add benchmark for cursor moves

bench/Cargo.toml

@@ -23,3 +23,7 @@ harness = false
 [[bench]]
 name = "search"
 harness = false
+
+[[bench]]
+name = "cursor"
+harness = false

bench/benches/cursor.rs

@@ -0,0 +1,102 @@
+use criterion::{black_box, criterion_group, criterion_main, Criterion};
+use tui_textarea::{CursorMove, TextArea};
+use tui_textarea_bench::{dummy_terminal, TerminalExt, LOREM};
+
+#[derive(Clone, Copy)]
+enum Restore {
+    TopLeft,
+    BottomLeft,
+    BottomRight,
+    None,
+}
+
+impl Restore {
+    fn cursor_move(self) -> Option<CursorMove> {
+        match self {
+            Self::TopLeft => Some(CursorMove::Jump(0, 0)),
+            Self::BottomLeft => Some(CursorMove::Jump(u16::MAX, 0)),
+            Self::BottomRight => Some(CursorMove::Jump(u16::MAX, u16::MAX)),
+            Self::None => None,
+        }
+    }
+}
+
+fn run(moves: &[CursorMove], restore: Restore, repeat: usize) -> (usize, usize) {
+    let mut lines = Vec::with_capacity(LOREM.len() * 2 + 1);
+    lines.extend(LOREM.iter().map(|s| s.to_string()));
+    lines.push("".to_string());
+    lines.extend(LOREM.iter().map(|s| s.to_string()));
+
+    let mut textarea = TextArea::new(lines);
+    let mut term = dummy_terminal();
+
+    let mut prev = textarea.cursor();
+    for _ in 0..repeat {
+        for m in moves {
+            textarea.move_cursor(*m);
+            term.draw_textarea(&textarea);
+        }
+        if let Some(m) = restore.cursor_move() {
+            if textarea.cursor() == prev {
+                textarea.move_cursor(m);
+                prev = textarea.cursor();
+            }
+        }
+    }
+
+    textarea.cursor()
+}
+
+fn move_char(c: &mut Criterion) {
+    c.bench_function("cursor::char::forward", |b| {
+        b.iter(|| black_box(run(&[CursorMove::Forward], Restore::TopLeft, 1000)))
+    });
+    c.bench_function("cursor::char::back", |b| {
+        b.iter(|| black_box(run(&[CursorMove::Back], Restore::BottomRight, 1000)))
+    });
+    c.bench_function("cursor::char::down", |b| {
+        b.iter(|| black_box(run(&[CursorMove::Down], Restore::TopLeft, 1000)))
+    });
+    c.bench_function("cursor::char::up", |b| {
+        b.iter(|| black_box(run(&[CursorMove::Up], Restore::BottomLeft, 1000)))
+    });
+}
+fn move_word(c: &mut Criterion) {
+    c.bench_function("cursor::word::forward", |b| {
+        b.iter(|| black_box(run(&[CursorMove::WordForward], Restore::TopLeft, 1000)))
+    });
+    c.bench_function("cursor::word::back", |b| {
+        b.iter(|| black_box(run(&[CursorMove::WordBack], Restore::BottomRight, 1000)))
+    });
+}
+fn move_paragraph(c: &mut Criterion) {
+    c.bench_function("cursor::paragraph::down", |b| {
+        b.iter(|| black_box(run(&[CursorMove::ParagraphForward], Restore::TopLeft, 1000)))
+    });
+    c.bench_function("cursor::paragraph::up", |b| {
+        b.iter(|| black_box(run(&[CursorMove::ParagraphBack], Restore::BottomLeft, 1000)))
+    });
+}
+fn move_edge(c: &mut Criterion) {
+    c.bench_function("cursor::edge::head_end", |b| {
+        b.iter(|| {
+            black_box(run(
+                &[CursorMove::End, CursorMove::Head],
+                Restore::None,
+                500,
+            ))
+        })
+    });
+    c.bench_function("cursor::edge::top_bottom", |b| {
+        b.iter(|| {
+            black_box(run(
+                &[CursorMove::Bottom, CursorMove::Top],
+                Restore::None,
+                500,
+            ))
+        })
+    });
+}
+
+criterion_group!(cursor, move_char, move_word, move_paragraph, move_edge);
+criterion_main!(cursor);

bench/src/lib.rs

@@ -31,8 +31,8 @@ pub struct DummyBackend {
 impl Default for DummyBackend {
     fn default() -> Self {
         Self {
-            width: 80,
+            width: 40,
-            height: 24,
+            height: 12,
             cursor: (0, 0),
         }
     }