compile time optimisation - avoids allocs during parsing

src/Peachpie.CodeAnalysis/Syntax/PhpSourceUnit.cs

@@ -63,11 +63,6 @@ public override void Parse(INodesFactory<LangElement, Span> factory, IErrorSink<
             Parse((NodesFactory)factory, errors, recovery, LanguageFeatures.Basic, Lexer.LexicalStates.INITIAL);
         }
 
-        static ILineBreaks CreateLineBreaks(SourceText source)
-        {
-            return Devsense.PHP.Text.LineBreaks.Create(
-                source.ToString(),
-                source.Lines.Select(line => line.EndIncludingLineBreak).ToList());
-        }
+        static ILineBreaks CreateLineBreaks(SourceText source) => new SourceLineBreaks(source);
     }
 }

src/Peachpie.CodeAnalysis/Syntax/SourceLineBreaks.cs

@@ -0,0 +1,22 @@
+using Devsense.PHP.Text;
+using Microsoft.CodeAnalysis.Text;
+
+namespace Peachpie.CodeAnalysis.Syntax
+{
+    /// <summary>
+    /// Implements <see cref="ILineBreaks"/> of <see cref="SourceText"/>.
+    /// </summary>
+    sealed class SourceLineBreaks : LineBreaks
+    {
+        private readonly SourceText/*!*/_source;
+
+        public SourceLineBreaks(SourceText source) : base(source.Length)
+        {
+            _source = source;
+        }
+
+        public override int EndOfLineBreak(int index) => _source.Lines[index].EndIncludingLineBreak;
+
+        public override int Count => _source.Lines.Count - 1;
+    }
+}