542 lines
17 KiB
Rust
542 lines
17 KiB
Rust
//! A cursor implementation that can be used to navigate and edit text.
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use std::{cmp::Ordering, ops::Range};
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use keyboard_types::{Code, Key, Modifiers};
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/// This contains the information about the text that is used by the cursor to handle navigation.
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pub trait Text {
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/// Returns the line at the given index.
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fn line(&self, number: usize) -> Option<&Self>;
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/// Returns the length of the text in characters.
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fn length(&self) -> usize;
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/// Returns the number of lines in the text.
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fn line_count(&self) -> usize;
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/// Returns the character at the given character index.
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fn character(&self, idx: usize) -> Option<char>;
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/// Returns the length of the text before the given line in characters.
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fn len_before_line(&self, line: usize) -> usize;
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}
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impl Text for str {
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fn line(&self, number: usize) -> Option<&str> {
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self.lines().nth(number)
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}
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fn length(&self) -> usize {
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self.chars().count()
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}
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fn line_count(&self) -> usize {
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self.lines().count()
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}
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fn character(&self, idx: usize) -> Option<char> {
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self.chars().nth(idx)
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}
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fn len_before_line(&self, line: usize) -> usize {
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self.lines()
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.take(line)
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.map(|l| l.chars().count())
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.sum::<usize>()
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}
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}
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/// This contains the information about the text that is used by the cursor to handle editing text.
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pub trait TextEditable<T: Text + ?Sized>: AsRef<T> {
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/// Inserts a character at the given character index.
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fn insert_character(&mut self, idx: usize, text: char);
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/// Deletes the given character range.
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fn delete_range(&mut self, range: Range<usize>);
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}
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impl TextEditable<str> for String {
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fn insert_character(&mut self, idx: usize, text: char) {
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self.insert(idx, text);
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}
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fn delete_range(&mut self, range: Range<usize>) {
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self.replace_range(range, "");
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}
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}
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/// A cursor position
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#[derive(Debug, Clone, PartialEq, Eq)]
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pub struct Pos {
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/// The virtual column of the cursor. This can be more than the line length. To get the realized column, use [`Pos::col()`].
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pub col: usize,
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/// The row of the cursor.
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pub row: usize,
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}
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impl Pos {
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/// Creates a new cursor position.
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pub fn new(col: usize, row: usize) -> Self {
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Self { row, col }
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}
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/// Moves the position up by one line.
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pub fn up(&mut self, text: &(impl Text + ?Sized)) {
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self.move_row(-1, text);
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}
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/// Moves the position down by one line.
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pub fn down(&mut self, text: &(impl Text + ?Sized)) {
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self.move_row(1, text);
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}
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/// Moves the position right by one character.
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pub fn right(&mut self, text: &(impl Text + ?Sized)) {
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self.move_col(1, text);
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}
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/// Moves the position left by one character.
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pub fn left(&mut self, text: &(impl Text + ?Sized)) {
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self.move_col(-1, text);
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}
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/// Move the position's row by the given amount. (positive is down, negative is up)
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pub fn move_row(&mut self, change: i32, text: &(impl Text + ?Sized)) {
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let new = self.row as i32 + change;
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if new >= 0 && new < text.line_count() as i32 {
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self.row = new as usize;
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}
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}
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/// Move the position's column by the given amount. (positive is right, negative is left)
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pub fn move_col(&mut self, change: i32, text: &(impl Text + ?Sized)) {
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self.realize_col(text);
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let idx = self.idx(text) as i32;
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if idx + change >= 0 && idx + change <= text.length() as i32 {
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let len_line = self.len_line(text) as i32;
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let new_col = self.col as i32 + change;
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let diff = new_col - len_line;
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if diff > 0 {
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self.down(text);
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self.col = 0;
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self.move_col(diff - 1, text);
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} else if new_col < 0 {
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self.up(text);
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self.col = self.len_line(text);
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self.move_col(new_col + 1, text);
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} else {
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self.col = new_col as usize;
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}
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}
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}
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/// Get the realized column of the position. This is the column, but capped at the line length.
