redo

Undo / Redo are currently bound to Pageup/down. This is ideally temporary, I just need to figure out ctrl+r for redo. "u" is also bound to undo as it should be

README.md

@@ -2,8 +2,12 @@
 
 *New* Spreadsheet Calculator Improved
 
+![Screenshot](readme/screenshot.png)
+
 Based loosely off sc-im (spreadsheet calculator improvised), which has dumb keybinds and not many features.
 
+[Checkout a demo file](readme/demo.nscim), download, then open with `neoscim demo.nscim`.
+
 ## Keybinds
 
 ### Normal mode
@@ -64,6 +68,7 @@ These commands operate on selections.
 | - | - |
 | `:plot` | Plots the current selection to `plot.png` using gnuplot |
 | `:export <filename>` | Exports the current selection to a new file |
+| `:fill <value>` | (Aliased as `f`) Fill the selection with `<value>`, special variables `x`,`y`,`xi`, and `yi` are avaliable. Variables `x` and `y` are the global coordinates of the cell, and `xi` and `yi` are the local coordinates of the selection. |
 
 ## Math / Functions
 

readme/demo.nscim

@@ -0,0 +1,21 @@
+,,,
+Most of vim's movement works here as well,,,
+,,,
+,i,,
+j,Movement,l,
+,j,,
+,,,
+,"insert text with r, i, or a",,
+,,,
+1,,,
+1,Text can overflow cells,,
+1,But may get cut off if it's too long,,10
+1,,,If it reaches another cell
+1,,,
+Total:,=sum(A:A),Sum A:A,
+,=math::log2(B14),Do math on the output of another function,
+,,,
+,,,
+,,11,Number.
+,,=C18+1,Referencing the number and adding 1
+,,,Copying the cell down will translate the reference

src/app/app.rs

@@ -18,7 +18,10 @@ use ratatui::{
 use crate::app::{
     clipboard::Clipboard,
     error_msg::StatusMessage,
-    logic::{self, calc::{Grid, get_header_size}, cell::CellType},
+    logic::{
+        calc::{Grid, get_header_size},
+        cell::CellType,
+    },
     mode::Mode,
     screen::ScreenSpace,
 };
@@ -42,7 +45,7 @@ impl Widget for &App {
         let (x_max, y_max) = self.screen.how_many_cells_fit_in(&area, &self.vars);
 
         let is_selected = |x: usize, y: usize| -> bool {
-            if let Mode::Visual((mut x1, mut y1)) | Mode::VisualCmd((mut x1, mut y1), _)= self.mode {
+            if let Mode::Visual((mut x1, mut y1)) | Mode::VisualCmd((mut x1, mut y1), _) = self.mode {
                 let (mut x2, mut y2) = self.grid.cursor();
                 x1 += 1;
                 y1 += 1;
@@ -63,7 +66,7 @@ impl Widget for &App {
         for x in 0..x_max {
             for y in 0..y_max {
                 let mut display = String::new();
-                let mut style = Style::new().fg(Color::White);
+                let mut style = Style::new();
 
                 // Custom width for the header of each row
                 let row_header_width = get_header_size() as u16;
@@ -78,7 +81,7 @@ impl Widget for &App {
                 let mut x_idx: usize = 0;
                 let mut y_idx: usize = 0;
                 if x != 0 {
-                    x_idx = x as usize -1 + self.screen.scroll_x();
+                    x_idx = x as usize - 1 + self.screen.scroll_x();
                 }
                 if y != 0 {
                     y_idx = y as usize - 1 + self.screen.scroll_y();
@@ -93,9 +96,9 @@ impl Widget for &App {
                 /// Center the text "99  " -> " 99 "
                 fn center_text(text: &str, avaliable_space: i32) -> String {
                     let margin = avaliable_space - text.len() as i32;
-                    let margin = margin/2;
-                    let l_margin  = (0..margin).into_iter().map(|_| ' ').collect::<String>();
-                    let r_margin = (0..(margin-(l_margin.len() as i32))).into_iter().map(|_| ' ').collect::<String>();
+                    let margin = margin / 2;
+                    let l_margin = (0..margin).into_iter().map(|_| ' ').collect::<String>();
+                    let r_margin = (0..(margin - (l_margin.len() as i32))).into_iter().map(|_| ' ').collect::<String>();
                     format!("{l_margin}{text}{r_margin}")
                 }
 
@@ -148,6 +151,9 @@ impl Widget for &App {
                                             Ok(val) => {
                                                 display = val.to_string();
                                                 style = Style::new()
+                                                    .fg(Color::White)
+                                                    // TODO This breaks dumb terminals like the windows
+                                                    // terminal
                                                     .underline_color(Color::DarkGray)
                                                     .add_modifier(Modifier::UNDERLINED);
                                             }
@@ -211,7 +217,7 @@ impl Widget for &App {
                     }
 
                     // If this is the row header column
-                    let area = if x==0 && y != 0 {
+                    let area = if x == 0 && y != 0 {
                         Rect::new(x_off, y_off, row_header_width, cell_height)
                     } else if let Some(suggestion) = suggest_upper_bound {
                         let max_available_width = area.width - x_off;
@@ -384,17 +390,20 @@ impl App {
                     event::KeyCode::Enter => {
                         let v = editor.as_string();
 
-                        // try to insert as a float
-                        if let Ok(v) = v.parse::<f64>() {
-                            self.grid.set_cell_raw(self.grid.cursor(), Some(v));
-                        } else {
-                            // if you can't, then insert as a string
-                            if !v.is_empty() {
-                                self.grid.set_cell_raw(self.grid.cursor(), Some(v));
+                        let cursor = self.grid.cursor();
+                        self.grid.transact_on_grid(|grid| {
+                            // try to insert as a float
+                            if let Ok(v) = v.parse::<f64>() {
+                                grid.set_cell_raw(cursor, Some(v));
                             } else {
-                                self.grid.set_cell_raw::<CellType>(self.grid.cursor(), None);
+                                // if you can't, then insert as a string
+                                if !v.is_empty() {
+                                    grid.set_cell_raw(cursor, Some(v.to_owned()));
+                                } else {
+                                    grid.set_cell_raw::<CellType>(cursor, None);
+                                }
                             }
-                        }
+                        });
 
