");
 
                 // TestHlsf();
 

test/StgSharpDebug/TestRegexGenerate.cs

@@ -1,6 +1,6 @@
 // -----------------------------------------------------------------------------
 // file="TestRegexGenerate"
-// Project: Nitload
+// Project: StgSharp
 // Copyright (c) Nitload.
 // SPDX-License-Identifier: MIT
 // -----------------------------------------------------------------------------
@@ -16,29 +16,19 @@ namespace Nitload
 {
     internal static class TestRegexGenerate
     {
-        public static int Run(params string[] args)
+
+        public static int Run(
+                          string arg
+        )
         {
-            if (args.Length > 1) {
+            Console.WriteLine($"Text regex to be tested: {arg} :\n\n\n");
-                throw new ArgumentException("Expected at most one regex pattern.", nameof(args));
+            Print(arg);
-            }
-            if (args.Length == 1)
-            {
-                Print(args[0]);
             return 0;
         }
 
-            while (true)
+        private static void Print(
-            {
+                            string pattern
-                Console.Write("regex> ");
+        )
-                string? pattern = Console.ReadLine();
-                if (pattern is null or ":exit") {
-                    return 0;
-                }
-                Print(pattern);
-            }
-        }
-
-        private static void Print(string pattern)
         {
             TextRegexSource analysis = RegexAnalyzer.Analyze(pattern);
             if (analysis.AnalyseException is not null) {
@@ -61,5 +51,6 @@ namespace Nitload
                 }
             }
         }
+
     }
 }