More cursor movements

MApplication/ConsoleWindowView.cs

@@ -20,6 +20,11 @@ namespace MApplication
 
         public int Height { get; }
 
+        public void HideCursor()
+        {
+            Console.CursorVisible = false;
+        }
+
         public void MoveCursorTo(int column, int line)
         {
             Console.CursorLeft = StartingColumn + column;
@@ -39,6 +44,11 @@ namespace MApplication
             }
         }
 
+        public void ShowCursor()
+        {
+            Console.CursorVisible = true;
+        }
+
         public void WriteText(string s)
         {
             Console.Write(s);

MApplication/DisplayLine.cs

@@ -1,14 +1,18 @@
 using System.Collections.Immutable;
+using System.Linq;
 
 namespace MApplication
 {
     internal class DisplayLine
     {
-        public ImmutableList<DisplayLineChunk> Chunks { get; }
-
         public DisplayLine(ImmutableList<DisplayLineChunk> chunks)
         {
             Chunks = chunks;
-        }
+            Width = chunks.Sum(c => c.Width);
+        }
+
+        public ImmutableList<DisplayLineChunk> Chunks { get; }
+
+        public int Width { get; }
     }
 }

MApplication/DisplayTextViewPort.cs

@@ -9,13 +9,17 @@ namespace MApplication
             int width,
             int height,
             int startingColumn = 0,
-            int startingLine = 0)
+            int startingLine = 0,
+            int cursorRelativeColumn = 0,
+            int cursorRelativeLine = 0)
         {
             Text = text;
             Width = width;
             Height = height;
             StartingColumn = startingColumn;
             StartingLine = startingLine;
+            CursorRelativeColumn = cursorRelativeColumn;
+            CursorRelativeLine = cursorRelativeLine;
         }
 
         public DisplayText Text { get; }
@@ -28,8 +32,138 @@ namespace MApplication
 
         public int StartingLine { get; }
 
+        public int CursorRelativeColumn { get; }
+
+        public int CursorRelativeLine { get; }
+
+        public int CursorAbsoluteColumn => CursorRelativeColumn + StartingColumn;
+
+        public int CursorAbsoluteLine => CursorRelativeLine + StartingLine;
+
+        public int CurrentLineWidth => Text.Lines[CursorAbsoluteLine].Width;
+
+        public DisplayTextViewPort CursorLeft(out bool needsRedraw)
+        {
+            if (CursorRelativeColumn == 0)
+            {
+                return ShiftLeft(out needsRedraw);
+            }
+            else
+            {
+                return With(out needsRedraw, cursorRelativeColumn: CursorRelativeColumn - 1);
+            }
+        }
+
+        public DisplayTextViewPort CursorRight(out bool needsRedraw)
+        {
+            if (CursorRelativeColumn == Width - 1)
+            {
+                return ShiftRight(out needsRedraw);
+            }
+            else
+            {
+                return With(out needsRedraw, cursorRelativeColumn: CursorRelativeColumn + 1);
+            }
+        }
+
+        private DisplayTextViewPort SnapToLine(out bool needsRedraw)
+        {
+            if (CursorAbsoluteColumn > CurrentLineWidth)
+            {
+                needsRedraw = true;
+                var toSubtract = CursorAbsoluteColumn - CurrentLineWidth;
+                if (toSubtract < CursorRelativeColumn)
+                {
+                    return With(out var _, cursorRelativeColumn: CursorRelativeColumn - toSubtract);
+                }
+
+                return With(
+                    out var _,
+                    startingColumn: StartingColumn - (toSubtract - CursorRelativeColumn),
+                    cursorRelativeColumn: 0);
+            }
+            else
+            {
+                needsRedraw = false;
+                return this;
+            }
+        }
+
+        public DisplayTextViewPort CursorUp(out bool needsRedraw)
+        {
+            bool changed1;
+            var result1 = CursorRelativeLine switch
+            {
+                0 => ShiftUp(out changed1),
+                _ => With(out changed1, cursorRelativeLine: CursorRelativeLine - 1),
+            };
+            var result = result1.SnapToLine(out var changed2);
+            needsRedraw = changed1 || changed2;
+            return result;
+        }
+
+        public DisplayTextViewPort CursorDown(out bool needsRedraw)
+        {
+            bool changed1;
+            var result1 = CursorRelativeLine switch
+            {
+                _ when CursorRelativeLine == Height - 1 => ShiftDown(out changed1),
+                _ => With(out changed1, cursorRelativeLine: CursorRelativeLine + 1),
+            };
+            var result = result1.SnapToLine(out var changed2);
+            needsRedraw = changed1 || changed2;
+            return result;
+        }
+
+        public DisplayTextViewPort CursorHome(out bool needsRedraw)
+        {
+            return With(out needsRedraw, startingColumn: 0, cursorRelativeColumn: 0);
+        }
+
+        public DisplayTextViewPort CursorEnd(out bool needsRedraw)
+        {
+            var lineWidth = Text.Lines[CursorAbsoluteLine].Width;
+            var toAdd = lineWidth - CursorAbsoluteColumn;
+            if (toAdd == 0)
+            {
+                needsRedraw = false;
+                return this;
+            }
+
+            if (CursorRelativeColumn + toAdd < Width)
+            {
+                return With(out needsRedraw, cursorRelativeColumn: CursorRelativeColumn + toAdd);
+            }
+
+            return With(
+                out needsRedraw,
+                startingColumn: StartingColumn + CursorRelativeColumn + toAdd - Width + 1,
+                cursorRelativeColumn: Width - 1);
+        }
+
+        public DisplayTextViewPort ShiftLeft(out bool needsRedraw)
+        {
+            return With(out needsRedraw, startingColumn: Math.Max(StartingColumn - 1, 0));
+        }
+
+        public DisplayTextViewPort ShiftRight(out bool needsRedraw)
+        {
+            return With(out needsRedraw, startingColumn: StartingColumn + 1);
+        }
+
+        public DisplayTextViewPort ShiftUp(out bool needsRedraw)
+        {
+            return With(out needsRedraw, startingLine: Math.Max(StartingLine - 1, 0));
+        }
+
+        public DisplayTextViewPort ShiftDown(out bool needsRedraw)
+        {
+            return With(out needsRedraw, startingLine: StartingLine + 1);
+        }
+
         public void RenderTo(IOutputView view)
         {
+            view.HideCursor();
             for (var lineNumber = StartingLine; lineNumber < StartingLine + Height; lineNumber++)
             {
                 view.MoveCursorTo(0, lineNumber - StartingLine);
@@ -63,32 +197,45 @@ namespace MApplication
                     view.WriteText(new string(' ', numberOfSpaces));
                 }
             }
+            view.MoveCursorTo(column: CursorRelativeColumn, line: CursorRelativeLine);
+            view.ShowCursor();
         }
 