                         self.mode = Mode::Normal;
                     }
@@ -410,10 +419,23 @@ impl App {
             },
             Mode::Normal => match event::read()? {
                 event::Event::Key(key_event) => match key_event.code {
-                    event::KeyCode::F(_) => todo!(),
-                    event::KeyCode::Char(c) => {
-                        Mode::process_key(self, c);
-                    }
+                    event::KeyCode::F(n) => {},
+                    event::KeyCode::Char(c) => Mode::process_key(self, c),
+                    // Pretend that the arrow keys are vim movement keys
+                    event::KeyCode::Left => Mode::process_key(self, 'h'),
+                    event::KeyCode::Right => Mode::process_key(self, 'l'),
+                    event::KeyCode::Up => Mode::process_key(self, 'k'),
+                    event::KeyCode::Down => Mode::process_key(self, 'j'),
+                    // Getting ctrl to work isn't going will right now. Use page keys for the time being.
+                    event::KeyCode::PageUp => self.grid.redo(),
+                    event::KeyCode::PageDown => self.grid.undo(),
+                    event::KeyCode::Modifier(modifier_key_code) => {
+                        if let event::ModifierKeyCode::LeftControl | event::ModifierKeyCode::RightControl = modifier_key_code {
+                            // TODO my terminal (alacritty) isn't showing me ctrl presses. I know
+                            // that they work tho, since ctrl+r works here in neovim.
+                            // panic!("heard ctrl");
+                        }
+                    },
                     _ => {}
                 },
                 _ => {}

src/app/clipboard.rs

@@ -18,12 +18,7 @@ pub struct Clipboard {
 
 impl Clipboard {
     pub fn new() -> Self {
-        Self {
-            clipboard: Vec::new(),
-            last_paste_cell: (0, 0),
-            momentum: (0, 1),
-            source_cell: (0, 0),
-        }
+        Self { clipboard: Vec::new(), last_paste_cell: (0, 0), momentum: (0, 1), source_cell: (0, 0) }
     }
 
     /// Panics if clipboard is 0 length (if you call after you
@@ -49,25 +44,28 @@ impl Clipboard {
         // cursor
         let (cx, cy) = into.cursor();
 
-        // iterate thru the clipbaord's cells
-        for (x, row) in self.clipboard.iter().enumerate() {
-            for (y, cell) in row.iter().enumerate() {
-                let idx = (x + cx, y + cy);
+        let cursor = into.cursor();
+        into.transact_on_grid(|grid| {
+            // iterate thru the clipbaord's cells
+            for (x, row) in self.clipboard.iter().enumerate() {
+                for (y, cell) in row.iter().enumerate() {
+                    let idx = (x + cx, y + cy);
 
-                if translate {
-                    if let Some(cell) = cell {
-                        let trans = cell.translate_cell(self.source_cell, into.cursor());
-                        into.set_cell_raw(idx, Some(trans));
+                    if translate {
+                        if let Some(cell) = cell {
+                            let trans = cell.translate_cell(self.source_cell, cursor);
+                            grid.set_cell_raw(idx, Some(trans));
+                        } else {
+                            // The cell at this location doesn't exist (empty)
+                            grid.set_cell_raw::<CellType>(idx, None);
+                        }
                     } else {
-                        // The cell at this location doesn't exist (empty)
-                        into.set_cell_raw::<CellType>(idx, None);
+                        // translate = false
+                        grid.set_cell_raw::<CellType>(idx, cell.clone());
                     }
-                } else {
-                    // translate = false
-                    into.set_cell_raw::<CellType>(idx, cell.clone());
                 }
             }
-        }
+        });
 
         let (lx, ly) = self.last_paste_cell;
         self.momentum = (cx as i32 - lx as i32, cy as i32 - ly as i32);
@@ -109,16 +107,19 @@ impl Clipboard {
 
         // size the clipboard appropriately
         self.clipboard.clear();
-        // clone data into clipboard
-        for x in low_x..=hi_x {
-            let mut col = Vec::new();
-            for y in low_y..=hi_y {
-                let a = from.get_cell_raw(x, y);
-                col.push(a.clone());
-                from.set_cell_raw::<CellType>((x, y), None);
+
+        from.transact_on_grid(|grid| {
+            // clone data into clipboard
+            for x in low_x..=hi_x {
+                let mut col = Vec::new();
+                for y in low_y..=hi_y {
+                    let a = grid.get_cell_raw(x, y);
+                    col.push(a.clone());
+                    grid.set_cell_raw::<CellType>((x, y), None);
+                }
+                self.clipboard.push(col);
             }
-            self.clipboard.push(col);
-        }
+        });
         self.last_paste_cell = (low_x, low_y);
     }
 }
@@ -353,7 +354,7 @@ fn copy_paste_y_locked_var() {
 }
 
 #[test]
-fn issue_47() {
+fn copy_paste_var_in_function() {
     let mut app = App::new();
     app.grid.set_cell("A0", 4.to_string());
     Mode::process_key(&mut app, 'j');
@@ -367,3 +368,31 @@ fn issue_47() {
     let a = app.grid.get_cell("A2").as_ref().expect("Should've been set by paste");
     assert_eq!(a.to_string(), "=math::log2(A1)");
 }
+
+#[test]
+fn copy_paste_range_in_function() {
+    let mut app = App::new();
+    app.grid.set_cell("A0", 1.to_string());
+    app.grid.set_cell("A1", 1.to_string());
+    app.grid.set_cell("A2", 1.to_string());
+
+    app.grid.set_cell("B0", "=sum(A:A)".to_string());
+    app.grid.mv_cursor_to(1, 0);
+    app.mode = super::mode::Mode::Chord(Chord::new('y'));
+    Mode::process_key(&mut app, 'y');
+    Mode::process_key(&mut app, 'l');
+    Mode::process_key(&mut app, 'p');
+
+    let a = app.grid.get_cell("C0").as_ref().expect("Should've been set by paste");
+    assert_eq!(a.to_string(), "=sum(B:B)");
+
+    // now copy the range the other direction
+    app.grid.mv_cursor_to(2, 0);
+    app.mode = super::mode::Mode::Chord(Chord::new('y'));
+    Mode::process_key(&mut app, 'y');
+    app.grid.mv_cursor_to(1, 1);
+    Mode::process_key(&mut app, 'p');
+
+    let a = app.grid.get_cell("B1").as_ref().expect("Should've been set by paste");
+    assert_eq!(a.to_string(), "=sum(A:A)");
+}

src/app/logic/calc.rs

@@ -2,20 +2,21 @@ use std::{
     cmp::{max, min},
     fs::{self, File},
     io::{Read, Write},
-    path::PathBuf
+    path::PathBuf,
 };
 
 use evalexpr::*;
 
-use crate::app::{
-    logic::{
-        cell::{CSV_DELIMITER, CellType},
-        ctx,
-    }, mode::Mode,
+use crate::app::logic::{
+    calc::internal::CellGrid,
+    cell::{CSV_DELIMITER, CellType},
+    ctx,
 };
 
 #[cfg(test)]
 use crate::app::app::App;
+#[cfg(test)]
+use crate::app::mode::Mode;
 
 pub fn get_header_size() -> usize {
     let row_header_width = LEN.to_string().len();
@@ -26,13 +27,109 @@ pub const LEN: usize = 1001;
 pub const CSV_EXT: &str = "csv";
 pub const CUSTOM_EXT: &str = "nscim";
 
