Command line option to apply line number style to unchanged lines

4 files changed, 158 insertions, 93 deletions

diff --git a/src/cli.rs b/src/cli.rs
index c05874be..e0a227c8 100644
--- a/src/cli.rs
+++ b/src/cli.rs
@@ -157,9 +157,10 @@ within a style string):
 LINE NUMBERS
 ------------
 
-Options --number-minus-format and --number-plus-format allow you to specify a custom string to
+Options --number-left-format and --number-right-format allow you to specify a custom string to
 display for the line number columns. The string should specify the location of the line number
-using the placeholder %ln.
+using the placeholder %lm for the line number associated with the original file and %lp for the
+line number associated with the updated file.
 
 For example, to display the line numbers like
 
@@ -167,8 +168,8 @@ For example, to display the line numbers like
 
 you would use
 
---number-minus-format '%ln ⋮'
---number-plus-format '%ln │'
+--number-left-format '%lm ⋮'
+--number-right-format '%lp │'
 
 If something isn't working correctly, or you have a feature request, please open an issue at
 https://github.com/dandavison/delta/issues.
@@ -298,41 +299,50 @@ pub struct Opt {
     #[structopt(short = "n", long = "number")]
     pub show_line_numbers: bool,
 
-    /// Style (foreground, background, attributes) for the left (minus) column of line numbers
+    /// Style (foreground, background, attributes) for the minus line numbers
     /// (--number), if --number is set. See STYLES section. Defaults to
     /// --hunk-header-decoration-style.
     #[structopt(long = "number-minus-style", default_value = "auto")]
     pub number_minus_style: String,
 
-    /// Style (foreground, background, attributes) for the right (plus) column of line numbers
+    /// Style (foreground, background, attributes) for the plus line numbers
     /// (--number), if --number is set. See STYLES section. Defaults to
     /// --hunk-header-decoration-style.
     #[structopt(long = "number-plus-style", default_value = "auto")]
     pub number_plus_style: 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.
+    /// 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 column of line numbers (--number), if --number is set. Displays
+    /// the minus column by default.
+    /// Should include the placeholder %lm or %lp to indicate the position of the minus or plus
+    /// line number, respectively.
     /// See the LINE NUMBERS section.
-    #[structopt(long = "number-minus-format", default_value = "%ln⋮")]
-    pub number_minus_format: String,
+    #[structopt(long = "number-left-format", default_value = "%lm⋮")]
+    pub number_left_format: String,
 
-    /// Format string for the right (plus) column of line numbers (--number), if --number is set.
-    /// Should include the placeholder %ln to indicate the position of the line number.
+    /// Format string for the right column of line numbers (--number), if --number is set. Displays
+    /// the plus column by default.
+    /// Should include the placeholder %lm or %lp to indicate the position of the minus or plus
+    /// line number, respectively.
     /// See the LINE NUMBERS section.
-    #[structopt(long = "number-plus-format", default_value = "%ln│ ")]
-    pub number_plus_format: String,
+    #[structopt(long = "number-right-format", default_value = "%lp│ ")]
+    pub number_right_format: String,
 
-    /// Style (foreground, background, attributes) for the left (minus) line number format string
+    /// Style (foreground, background, attributes) for the left line number format string
     /// (--number), if --number is set. See STYLES section. Defaults to
     /// --hunk-header-decoration-style.
-    #[structopt(long = "number-minus-format-style", default_value = "auto")]
-    pub number_minus_format_style: String,
+    #[structopt(long = "number-left-format-style", default_value = "auto")]
+    pub number_left_format_style: String,
 
-    /// Style (foreground, background, attributes) for the right (plus) line number format string
+    /// Style (foreground, background, attributes) for the right line number format string
     /// (--number), if --number is set. See STYLES section. Defaults to
     /// --hunk-header-decoration-style.
-    #[structopt(long = "number-plus-format-style", default_value = "auto")]
-    pub number_plus_format_style: String,
+    #[structopt(long = "number-right-format-style", default_value = "auto")]
+    pub number_right_format_style: String,
 
