1 files changed, 81 insertions, 0 deletions
diff --git a/rust/src/editor.rs b/rust/src/editor.rs
new file mode 100644
index 0000000..7d83904
--- /dev/null
+++ b/rust/src/editor.rs
@@ -0,0 +1,81 @@
+use std::io::Write;
+use termion::event::Key;
+
+#[derive(Debug, Default)]
+pub struct Editor {
+    s: String,
+    left: usize,
+    cursor: usize,
+    wid: usize,
+}
+
+impl Editor {
+    pub fn keypress(&mut self, key: Key) -> Option<String> {
+        let mut ret = None;
+
+        match key {
+            Key::Char('\n') => {
+                ret = Some(String::new());
+                std::mem::swap(ret.as_mut().unwrap(), &mut self.s);
+                self.cursor = 0;
+            }
+
+            Key::Char(c) if !c.is_control() => {
+                self.s.insert(self.cursor, c);
+                self.cursor += 1;
+            }
+
+            Key::Backspace if self.cursor > 0 => {
+                self.cursor -= 1;
+                self.s.remove(self.cursor);
+            }
+
+            Key::Delete if self.s.len() > self.cursor => {
+                self.s.remove(self.cursor);
+            }
+
+            Key::Home | Key::Ctrl('a') => {
+                self.cursor = 0;
+            }
+
+            Key::End | Key::Ctrl('e') => {
+                self.cursor = self.s.len();
+            }
+
+            Key::Left | Key::Ctrl('b') if self.cursor > 0 => {
+                self.cursor -= 1;
+            }
+
+            Key::Right | Key::Ctrl('f') if self.cursor < self.s.len() => {
+                self.cursor += 1;
+            }
+
+            Key::Ctrl('u') => {
+                self.s.replace_range(0..self.cursor, "");
+                self.cursor = 0;
+            }
+
+            _ => {
+                print!("\x07");
+                std::io::stdout().flush().unwrap();
+            }
+        };
+
+        self.fix_left();
+        ret
+    }
+
+    pub fn set_wid(&mut self, wid: usize) {
+        self.wid = wid;
+        self.fix_left();
+    }
+
+    pub fn displayed(&self) -> (&str, usize) {
+        let endidx = (self.left + self.wid).min(self.s.len());
+        (&self.s[self.left .. endidx], self.cursor - self.left)
+    }
+
+    fn fix_left(&mut self) {
+        self.left = self.left.min(self.cursor).max(self.cursor + 1 - self.wid.min(self.cursor + 1));
+    }
+}