+mod internal {
+    use crate::app::logic::{calc::LEN, cell::CellType};
+
+    #[derive(Clone)]
+    pub struct CellGrid {
+        //  a b c ...
+        // 0
+        // 1
+        // 2
+        // ...
+        cells: Vec<Vec<Option<CellType>>>,
+    }
+
+    impl CellGrid {
+        pub fn new() -> Self {
+            let mut a = Vec::with_capacity(LEN);
+            for _ in 0..LEN {
+                let mut b = Vec::with_capacity(LEN);
+                for _ in 0..LEN {
+                    b.push(None)
+                }
+                a.push(b)
+            }
+            Self { cells: a }
+        }
+
+        pub fn insert_row(&mut self, y: usize) {
+            for x in 0..LEN {
+                self.cells[x].insert(y, None);
+                self.cells[x].pop();
+            }
+        }
+
+        pub fn insert_column(&mut self, x: usize) {
+            let mut v = Vec::with_capacity(LEN);
+            for _ in 0..LEN {
+                v.push(None);
+            }
+            // let clone = self.grid_history[self.current_grid].clone();
+            self.cells.insert(x, v);
+            // keep the grid LEN
+            self.cells.pop();
+        }
+
+        pub fn get_cell_raw(&self, x: usize, y: usize) -> &Option<CellType> {
+            if x >= LEN || y >= LEN {
+                return &None;
+            }
+            &self.cells[x][y]
+        }
+        pub fn set_cell_raw<T: Into<CellType>>(&mut self, (x, y): (usize, usize), val: Option<T>) {
+            // TODO check oob
+            self.cells[x][y] = val.map(|v| v.into());
+        }
+        /// Iterate over the entire grid and see where
+        /// the farthest modified cell is.
+        #[must_use]
+        pub fn max(&self) -> (usize, usize) {
+            let mut max_x = 0;
+            let mut max_y = 0;
+
+            for (xi, x) in self.cells.iter().enumerate() {
+                for (yi, cell) in x.iter().enumerate() {
+                    if cell.is_some() {
+                        if yi > max_y {
+                            max_y = yi
+                        }
+                        if xi > max_x {
+                            max_x = xi
+                        }
+                    }
+                }
+            }
+
+            (max_x, max_y)
+        }
+
+        #[must_use]
+        pub fn max_y_at_x(&self, x: usize) -> usize {
+            let mut max_y = 0;
+            if let Some(col) = self.cells.get(x) {
+                // we could do fancy things like .take_while(not null) but then
+                // we would have to deal with empty cells and stuff, which sounds
+                // boring. This will be fast "enough", considering the grid is
+                // probably only like 1k cells
+                for (yi, cell) in col.iter().enumerate() {
+                    if cell.is_some() {
+                        if yi > max_y {
+                            max_y = yi
+                        }
+                    }
+                }
+            }
+            max_y
+        }
+    }
+}
+
 pub struct Grid {
-    //  a b c ...
-    // 0
-    // 1
-    // 2
-    // ...
-    cells: Vec<Vec<Option<CellType>>>,
+    /// Which grid in history are we currently on
+    current_grid: usize,
+    /// An array of grids, thru history
+    grid_history: Vec<CellGrid>,
     /// (X, Y)
     selected_cell: (usize, usize),
     /// Have unsaved modifications been made?
@@ -47,20 +144,9 @@ impl std::fmt::Debug for Grid {
 
 impl Grid {
     pub fn new() -> Self {
-        let mut a = Vec::with_capacity(LEN);
-        for _ in 0..LEN {
-            let mut b = Vec::with_capacity(LEN);
-            for _ in 0..LEN {
-                b.push(None)
-            }
-            a.push(b)
-        }
+        let x = CellGrid::new();
 
-        Self {
-            cells: a,
-            selected_cell: (0, 0),
-            dirty: false,
-        }
+        Self { current_grid: 0, grid_history: vec![x], selected_cell: (0, 0), dirty: false }
     }
 
     pub fn new_from_file(file: &mut File) -> std::io::Result<Self> {
@@ -68,14 +154,17 @@ impl Grid {
 
         let mut buf = String::new();
         file.read_to_string(&mut buf)?;
-        for (yi, line) in buf.lines().enumerate() {
-            let cells = Self::parse_csv_line(line);
 
-            for (xi, cell) in cells.into_iter().enumerate() {
-                // This gets automatically duck-typed
-                grid.set_cell_raw((xi, yi), cell);
+        grid.transact_on_grid(|grid| {
+            for (yi, line) in buf.lines().enumerate() {
+                let cells = Self::parse_csv_line(line);
+
+                for (xi, cell) in cells.into_iter().enumerate() {
+                    // This gets automatically duck-typed
+                    grid.set_cell_raw((xi, yi), cell);
+                }
             }
-        }
+        });
 
         // force dirty back off, we just read the data so it's gtg
         grid.dirty = false;
@@ -112,19 +201,15 @@ impl Grid {
         }
 
         let mut f = fs::OpenOptions::new().write(true).append(false).truncate(true).create(true).open(path)?;
-        let (mx, my) = self.max();
+        let (mx, my) = self.get_grid().max();
         for y in 0..=my {
             for x in 0..=mx {
-                let cell = &self.cells[x][y];
+                let cell = &self.get_grid().get_cell_raw(x, y);
 
                 // newline after the cell, because it's end of line.
                 // else, just put a comma after the cell.
-                let is_last = x==mx;
-                let delim = if is_last {
-                    '\n'
-                } else {
-                    CSV_DELIMITER
-                };
+                let is_last = x == mx;
+                let delim = if is_last { '\n' } else { CSV_DELIMITER };
 
                 let data = if let Some(cell) = cell {
                     if let Ok(val) = self.evaluate(&cell.to_string())
@@ -146,6 +231,40 @@ impl Grid {
         Ok(())
     }
 
+    pub fn get_grid<'a>(&'a self) -> &'a CellGrid {
+        &self.grid_history[self.current_grid]
+    }
+
+    fn get_grid_mut<'a>(&'a mut self) -> &'a mut CellGrid {
+        &mut self.grid_history[self.current_grid]
+    }
+
+    pub fn undo(&mut self) {
+        self.current_grid = self.current_grid.saturating_sub(1);
+    }
+    pub fn redo(&mut self) {
+        self.current_grid = min(self.grid_history.len() - 1, self.current_grid + 1);
+    }
+
+    pub fn transact_on_grid<F>(&mut self, mut action: F)
+    where
+        F: FnMut(&mut CellGrid) -> (),
+    {
+        // push on a new reality
+        let new = self.get_grid().clone();
+        self.grid_history.push(new);
+        self.current_grid += 1;
+
+        // delete the other fork of the history
+        for i in self.current_grid + 1..self.grid_history.len() {
+            self.grid_history.remove(i);
+        }
+
+        action(&mut self.grid_history[self.current_grid]);
+
+        self.dirty = true;
+    }
+
     pub fn needs_to_be_saved(&self) -> bool {
         self.dirty
     }
@@ -252,101 +371,59 @@ impl Grid {
     }
 
