commit 04dff697d9783cbe522075a84ada8e7efc1a0186
Author: osmedile <osmedile@gmail.com>
Date:   Thu Oct 27 22:59:31 2022 +0200

    Replace ImmutableList by interface

diff --git a/TypeCobol.Test/Parser/Scanner/ScannerUtils.cs b/TypeCobol.Test/Parser/Scanner/ScannerUtils.cs
index 70a5db13a..a7b5cc13e 100644
--- a/TypeCobol.Test/Parser/Scanner/ScannerUtils.cs
+++ b/TypeCobol.Test/Parser/Scanner/ScannerUtils.cs
@@ -75,7 +75,7 @@ namespace TypeCobol.Test.Parser.Scanner
             tokensLinesList.AddRange(tokensLines);
 
             var initialScanState = new MultilineScanState(TextSourceInfo.EncodingForAlphanumericLiterals);
-            ScannerStep.ScanDocument(TextSourceInfo, tokensLinesList, CompilerOptions, CopyTextNameVariations, initialScanState);
+            ScannerStep.ScanDocument(TextSourceInfo, tokensLinesList.ToImmutable(), CompilerOptions, CopyTextNameVariations, initialScanState);
 
             StringBuilder sbResult = new StringBuilder();
             for (int i = 0; i < tokensLines.Length; i++)
diff --git a/TypeCobol/Compiler/CompilationDocument.cs b/TypeCobol/Compiler/CompilationDocument.cs
index 3d24b3192..093e5b5c9 100644
--- a/TypeCobol/Compiler/CompilationDocument.cs
+++ b/TypeCobol/Compiler/CompilationDocument.cs
@@ -654,10 +654,10 @@ namespace TypeCobol.Compiler
                     if (tokensDocument != null)
                     {
                         // Process all lines of the document for the first time
-                        PreprocessorStep.ProcessDocument(this, ((ImmutableList<CodeElementsLine>)tokensDocument.Lines), _documentImporter, perfStatsForParserInvocation, out missingCopies);
+                        PreprocessorStep.ProcessDocument(this, ((ISearchableReadOnlyList<ProcessedTokensLine>)tokensDocument.Lines), _documentImporter, perfStatsForParserInvocation, out missingCopies);
 
                         // Create the first processed tokens document snapshot
-                        ProcessedTokensDocumentSnapshot = CreateProcessedTokensDocument(new DocumentVersion<IProcessedTokensLine>(this), (ISearchableReadOnlyList<CodeElementsLine>) tokensDocument.Lines);
+                        ProcessedTokensDocumentSnapshot = CreateProcessedTokensDocument(new DocumentVersion<IProcessedTokensLine>(this), (ISearchableReadOnlyList<ICodeElementsLine>) tokensDocument.Lines);
                     }
                     else
                     {
@@ -667,9 +667,8 @@ namespace TypeCobol.Compiler
                 }
                 else
                 {
-                    ImmutableList<CodeElementsLine>.Builder processedTokensDocumentLines = ((ImmutableList<CodeElementsLine>) tokensDocument.Lines).ToBuilder();
                     IList<DocumentChange<IProcessedTokensLine>> documentChanges = PreprocessorStep.ProcessChanges(this,
-                        processedTokensDocumentLines, tokensLineChanges, PrepareDocumentLineForUpdate,
+                        (ISearchableReadOnlyList<ProcessedTokensLine>)tokensDocument.Lines, tokensLineChanges, PrepareDocumentLineForUpdate,
                         _documentImporter, perfStatsForParserInvocation, out missingCopies);
 
                     // Create a new version of the document to track these changes
@@ -685,7 +684,7 @@ namespace TypeCobol.Compiler
                     ProcessedTokensDocumentSnapshot = CreateProcessedTokensDocument(currentProcessedTokensLineVersion, processedTokensDocumentLines.ToImmutable());
                 }
 
-                ProcessedTokensDocument CreateProcessedTokensDocument(DocumentVersion<IProcessedTokensLine> version, ISearchableReadOnlyList<CodeElementsLine> lines)
+                ProcessedTokensDocument CreateProcessedTokensDocument(DocumentVersion<IProcessedTokensLine> version, ISearchableReadOnlyList<ICodeElementsLine> lines)
                 {
                     //Apply automatic replacing of partial-words for direct copy parsing mode
                     return UseDirectCopyParsing
diff --git a/TypeCobol/Compiler/CompilationUnit.cs b/TypeCobol/Compiler/CompilationUnit.cs
index 4c64bad8e..87c6273ff 100644
--- a/TypeCobol/Compiler/CompilationUnit.cs
+++ b/TypeCobol/Compiler/CompilationUnit.cs
@@ -98,7 +98,7 @@ namespace TypeCobol.Compiler
                         CodeElementsParserStep.ParseDocument(processedTokensDocument, CompilerOptions, perfStatsForParserInvocation);
 
