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feat(maestro): add shared text-input widget with cursor motion and word ops

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This commit is contained in:
Miguel Palhas
2026-08-23 19:50:37 +01:00
parent d5485b8f5d
commit dfc4ee91e1
2 changed files with 458 additions and 0 deletions
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crates/maestro-tui/src/lib.rs
+1
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@@ -18,6 +18,7 @@ pub mod sidebar;
pub mod state;
pub mod tabs;
pub mod terminal;
pub mod text_input;
use std::path::PathBuf;
use std::time::Duration;
crates/maestro-tui/src/text_input.rs
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@@ -0,0 +1,457 @@
//! Single-line text-input primitive shared by every TUI form field.
//!
//! Owns a `String`, a character-indexed cursor, and horizontal scroll state.
//! All editing goes through [`TextInput::handle_key`] so callers feed the same
//! canonical [`InputKey`] stream the rest of the app uses; bracketed paste
//! arrives as one [`InputKey::Paste`] and is inserted as a single operation.
//!
//! This is the one piece of the TUI form layer that unit-tests without a
//! terminal: drive it with `InputKey` sequences and inspect value/cursor.
use ratatui::buffer::Buffer;
use ratatui::layout::Rect;
use ratatui::style::Style;
use crate::input::InputKey;
#[derive(Debug, Default, Clone)]
pub struct TextInput {
value: String,
/// Cursor position as a char offset into `value`.
cursor: usize,
/// Char offset of the leftmost visible cell.
scroll: usize,
}
impl TextInput {
pub fn with_value(value: impl Into<String>) -> Self {
let mut input = Self {
value: value.into(),
..Self::default()
};
input.cursor = input.value.chars().count();
input
}
pub fn value(&self) -> &str {
&self.value
}
pub fn cursor(&self) -> usize {
self.cursor
}
/// Char offset of the leftmost visible cell; only meaningful after
/// [`TextInput::render`] has clamped it to the field width.
pub fn scroll_offset(&self) -> usize {
self.scroll
}
/// Insert `text` at the cursor as one operation. Used both for typed
/// characters and for whole bracketed-paste payloads.
pub fn insert(&mut self, text: &str) {
let at = self.byte_offset(self.cursor);
self.value.insert_str(at, text);
self.cursor += text.chars().count();
}
pub fn handle_key(&mut self, key: &InputKey) {
match key {
InputKey::Char {
c,
ctrl: false,
alt: false,
..
} => self.insert(&c.to_string()),
InputKey::Char {
c: 'w', ctrl: true, ..
} => self.delete_word_backwards(),
InputKey::Char {
c: 'k', ctrl: true, ..
} => self.kill_to_end(),
// Emacs-style word motion; ctrl-arrow reaches us as a plain
// Left/Right today, so these are the dependable binding.
InputKey::Char {
c: 'b', ctrl: true, ..
} => self.cursor = self.word_left(),
InputKey::Char {
c: 'f', ctrl: true, ..
} => self.cursor = self.word_right(),
InputKey::Left => {
self.cursor = self.cursor.saturating_sub(1);
}
InputKey::Right => {
if self.cursor < self.value.chars().count() {
self.cursor += 1;
}
}
InputKey::Home => self.cursor = 0,
InputKey::End => self.cursor = self.value.chars().count(),
InputKey::Backspace => {
if self.cursor > 0 {
let at = self.byte_offset(self.cursor - 1);
let end = self.byte_offset(self.cursor);
self.value.replace_range(at..end, "");
self.cursor -= 1;
}
}
InputKey::Delete => {
if self.cursor < self.value.chars().count() {
let at = self.byte_offset(self.cursor);
let end = self.byte_offset(self.cursor + 1);
self.value.replace_range(at..end, "");
}
}
InputKey::Paste(text) => self.insert(text),
_ => {}
}
}
/// Draw into `area` (expected one row tall), scrolling horizontally so the
/// cursor stays visible, and return the screen column where the caller
/// should place the terminal cursor.
pub fn render(&mut self, area: Rect, buf: &mut Buffer, style: Style) -> u16 {
let width = area.width as usize;
let len = self.value.chars().count();
self.scroll = self.scroll.min(len);
if self.cursor < self.scroll {
self.scroll = self.cursor;
} else if width > 0 && self.cursor.saturating_sub(self.scroll) >= width {
self.scroll = self.cursor + 1 - width;
}
for (col, c) in self.value.chars().skip(self.scroll).take(width).enumerate() {
buf[(area.x + col as u16, area.y)]
.set_symbol(&c.to_string())
.set_style(style);
}
area.x + self.cursor.saturating_sub(self.scroll) as u16
}
fn byte_offset(&self, char_index: usize) -> usize {
self.value
.char_indices()
.nth(char_index)
.map(|(b, _)| b)
.unwrap_or(self.value.len())
}
fn is_word_char(c: char) -> bool {
c.is_alphanumeric() || c == '_'
}
/// Start of the word before the cursor, skipping any separators first —
/// emacs `backward-word`.