     pub fn insert_row_above(&mut self, (_x, insertion_y): (usize, usize)) {
-        for x in 0..LEN {
-            self.cells[x].insert(insertion_y, None);
-            self.cells[x].pop();
-            for y in 0..LEN {
-                if let Some(cell) = self.get_cell_raw(x, y).as_ref().map(|f| {
-                    f.custom_translate_cell((0, 0), (0, 1), |rolling, old, new| {
-                        if let Some((_, arg_y)) = Grid::parse_to_idx(old) {
-                            if arg_y < insertion_y { rolling.to_owned() } else { rolling.replace(old, new)  }
-                        } else {
-                            unimplemented!("Invalid variable wanted to be translated")
-                        }
+        self.transact_on_grid(|grid: &mut CellGrid| {
+            grid.insert_row(insertion_y);
+            for x in 0..LEN {
+                for y in 0..LEN {
+                    if let Some(cell) = grid.get_cell_raw(x, y).as_ref().map(|f| {
+                        f.custom_translate_cell((0, 0), (0, 1), |rolling, old, new| {
+                            if let Some((_, arg_y)) = Grid::parse_to_idx(old) {
+                                if arg_y < insertion_y { rolling.to_owned() } else { rolling.replace(old, new) }
+                            } else {
+                                unimplemented!("Invalid variable wanted to be translated")
+                            }
+                        })
+                    }) {
+                        grid.set_cell_raw((x, y), Some(cell));
                     }
-                    )}) {
-                    self.set_cell_raw((x,y), Some(cell));
                 }
             }
-        }
+        });
     }
+
     pub fn insert_row_below(&mut self, (x, y): (usize, usize)) {
-        self.insert_row_above((x,y+1));
+        self.insert_row_above((x, y + 1));
     }
+
     pub fn insert_column_before(&mut self, (insertion_x, _y): (usize, usize)) {
-        let mut v = Vec::with_capacity(LEN);
-        for _ in 0..LEN {
-            v.push(None);
-        }
-        self.cells.insert(insertion_x, v);
-        // keep the grid LEN
-        self.cells.pop();
-        for x in 0..LEN {
-            for y in 0..LEN {
-                if let Some(cell) = self.get_cell_raw(x, y).as_ref().map(|f| {
-                    f.custom_translate_cell((0, 0), (1, 0), |rolling, old, new| {
-                        if let Some((arg_x, _)) = Grid::parse_to_idx(old) {
-                            // add 1 because of the insertion
-                            if arg_x < insertion_x { rolling.to_owned() } else { rolling.replace(old, new) }
-                        } else {
-                            unimplemented!("Invalid variable wanted to be translated")
-                        }
-                    })
-                }) {
-                    self.set_cell_raw((x, y), Some(cell));
+        self.transact_on_grid(|grid| {
+            grid.insert_column(insertion_x);
+            for x in 0..LEN {
+                for y in 0..LEN {
+                    if let Some(cell) = grid.get_cell_raw(x, y).as_ref().map(|f| {
+                        f.custom_translate_cell((0, 0), (1, 0), |rolling, old, new| {
+                            if let Some((arg_x, _)) = Grid::parse_to_idx(old) {
+                                // add 1 because of the insertion
+                                if arg_x < insertion_x { rolling.to_owned() } else { rolling.replace(old, new) }
+                            } else {
+                                unimplemented!("Invalid variable wanted to be translated")
+                            }
+                        })
+                    }) {
+                        grid.set_cell_raw((x, y), Some(cell));
+                    }
                 }
             }
-        }
+        });
     }
+
     pub fn insert_column_after(&mut self, (x, y): (usize, usize)) {
         self.insert_column_before((x + 1, y));
     }
-    /// Iterate over the entire grid and see where
-    /// the farthest modified cell is.
-    #[must_use]
-    fn max(&self) -> (usize, usize) {
-        let mut max_x = 0;
-        let mut max_y = 0;
-
-        for (xi, x) in self.cells.iter().enumerate() {
-            for (yi, cell) in x.iter().enumerate() {
-                if cell.is_some() {
-                    if yi > max_y {
-                        max_y = yi
-                    }
-                    if xi > max_x {
-                        max_x = xi
-                    }
-                }
-            }
-        }
-
-        (max_x, max_y)
-    }
-
-    #[must_use]
-    pub fn max_y_at_x(&self, x: usize) -> usize {
-        let mut max_y = 0;
-        if let Some(col) = self.cells.get(x) {
-            // we could do fancy things like .take_while(not null) but then
-            // we would have to deal with empty cells and stuff, which sounds
-            // boring. This will be fast "enough", considering the grid is
-            // probably only like 1k cells
-            for (yi, cell) in col.iter().enumerate() {
-                if cell.is_some() {
-                    if yi > max_y {
-                        max_y = yi
-                    }
-                }
-            }
-        }
-
-        max_y
-    }
 
     /// Only evaluates equations, such as `=10` or `=A1/C2`, not
     /// strings or numbers.
-    pub fn evaluate(&self, mut eq: &str) -> Result<f64, String> {
+    pub fn evaluate(&self, mut eq: &str) -> Result<CellType, String> {
         if eq.starts_with('=') {
             eq = &eq[1..];
         } else {
@@ -360,11 +437,15 @@ impl Grid {
             if v.is_number() {
                 if v.is_float() {
                     let val = v.as_float().expect("Value lied about being a float");
-                    return Ok(val);
+                    return Ok(CellType::Number(val));
                 } else if v.is_int() {
-                    let i = v.as_int().expect("Value lied about being an int");
-                    return Ok(i as f64);
+                    let val = v.as_int().expect("Value lied about being an int");
+                    return Ok(CellType::Number(val as f64));
                 }
+            } else if v.is_string() {
+                // ^^ This allows for functions to return a string
+                let s = v.as_string().expect("Value lied about being a String");
+                return Ok(CellType::String(s));
             }
             return Err("Result is NaN".to_string());
         };
@@ -377,10 +458,7 @@ impl Grid {
                 EvalexprError::VariableIdentifierNotFound(var_not_found) => {
                     return Err(format!("\"{var_not_found}\" is not a variable"));
                 }
-                EvalexprError::TypeError {
-                    expected: e,
-                    actual: a,
-                } => {
+                EvalexprError::TypeError { expected: e, actual: a } => {
                     // IE: You put a string into a function that wants a float
                     return Err(format!("Wanted {e:?}, got {a}"));
                 }
@@ -389,12 +467,22 @@ impl Grid {
         }
     }
 
+    pub fn char_to_idx(i: &str) -> usize {
+        let x_idx = i
+            .chars()
+            .filter(|f| f.is_alphabetic())
+            .enumerate()
+            .map(|(idx, c)| ((c.to_ascii_lowercase() as usize).saturating_sub(97)) + (26 * idx))
+            .fold(0, |a, b| a + b);
+        x_idx
+    }
+
     /// Parse values in the format of A0, C10 ZZ99, etc, and
     /// turn them into an X,Y index.
     pub fn parse_to_idx(i: &str) -> Option<(usize, usize)> {
         let i = i.replace('$', "");
 
