Merge pull request 'feat: implemented widget iterator' (#6) from coding-agent/zenolith:master into master

Reviewed-on: https://git.mzte.de/zenolith/zenolith/pulls/6

src/WidgetIter.zig

@@ -0,0 +1,27 @@
+//! This is a iterator to iterate over the widget tree
+//! Depth-first
+const std = @import("std");
+
+const Widget = @import("widget.zig").Widget;
+
+current: *Widget,
+
+const WidgetIter = @This();
+
+pub fn next(self: *WidgetIter) ?*Widget {
+    var last: ?*Widget = null;
+    while (true) {
+        const children = self.current.children();
+        const slice = if (last) |l|
+            children[std.mem.indexOfScalar(*Widget, children, l).? + 1 ..]
+        else
+            children;
+        if (slice.len == 0) {
+            last = self.current;
+            self.current = self.current.data.parent orelse return null;
+        } else {
+            self.current = slice[0];
+            return self.current;
+        }
+    }
+}

src/main.zig

@@ -16,6 +16,7 @@ test {
     _ = widget;
 
     _ = Color;
+    _ = WidgetIter;
 }
 
 pub const attreebute = @import("attreebute.zig");
@@ -31,6 +32,7 @@ pub const util = @import("util.zig");
 pub const widget = @import("widget.zig");
 
 pub const Color = @import("Color.zig");
+pub const WidgetIter = @import("WidgetIter.zig");
 
 /// List of the default widget implementations included with Zenolith.
 /// If you set zenolith_options.widget_impls, include this if you want to use Zenolith's widgets.