feat: add highlight_columns initial basic implementation

closes #208

src/config.zig

@@ -10,6 +10,7 @@ enable_terminal_cursor: bool = true,
 enable_terminal_color_scheme: bool = builtin.os.tag != .windows,
 highlight_current_line: bool = true,
 highlight_current_line_gutter: bool = true,
+highlight_columns: []const u8 = "",
 whitespace_mode: []const u8 = "none",
 inline_diagnostics: bool = true,
 animation_min_lag: usize = 0, //milliseconds

src/tui/editor.zig

@@ -914,6 +914,7 @@ pub const Editor = struct {
             match_idx: usize = 0,
             theme: *const Widget.Theme,
             hl_row: ?usize,
+            hl_cols: []const usize,
             leading: bool = true,
             cell_map: CellMap,
 
@@ -965,6 +966,8 @@ pub const Editor = struct {
                         9 => .tab,
                         else => .character,
                     };
+                    for (ctx.hl_cols) |hl_col| if (hl_col == ctx.buf_col)
+                        self_.render_column_highlight_cell(ctx.theme, c);
                     if (ctx.hl_row) |hl_row| if (hl_row == ctx.buf_row)
                         self_.render_line_highlight_cell(ctx.theme, c);
                     self_.render_matches(&ctx.match_idx, ctx.theme, c);
@@ -989,6 +992,8 @@ pub const Editor = struct {
                         if (ctx.x >= view.cols) break;
                         var cell_ = n.cell_init();
                         const c_ = &cell_;
+                        for (ctx.hl_cols) |hl_col| if (hl_col == ctx.buf_col)
+                            self_.render_column_highlight_cell(ctx.theme, c);
                         if (ctx.hl_row) |hl_row| if (hl_row == ctx.buf_row)
                             self_.render_line_highlight_cell(ctx.theme, c_);
                         self_.render_matches(&ctx.match_idx, ctx.theme, c_);
@@ -1006,12 +1011,16 @@ pub const Editor = struct {
                 if (leaf.eol) {
                     if (ctx.buf_col >= view.col) {
                         var c = ctx.self.render_eol(n);
+                        for (ctx.hl_cols) |hl_col| if (hl_col == ctx.buf_col)
+                            self_.render_column_highlight_cell(ctx.theme, &c);
                         if (ctx.hl_row) |hl_row| if (hl_row == ctx.buf_row)
                             self_.render_line_highlight_cell(ctx.theme, &c);
                         self_.render_matches(&ctx.match_idx, ctx.theme, &c);
                         self_.render_selections(ctx.theme, &c);
                         _ = n.putc(&c) catch {};
                         var term_cell = render_terminator(n, ctx.theme);
+                        for (ctx.hl_cols) |hl_col| if (hl_col == ctx.buf_col + 1)
+                            self_.render_column_highlight_cell(ctx.theme, &term_cell);
                         if (ctx.hl_row) |hl_row| if (hl_row == ctx.buf_row)
                             self_.render_line_highlight_cell(ctx.theme, &term_cell);
                         _ = n.putc(&term_cell) catch {};
@@ -1036,11 +1045,25 @@ pub const Editor = struct {
                             break :blk null;
             break :blk self.get_primary().cursor.row;
         } else null;
+        const highlight_columns = tui.config().highlight_columns;
+        var highlight_columns_buf: [6]usize = undefined;
+        const hl_cols: []const usize = if (highlight_columns.len > 0) blk: {
+            var idx: usize = 0;
+            var it = std.mem.splitScalar(u8, highlight_columns, ' ');
+            while (it.next()) |arg| {
+                var col = std.fmt.parseInt(usize, arg, 10) catch 1;
+                if (col > 0) col -= 1;
+                highlight_columns_buf[idx] = col;
+                idx += 1;
+            }
+            break :blk highlight_columns_buf[0..idx];
+        } else &.{};
         var ctx_: ctx = .{
             .self = self,
             .buf_row = self.view.row,
             .theme = theme,
             .hl_row = hl_row,
+            .hl_cols = hl_cols,
             .cell_map = CellMap.init(self.allocator, self.view.rows, self.view.cols) catch @panic("OOM"),
         };
         defer ctx_.cell_map.deinit(self.allocator);
@@ -1052,6 +1075,8 @@ pub const Editor = struct {
 
             self.plane.set_base_style(theme.editor);
             self.plane.erase();
+            for (hl_cols) |hl_col|
+                self.render_column_highlight(hl_col, theme) catch {};
             if (hl_row) |_|
                 self.render_line_highlight(&self.get_primary().cursor, theme) catch {};
             self.plane.home();
@@ -1130,6 +1155,16 @@ pub const Editor = struct {
         cell_map.set_yx(y, x, .{ .cursor = true, .cell_type = cell_type });
     }
 
+    fn render_column_highlight(self: *Self, col: usize, theme: *const Widget.Theme) !void {
+        for (0..self.view.rows) |row| {
+            self.plane.cursor_move_yx(@intCast(row), @intCast(col)) catch return;
+            var cell = self.plane.cell_init();
+            _ = self.plane.at_cursor_cell(&cell) catch return;
+            self.render_column_highlight_cell(theme, &cell);
+            _ = self.plane.putc(&cell) catch {};
+        }
+    }
+
     fn render_line_highlight(self: *Self, cursor: *const Cursor, theme: *const Widget.Theme) !void {
         const row_min = self.view.row;
         const row_max = row_min + self.view.rows;
@@ -1235,6 +1270,10 @@ pub const Editor = struct {
         cell.set_style_bg(if (match.style) |style| style else theme.editor_match);
     }
 
+    inline fn render_column_highlight_cell(_: *const Self, theme: *const Widget.Theme, cell: *Cell) void {
+        cell.set_style_bg(theme.editor_line_highlight);
+    }
+
     inline fn render_line_highlight_cell(_: *const Self, theme: *const Widget.Theme, cell: *Cell) void {
         cell.set_style_bg(theme.editor_line_highlight);
     }

src/tui/tui.zig

@@ -109,6 +109,7 @@ fn init(allocator: Allocator) InitError!*Self {
     conf.top_bar = try allocator.dupe(u8, conf.top_bar);
     conf.bottom_bar = try allocator.dupe(u8, conf.bottom_bar);
     conf.include_files = try allocator.dupe(u8, conf.include_files);
+    conf.highlight_columns = try allocator.dupe(u8, conf.highlight_columns);
     if (build_options.gui) conf.enable_terminal_cursor = false;
 
     const frame_rate: usize = @intCast(tp.env.get().num("frame-rate"));