-        let chars = i.chars().take_while(|c| c.is_alphabetic()).collect::<Vec<char>>();
+        let chars = i.chars().take_while(|c| c.is_alphabetic()).collect::<String>();
         let nums = i.chars().skip(chars.len()).take_while(|c| c.is_numeric()).collect::<String>();
 
         // At least half the arguments are gone
@@ -403,11 +491,7 @@ impl Grid {
         }
 
         // get the x index from the chars
-        let x_idx = chars
-            .iter()
-            .enumerate()
-            .map(|(idx, c)| (c.to_ascii_lowercase() as usize - 97) + (26 * idx))
-            .fold(0, |a, b| a + b);
+        let x_idx = Self::char_to_idx(&chars);
 
         // get the y index from the numbers
         if let Ok(y_idx) = nums.parse::<usize>() {
@@ -419,15 +503,13 @@ impl Grid {
 
     /// Helper for tests
     #[cfg(test)]
+    /// Don't ever remove this from being just a test-helper.
+    /// This function doesn't correctly use the undo/redo api, which would require doing
+    /// transactions on the grid instead of direct access.
     pub fn set_cell<T: Into<CellType>>(&mut self, cell_id: &str, val: T) {
         if let Some(loc) = Self::parse_to_idx(cell_id) {
-            self.set_cell_raw(loc, Some(val));
+            self.get_grid_mut().set_cell_raw(loc, Some(val))
         }
-    }
-
-    pub fn set_cell_raw<T: Into<CellType>>(&mut self, (x, y): (usize, usize), val: Option<T>) {
-        // TODO check oob
-        self.cells[x][y] = val.map(|v| v.into());
         self.dirty = true;
     }
 
@@ -446,7 +528,7 @@ impl Grid {
         if x >= LEN || y >= LEN {
             return &None;
         }
-        &self.cells[x][y]
+        &self.get_grid().get_cell_raw(x, y)
     }
 
     pub fn num_to_char(idx: usize) -> String {
@@ -499,11 +581,11 @@ fn saving_csv() {
     // insure that the cells are there
     let cell = app.grid.get_cell_raw(0, 10).as_ref().expect("Should've been set");
     let res = app.grid.evaluate(&cell.to_string()).expect("Should evaluate");
-    assert_eq!(res, 11.0);
+    assert_eq!(res, (11.0).into());
     assert_eq!(cell.escaped_csv_string(), "=A9+A$0");
     let cell = app.grid.get_cell_raw(1, 10).as_ref().expect("Should've been set");
     let res = app.grid.evaluate(&cell.to_string()).expect("Should evaluate");
-    assert_eq!(res, 121.0);
+    assert_eq!(res, (121.0).into());
     assert_eq!(cell.escaped_csv_string(), "=A10^2");
 
     // set saving the file
@@ -542,11 +624,11 @@ fn saving_neoscim() {
     // insure that the cells are there
     let cell = app.grid.get_cell_raw(0, 10).as_ref().expect("Should've been set");
     let res = app.grid.evaluate(&cell.to_string()).expect("Should evaluate");
-    assert_eq!(res, 11.0);
+    assert_eq!(res, (11.0).into());
     assert_eq!(cell.escaped_csv_string(), "=A9+A$0");
     let cell = app.grid.get_cell_raw(1, 10).as_ref().expect("Should've been set");
     let res = app.grid.evaluate(&cell.to_string()).expect("Should evaluate");
-    assert_eq!(res, 121.0);
+    assert_eq!(res, (121.0).into());
     assert_eq!(cell.escaped_csv_string(), "=A10^2");
 
     // set saving the file
@@ -564,7 +646,7 @@ fn saving_neoscim() {
 fn cell_strings() {
     let mut grid = Grid::new();
 
-    assert!(&grid.cells[0][0].is_none());
+    assert!(&grid.get_grid().get_cell_raw(0, 0).is_none());
     grid.set_cell("A0", "Hello".to_string());
     assert!(grid.get_cell("A0").is_some());
 
@@ -587,6 +669,7 @@ fn alphanumeric_indexing() {
     assert_eq!(Grid::parse_to_idx("A"), None);
     assert_eq!(Grid::parse_to_idx(":"), None);
     assert_eq!(Grid::parse_to_idx("="), None);
+    assert_eq!(Grid::parse_to_idx("A:A"), None);
 
     assert_eq!(Grid::num_to_char(0).trim(), "A");
     assert_eq!(Grid::num_to_char(25).trim(), "Z");
@@ -607,31 +690,31 @@ fn valid_equations() {
     // cell math
     let cell = grid.get_cell("C0").as_ref().expect("Just set it");
     let res = grid.evaluate(&cell.to_string()).expect("Should evaluate.");
-    assert_eq!(res, 3.);
+    assert_eq!(res, (3.).into());
 
     // divide floats
     grid.set_cell("D0", "=5./2.".to_string());
     let cell = grid.get_cell("D0").as_ref().expect("I just set this");
     let res = grid.evaluate(&cell.to_string()).expect("Should be ok");
-    assert_eq!(res, 2.5);
+    assert_eq!(res, (2.5).into());
 
     // Float / Int mix
     grid.set_cell("D0", "=5./2".to_string());
     let cell = grid.get_cell("D0").as_ref().expect("I just set this");
     let res = grid.evaluate(&cell.to_string()).expect("Should be ok");
-    assert_eq!(res, 2.5);
+    assert_eq!(res, (2.5).into());
 
     // divide "ints" (should become floats)
     grid.set_cell("D0", "=5/2".to_string());
     let cell = grid.get_cell("D0").as_ref().expect("I just set this");
     let res = grid.evaluate(&cell.to_string()).expect("Should be ok");
-    assert_eq!(res, 2.5);
+    assert_eq!(res, (2.5).into());
 
     // Non-equation that should still be valid
     grid.set_cell("D0", "=10".to_string());
     let cell = grid.get_cell("D0").as_ref().expect("I just set this");
     let res = grid.evaluate(&cell.to_string()).expect("Should be ok");
-    assert_eq!(res, 10.);
+    assert_eq!(res, (10.).into());
 }
 
 // Cell = output of Cell = value of Cells.
@@ -648,7 +731,7 @@ fn fn_of_fn() {
         let res = grid.evaluate(&cell.to_string());
 
         assert!(res.is_ok());
-        assert_eq!(res.unwrap(), 6.);
+        assert_eq!(res.unwrap(), (6.).into());
         return;
     }
     panic!("Cell not found");
@@ -684,7 +767,7 @@ fn invalid_equations() {
     let cell = grid.get_cell("B0").as_ref().expect("Just set the cell");
     let res = grid.evaluate(&cell.to_string());
     assert!(res.is_ok());
-    assert!(res.is_ok_and(|v| v == 10.));
+    assert!(res.is_ok_and(|v| v == (10.).into()));
 