fn word_left(&self) -> usize {
let chars: Vec<char> = self.value.chars().collect();
let mut i = self.cursor;
while i > 0 && !Self::is_word_char(chars[i - 1]) {
i -= 1;
}
while i > 0 && Self::is_word_char(chars[i - 1]) {
i -= 1;
}
i
}
/// Start of the word after the cursor, skipping the rest of the current
/// word first — emacs `forward-word`.
fn word_right(&self) -> usize {
let chars: Vec<char> = self.value.chars().collect();
let len = chars.len();
let mut i = self.cursor;
while i < len && !Self::is_word_char(chars[i]) {
i += 1;
}
while i < len && Self::is_word_char(chars[i]) {
i += 1;
}
i
}
fn kill_to_end(&mut self) {
let at = self.byte_offset(self.cursor);
self.value.truncate(at);
}
/// Shell-style ctrl-w: kill back to the previous whitespace, taking any
/// trailing whitespace run with it — so `cd /tmp/foo` loses the whole
/// path segment in one keystroke.
fn delete_word_backwards(&mut self) {
let chars: Vec<char> = self.value.chars().collect();
let mut i = self.cursor;
while i > 0 && chars[i - 1].is_whitespace() {
i -= 1;
}
while i > 0 && !chars[i - 1].is_whitespace() {
i -= 1;
}
let at = self.byte_offset(i);
let end = self.byte_offset(self.cursor);
self.value.replace_range(at..end, "");
self.cursor = i;
}
}
#[cfg(test)]
mod tests {
use super::*;
use InputKey::{Backspace, Delete, End, Home, Left, Right};
fn typed(s: &str) -> Vec<InputKey> {
s.chars().map(InputKey::char).collect()
}
fn fed(keys: &[InputKey]) -> TextInput {
let mut input = TextInput::default();
for k in keys {
input.handle_key(k);
}
input
}
fn ctrl(c: char) -> InputKey {
InputKey::ctrl_char(c)
}
#[test]
fn typing_lands_in_order() {
let input = fed(&typed("hello"));
assert_eq!(input.value(), "hello");
assert_eq!(input.cursor(), 5);
}
#[test]
fn backspace_removes_the_last_typed_char() {
let mut input = fed(&typed("hello"));
input.handle_key(&Backspace);
assert_eq!(input.value(), "hell");
assert_eq!(input.cursor(), 4);
}
#[test]
fn left_then_insert_fixes_a_middle_typo() {
let mut input = fed(&typed("helo"));
input.handle_key(&Left);
input.handle_key(&Left);
input.handle_key(&InputKey::char('l'));
assert_eq!(input.value(), "hello");
assert_eq!(input.cursor(), 3);
}
#[test]
fn motion_keys_stop_at_the_edges() {
let mut input = fed(&typed("abc"));
for _ in 0..5 {
input.handle_key(&Left);
}
assert_eq!(input.cursor(), 0);
input.handle_key(&Left);
assert_eq!(input.cursor(), 0);
for _ in 0..5 {
input.handle_key(&Right);
}
assert_eq!(input.cursor(), 3);
}
#[test]
fn home_and_end_jump_to_the_ends() {
let mut input = fed(&typed("abcdef"));
input.handle_key(&Home);
assert_eq!(input.cursor(), 0);
input.handle_key(&InputKey::char('x'));
assert_eq!(input.value(), "xabcdef");
input.handle_key(&End);
input.handle_key(&InputKey::char('!'));
assert_eq!(input.value(), "xabcdef!");
}
/// Cursor starts after the final `/`; word-left lands on word starts,
/// never inside a separator run.
#[test]
fn ctrl_b_walks_left_one_word_at_a_time() {
let mut input = TextInput::with_value("/tmp/foo bar-baz/");
assert_eq!(input.cursor(), 17);
for expected in [13, 9, 5, 1, 0, 0] {
input.handle_key(&ctrl('b'));
assert_eq!(input.cursor(), expected);
}
}
#[test]
fn ctrl_f_walks_right_one_word_at_a_time() {
let mut input = TextInput::with_value("/tmp/foo bar");
input.handle_key(&Home);
for expected in [4, 8, 12, 12] {
input.handle_key(&ctrl('f'));
assert_eq!(input.cursor(), expected);
}
}
#[test]
fn backspace_deletes_before_the_cursor() {
let mut input = fed(&typed("abcdef"));
input.handle_key(&Left);
input.handle_key(&Left);
input.handle_key(&Left);
input.handle_key(&Backspace);
assert_eq!(input.value(), "abdef");
assert_eq!(input.cursor(), 2);
}
#[test]
fn backspace_on_empty_input_is_a_noop() {
let mut input = TextInput::default();
input.handle_key(&Backspace);
assert_eq!(input.value(), "");
assert_eq!(input.cursor(), 0);
}
#[test]
fn delete_removes_the_char_under_the_cursor() {
let mut input = fed(&typed("abcdef"));
input.handle_key(&Home);
input.handle_key(&Delete);
assert_eq!(input.value(), "bcdef");
assert_eq!(input.cursor(), 0);
}
#[test]
fn delete_past_the_end_is_a_noop() {
let mut input = TextInput::with_value("abc");
input.handle_key(&End);
input.handle_key(&Delete);
assert_eq!(input.value(), "abc");
}
/// `cd /tmp/foo` with ctrl-w leaves `cd ` — the whole path segment is one
/// word to a shell (readline kills back to whitespace, spaces included).
