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use crate::word::{find_word_start_backward, find_word_start_forward};
use std::cmp;
/// Specify how to move the cursor.
#[derive(Clone, Copy, Debug)]
pub enum CursorMove {
/// Move cursor forward by one character. When the cursor is at the end of line, it moves to the head of next line.
/// ```
/// use tui_textarea::{TextArea, CursorMove};
///
/// let mut textarea = TextArea::from(["abc"]);
///
/// textarea.move_cursor(CursorMove::Forward);
/// assert_eq!(textarea.cursor(), (0, 1));
/// textarea.move_cursor(CursorMove::Forward);
/// assert_eq!(textarea.cursor(), (0, 2));
/// ```
Forward,
/// Move cursor backward by one character. When the cursor is at the head of line, it moves to the end of previous
/// line.
/// ```
/// use tui_textarea::{TextArea, CursorMove};
///
/// let mut textarea = TextArea::from(["abc"]);
///
/// textarea.move_cursor(CursorMove::Forward);
/// textarea.move_cursor(CursorMove::Forward);
/// textarea.move_cursor(CursorMove::Back);
/// assert_eq!(textarea.cursor(), (0, 1));
/// ```
Back,
/// Move cursor up by one line.
/// ```
/// use tui_textarea::{TextArea, CursorMove};
///
/// let mut textarea = TextArea::from(["a", "b", "c"]);
///
/// textarea.move_cursor(CursorMove::Down);
/// textarea.move_cursor(CursorMove::Down);
/// textarea.move_cursor(CursorMove::Up);
/// assert_eq!(textarea.cursor(), (1, 0));
/// ```
Up,
/// Move cursor down by one line.
/// ```
/// use tui_textarea::{TextArea, CursorMove};
///
/// let mut textarea = TextArea::from(["a", "b", "c"]);
///
/// textarea.move_cursor(CursorMove::Down);
/// assert_eq!(textarea.cursor(), (1, 0));
/// textarea.move_cursor(CursorMove::Down);
/// assert_eq!(textarea.cursor(), (2, 0));
/// ```
Down,
/// Move cursor to the head of line. When the cursor is at the head of line, it moves to the end of previous line.
/// ```
/// use tui_textarea::{TextArea, CursorMove};
///
/// let mut textarea = TextArea::from(["abc"]);
///
/// textarea.move_cursor(CursorMove::Forward);
/// textarea.move_cursor(CursorMove::Forward);
/// textarea.move_cursor(CursorMove::Head);
/// assert_eq!(textarea.cursor(), (0, 0));
/// ```
Head,
/// Move cursor to the end of line. When the cursor is at the end of line, it moves to the head of next line.
/// ```
/// use tui_textarea::{TextArea, CursorMove};
///
/// let mut textarea = TextArea::from(["abc"]);
///
/// textarea.move_cursor(CursorMove::End);
/// assert_eq!(textarea.cursor(), (0, 3));
/// ```
End,
/// Move cursor to the top of lines.
/// ```
/// use tui_textarea::{TextArea, CursorMove};
///
/// let mut textarea = TextArea::from(["a", "b", "c"]);
///
/// textarea.move_cursor(CursorMove::Down);
/// textarea.move_cursor(CursorMove::Down);
/// textarea.move_cursor(CursorMove::Top);
/// assert_eq!(textarea.cursor(), (0, 0));
/// ```
Top,
/// Move cursor to the bottom of lines.
/// ```
/// use tui_textarea::{TextArea, CursorMove};
///
/// let mut textarea = TextArea::from(["a", "b", "c"]);
///
/// textarea.move_cursor(CursorMove::Bottom);
/// assert_eq!(textarea.cursor(), (2, 0));
/// ```
Bottom,
/// Move cursor forward by one word. Word boundary appears at spaces, punctuations, and others. For example
/// `fn foo(a)` consists of words `fn`, `foo`, `(`, `a`, `)`. When the cursor is at the end of line, it moves to the
/// head of next line.
/// ```
/// use tui_textarea::{TextArea, CursorMove};
///
/// let mut textarea = TextArea::from(["aaa bbb ccc"]);
///
/// textarea.move_cursor(CursorMove::WordForward);
/// assert_eq!(textarea.cursor(), (0, 4));
/// textarea.move_cursor(CursorMove::WordForward);
/// assert_eq!(textarea.cursor(), (0, 8));
/// ```
WordForward,
/// Move cursor backward by one word. Word boundary appears at spaces, punctuations, and others. For example
/// `fn foo(a)` consists of words `fn`, `foo`, `(`, `a`, `)`.When the cursor is at the head of line, it moves to
/// the end of previous line.
/// ```
/// use tui_textarea::{TextArea, CursorMove};
///
/// let mut textarea = TextArea::from(["aaa bbb ccc"]);
///
/// textarea.move_cursor(CursorMove::End);
/// textarea.move_cursor(CursorMove::WordBack);
/// assert_eq!(textarea.cursor(), (0, 8));
/// textarea.move_cursor(CursorMove::WordBack);
/// assert_eq!(textarea.cursor(), (0, 4));
/// textarea.move_cursor(CursorMove::WordBack);
/// assert_eq!(textarea.cursor(), (0, 0));
/// ```
WordBack,
/// Move cursor down by one paragraph. Paragraph is a chunk of non-empty lines. Cursor moves to the first line of paragraph.