     // Trailing comma in function call
     grid.set_cell("A0", 5.);
@@ -692,7 +775,7 @@ fn invalid_equations() {
     grid.set_cell("B0", "=avg(A0,A1,)".to_string());
     let cell = grid.get_cell("B0").as_ref().expect("Just set the cell");
     let res = grid.evaluate(&cell.to_string());
-    assert_eq!(res.unwrap(), 7.5);
+    assert_eq!(res.unwrap(), (7.5).into());
 }
 
 #[test]
@@ -700,17 +783,17 @@ fn grid_max() {
     let mut grid = Grid::new();
 
     grid.set_cell("A0", 1.);
-    let (mx, my) = grid.max();
+    let (mx, my) = grid.get_grid().max();
     assert_eq!(mx, 0);
     assert_eq!(my, 0);
 
     grid.set_cell("B0", 1.);
-    let (mx, my) = grid.max();
+    let (mx, my) = grid.get_grid().max();
     assert_eq!(mx, 1);
     assert_eq!(my, 0);
 
     grid.set_cell("B5", 1.);
-    let (mx, my) = grid.max();
+    let (mx, my) = grid.get_grid().max();
     assert_eq!(mx, 1);
     assert_eq!(my, 5);
 }
@@ -723,19 +806,19 @@ fn avg_function() {
     let cell = grid.get_cell("A0").as_ref().expect("Just set the cell");
     let res = grid.evaluate(&cell.to_string());
     assert!(res.is_ok());
-    assert_eq!(res.unwrap(), 5.);
+    assert_eq!(res.unwrap(), (5.).into());
 
     grid.set_cell("A0", "=avg(5,10)".to_string());
     let cell = grid.get_cell("A0").as_ref().expect("Just set the cell");
     let res = grid.evaluate(&cell.to_string());
     assert!(res.is_ok());
-    assert_eq!(res.unwrap(), 7.5);
+    assert_eq!(res.unwrap(), (7.5).into());
 
     grid.set_cell("A0", "=avg(5,10,15)".to_string());
     let cell = grid.get_cell("A0").as_ref().expect("Just set the cell");
     let res = grid.evaluate(&cell.to_string());
     assert!(res.is_ok());
-    assert_eq!(res.unwrap(), 10.);
+    assert_eq!(res.unwrap(), (10.).into());
 
     grid.set_cell("A0", "=avg(foo)".to_string());
     let cell = grid.get_cell("A0").as_ref().expect("Just set the cell");
@@ -761,13 +844,13 @@ fn sum_function() {
     let cell = grid.get_cell("A0").as_ref().expect("Just set the cell");
     let res = grid.evaluate(&cell.to_string());
     assert!(res.is_ok());
-    assert_eq!(res.unwrap(), 5.);
+    assert_eq!(res.unwrap(), (5.).into());
 
     grid.set_cell("A0", "=sum(5,10)".to_string());
     let cell = grid.get_cell("A0").as_ref().expect("Just set the cell");
     let res = grid.evaluate(&cell.to_string());
     assert!(res.is_ok());
-    assert_eq!(res.unwrap(), 15.);
+    assert_eq!(res.unwrap(), (15.).into());
 
     grid.set_cell("A0", "=sum(foo)".to_string());
     let cell = grid.get_cell("A0").as_ref().expect("Just set the cell");
@@ -797,7 +880,7 @@ fn xlookup_function() {
     let cell = grid.get_cell("B0").as_ref().expect("Just set the cell");
     let res = grid.evaluate(&cell.to_string());
     assert!(res.is_ok());
-    assert_eq!(res.unwrap(), 31.);
+    assert_eq!(res.unwrap(), (31.).into());
 }
 
 #[test]
@@ -851,6 +934,19 @@ fn parse_csv() {
     );
 }
 
+#[test]
+fn invalid_ranges() {
+    let mut grid = Grid::new();
+
+    grid.set_cell("A0", 2.);
+    grid.set_cell("A1", 1.);
+    // ASCII to number conversion needs to not overflow
+    grid.set_cell("B0", "=sum($:A)".to_string());
+
+    let cell = grid.get_cell("B0").as_ref().expect("Just set it");
+    let _ = grid.evaluate(&cell.to_string()).expect("Should evaluate.");
+}
+
 #[test]
 fn ranges() {
     let mut grid = Grid::new();
@@ -862,13 +958,13 @@ fn ranges() {
     // range with numbers
     let cell = grid.get_cell("B0").as_ref().expect("Just set it");
     let res = grid.evaluate(&cell.to_string()).expect("Should evaluate.");
-    assert_eq!(res, 3.);
+    assert_eq!(res, (3.).into());
 
     // use range output as input for other function
     grid.set_cell("B1", "=B0*2".to_string());
     let cell = grid.get_cell("B1").as_ref().expect("Just set it");
     let res = grid.evaluate(&cell.to_string()).expect("Should evaluate.");
-    assert_eq!(res, 6.);
+    assert_eq!(res, (6.).into());
 
     // use equation outputs as range input
     grid.set_cell("A2", "=C0+1".to_string());
@@ -876,11 +972,11 @@ fn ranges() {
 
     let cell = grid.get_cell("A2").as_ref().expect("Just set it");
     let res = grid.evaluate(&cell.to_string()).expect("Should evaluate.");
-    assert_eq!(res, 6.);
+    assert_eq!(res, (6.).into());
 
     let cell = grid.get_cell("B0").as_ref().expect("Just set it");
     let res = grid.evaluate(&cell.to_string()).expect("Should evaluate.");
-    assert_eq!(res, 9.);
+    assert_eq!(res, (9.).into());
 
     // use function outputs as range input
     grid.set_cell("B1", 2.);
@@ -889,7 +985,7 @@ fn ranges() {
 
     let cell = grid.get_cell("C0").as_ref().expect("Just set it");
     let res = grid.evaluate(&cell.to_string()).expect("Should evaluate.");
-    assert_eq!(res, 5.);
+    assert_eq!(res, (5.).into());
 
     // use range outputs as range input
     grid.set_cell("D0", "=sum(C:C)".to_string());
@@ -897,7 +993,7 @@ fn ranges() {
 
     let cell = grid.get_cell("D0").as_ref().expect("Just set it");
     let res = grid.evaluate(&cell.to_string()).expect("Should evaluate.");
-    assert_eq!(res, 6.);
+    assert_eq!(res, (6.).into());
 }
 
 #[test]
@@ -1048,7 +1144,7 @@ fn insert_row_above_3() {
 #[test]
 fn cell_eval_depth() {
     use crate::app::mode::*;
-    let mut app= App::new();
+    let mut app = App::new();
 
     app.grid.set_cell("A0", 1.);
     app.grid.set_cell("A1", "=A0+$A$0".to_string());
@@ -1067,6 +1163,34 @@ fn cell_eval_depth() {
     assert_eq!(c.to_string(), "=A5+$A$0");
 
     let res = app.grid.evaluate(&c.to_string()).expect("Should evaluate");
-    assert_eq!(res, 7.);
+    assert_eq!(res, (7.).into());
 }
 