                         // Create the first code elements document snapshot
-                        CodeElementsDocumentSnapshot = new CodeElementsDocument(processedTokensDocument, new DocumentVersion<ICodeElementsLine>(this), ((ImmutableList<CodeElementsLine>)processedTokensDocument.Lines));
+                        CodeElementsDocumentSnapshot = new CodeElementsDocument(processedTokensDocument, new DocumentVersion<ICodeElementsLine>(this), ((ISearchableReadOnlyList<ICodeElementsLine>)processedTokensDocument.Lines));
                     }
                 }
                 else
@@ -115,8 +115,7 @@ namespace TypeCobol.Compiler
                     currentCodeElementsLinesVersion = currentCodeElementsLinesVersion.next;
 
                     // Update the code elements document snapshot
-                    ImmutableList<CodeElementsLine>.Builder codeElementsDocumentLines = ((ImmutableList<CodeElementsLine>)processedTokensDocument.Lines).ToBuilder();
-                    CodeElementsDocumentSnapshot = new CodeElementsDocument(processedTokensDocument, currentCodeElementsLinesVersion, codeElementsDocumentLines.ToImmutable());
+                    CodeElementsDocumentSnapshot = new CodeElementsDocument(processedTokensDocument, currentCodeElementsLinesVersion, (ISearchableReadOnlyList<ICodeElementsLine>) processedTokensDocument.Lines);
                 }
 
                 // Stop perf measurement
@@ -253,10 +252,9 @@ namespace TypeCobol.Compiler
                     var customAnalyzers = _analyzerProvider?.CreateSyntaxDrivenAnalyzers(CompilerOptions, TextSourceInfo);
 
                     // Program and Class parsing is not incremental : the objects are rebuilt each time this method is called
-                    //TODO cast to ImmutableList<CodeElementsLine> sometimes fails here
                     ProgramClassParserStep.CupParseProgramOrClass(
                         TextSourceInfo,
-                        (ImmutableList<CodeElementsLine>) codeElementsDocument.Lines,
+                        codeElementsDocument.Lines,
                         CompilerOptions,
                         CustomSymbols,
                         perfStatsForParserInvocation,
diff --git a/TypeCobol/Compiler/CupParser/CodeElementTokenizer.cs b/TypeCobol/Compiler/CupParser/CodeElementTokenizer.cs
index ae7fd126a..ec1157cab 100644
--- a/TypeCobol/Compiler/CupParser/CodeElementTokenizer.cs
+++ b/TypeCobol/Compiler/CupParser/CodeElementTokenizer.cs
@@ -31,7 +31,7 @@ namespace TypeCobol.Compiler.CupParser
         /// <param name="lines">CodeElement lines to enumerate as symbols.</param>
         /// <param name="before">Optional fake CodeElements to enumerate before real ones.</param>
         /// <param name="after">Optional fake CodeElements to enumerate after real ones.</param>
-        public CodeElementTokenizer(IEnumerable<CodeElementsLine> lines, IEnumerable<CodeElement> before = null, IEnumerable<CodeElement> after = null)
+        public CodeElementTokenizer(IEnumerable<ICodeElementsLine> lines, IEnumerable<CodeElement> before = null, IEnumerable<CodeElement> after = null)
             : this(before?.Select(ToSymbol), lines, after?.Select(ToSymbol))
         {
 
@@ -53,7 +53,7 @@ namespace TypeCobol.Compiler.CupParser
 
         }
 
-        private CodeElementTokenizer(IEnumerable<Symbol> before, IEnumerable<CodeElementsLine> lines, IEnumerable<Symbol> after)
+        private CodeElementTokenizer(IEnumerable<Symbol> before, IEnumerable<ICodeElementsLine> lines, IEnumerable<Symbol> after)
         {
             _enumerator = Enumerator(before, lines, after);
         }
@@ -68,7 +68,7 @@ namespace TypeCobol.Compiler.CupParser
             return null;
         }
 
