Basic insertion and deletion

src/document.rs

@@ -1,3 +1,4 @@
+use crate::Position;
 use crate::Row;
 use std::fs;
 
@@ -34,4 +35,24 @@ impl Document {
     pub fn len(&self) -> usize {
         self.rows.len()
     }
+
+    pub fn insert(&mut self, at: &Position, c: char) {
+        if at.y == self.len() {
+            let mut row = Row::default();
+            row.insert(0, c);
+            self.rows.push(row);
+        } else if at.y < self.len() {
+            let row = self.rows.get_mut(at.y).unwrap();
+            row.insert(at.x, c);
+        }
+    }
+
+    pub fn delete(&mut self, at: &Position) {
+        if at.y >= self.len() {
+            return
+        }
+
+        let row = self.rows.get_mut(at.y).unwrap();
+        row.delete(at.x);
+    }
 }

src/editor.rs

@@ -145,6 +145,17 @@ impl Editor {
         let pressed_key = Terminal::read_key()?;
         match pressed_key {
             Key::Ctrl('q') => self.should_quit = true,
+            Key::Char(c) => {
+                self.document.insert(&self.cursor_position, c);
+                self.move_cursor(Key::Right);
+            },
+            Key::Delete => self.document.delete(&self.cursor_position),
+            Key::Backspace => {
+                if self.cursor_position.x > 0 || self.cursor_position.y > 0 {
+                    self.move_cursor(Key::Left);
+                    self.document.delete(&self.cursor_position);
+                }
+            }
             Key::Up
             | Key::Down
             | Key::Left

src/row.rs

@@ -1,6 +1,7 @@
 use std::cmp;
 use unicode_segmentation::UnicodeSegmentation;
 
+#[derive(Default)]
 pub struct Row {
     string: String,
     len: usize,
@@ -51,4 +52,35 @@ impl Row {
     fn update_len(&mut self) {
         self.len = self.string[..].graphemes(true).count();
     }
+
+    pub fn insert(&mut self, at: usize, c: char) {
+        if at >= self.len() {
+            self.string.push(c);
+        } else {
+            let mut result: String = self.string[..].graphemes(true).take(at).collect();
+            let remainder: String = self.string[..].graphemes(true).skip(at).collect();
+
+            result.push(c);
+            result.push_str(&remainder);
+
+            self.string = result;
+        }
+
+        self.update_len();
+    }
+
+    pub fn delete(&mut self, at: usize) {
+        if at >= self.len() {
+            return
+        } else {
+            let mut result: String = self.string[..].graphemes(true).take(at).collect();
+            let remainder: String = self.string[..].graphemes(true).skip(at + 1).collect();
+
+            result.push_str(&remainder);
+
+            self.string = result;
+        }
+
+        self.update_len();
+    }
 }