+#[test]
+fn return_string_from_fn() {
+    let mut grid = Grid::new();
+    grid.set_cell("A0", "=if(2>1, \"A\", \"B\")".to_string()); // true, A
+    grid.set_cell("A1", "=if(1>2, \"A\", \"B\")".to_string()); // false, B
+
+    let cell = grid.get_cell("A0").as_ref().expect("Just set the cell");
+    let res = grid.evaluate(&cell.to_string());
+    assert!(res.is_ok());
+    if let Ok(f) = res {
+        if let CellType::String(s) = f {
+            assert_eq!("A", s);
+        } else {
+            unreachable!();
+        }
+    }
+
+    let cell = grid.get_cell("A1").as_ref().expect("Just set the cell");
+    let res = grid.evaluate(&cell.to_string());
+    assert!(res.is_ok());
+    if let Ok(f) = res {
+        if let CellType::String(s) = f {
+            assert_eq!("B", s);
+        } else {
+            unreachable!();
+        }
+    }
+}

src/app/logic/cell.rs

@@ -63,7 +63,7 @@ impl CellType {
             CellType::Equation(eq) => {
                 // Populate the context
                 let ctx = ExtractionContext::new();
-                let _ = eval_with_context(eq, &ctx);
+                let _ = eval_with_context(&eq[1..], &ctx);
 
                 let mut equation = eq.clone();
                 // translate standard vars A0 -> A1
@@ -73,7 +73,10 @@ impl CellType {
                     let mut lock_y = false;
 
                     if old_var.contains('$') {
-                        let locations = old_var.char_indices().filter(|(_, c)| *c == '$').map(|(i, _)| i).collect::<Vec<usize>>();
+                        let locations = old_var
+                            .char_indices()
+                            .filter(|(_, c)| *c == '$').map(|(i, _)| i)
+                            .collect::<Vec<usize>>();
                         match locations.len() {
                             1 => {
                                 if locations[0] == 0 {
@@ -136,6 +139,40 @@ impl CellType {
                         // rolling = rolling.replace(&old_var, &new_var);
                     } else {
                         // why you coping invalid stuff, nerd?
+                        //
+                        // could be copying a range
+                        if old_var.contains(':') {
+                            let parts = old_var.split(':').collect::<Vec<&str>>();
+                            // This means the var was formatted as X:X
+                            if parts.len() == 2 {
+                                // how far is the movement?
+                                let dx = to.0 as i32 - from.0 as i32;
+
+                                let range_start = parts[0];
+                                let range_end = parts[1];
+
+                                // get the letters as numbers
+                                let xs = Grid::char_to_idx(range_start) as i32;
+                                let xe = Grid::char_to_idx(range_end) as i32;
+                                
+                                // apply movement
+                                let mut new_range_start = xs+dx;
+                                let mut new_range_end = xe+dx;
+
+                                // bottom out at 0
+                                if new_range_start < 0 {
+                                    new_range_start = 0;
+                                }
+                                if new_range_end < 0 {
+                                    new_range_end = 0;
+                                }
+
+                                // convert the index back into a letter and then submit it
+                                let start = Grid::num_to_char(new_range_start as usize);
+                                let end = Grid::num_to_char(new_range_end as usize);
+                                equation = replace_fn(&equation, &old_var, &format!("{}:{}", start.trim(), end.trim())); 
+                            }
+                        }
                     }
                 }
                 return equation.into();
@@ -158,3 +195,15 @@ impl Display for CellType {
         write!(f, "{d}")
     }
 }
+
+impl PartialEq for CellType {
+    fn eq(&self, other: &Self) -> bool {
+        match (self, other) {
+            (Self::Number(left), Self::Number(right)) => left == right,
+            (Self::String(left), Self::String(right)) => left == right,
+            (Self::Equation(left), Self::Equation(right)) => left == right,
+            _ => false,
+        }
+    }
+}
+

src/app/logic/ctx.rs

@@ -24,7 +24,7 @@ impl<'a> CallbackContext<'a> {
             let as_index = |s: &str| {
                 s.char_indices()
                     // .filter(|f| f.1 as u8 >= 97) // prevent sub with overflow errors
-                    .map(|(idx, c)| (c.to_ascii_lowercase() as usize - 97) + (26 * idx))
+                    .map(|(idx, c)| ((c.to_ascii_lowercase() as usize).saturating_sub(97)) + (26 * idx))
                     .fold(0, |a, b| a + b)
             };
 
@@ -34,8 +34,8 @@ impl<'a> CallbackContext<'a> {
             let mut buf = Vec::new();
 
             for x in start_idx..=end_idx {
-                for y in 0..=self.variables.max_y_at_x(x) {
-                    if let Some(s) = self.variables.get_cell_raw(x, y) {
+                for y in 0..=self.variables.get_grid().max_y_at_x(x) {
+                    if let Some(s) = self.variables.get_grid().get_cell_raw(x, y) {
                         buf.push(s);
                     }
                 }
@@ -162,8 +162,8 @@ impl<'a> Context for CallbackContext<'a> {
         }
 
         if let Ok(mut trail) = self.eval_breadcrumbs.write() {
-            let find = trail.iter().filter(|id| *id == identifier).collect::<Vec<&String>>();
-            if find.len() > 0 {
+            let find = trail.iter().filter(|id| *id == identifier).count();
+            if find > 0 {
                 // recursion detected
                 return None;
             } else {
@@ -195,7 +195,7 @@ impl<'a> Context for CallbackContext<'a> {
                         },
                         Err(e) => {
                             match e {
-                                EvalexprError::VariableIdentifierNotFound(_) => {
+                                EvalexprError::VariableIdentifierNotFound(_err) => {
                                     // If the variable isn't found, that's ~~probably~~ because
                                     // of recursive reference, considering all references
                                     // are grabbed straight from the table.
@@ -217,8 +217,14 @@ impl<'a> Context for CallbackContext<'a> {
                         CellType::Number(e) => vals.push(Value::Float(*e)),
                         CellType::String(s) => vals.push(Value::String(s.to_owned())),
                         CellType::Equation(eq) => {
-                            if let Ok(val) = eval_with_context(&eq[1..], self) {
-                                vals.push(val);
+                            match eval_with_context(&eq[1..], self) {
+                                Ok(val) => vals.push(val),
+                                Err(_err) => {
+                                    // At this point we are getting an error because
+                                    // recursion protection made this equation return
+                                    // None. We now don't get any evaluation.
+                                    return None
+                                },
                             }
                         }
                     }
@@ -270,10 +276,19 @@ impl ExtractionContext {
         }
     }
     pub fn dump_vars(&self) -> Vec<String> {
-        if let Ok(r) = self.var_registry.read() { r.clone() } else { Vec::new() }
+        if let Ok(r) = self.var_registry.read() {
+            r.clone()
+        } else {
+            Vec::new()
+        }
     }
+    #[allow(dead_code)]
     pub fn dump_fns(&self) -> Vec<String> {
-        if let Ok(r) = self.fn_registry.read() { r.clone() } else { Vec::new() }
+        if let Ok(r) = self.fn_registry.read() {
+            r.clone()
+        } else {
+            Vec::new()
+        }
     }
 }
 