     #[structopt(long = "color-only")]
     /// Do not alter the input in any way other than applying colors. Equivalent to
diff --git a/src/config.rs b/src/config.rs
index 3ee7c85a..28020202 100644
--- a/src/config.rs
+++ b/src/config.rs
@@ -48,12 +48,13 @@ pub struct Config {
     pub navigate: bool,
     pub null_style: Style,
     pub null_syntect_style: SyntectStyle,
-    pub number_minus_format: String,
-    pub number_minus_format_style: Style,
+    pub number_left_format: String,
+    pub number_left_format_style: Style,
     pub number_minus_style: Style,
-    pub number_plus_format: String,
-    pub number_plus_format_style: Style,
     pub number_plus_style: Style,
+    pub number_right_format: String,
+    pub number_right_format_style: Style,
+    pub number_zero_style: Option<Style>,
     pub paging_mode: PagingMode,
     pub plus_emph_style: Style,
     pub plus_empty_line_marker_style: Style,
@@ -156,10 +157,11 @@ impl From<cli::Opt> for Config {
             make_commit_file_hunk_header_styles(&opt, true_color);
 
         let (
-            number_minus_format_style,
+            number_left_format_style,
             number_minus_style,
-            number_plus_format_style,
+            number_right_format_style,
             number_plus_style,
+            number_zero_style,
         ) = make_line_number_styles(
             &opt,
             hunk_header_style.decoration_ansi_term_style(),
@@ -214,12 +216,13 @@ impl From<cli::Opt> for Config {
             navigate: opt.navigate,
             null_style: Style::new(),
             null_syntect_style: SyntectStyle::default(),
-            number_minus_format: opt.number_minus_format,
-            number_minus_format_style,
+            number_left_format: opt.number_left_format,
+            number_left_format_style,
             number_minus_style,
-            number_plus_format: opt.number_plus_format,
-            number_plus_format_style,
             number_plus_style,
+            number_right_format: opt.number_right_format,
+            number_right_format_style,
+            number_zero_style,
             paging_mode,
             plus_emph_style,
             plus_empty_line_marker_style,
@@ -380,14 +383,14 @@ 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),
     };
 
-    let number_minus_format_style = Style::from_str(
-        &opt.number_minus_format_style,
+    let number_left_format_style = Style::from_str(
+        &opt.number_left_format_style,
         default_foreground,
         default_background,
         None,
@@ -404,8 +407,8 @@ fn make_line_number_styles<'a>(
         false,
     );
 
-    let number_plus_format_style = Style::from_str(
-        &opt.number_plus_format_style,
+    let number_plus_style = Style::from_str(
+        &opt.number_plus_style,
         default_foreground,
         default_background,
         None,
@@ -413,8 +416,8 @@ fn make_line_number_styles<'a>(
         false,
     );
 
-    let number_plus_style = Style::from_str(
-        &opt.number_plus_style,
+    let number_right_format_style = Style::from_str(
+        &opt.number_right_format_style,
         default_foreground,
         default_background,
         None,
@@ -422,11 +425,24 @@ 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_left_format_style,
         number_minus_style,
-        number_plus_format_style,
+        number_right_format_style,
         number_plus_style,
+        number_zero_style,
     )
 }
 
diff --git a/src/paint.rs b/src/paint.rs
index 97ed4834..328f35d2 100644
--- a/src/paint.rs
+++ b/src/paint.rs
@@ -166,34 +166,7 @@ impl<'a> Painter<'a> {
 
             let mut handled_prefix = false;
             let mut ansi_strings = if config.show_line_numbers && line_numbers.is_some() {
-                let (minus, plus) = line_numbers.unwrap();
-                let (minus_before, minus_number, minus_after) =
-                    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);
-                vec![
-                    config
-                        .number_minus_format_style
-                        .ansi_term_style
-                        .paint(minus_before),
-                    config
-                        .number_minus_style
-                        .ansi_term_style
-                        .paint(minus_number),
-                    config
-                        .number_minus_format_style
-                        .ansi_term_style
-                        .paint(minus_after),
-                    config
-                        .number_plus_format_style
-                        .ansi_term_style
-                        .paint(plus_before),
-                    config.number_plus_style.paint(plus_number),
-                    config
-                        .number_plus_format_style
-                        .ansi_term_style
-                        .paint(plus_after),
-                ]
+                get_formatted_line_number_components(line_numbers, config)
             } else {
                 Vec::new()
             };
@@ -623,7 +596,7 @@ mod superimpose_style_sections {
 
 lazy_static! {
     static ref LINE_NUMBER_REGEXP: Regex =
-        Regex::new(r"(?P<before>.*)(?P<ln>%ln)(?P<after>.*)").unwrap();
+        Regex::new(r"(?P<before>.*?)(?P<ln>(%(lm|lp)))(?P<after>.*)").unwrap();
 }
 
 fn format_line_number(line_number: Option<usize>) -> String {
@@ -633,25 +606,89 @@ fn format_line_number(line_number: Option<usize>) -> String {
     }
 }
 
