C#: Add shared base class for line and line span pragmas.

csharp/extractor/Semmle.Extraction.CSharp/Entities/PreprocessorDirectives/LineOrSpanDirective.cs

@@ -0,0 +1,32 @@
+using Microsoft.CodeAnalysis;
+using Microsoft.CodeAnalysis.CSharp;
+using Microsoft.CodeAnalysis.CSharp.Syntax;
+using System.IO;
+
+namespace Semmle.Extraction.CSharp.Entities
+{
+    internal enum LineDirectiveKind
+    {
+        Default = 0,
+        Hidden = 1,
+        Numeric = 2,
+        Span = 3
+    }
+
+    internal abstract class LineOrSpanDirective<T> : PreprocessorDirective<T> where T : LineOrSpanDirectiveTriviaSyntax
+    {
+        protected LineOrSpanDirective(Context cx, T trivia)
+            : base(cx, trivia)
+        {
+        }
+
+        protected override void PopulatePreprocessor(TextWriter trapFile)
+        {
+            if (!string.IsNullOrWhiteSpace(Symbol.File.ValueText))
+            {
+                var file = File.Create(Context, Symbol.File.ValueText);
+                trapFile.directive_line_file(this, file);
+            }
+        }
+    }
+}