@@ -301,8 +316,7 @@ impl Context for ExtractionContext {
         } else {
             panic!("The RwLock should always be write-able")
         }
-        // Ok(Value::Int(1))
-        unimplemented!("Extracting function identifier not implemented yet")
+        Ok(Value::Int(1))
     }
 
     fn are_builtin_functions_disabled(&self) -> bool {

src/app/mode.rs

@@ -2,7 +2,8 @@ use std::{
     cmp::{max, min},
     fmt::Display,
     fs,
-    path::PathBuf, process::Command,
+    path::PathBuf,
+    process::Command,
 };
 
 use ratatui::{
@@ -15,7 +16,7 @@ use crate::app::{
     app::App,
     error_msg::StatusMessage,
     logic::{
-        calc::{CSV_EXT, CUSTOM_EXT, Grid, LEN},
+        calc::{Grid, LEN},
         cell::CellType,
     },
 };
@@ -153,11 +154,13 @@ impl Mode {
 
             let mut save_range = |to: &str| {
                 let mut g = Grid::new();
-                for (i, x) in (low_x..=hi_x).enumerate() {
-                    for (j, y) in (low_y..=hi_y).enumerate() {
-                        g.set_cell_raw((i, j), app.grid.get_cell_raw(x, y).clone());
+                g.transact_on_grid(|grid| {
+                    for (i, x) in (low_x..=hi_x).enumerate() {
+                        for (j, y) in (low_y..=hi_y).enumerate() {
+                            grid.set_cell_raw((i, j), grid.get_cell_raw(x, y).clone());
+                        }
                     }
-                }
+                });
                 if let Err(_e) = g.save_to(to) {
                     app.msg = StatusMessage::error("Failed to save file");
                 }
@@ -171,10 +174,27 @@ impl Mode {
                         }
                     }
                 }
-                return "unknown"
+                return "unknown";
             };
 
             match args[0] {
+                "f" | "fill" => {
+                    app.grid.transact_on_grid(|grid| {
+                        for (i, x) in (low_x..=hi_x).enumerate() {
+                            for (j, y) in (low_y..=hi_y).enumerate() {
+                                let arg = args
+                                    .get(1)
+                                    .map(|s| s.replace("xi", &i.to_string()))
+                                    .map(|s| s.replace("yi", &j.to_string()))
+                                    .map(|s| s.replace("x", &x.to_string()))
+                                    .map(|s| s.replace("y", &y.to_string()));
+                                grid.set_cell_raw((x, y), arg);
+                            }
+                        }
+                    });
+
+                    app.mode = Mode::Normal
+                }
                 "export" => {
                     if let Some(arg1) = args.get(1) {
                         save_range(&arg1);
@@ -187,11 +207,7 @@ impl Mode {
                     // Use gnuplot to plot the selected data.
                     // * Temp data will be stored in /tmp/
                     // * Output will either be plot.png or a name that you pass in
-                    let output_filename = if let Some(arg1) = args.get(1) {
-                        arg1
-                    } else {
-                        "plot.png"
-                    };
+                    let output_filename = if let Some(arg1) = args.get(1) { arg1 } else { "plot.png" };
 
                     save_range("/tmp/plot.csv");
                     let plot = include_str!("../../template.gnuplot");
@@ -202,10 +218,12 @@ impl Mode {
                     let s = s.replace("$OUTPUT", "/tmp/output.png");
                     let _ = fs::write("/tmp/plot.p", s);
 
-                    let cmd_res= Command::new("gnuplot").arg("/tmp/plot.p").output();
+                    let cmd_res = Command::new("gnuplot").arg("/tmp/plot.p").output();
                     if let Err(err) = cmd_res {
                         match err.kind() {
-                            std::io::ErrorKind::NotFound => app.msg = StatusMessage::error("Error - Is gnuplot installed?"),
+                            std::io::ErrorKind::NotFound => {
+                                app.msg = StatusMessage::error("Error - Is gnuplot installed?")
+                            }
                             _ => app.msg = StatusMessage::error(format!("{err}")),
                         };
                     } else {
@@ -261,7 +279,7 @@ impl Mode {
                     // Go to bottom of column
                     'G' => {
                         let (x, _) = app.grid.cursor();
-                        app.grid.mv_cursor_to(x, super::logic::calc::LEN,);
+                        app.grid.mv_cursor_to(x, super::logic::calc::LEN);
                         return;
                     }
                     // edit cell
@@ -304,6 +322,11 @@ impl Mode {
                             app.mode = Mode::Command(Chord::new(':'))
                         }
                     }
+                    // undo
+                    'u' => {
+                        app.grid.undo();
+                    }
+                    // paste
                     'p' => {
                         app.clipboard.paste(&mut app.grid, true);
                         app.grid.apply_momentum(app.clipboard.momentum());
@@ -383,7 +406,7 @@ impl Mode {
                                 let (_, y_height) = app.screen.get_screen_size(&app.vars);
                                 let y_origin = app.screen.scroll_y();
 
-                                app.grid.mv_cursor_to(x, y_origin+y_height);
+                                app.grid.mv_cursor_to(x, y_origin + y_height);
                                 app.mode = Mode::Normal;
                                 return;
                             }
@@ -393,7 +416,7 @@ impl Mode {
                                 let (x_width, _) = app.screen.get_screen_size(&app.vars);
                                 let x_origin = app.screen.scroll_x();
 
-                                app.grid.mv_cursor_to(x_origin+x_width, y);
+                                app.grid.mv_cursor_to(x_origin + x_width, y);
                                 app.mode = Mode::Normal;
                             }
                             // Go to the left edge of the current window
@@ -493,9 +516,7 @@ pub struct Chord {
 impl From<String> for Chord {
     fn from(value: String) -> Self {
         let b = value.as_bytes().iter().map(|f| *f as char).collect();
-        Chord {
-            buf: b,
-        }
+        Chord { buf: b }
     }
 }
 
@@ -504,9 +525,7 @@ impl Chord {
         let mut buf = Vec::new();
         buf.push(inital);
 
-        Self {
-            buf,
-        }
+        Self { buf }
     }
 
     pub fn backspace(&mut self) {

src/app/screen.rs

@@ -2,7 +2,7 @@ use std::{collections::HashMap, sync::RwLock};
 
 use ratatui::prelude;
 
-use crate::app::logic::calc::{self, LEN};
+use crate::app::logic::calc::LEN;
 
 pub struct ScreenSpace {
     /// This is measured in cells.