         public DisplayTextViewPort With(
+            out bool changed,
             int? width = null,
             int? height = null,
             int? startingColumn = null,
-            int? startingLine = null)
+            int? startingLine = null,
+            int? cursorRelativeColumn = null,
+            int? cursorRelativeLine = null)
         {
             var widthValue = width ?? Width;
             var heightValue = height ?? Height;
             var startingColumnValue = startingColumn ?? StartingColumn;
             var startingLineValue = startingLine ?? StartingLine;
+            var cursorRelativeColumnValue = cursorRelativeColumn ?? CursorRelativeColumn;
+            var cursorRelativeLineValue = cursorRelativeLine ?? CursorRelativeLine;
             if (widthValue == Width &&
                 heightValue == Height &&
                 startingColumnValue == StartingColumn &&
-                startingLineValue == StartingLine)
+                startingLineValue == StartingLine &&
+                cursorRelativeColumnValue == CursorRelativeColumn &&
+                cursorRelativeLineValue == CursorRelativeLine)
             {
+                changed = false;
                 return this;
             }
 
+            changed = true;
             return new DisplayTextViewPort(
                 text: Text,
                 width: widthValue,
                 height: heightValue,
                 startingColumn: startingColumnValue,
-                startingLine: startingLineValue);
+                startingLine: startingLineValue,
+                cursorRelativeColumn: cursorRelativeColumnValue,
+                cursorRelativeLine: cursorRelativeLineValue);
         }
     }
 }

MApplication/IOutputView.cs

@@ -5,6 +5,8 @@
         int Width { get; }
         int Height { get; }
         void MoveCursorTo(int column, int line);
+        void ShowCursor();
+        void HideCursor();
         void SetStyle(Style style);
         void WriteText(string s);
     }

MApplication/Program.cs

@@ -4,6 +4,80 @@ using System.IO;
 
