private Cursor Clamp(EditorBuffer buffer)
{
var row = this.row.Clamp(0, buffer.LinesCount - 1);
var col = this.col.Clamp(0, buffer.Lines[row].Length);
return(new Cursor(row, col));
}
public Editor()
{
this.buffer = new EditorBuffer(new List <string>
{
"One line",
"Two lines",
"",
"Last line, maybe"
}.ToImmutableList());
this.cursor = new Cursor(0, 0);
}
private void HandleInput()
{
var c = Console.ReadKey(true);
// ctrl-q exits
if (c.Key == ConsoleKey.Q && c.Modifiers.HasFlag(ConsoleModifiers.Control))
{
Environment.Exit(0);
}
if (c.Key == ConsoleKey.RightArrow)
{
cursor = cursor.MoveRight(buffer);
return;
}
if (c.Key == ConsoleKey.LeftArrow)
{
cursor = cursor.MoveLeft(buffer);
return;
}
if (c.Key == ConsoleKey.UpArrow)
{
cursor = cursor.MoveUp(buffer);
return;
}
if (c.Key == ConsoleKey.DownArrow)
{
cursor = cursor.MoveDown(buffer);
return;
}
if (c.Key == ConsoleKey.Enter)
{
buffer = buffer.InsertNewLine(this.cursor.Row, this.cursor.Col);
cursor = cursor.MoveDown(buffer).MoveToBeginningOfLine(buffer);
return;
}
if (c.Key == ConsoleKey.Backspace)
{
buffer = buffer.DeleteBack(this.cursor.Row, this.cursor.Col);
cursor = cursor.MoveLeft(buffer);
return;
}
// in all other cases, insert into the current position
buffer = buffer.Insert(c.KeyChar, this.cursor.Row, this.cursor.Col);
cursor = cursor.MoveRight(buffer);
}
internal Cursor MoveToBeginningOfLine(EditorBuffer buffer)
{
return(new Cursor(row, 0));
}
public Cursor MoveDown(EditorBuffer buffer)
{
return(new Cursor(this.Row + 1, this.Col).Clamp(buffer));
}
public Cursor MoveLeft(EditorBuffer buffer)
{
return(new Cursor(this.Row, this.Col - 1).Clamp(buffer));
}