1 files changed, 89 insertions, 0 deletions
diff --git a/libtui/widget/widget.ha b/libtui/widget/widget.ha
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+++ b/libtui/widget/widget.ha
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+// License: MPL-2.0
+// (c) 2022 Julian Hurst <ark@mansus.space>
+
+use libtui;
+use io;
+use unix::tty;
+
+export type error = !(io::error | tty::error);
+
+// A function that displays the widget.
+export type print = fn(w: *widget) (void | error);
+
+// A function that frees the resources associated to the widget.
+export type finish = fn(w: *widget) void;
+
+// An input listener on a widget. The returning value is intended to be used as
+// a signal that will be returned by [[notify]] in order to trigger certain more
+// global ui events (terminate the program, change widget focus, etc.). To
+// register a listener with a widget, use [[addlistener]].
+export type listener = *fn(w: *widget, r: libtui::key) bool;
+
+// A widget is an abstraction around a user-defined UI component. Custom widgets
+// can be created through sub-typing:
+//
+// 	export type my_widget = struct {
+// 		widget: widget::widget,
+// 		lines: []str,
+// 	};
+//
+// 	fn print(w: *widget::widget) (void | widget::error) = {
+// 		const w = w: *my_widget;
+// 		for (let i = 0z; i < len(w.lines); i += 1) {
+//	 		fmt::println(w.lines[i])!;
+//	 	};
+// 	};
+//
+// 	fn finish(w: *widget::widget) void = {
+// 		const w = w: *my_widget;
+//		free(w.lines);
+//		widget::finishcommon(w);
+// 	};
+//
+// 	let list = my_widget {
+// 		widget = widget::widget {
+//			print = &print,
+//			finish = &finish,
+//			...
+// 		};
+// 		lines = strings::split("one,two,three", ","),
+// 	};
+// 	let l = layout::newlayout(list);
+// 	layout::print(l)!;
+export type widget = struct {
+	print: nullable *print,
+	finish: nullable *finish,
+	listeners: []listener,
+	ui: libtui::ttyui,
+};
+
+// Add a listener to the given widget.
+export fn addlistener(w: *widget, listener: listener) void = {
+	append(w.listeners, listener);
+};
+
+// Delete a listener from the given widget.
+export fn dellistener(w: *widget, idx: size) void = {
+	delete(w.listeners[idx]);
+};
+
+// Clear the listeners of the given widget.
+export fn clearlisteners(w: *widget) void = {
+	w.listeners = [];
+};
+
+// Free the widget's listeners.
+export fn finishcommon(w: *widget) void = {
+	free(w.listeners);
+};
+
+// Notify (call) the widget's listeners with the widget and r as a parameter.
+// Returns true if a listener returned true, false otherwise.
+export fn notify(w: *widget, r: (rune | libtui::specialkey)) bool = {
+	for (let i = 0z; i < len(w.listeners); i += 1) {
+		if (w.listeners[i](w, r)) {
+			return true;
+		};
+	};
+	return false;
+};