Command line option to apply line number style to unchanged lines

src/cli.rs

@@ -300,6 +300,11 @@ pub struct Opt {
     #[structopt(long = "number-plus-style", default_value = "auto")]
     pub number_plus_style: String,
 
+    /// Style (foreground, background, attributes) to apply on unchanged lines (if --number is set),
+    /// overriding --number-minus-style and --number-plus-style. See STYLES section.
+    #[structopt(long = "number-zero-style")]
+    pub number_zero_style: Option<String>,
+
     /// Format string for the left (minus) column of line numbers (--number), if --number is set.
     /// Should include the placeholder %ln to indicate the position of the line number.
     /// See the LINE NUMBERS section.

src/config.rs

@@ -47,6 +47,7 @@ pub struct Config<'a> {
     pub number_plus_format: String,
     pub number_plus_format_style: Style,
     pub number_plus_style: Style,
+    pub number_zero_style: Option<Style>,
     pub paging_mode: PagingMode,
     pub plus_emph_style: Style,
     pub plus_file: Option<PathBuf>,
@@ -132,6 +133,7 @@ pub fn get_config<'a>(
         number_minus_style,
         number_plus_format_style,
         number_plus_style,
+        number_zero_style,
     ) = make_line_number_styles(
         &opt,
         hunk_header_style.decoration_ansi_term_style(),
@@ -188,6 +190,7 @@ pub fn get_config<'a>(
         number_plus_format: opt.number_plus_format,
         number_plus_format_style: number_plus_format_style,
         number_plus_style: number_plus_style,
+        number_zero_style: number_zero_style,
         paging_mode,
         plus_emph_style,
         plus_file: opt.plus_file.map(|s| s.clone()),
@@ -293,7 +296,7 @@ fn make_line_number_styles<'a>(
     opt: &'a cli::Opt,
     default_style: Option<ansi_term::Style>,
     true_color: bool,
-) -> (Style, Style, Style, Style) {
+) -> (Style, Style, Style, Style, Option<Style>) {
     let (default_foreground, default_background) = match default_style {
         Some(default_style) => (default_style.foreground, default_style.background),
         None => (None, None),
@@ -335,11 +338,24 @@ fn make_line_number_styles<'a>(
         false,
     );
 
+    let number_zero_style = match &opt.number_zero_style {
+        Some(x) => Some(Style::from_str(
+            x,
+            default_foreground,
+            default_background,
+            None,
+            true_color,
+            false,
+        )),
+        None => None,
+    };
+
     (
         number_minus_format_style,
         number_minus_style,
         number_plus_format_style,
         number_plus_style,
+        number_zero_style,
     )
 }
 

src/paint.rs

@@ -159,15 +159,26 @@ impl<'a> Painter<'a> {
                     get_line_number_components(minus, &config.number_minus_format);
                 let (plus_before, plus_number, plus_after) =
                     get_line_number_components(plus, &config.number_plus_format);
+
+                let number_minus_style = get_zero_or_default_style(
+                    minus,
+                    plus,
+                    config.number_zero_style,
+                    config.number_minus_style,
+                );
+                let number_plus_style = get_zero_or_default_style(
+                    minus,
+                    plus,
+                    config.number_zero_style,
+                    config.number_plus_style,
+                );
+
                 vec![
                     config
                         .number_minus_format_style
                         .ansi_term_style
                         .paint(minus_before),
-                    config
-                        .number_minus_style
-                        .ansi_term_style
-                        .paint(minus_number),
+                    number_minus_style.ansi_term_style.paint(minus_number),
                     config
                         .number_minus_format_style
                         .ansi_term_style
@@ -176,7 +187,7 @@ impl<'a> Painter<'a> {
                         .number_plus_format_style
                         .ansi_term_style
                         .paint(plus_before),
-                    config.number_plus_style.ansi_term_style.paint(plus_number),
+                    number_plus_style.ansi_term_style.paint(plus_number),
                     config
                         .number_plus_format_style
                         .ansi_term_style
@@ -567,6 +578,18 @@ fn format_line_number(line_number: Option<usize>) -> String {
     }
 }
 
+fn get_zero_or_default_style(
+    minus: Option<usize>,
+    plus: Option<usize>,
+    zero_style: Option<Style>,
+    default_style: Style,
+) -> Style {
+    match (zero_style, minus, plus) {
+        (Some(z), Some(_), Some(_)) => z,
+        _ => default_style,
+    }
+}
+
 fn get_line_number_components(
     number: Option<usize>,
     number_format: &str,

src/rewrite.rs

@@ -100,7 +100,11 @@ fn _rewrite_options_to_honor_git_config(
         arg_matches
     );
     set_delta_options__option_string!(
-        [("syntax_theme", syntax_theme), ("width", width)],
+        [
+            ("number-zero-style", number_zero_style),
+            ("syntax_theme", syntax_theme),
+            ("width", width)
+        ],
         opt,
         git_config,
         arg_matches