-        private IEnumerator<Symbol> Enumerator(IEnumerable<Symbol> before, IEnumerable<CodeElementsLine> lines, IEnumerable<Symbol> after)
+        private IEnumerator<Symbol> Enumerator(IEnumerable<Symbol> before, IEnumerable<ICodeElementsLine> lines, IEnumerable<Symbol> after)
         {
             //symbols before
             if (before != null)
diff --git a/TypeCobol/Compiler/CupParser/NodeBuilder/ProgramClassBuilder.cs b/TypeCobol/Compiler/CupParser/NodeBuilder/ProgramClassBuilder.cs
index 29b0c1e3c..7ba00ecff 100644
--- a/TypeCobol/Compiler/CupParser/NodeBuilder/ProgramClassBuilder.cs
+++ b/TypeCobol/Compiler/CupParser/NodeBuilder/ProgramClassBuilder.cs
@@ -87,9 +87,9 @@ namespace TypeCobol.Compiler.CupParser.NodeBuilder
         private readonly SymbolTable TableOfIntrinsics;
         private readonly SymbolTable TableOfNamespaces;
 
-        private readonly IReadOnlyList<CodeElementsLine> _codeElementsLines;
+        private readonly IReadOnlyList<ICodeElementsLine> _codeElementsLines;
 
-        public ProgramClassBuilder(IReadOnlyList<CodeElementsLine> codeElementsLines)
+        public ProgramClassBuilder(IReadOnlyList<ICodeElementsLine> codeElementsLines)
         {
             // Intrinsics and Namespaces always exist. Intrinsic table has no enclosing scope.
             TableOfIntrinsics = new SymbolTable(null, SymbolTable.Scope.Intrinsic);
diff --git a/TypeCobol/Compiler/Parser/ICodeElementsLine.cs b/TypeCobol/Compiler/Parser/ICodeElementsLine.cs
index 957a44b30..d85472080 100644
--- a/TypeCobol/Compiler/Parser/ICodeElementsLine.cs
+++ b/TypeCobol/Compiler/Parser/ICodeElementsLine.cs
@@ -15,7 +15,12 @@ namespace TypeCobol.Compiler.Parser
         /// Code elements STARTING on this line 
         /// </summary>
         IList<CodeElement> CodeElements { get; }
-        
+
+        /// <summary>
+        /// True if a code element starts on the current line
+        /// </summary>
+        bool HasCodeElements { get; }
+
         /// <summary>
         /// Error and warning messages produced while parsing the source text line
         /// </summary>
diff --git a/TypeCobol/Compiler/Parser/ProgramClassParserStep.cs b/TypeCobol/Compiler/Parser/ProgramClassParserStep.cs
index f148ee5e0..241020579 100644
--- a/TypeCobol/Compiler/Parser/ProgramClassParserStep.cs
+++ b/TypeCobol/Compiler/Parser/ProgramClassParserStep.cs
@@ -42,7 +42,7 @@ namespace TypeCobol.Compiler.Parser
         }
         public static void CupParseProgramOrClass(
             TextSourceInfo textSourceInfo,
-            ISearchableReadOnlyList<CodeElementsLine> codeElementsLines,
+            ISearchableReadOnlyList<ICodeElementsLine> codeElementsLines,
             TypeCobolOptions compilerOptions,
             SymbolTable customSymbols,
             PerfStatsForParserInvocation perfStatsForParserInvocation,
diff --git a/TypeCobol/Compiler/Preprocessor/AutoReplacePartialWordsTokensDocument.cs b/TypeCobol/Compiler/Preprocessor/AutoReplacePartialWordsTokensDocument.cs
index 5dcb793db..20c3fe1bb 100644
--- a/TypeCobol/Compiler/Preprocessor/AutoReplacePartialWordsTokensDocument.cs
+++ b/TypeCobol/Compiler/Preprocessor/AutoReplacePartialWordsTokensDocument.cs
@@ -82,7 +82,7 @@ namespace TypeCobol.Compiler.Preprocessor
 
         private readonly TypeCobolOptions _compilerOptions;
 
-        public AutoReplacePartialWordsTokensDocument(TokensDocument previousStepSnapshot, DocumentVersion<IProcessedTokensLine> processedTokensLinesVersion, ISearchableReadOnlyList<CodeElementsLine> processedTokensLines, TypeCobolOptions compilerOptions)
+        public AutoReplacePartialWordsTokensDocument(TokensDocument previousStepSnapshot, DocumentVersion<IProcessedTokensLine> processedTokensLinesVersion, ISearchableReadOnlyList<ICodeElementsLine> processedTokensLines, TypeCobolOptions compilerOptions)
             : base(previousStepSnapshot, processedTokensLinesVersion, processedTokensLines, compilerOptions)
         {
             _compilerOptions = compilerOptions;