From 0ac7773ac08a0f8cc40f26a6f1ce37eab01103eb Mon Sep 17 00:00:00 2001
From: ig <ig ig@devnullmail.com>
Date: Thu, 4 May 2023 09:46:50 +0200
Subject: [PATCH] add/group extensions to parse strings

---
 csharp/Lib/Utils/StringParsing.cs | 87 +++++++++++++++++++++++++++++++
 1 file changed, 87 insertions(+)
 create mode 100644 csharp/Lib/Utils/StringParsing.cs

diff --git a/csharp/Lib/Utils/StringParsing.cs b/csharp/Lib/Utils/StringParsing.cs
new file mode 100644
index 000000000..37a3fd13b
--- /dev/null
+++ b/csharp/Lib/Utils/StringParsing.cs
@@ -0,0 +1,87 @@
+using System.Reactive.Linq;
+using System.Text;
+
+namespace InnovEnergy.Lib.Utils;
+
+public static class StringParsing
+{
+    public static IObservable<String> ParseLines(this IObservable<ReadOnlyMemory<Byte>> source, String eol = "\n")
+    {
+        return ParseLines(source, Encoding.UTF8, eol);
+    }
+
+    public static IObservable<String> ParseLines(this IObservable<ReadOnlyMemory<Byte>> source, Encoding encoding, String eol = "\n")
+    {
+        return source
+              .Select(d => encoding.GetString(d.Span))
+              .ParseLines(eol);
+    }
+
+    public static IObservable<String> ParseLines(this IObservable<String> source, String eol = "\n")
+    {
+        var accumulator = new StringBuilder();
+         
+        return source
+              .Append(eol)
+              .SelectMany(SplitLines);
+         
+        IEnumerable<String> SplitLines(String s)
+        {
+            if (!s.Contains(eol))
+            {
+                accumulator.Append(s);
+                yield break;
+            }
+    
+            var split = s.Split(eol); // scatter
+    
+            yield return accumulator.Append(split[0]).ToString(); // gather    
+          
+            foreach (var line in split[1..^1])
+                yield return line;
+            
+            accumulator.Clear();
+            accumulator.Append(split[^1]);
+        }        
+    }
+
+    public static IEnumerable<String> ParseLines(this IEnumerable<ReadOnlyMemory<Byte>> source, String eol = "\n")
+    {
+        return ParseLines(source, Encoding.UTF8, eol);
+    }
+
+    public static IEnumerable<String> ParseLines(this IEnumerable<ReadOnlyMemory<Byte>> source, Encoding encoding, String eol = "\n")
+    {
+        return source
+              .Select(d => encoding.GetString(d.Span))
+              .ParseLines(eol);
+    }
+
+    public static IEnumerable<String> ParseLines(this IEnumerable<String> source, String eol = "\n")
+    {
+        var accumulator = new StringBuilder();
+         
+        return source
+              .Append(eol)
+              .SelectMany(SplitLines);
+         
+        IEnumerable<String> SplitLines(String s)
+        {
+            if (!s.Contains(eol))
+            {
+                accumulator.Append(s);
+                yield break;
+            }
+    
+            var split = s.Split(eol); // scatter
+    
+            yield return accumulator.Append(split[0]).ToString(); // gather    
+          
+            foreach (var line in split[1..^1])
+                yield return line;
+            
+            accumulator.Clear();
+            accumulator.Append(split[^1]);
+        }        
+    }
+}
\ No newline at end of file