#[test]
fn ctrl_w_deletes_the_word_behind_the_cursor() {
let mut input = fed(&[typed("cd ").as_slice(), typed("/tmp/foo").as_slice()].concat());
input.handle_key(&ctrl('w'));
assert_eq!(input.value(), "cd ");
assert_eq!(input.cursor(), 3);
}
#[test]
fn ctrl_w_stops_before_the_separator_run() {
let mut input = TextInput::with_value("a b");
input.cursor = 5;
input.handle_key(&ctrl('w'));
assert_eq!(input.value(), "a ");
assert_eq!(input.cursor(), 4);
}
#[test]
fn ctrl_k_kills_everything_after_the_cursor() {
let mut input = fed(&typed("spawn --debug extra"));
for _ in 0..14 {
input.handle_key(&Left);
}
input.handle_key(&ctrl('k'));
assert_eq!(input.value(), "spawn");
assert_eq!(input.cursor(), 5);
}
/// A paste arrives as one event carrying the whole payload and must land
/// at the cursor as a single insertion, not per-character.
#[test]
fn paste_inserts_whole_payload_at_the_cursor() {
let mut input = fed(&typed("cd "));
input.handle_key(&InputKey::Paste("/srv/work".into()));
assert_eq!(input.value(), "cd /srv/work");
assert_eq!(input.cursor(), 12);
// What follows still behaves like ordinary typed text.
input.handle_key(&InputKey::char('/'));
assert_eq!(input.value(), "cd /srv/work/");
}
#[test]
fn paste_between_existing_text_keeps_both_halves() {
let mut input = TextInput::with_value("ac");
input.handle_key(&Left);
input.handle_key(&InputKey::Paste("b×".into()));
assert_eq!(input.value(), "ab×c");
assert_eq!(input.cursor(), 3, "cursor counts chars, not bytes");
}
#[test]
fn rendering_an_empty_field_points_at_its_first_column() {
let mut input = TextInput::default();
let area = Rect::new(10, 5, 20, 1);
let mut buf = Buffer::empty(area);
let col = input.render(area, &mut buf, Style::default());
assert_eq!(col, 10);
}
#[test]
fn rendering_reports_the_visible_cursor_column() {
let mut input = TextInput::with_value("hello");
input.handle_key(&Left);
input.handle_key(&Left);
let area = Rect::new(10, 5, 20, 1);
let mut buf = Buffer::empty(area);
let col = input.render(area, &mut buf, Style::default());
assert_eq!(col, 13);
for (i, expected) in ["h", "e", "l", "l", "o"].iter().enumerate() {
assert_eq!(buf[(10 + i as u16, 5)].symbol(), *expected);
}
}
#[test]
fn rendering_a_value_wider_than_the_field_shows_its_tail() {
let value = "0123456789abcdefghij";
let mut input = TextInput::with_value(value);
let area = Rect::new(0, 0, 10, 1);
let mut buf = Buffer::empty(area);
let col = input.render(area, &mut buf, Style::default());
assert_eq!(col, 9, "cursor sits on the last visible column");
for (i, expected) in value.chars().skip(input.scroll_offset()).enumerate() {
assert_eq!(
buf[(i as u16, 0)].symbol(),
expected.to_string(),
"cell {i}"
);
}
}
/// Moving left into the hidden region must scroll the window back so the
/// cursor never disappears off the left edge.
#[test]
fn moving_left_into_the_hidden_region_scrolls_back() {
let value = "0123456789abcdefghij";
let mut input = TextInput::with_value(value);
let area = Rect::new(0, 0, 10, 1);
let mut buf = Buffer::empty(area);
input.render(area, &mut buf, Style::default());
assert_eq!(input.cursor(), 20);
input.handle_key(&Home);
for _ in 0..5 {
input.handle_key(&Right);
}
let mut buf = Buffer::empty(area);
let col = input.render(area, &mut buf, Style::default());
assert_eq!(input.cursor(), 5);
assert_eq!(
input.value().chars().nth(input.scroll),
Some('5'),
"window scrolled back to the cursor"
);
assert_eq!(col, 0);
assert_eq!(buf[(0, 0)].symbol(), "5");
}
#[test]
fn shrinking_the_value_clamps_scroll_and_cursor() {
let mut input = TextInput::with_value("0123456789abcdefghij");
input.handle_key(&Home);
input.handle_key(&ctrl('k'));
let area = Rect::new(0, 0, 10, 1);
let mut buf = Buffer::empty(area);
let col = input.render(area, &mut buf, Style::default());
assert_eq!(input.value(), "");
assert_eq!(col, 0);
}
}