Merge pull request #235 from mitchellh/insert-mode

terminal: implement insert mode (mode = 4)

src/terminal/Terminal.zig

@@ -83,6 +83,7 @@ modes: packed struct {
     const Self = @This();
 
     cursor_keys: bool = false, // 1
+    insert: bool = false, // 4
     reverse_colors: bool = false, // 5,
     origin: bool = false, // 6
     autowrap: bool = true, // 7
@@ -107,7 +108,7 @@ modes: packed struct {
         // We have this here so that we explicitly fail when we change the
         // size of modes. The size of modes is NOT particularly important,
         // we just want to be mentally aware when it happens.
-        try std.testing.expectEqual(2, @sizeOf(Self));
+        try std.testing.expectEqual(4, @sizeOf(Self));
     }
 } = .{},
 
@@ -689,6 +690,11 @@ pub fn print(self: *Terminal, c: u21) !void {
     if (self.screen.cursor.pending_wrap and self.modes.autowrap)
         try self.printWrap();
 
+    // If we have insert mode enabled then we need to handle that. We
+    // only do insert mode if we're not at the end of the line.
+    if (self.modes.insert and self.screen.cursor.x + width < self.cols)
+        self.insertBlanks(width);
+
     switch (width) {
         // Single cell is very easy: just write in the cell
         1 => _ = @call(.always_inline, printCell, .{ self, c }),

src/terminal/ansi.zig

@@ -62,6 +62,10 @@ pub const Mode = enum(u16) {
     /// wide. When unset, resizes to 80 columns.
     @"132_column" = 3,
 
+    /// Insert mode. This mode writes a character and pushes all existing
+    /// characters to the right. The existing contents are never wrapped.
+    insert = 4,
+
     /// Reverses the foreground and background colors of all cells.
     reverse_colors = 5,
 

src/termio/Exec.zig

@@ -1182,6 +1182,10 @@ const StreamHandler = struct {
                 self.terminal.modes.cursor_keys = enabled;
             },
 
+            .insert => {
+                self.terminal.modes.insert = enabled;
+            },
+
             .reverse_colors => {
                 self.terminal.modes.reverse_colors = enabled;