add(widget/Spacer): empty widget implementation

src/main.zig

@@ -34,15 +34,18 @@ pub fn main() !void {
     var appFileText = App.Widget.RawText.init(allocator, appFile);
     appFile.close();
 
+    var spacer = App.Widget.Spacer.init();
     var framing = App.Layout.Framing.init(allocator, .{
         .widget = App.Widget.createFrom(&mainFileText),
     });
     var hstack = App.Layout.HStack.init(allocator, .{
         App.Layout.createFrom(&framing),
     });
+    // TODO: corresponding contents need to be filled out by the layout accordingly!
     var vstack = App.Layout.VStack.init(allocator, .{
         App.Widget.createFrom(&appFileText),
         App.Layout.createFrom(&hstack),
+        App.Widget.createFrom(&spacer),
     });
     var layout = App.Layout.createFrom(&vstack);
     defer layout.deinit();

src/widget.zig

@@ -74,5 +74,6 @@ pub fn Widget(comptime Event: type) type {
 
         // TODO: import and export of `Widget` implementations (with corresponding initialization using `Event`)
         pub const RawText = @import("widget/RawText.zig").Widget(Event);
+        pub const Spacer = @import("widget/Spacer.zig").Widget(Event);
     };
 }

src/widget/Spacer.zig

@@ -0,0 +1,33 @@
+const std = @import("std");
+const terminal = @import("../terminal.zig");
+
+const isTaggedUnion = @import("../event.zig").isTaggedUnion;
+const Error = @import("../event.zig").Error;
+
+const log = std.log.scoped(.widget_spacer);
+
+pub fn Widget(comptime Event: type) type {
+    if (!isTaggedUnion(Event)) {
+        @compileError("Provided user event `Event` for `Layout(comptime Event: type)` is not of type `union(enum)`.");
+    }
+    return struct {
+        pub fn init() @This() {
+            return .{};
+        }
+
+        pub fn deinit(this: *@This()) void {
+            this.* = undefined;
+        }
+
+        pub fn handle(this: *@This(), event: Event) ?Event {
+            _ = this;
+            _ = event;
+            return null;
+        }
+
+        pub fn content(this: *@This()) ![]u8 {
+            _ = this;
+            return &[0]u8{};
+        }
+    };
+}