examples: add readline example

build.zig

@@ -43,6 +43,7 @@ pub fn build(b: *std.Build) void {
         main,
         nvim,
         pathological,
+        readline,
         shell,
         table,
         text_input,

examples/readline.zig

@@ -0,0 +1,75 @@
+const std = @import("std");
+const vaxis = @import("vaxis");
+const Cell = vaxis.Cell;
+const TextInput = vaxis.widgets.TextInput;
+const border = vaxis.widgets.border;
+
+const log = std.log.scoped(.main);
+
+const Event = union(enum) {
+    key_press: vaxis.Key,
+    winsize: vaxis.Winsize,
+};
+
+pub fn main() !void {
+    var gpa = std.heap.GeneralPurposeAllocator(.{}){};
+    defer {
+        const deinit_status = gpa.deinit();
+        //fail test; can't try in defer as defer is executed after we return
+        if (deinit_status == .leak) {
+            log.err("memory leak", .{});
+        }
+    }
+    const alloc = gpa.allocator();
+
+    var line: ?[]const u8 = null;
+    defer {
+        // do this in defer so that vaxis cleans up terminal state before we
+        // print to stdout
+        if (line) |_| {
+            const stdout = std.io.getStdOut().writer();
+            stdout.print("\n{s}\n", .{line.?}) catch {};
+            alloc.free(line.?);
+        }
+    }
+    var vx = try vaxis.init(alloc, .{});
+    defer vx.deinit(alloc);
+
+    var loop: vaxis.Loop(Event) = .{ .vaxis = &vx };
+    try loop.run();
+    defer loop.stop();
+
+    var text_input = TextInput.init(alloc, &vx.unicode);
+    defer text_input.deinit();
+
+    try vx.queryTerminal();
+
+    const prompt: vaxis.Segment = .{ .text = "$ " };
+
+    while (true) {
+        const event = loop.nextEvent();
+        switch (event) {
+            .key_press => |key| {
+                if (key.matches('c', .{ .ctrl = true })) {
+                    break;
+                } else if (key.matches(vaxis.Key.enter, .{})) {
+                    line = try text_input.toOwnedSlice();
+                    text_input.clearAndFree();
+                    break;
+                } else {
+                    try text_input.update(.{ .key_press = key });
+                }
+            },
+            .winsize => |ws| try vx.resize(alloc, ws),
+        }
+
+        const win = vx.window();
+
+        win.clear();
+        _ = try win.printSegment(prompt, .{});
+
+        const input_win = win.child(.{ .x_off = 2 });
+        text_input.draw(input_win);
+        try vx.render();
+    }
+}