1 files changed, 156 insertions, 0 deletions
diff --git a/src/command/client/search/cursor.rs b/src/command/client/search/cursor.rs
new file mode 100644
index 00000000..1d0e6b8e
--- /dev/null
+++ b/src/command/client/search/cursor.rs
@@ -0,0 +1,156 @@
+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()
+    }
+
+    /// 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");
+    }
+}