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pub fn col(&self, text: &(impl Text + ?Sized)) -> usize {
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self.col.min(self.len_line(text))
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}
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/// Get the row of the position.
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pub fn row(&self) -> usize {
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self.row
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}
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fn len_line(&self, text: &(impl Text + ?Sized)) -> usize {
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if let Some(line) = text.line(self.row) {
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let len = line.length();
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if len > 0 && line.character(len - 1) == Some('\n') {
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len - 1
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} else {
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len
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}
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} else {
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0
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}
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}
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/// Get the character index of the position.
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pub fn idx(&self, text: &(impl Text + ?Sized)) -> usize {
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text.len_before_line(self.row) + self.col(text)
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}
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/// If the column is more than the line length, cap it to the line length.
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pub fn realize_col(&mut self, text: &(impl Text + ?Sized)) {
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self.col = self.col(text);
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}
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}
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impl Ord for Pos {
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fn cmp(&self, other: &Self) -> Ordering {
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self.row.cmp(&other.row).then(self.col.cmp(&other.col))
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}
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}
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impl PartialOrd for Pos {
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fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
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Some(self.cmp(other))
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}
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}
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/// A cursor is a selection of text. It has a start and end position of the selection.
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#[derive(Debug, Clone, PartialEq, Eq)]
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pub struct Cursor {
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/// The start position of the selection. The start position is the origin of the selection, not necessarily the first position.
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pub start: Pos,
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/// The end position of the selection. If the end position is None, the cursor is a caret.
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pub end: Option<Pos>,
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}
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impl Cursor {
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/// Create a new cursor with the given start position.
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pub fn from_start(pos: Pos) -> Self {
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Self {
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start: pos,
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end: None,
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}
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}
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/// Create a new cursor with the given start and end position.
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pub fn new(start: Pos, end: Pos) -> Self {
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Self {
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start,
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end: Some(end),
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}
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}
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/// Move the cursor position. If shift is true, the end position will be moved instead of the start position.
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pub fn move_cursor(&mut self, f: impl FnOnce(&mut Pos), shift: bool) {
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if shift {
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self.with_end(f);
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} else {
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f(&mut self.start);
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self.end = None;
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}
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}
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/// Delete the currently selected text and update the cursor position.
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pub fn delete_selection<T: Text + ?Sized>(&mut self, text: &mut impl TextEditable<T>) {
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let first = self.first();
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let last = self.last();
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text.delete_range(first.idx(text.as_ref())..last.idx(text.as_ref()));
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if let Some(end) = self.end.take() {
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if self.start > end {
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self.start = end;
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}
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}
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}
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/// Handle moving the cursor with the given key.
