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pub struct Cursor {
source: String,
index: usize,
}
impl From<String> for Cursor {
fn from(source: String) -> Self {
Self { source, index: 0 }
}
}
impl Cursor {
pub fn as_str(&self) -> &str {
self.source.as_str()
}
pub fn into_inner(self) -> String {
self.source
}
/// Returns the string before the cursor
pub fn substring(&self) -> &str {
&self.source[..self.index]
}
/// Returns the currently selected [`char`]
pub fn char(&self) -> Option<char> {
self.source[self.index..].chars().next()
}
pub fn right(&mut self) {
if self.index < self.source.len() {
loop {
self.index += 1;
if self.source.is_char_boundary(self.index) {
break;
}
}
}
}
pub fn left(&mut self) -> bool {
if self.index > 0 {
loop {
self.index -= 1;
if self.source.is_char_boundary(self.index) {
break true;
}
}
} else {
false
}
}
pub fn insert(&mut self, c: char) {
self.source.insert(self.index, c);
self.index += c.len_utf8();
}
pub fn remove(&mut self) -> char {
self.source.remove(self.index)
}
pub fn back(&mut self) -> Option<char> {
if self.left() {
Some(self.remove())
} else {
None
}
}
pub fn clear(&mut self) {
self.source.clear();
self.index = 0;
}
pub fn end(&mut self) {
self.index = self.source.len();
}
pub fn start(&mut self) {
self.index = 0;
}
}
#[cfg(test)]
mod cursor_tests {
use super::Cursor;
#[test]
fn right() {
// ö is 2 bytes
let mut c = Cursor::from(String::from("öaöböcödöeöfö"));
let indices = [0, 2, 3, 5, 6, 8, 9, 11, 12, 14, 15, 17, 18, 20, 20, 20, 20];
for i in indices {
assert_eq!(c.index, i);
c.right();
}
}
#[test]
fn left() {
// ö is 2 bytes
let mut c = Cursor::from(String::from("öaöböcödöeöfö"));
c.end();
let indices = [20, 18, 17, 15, 14, 12, 11, 9, 8, 6, 5, 3, 2, 0, 0, 0, 0];
for i in indices {
assert_eq!(c.index, i);
c.left();
}
}
#[test]
fn pop() {
let mut s = String::from("öaöböcödöeöfö");
let mut c = Cursor::from(s.clone());
c.end();
while !s.is_empty() {
let c1 = s.pop();
let c2 = c.back();
assert_eq!(c1, c2);
assert_eq!(s.as_str(), c.substring());
}
let c1 = s.pop();
let c2 = c.back();
assert_eq!(c1, c2);
}
#[test]
fn back() {
let mut c = Cursor::from(String::from("öaöböcödöeöfö"));
// move to ^
for _ in 0..4 {
c.right();
}
assert_eq!(c.substring(), "öaöb");
assert_eq!(c.back(), Some('b'));
assert_eq!(c.back(), Some('ö'));
assert_eq!(c.back(), Some('a'));
assert_eq!(c.back(), Some('ö'));
assert_eq!(c.back(), None);
assert_eq!(c.as_str(), "öcödöeöfö");
}
#[test]
fn insert() {
let mut c = Cursor::from(String::from("öaöböcödöeöfö"));
// move to ^
for _ in 0..4 {
c.right();
}
assert_eq!(c.substring(), "öaöb");
c.insert('ö');
c.insert('g');
c.insert('ö');
c.insert('h');
assert_eq!(c.substring(), "öaöbögöh");
assert_eq!(c.as_str(), "öaöbögöhöcödöeöfö");
}
}
|