-fn get_line_number_components(
-    number: Option<usize>,
-    number_format: &str,
-) -> (String, String, String) {
-    let captures = match LINE_NUMBER_REGEXP.captures(number_format) {
-        Some(captures) => captures,
-        None => return (number_format.to_string(), "".to_string(), "".to_string()),
-    };
-
-    let before = captures.name("before").unwrap().as_str();
-    let placeholder = captures.name("ln");
-    let after = captures.name("after").unwrap().as_str();
-    let number = match placeholder {
-        Some(_) => number,
-        None => None,
-    };
-    (
-        before.to_string(),
-        format_line_number(number),
-        after.to_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 format_number_components <'a>(
+    minus: Option<usize>,
+    plus: Option<usize>,
+    format_string: &'a str,
+    number_format_style: &Style,
+    number_minus_style: &Style,
+    number_plus_style: &Style,
+) -> Vec<ansi_term::ANSIGenericString<'a, str>> {
+    let mut formatted_number_strings = Vec::new();
+
+    for cap in LINE_NUMBER_REGEXP.captures_iter(&format_string) {
+        let number_placeholder = cap.name("ln");
+        let before = cap.name("before");
+        let after = cap.name("after");
+
+        match before {
+            Some(s) => formatted_number_strings.push(
+                number_format_style.paint(s.as_str())
+            ),
+            _ => (),
+        }
+
+        match number_placeholder {
+            Some(s) if Some(s.as_str()) == Some("%lm") => formatted_number_strings.push(
+                number_minus_style.paint(format_line_number(minus))
+            ),
+            Some(s) if Some(s.as_str()) == Some("%lp") => formatted_number_strings.push(
+                number_plus_style.paint(format_line_number(plus))
+            ),
+            Some(s) => formatted_number_strings.push(
+                number_format_style.paint(s.as_str())
+            ),
+            _ => (),
+        }
+
+        match after {
+            Some(s) => formatted_number_strings.push(
+                number_format_style.paint(s.as_str())
+            ),
+            _ => (),
+        }
+
+    }
+    formatted_number_strings
+}
+
+fn get_formatted_line_number_components <'a>(
+    line_numbers: &'a Option<(Option<usize>, Option<usize>)>,
+    config: &'a config::Config,
+) -> Vec<ansi_term::ANSIGenericString<'a, str>> {
+
+    let (minus, plus) = line_numbers.unwrap();
+
+    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,
+    );
+
+    let mut formatted_numbers = Vec::new();
+
+    formatted_numbers.extend(format_number_components(minus, plus, &config.number_left_format, &config.number_left_format_style, &number_minus_style, &number_plus_style));
+    formatted_numbers.extend(format_number_components(minus, plus,&config.number_right_format, &config.number_right_format_style, &number_minus_style, &number_plus_style));
+
+    formatted_numbers
 }
diff --git a/src/set_options.rs b/src/set_options.rs
index 73bfadaa..a1cadc6b 100644
--- a/src/set_options.rs
+++ b/src/set_options.rs
@@ -74,14 +74,16 @@ pub fn set_options(
                 minus_empty_line_marker_style
             ),
             ("minus-non-emph-style", minus_non_emph_style),
+            ("minus-non-emph-style", minus_non_emph_style),
             ("navigate", navigate),
             ("number", show_line_numbers),
-            ("number-minus-format", number_minus_format),
-            ("number-minus-format-style", number_minus_format_style),
+            ("number-left-format", number_left_format),
+            ("number-left-format-style", number_left_format_style),
             ("number-minus-style", number_minus_style),
-            ("number-plus-format", number_plus_format),
-            ("number-plus-format-style", number_plus_format_style),
             ("number-plus-style", number_plus_style),
+            ("number-right-format", number_right_format),
+            ("number-right-format-style", number_right_format_style),
+            ("number-zero-style", number_zero_style),
             ("paging-mode", paging_mode),
             // Hack: plus-style must come before plus-*emph-style because the latter default
             // dynamically to the value of the former.