From fe0938b1de0c46fc2afcaa3dcd6a0f4ec870d21a Mon Sep 17 00:00:00 2001
From: Nathan Reiner <nathan@nathanreiner.xyz>
Date: Fri, 2 Aug 2024 00:36:10 +0200
Subject: add state which is shared with the lua environment

---
 src/cursor.rs | 107 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 107 insertions(+)
 create mode 100644 src/cursor.rs

(limited to 'src/cursor.rs')

diff --git a/src/cursor.rs b/src/cursor.rs
new file mode 100644
index 0000000..ad6703e
--- /dev/null
+++ b/src/cursor.rs
@@ -0,0 +1,107 @@
+
+pub enum CursorMove {
+    Up(usize),
+    Down(usize),
+    Left(usize),
+    Right(usize),
+    Top,
+    Bottom,
+    Begin,
+    End,
+    Jump((usize, usize)),
+    Relative((isize, isize)),
+}
+
+#[derive(Default, Debug, Clone)]
+pub struct Cursor {
+    x: isize,
+    y: isize,
+    x_max: isize,
+    y_max: isize,
+}
+
+impl Cursor {
+    pub const fn new() -> Self {
+        Self {
+            x: 0,
+            y: 0,
+            x_max: 0,
+            y_max: 0,
+        }
+    }
+
+    pub fn with_position(mut self, x: isize, y: isize) -> Self {
+        self.x = x;
+        self.y = y;
+        self
+    }
+
+    pub fn with_max(mut self, x: isize, y: isize) -> Self {
+        self.x_max = x;
+        self.y_max = y;
+        self
+    }
+
+    pub fn x(&self) -> usize {
+        self.x as usize
+    }
+
+    pub fn y(&self) -> usize {
+        self.y as usize
+    }
+
+    pub fn set_x_max(&mut self, max: usize) {
+        self.x_max = max as isize;
+    }
+
+    pub fn set_y_max(&mut self, max: usize) {
+        self.y_max = max as isize;
+    }
+
+    pub fn move_checked(&mut self, m: CursorMove) {
+        self.move_unchecked(m);
+        self.correct_cursor_position();
+    }
+
+    pub fn move_unchecked(&mut self, m: CursorMove) {
+        match m {
+            CursorMove::Up(n) => self.y -= n as isize,
+            CursorMove::Down(n) => self.y += n as isize,
+            CursorMove::Left(n) => self.x -= n as isize,
+            CursorMove::Right(n) => self.x += n as isize,
+            CursorMove::Top => self.y = 0,
+            CursorMove::Bottom => self.y = self.y_max,
+            CursorMove::Begin => self.x = 0,
+            CursorMove::End => self.x = self.x_max,
+            CursorMove::Jump((x, y)) => {
+                self.x = x as isize;
+                self.y = y as isize;
+            },
+            CursorMove::Relative((x, y)) => {
+                self.x += x;
+                self.y += y;
+            }
+        };
+    }
+
+    pub fn correct_cursor_position(&mut self) {
+        self.y = self.y.max(0).min(self.y_max);
+        self.x = self.x.max(0).min(self.x_max);
+    }
+
+    pub fn is_at_start(&self) -> bool {
+        self.x == 0
+    }
+
+    pub fn is_at_end(&self) -> bool {
+        self.x == self.x_max
+    }
+
+    pub fn is_at_top(&self) -> bool {
+        self.y == 0
+    }
+
+    pub fn is_at_bottom(&self) -> bool {
+        self.y == self.y_max
+    }
+}
-- 
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