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pub fn handle_input<T: Text + ?Sized>(
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&mut self,
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code: &Code,
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key: &Key,
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modifiers: &Modifiers,
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text: &mut impl TextEditable<T>,
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max_text_length: usize,
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) {
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use Code::*;
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match code {
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ArrowUp => {
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self.move_cursor(
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|c| c.up(text.as_ref()),
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modifiers.contains(Modifiers::SHIFT),
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);
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}
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ArrowDown => {
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self.move_cursor(
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|c| c.down(text.as_ref()),
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modifiers.contains(Modifiers::SHIFT),
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);
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}
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ArrowRight => {
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if modifiers.contains(Modifiers::CONTROL) {
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self.move_cursor(
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|c| {
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let mut change = 1;
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let idx = c.idx(text.as_ref());
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let length = text.as_ref().length();
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while idx + change < length {
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let chr = text.as_ref().character(idx + change).unwrap();
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if chr.is_whitespace() {
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break;
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}
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change += 1;
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}
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c.move_col(change as i32, text.as_ref());
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},
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modifiers.contains(Modifiers::SHIFT),
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);
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} else {
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self.move_cursor(
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|c| c.right(text.as_ref()),
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modifiers.contains(Modifiers::SHIFT),
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);
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}
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}
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ArrowLeft => {
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if modifiers.contains(Modifiers::CONTROL) {
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self.move_cursor(
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|c| {
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let mut change = -1;
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let idx = c.idx(text.as_ref()) as i32;
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while idx + change > 0 {
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let chr = text.as_ref().character((idx + change) as usize).unwrap();
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if chr == ' ' {
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break;
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}
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change -= 1;
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}
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c.move_col(change, text.as_ref());
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},
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modifiers.contains(Modifiers::SHIFT),
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);
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} else {
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self.move_cursor(
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|c| c.left(text.as_ref()),
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modifiers.contains(Modifiers::SHIFT),
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);
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}
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}
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End => {
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self.move_cursor(
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|c| c.col = c.len_line(text.as_ref()),
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modifiers.contains(Modifiers::SHIFT),
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);
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}
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Home => {
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self.move_cursor(|c| c.col = 0, modifiers.contains(Modifiers::SHIFT));
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}
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Backspace => {
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self.start.realize_col(text.as_ref());
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let mut start_idx = self.start.idx(text.as_ref());
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if self.end.is_some() {
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self.delete_selection(text);
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} else if start_idx > 0 {
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self.start.left(text.as_ref());
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text.delete_range(start_idx - 1..start_idx);
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if modifiers.contains(Modifiers::CONTROL) {
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start_idx = self.start.idx(text.as_ref());
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while start_idx > 0
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&& text
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.as_ref()
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.character(start_idx - 1)
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.filter(|c| *c != ' ')
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.is_some()
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{
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self.start.left(text.as_ref());
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text.delete_range(start_idx - 1..start_idx);
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start_idx = self.start.idx(text.as_ref());
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}
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}
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}
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}
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Enter => {
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if text.as_ref().length() + 1 - self.selection_len(text.as_ref()) <= max_text_length
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{
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text.insert_character(self.start.idx(text.as_ref()), '\n');
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self.start.col = 0;
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self.start.down(text.as_ref());
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}
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}
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Tab => {
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if text.as_ref().length() + 1 - self.selection_len(text.as_ref()) <= max_text_length
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{
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self.start.realize_col(text.as_ref());
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self.delete_selection(text);
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text.insert_character(self.start.idx(text.as_ref()), '\t');
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self.start.right(text.as_ref());
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}
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}
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_ => {
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self.start.realize_col(text.as_ref());
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if let Key::Character(character) = key {
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if text.as_ref().length() + 1 - self.selection_len(text.as_ref())
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<= max_text_length
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{
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self.delete_selection(text);
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let character = character.chars().next().unwrap();
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text.insert_character(self.start.idx(text.as_ref()), character);
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self.start.right(text.as_ref());
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}
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}
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}
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}
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}
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/// Modify the end selection position
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pub fn with_end(&mut self, f: impl FnOnce(&mut Pos)) {
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let mut new = self.end.take().unwrap_or_else(|| self.start.clone());
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f(&mut new);
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self.end.replace(new);
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}
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/// Returns first position of the selection (this could be the start or the end depending on the position)
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pub fn first(&self) -> &Pos {
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if let Some(e) = &self.end {