/// ```
/// use tui_textarea::{TextArea, CursorMove};
///
/// // aaa
/// //
/// // bbb
/// //
/// // ccc
/// // ddd
/// let mut textarea = TextArea::from(["aaa", "", "bbb", "", "ccc", "ddd"]);
///
/// textarea.move_cursor(CursorMove::ParagraphForward);
/// assert_eq!(textarea.cursor(), (2, 0));
/// textarea.move_cursor(CursorMove::ParagraphForward);
/// assert_eq!(textarea.cursor(), (4, 0));
/// ```
ParagraphForward,
/// Move cursor up by one paragraph. Paragraph is a chunk of non-empty lines. Cursor moves to the first line of paragraph.
/// ```
/// use tui_textarea::{TextArea, CursorMove};
///
/// // aaa
/// //
/// // bbb
/// //
/// // ccc
/// // ddd
/// let mut textarea = TextArea::from(["aaa", "", "bbb", "", "ccc", "ddd"]);
///
/// textarea.move_cursor(CursorMove::Bottom);
/// textarea.move_cursor(CursorMove::ParagraphBack);
/// assert_eq!(textarea.cursor(), (4, 0));
/// textarea.move_cursor(CursorMove::ParagraphBack);
/// assert_eq!(textarea.cursor(), (2, 0));
/// textarea.move_cursor(CursorMove::ParagraphBack);
/// assert_eq!(textarea.cursor(), (0, 0));
/// ```
ParagraphBack,
/// Move cursor to (row, col) position. When the position points outside the text, the cursor position is made fit
/// within the text. Note that row and col are 0-based. (0, 0) means the first character of the first line.
///
/// When there are 10 lines, jumping to row 15 moves the cursor to the last line (row is 9 in the case). When there
/// are 10 characters in the line, jumping to col 15 moves the cursor to end of the line (col is 10 in the case).
/// ```
/// use tui_textarea::{TextArea, CursorMove};
///
/// let mut textarea = TextArea::from(["aaaa", "bbbb", "cccc"]);
///
/// textarea.move_cursor(CursorMove::Jump(1, 2));
/// assert_eq!(textarea.cursor(), (1, 2));
///
/// textarea.move_cursor(CursorMove::Jump(10, 10));
/// assert_eq!(textarea.cursor(), (2, 4));
/// ```
Jump(u16, u16),
}
impl CursorMove {
pub(crate) fn next_cursor(
&self,
(row, col): (usize, usize),
lines: &[String],
) -> Option<(usize, usize)> {
use CursorMove::*;
fn fit_col(col: usize, line: &str) -> usize {
cmp::min(col, line.chars().count())
}
match self {
Forward if col >= lines[row].chars().count() => {
(row + 1 < lines.len()).then(|| (row + 1, 0))
}
Forward => Some((row, col + 1)),
Back if col == 0 => {
let row = row.checked_sub(1)?;
Some((row, lines[row].chars().count()))
}
Back => Some((row, col - 1)),
Up => {
let row = row.checked_sub(1)?;
Some((row, fit_col(col, &lines[row])))
}
Down => (Some((row + 1, fit_col(col, lines.get(row + 1)?)))),
Head => Some((row, 0)),
End => Some((row, lines[row].chars().count())),
Top => Some((0, fit_col(col, &lines[0]))),
Bottom => {
let row = lines.len() - 1;
Some((row, fit_col(col, &lines[row])))
}
WordForward => {
if let Some(col) = find_word_start_forward(&lines[row], col) {
Some((row, col))
} else if row + 1 < lines.len() {
Some((row + 1, 0))
} else {
Some((row, lines[row].chars().count()))
}
}
WordBack => {
if let Some(col) = find_word_start_backward(&lines[row], col) {
Some((row, col))
} else if row > 0 {
Some((row - 1, lines[row - 1].chars().count()))
} else {
Some((row, 0))
}
}
ParagraphForward => {
let mut prev_is_empty = lines[row].is_empty();
for row in row + 1..lines.len() {
let line = &lines[row];
let is_empty = line.is_empty();
if !is_empty && prev_is_empty {
return Some((row, fit_col(col, line)));
}
prev_is_empty = is_empty;
}
let row = lines.len() - 1;
Some((row, fit_col(col, &lines[row])))
}
ParagraphBack => {
let row = row.checked_sub(1)?;
let mut prev_is_empty = lines[row].is_empty();
for row in (0..row).rev() {
let is_empty = lines[row].is_empty();
if is_empty && !prev_is_empty {
return Some((row + 1, fit_col(col, &lines[row + 1])));
}
prev_is_empty = is_empty;
}
Some((0, fit_col(col, &lines[0])))
}
Jump(row, col) => {
let row = cmp::min(*row as usize, lines.len() - 1);
let col = fit_col(*col as usize, &lines[row]);
Some((row, col))
}
}
}
}