 namespace MApplication
 {
+    internal class FileRenderer
+    {
+        private readonly IOutputView _outputView;
+
+        public FileRenderer(IOutputView outputView)
+        {
+            _outputView = outputView;
+        }
+
+        private static MParser CreateParser(ITextWindow window)
+        {
+            return new MParser(window);
+        }
+
+        private static SyntaxTree GetTree(string fileName)
+        {
+            var text = File.ReadAllText(fileName);
+            var window = new TextWindowWithNull(text, fileName);
+            var parser = CreateParser(window);
+            var tree = parser.Parse();
+            return tree;
+        }
+
+        public void RenderFile(string fileName)
+        {
+            var tree = GetTree(fileName);
+            var text = CodeProcessor.GetText(tree);
+            var viewPort = new DisplayTextViewPort(
+                text: text,
+                width: 80,
+                height: 24);
+
+            var needsRedraw = true;
+            while (true)
+            {
+                if (needsRedraw)
+                {
+                    viewPort.RenderTo(_outputView);
+                }
+
+                _outputView.MoveCursorTo(viewPort.CursorRelativeColumn, viewPort.CursorRelativeLine);
+
+                var key = Console.ReadKey(intercept: true);
+                switch (key.Key)
+                {
+                    case ConsoleKey.LeftArrow:
+                        viewPort = viewPort.CursorLeft(out needsRedraw);
+                        break;
+
+                    case ConsoleKey.RightArrow:
+                        viewPort = viewPort.CursorRight(out needsRedraw);
+                        break;
+
+                    case ConsoleKey.UpArrow:
+                        viewPort = viewPort.CursorUp(out needsRedraw);
+                        break;
+
+                    case ConsoleKey.DownArrow:
+                        viewPort = viewPort.CursorDown(out needsRedraw);
+                        break;
+
+                    case ConsoleKey.Home:
+                        viewPort = viewPort.CursorHome(out needsRedraw);
+                        break;
+
+                    case ConsoleKey.End:
+                        viewPort = viewPort.CursorEnd(out needsRedraw);
+                        break;
+                }
+            }
+        }
+
+    }
+
     class Program
     {
         private static readonly string BaseDirectory;
@@ -24,20 +98,6 @@ namespace MApplication
             }
         }
 
-        private static MParser CreateParser(ITextWindow window)
-        {
-            return new MParser(window);
-        }
-
-        private static SyntaxTree GetTree(string fileName)
-        {
-            var text = File.ReadAllText(fileName);
-            var window = new TextWindowWithNull(text, fileName);
-            var parser = CreateParser(window);
-            var tree = parser.Parse();
-            return tree;
-        }
-
         private static Style GetStyle()
         {
             return new Style(
@@ -57,56 +117,6 @@ namespace MApplication
             Console.Write(chunk.Text.ToString());
         }
 
-        private static void PrintLine(DisplayLine line)
-        {
-            foreach (var chunk in line.Chunks)
-            {
-                PrintChunk(chunk);
-            }
-        }
-
-        static void RenderFile(string fileName)
-        {
-            var tree = GetTree(fileName);
-            var text = CodeProcessor.GetText(tree);
-            var viewPort = new DisplayTextViewPort(
-                text: text,
-                width: 80,
-                height: 24);
-
-            var targetWidth = 80;
-            var targetHeight = 24;
-            var outputViewPort = new ConsoleWindowView(
-                startingColumn: (Console.WindowWidth - targetWidth) / 2,
-                startingLine: (Console.WindowHeight - targetHeight) / 2,
-                width: targetWidth,
-                height: targetHeight);
-
-            while (true)
-            {
-                viewPort.RenderTo(outputViewPort);
-                var key = Console.ReadKey(intercept: true);
-                switch (key.Key)
-                {
-                    case ConsoleKey.LeftArrow:
-                        viewPort = viewPort.With(startingColumn: Math.Max(viewPort.StartingColumn - 1, 0));
-                        break;
-
-                    case ConsoleKey.RightArrow:
-                        viewPort = viewPort.With(startingColumn: viewPort.StartingColumn + 1);
-                        break;
-
-                    case ConsoleKey.UpArrow:
-                        viewPort = viewPort.With(startingLine: Math.Max(viewPort.StartingLine - 1, 0));
-                        break;
-
-                    case ConsoleKey.DownArrow:
-                        viewPort = viewPort.With(startingLine: viewPort.StartingLine + 1);
-                        break;
-                }
-            }
-        }
-
         static void Main(string[] args)
         {
             var oldStyle = GetStyle();
@@ -115,15 +125,15 @@ namespace MApplication
                 "datatypes",
                 "@table",
                 "table.m");
-            Console.CursorVisible = false;
+            var targetWidth = 80;
-            RenderFile(fileName);
+            var targetHeight = 24;
-            Console.CursorVisible = true;
+            var outputViewPort = new ConsoleWindowView(
-
+                startingColumn: (Console.WindowWidth - targetWidth) / 2,
-            //foreach (var line in text.Lines)
+                startingLine: (Console.WindowHeight - targetHeight) / 2,
-            //{
+                width: targetWidth,
-            //    PrintLine(line);
+                height: targetHeight);
-            //    Console.WriteLine();
+            var renderer = new FileRenderer(outputViewPort);
-            //}
+            renderer.RenderFile(fileName);
 
             SetStyle(oldStyle);
         }