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e.min(&self.start)
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} else {
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&self.start
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}
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}
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/// Returns last position of the selection (this could be the start or the end depending on the position)
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pub fn last(&self) -> &Pos {
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if let Some(e) = &self.end {
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e.max(&self.start)
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} else {
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&self.start
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}
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}
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/// Returns the length of the selection
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pub fn selection_len(&self, text: &(impl Text + ?Sized)) -> usize {
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self.last().idx(text) - self.first().idx(text)
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}
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}
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impl Default for Cursor {
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fn default() -> Self {
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Self {
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start: Pos::new(0, 0),
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end: None,
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}
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}
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}
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#[test]
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fn pos_direction_movement() {
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let mut pos = Pos::new(100, 0);
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let text = "hello world\nhi";
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assert_eq!(pos.col(text), text.lines().next().unwrap_or_default().len());
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pos.down(text);
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assert_eq!(pos.col(text), text.lines().nth(1).unwrap_or_default().len());
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pos.up(text);
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assert_eq!(pos.col(text), text.lines().next().unwrap_or_default().len());
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pos.left(text);
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assert_eq!(
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pos.col(text),
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text.lines().next().unwrap_or_default().len() - 1
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);
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pos.right(text);
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assert_eq!(pos.col(text), text.lines().next().unwrap_or_default().len());
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}
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#[test]
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fn pos_col_movement() {
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let mut pos = Pos::new(100, 0);
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let text = "hello world\nhi";
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// move inside a row
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pos.move_col(-5, text);
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assert_eq!(
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pos.col(text),
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text.lines().next().unwrap_or_default().len() - 5
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);
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pos.move_col(5, text);
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assert_eq!(pos.col(text), text.lines().next().unwrap_or_default().len());
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// move between rows
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pos.move_col(3, text);
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assert_eq!(pos.col(text), 2);
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pos.move_col(-3, text);
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assert_eq!(pos.col(text), text.lines().next().unwrap_or_default().len());
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// don't panic if moving out of range
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pos.move_col(-100, text);
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pos.move_col(1000, text);
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}
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#[test]
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fn cursor_row_movement() {
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let mut pos = Pos::new(100, 0);
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let text = "hello world\nhi";
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pos.move_row(1, text);
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assert_eq!(pos.row(), 1);
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pos.move_row(-1, text);
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assert_eq!(pos.row(), 0);
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// don't panic if moving out of range
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pos.move_row(-100, text);
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pos.move_row(1000, text);
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}
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#[test]
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fn cursor_input() {
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let mut cursor = Cursor::from_start(Pos::new(0, 0));
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let mut text = "hello world\nhi".to_string();
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for _ in 0..5 {
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cursor.handle_input(
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&keyboard_types::Code::ArrowRight,
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&keyboard_types::Key::ArrowRight,
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&Modifiers::empty(),
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&mut text,
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10,
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);
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}
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for _ in 0..5 {
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cursor.handle_input(
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&keyboard_types::Code::Backspace,
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&keyboard_types::Key::Backspace,
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&Modifiers::empty(),
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&mut text,
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10,
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);
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}
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assert_eq!(text, " world\nhi");
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let goal_text = "hello world\nhi";
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let max_width = goal_text.len();
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cursor.handle_input(
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&keyboard_types::Code::KeyH,
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&keyboard_types::Key::Character("h".to_string()),
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&Modifiers::empty(),
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&mut text,
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max_width,
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);
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cursor.handle_input(
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&keyboard_types::Code::KeyE,
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&keyboard_types::Key::Character("e".to_string()),
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&Modifiers::empty(),
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&mut text,
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max_width,
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);
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cursor.handle_input(
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&keyboard_types::Code::KeyL,
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&keyboard_types::Key::Character("l".to_string()),
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&Modifiers::empty(),
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&mut text,
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max_width,
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);
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cursor.handle_input(
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&keyboard_types::Code::KeyL,
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&keyboard_types::Key::Character("l".to_string()),
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&Modifiers::empty(),
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&mut text,
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max_width,
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);
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cursor.handle_input(
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&keyboard_types::Code::KeyO,
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&keyboard_types::Key::Character("o".to_string()),
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&Modifiers::empty(),
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&mut text,
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max_width,
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);
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// these should be ignored
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for _ in 0..10 {
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cursor.handle_input(
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&keyboard_types::Code::KeyO,
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&keyboard_types::Key::Character("o".to_string()),
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&Modifiers::empty(),
|
|
&mut text,
|
|
max_width,
|
|
);
|
|
}
|
|
|
|
assert_eq!(text.to_string(), goal_text);
|
|
}
|