Do not fill entirely new/removed lines with non-emph style

3 files changed, 44 insertions, 5 deletions

diff --git a/src/features/side_by_side.rs b/src/features/side_by_side.rs
index 2a49728b..4f02c47c 100644
--- a/src/features/side_by_side.rs
+++ b/src/features/side_by_side.rs
@@ -6,6 +6,7 @@ use crate::ansi;
 use crate::cli;
 use crate::config::{self, delta_unreachable, Config};
 use crate::delta::State;
+use crate::edits;
 use crate::features::{line_numbers, OptionValueFunction};
 use crate::minusplus::*;
 use crate::paint::{BgFillMethod, BgShouldFill, LineSections, Painter};
@@ -111,6 +112,7 @@ pub fn paint_minus_and_plus_lines_side_by_side(
     lines: LeftRight<&Vec<(String, State)>>,
     syntax_sections: LeftRight<Vec<LineSections<SyntectStyle>>>,
     diff_sections: LeftRight<Vec<LineSections<Style>>>,
+    lines_have_homolog: LeftRight<Vec<bool>>,
     line_alignment: Vec<(Option<usize>, Option<usize>)>,
     line_numbers_data: &mut Option<LineNumbersData>,
     output_buffer: &mut String,
@@ -164,12 +166,18 @@ pub fn paint_minus_and_plus_lines_side_by_side(
     } else {
         (line_alignment, line_states, syntax_sections, diff_sections)
     };
+    let lines_have_homolog = if should_wrap {
+        edits::make_lines_have_homolog(&line_alignment)
+    } else {
+        lines_have_homolog
+    };
 
     for (minus_line_index, plus_line_index) in line_alignment {
         output_buffer.push_str(&paint_left_panel_minus_line(
             minus_line_index,
             &syntax_sections[Left],
             &diff_sections[Left],
+            &lines_have_homolog[Left],
             match minus_line_index {
                 Some(i) => &line_states[Left][i],
                 None => &State::HunkMinus(None),
@@ -182,6 +190,7 @@ pub fn paint_minus_and_plus_lines_side_by_side(
             plus_line_index,
             &syntax_sections[Right],
             &diff_sections[Right],
+            &lines_have_homolog[Right],
             match plus_line_index {
                 Some(i) => &line_states[Right][i],
                 None => &State::HunkPlus(None),
@@ -237,6 +246,7 @@ pub fn paint_zero_lines_side_by_side<'a>(
                 panel_line_is_empty,
                 Some(line_index),
                 &diff_style_sections,
+                None,
                 &state,
                 *panel_side,
                 background_color_extends_to_terminal_width,
@@ -253,6 +263,7 @@ fn paint_left_panel_minus_line<'a>(
     line_index: Option<usize>,
     syntax_style_sections: &[LineSections<'a, SyntectStyle>],
     diff_style_sections: &[LineSections<'a, Style>],
+    lines_have_homolog: &[bool],
     state: &'a State,
     line_numbers_data: &mut Option<&mut line_numbers::LineNumbersData>,
     background_color_extends_to_terminal_width: BgShouldFill,
@@ -272,6 +283,7 @@ fn paint_left_panel_minus_line<'a>(
         panel_line_is_empty,
         line_index,
         diff_style_sections,
+        Some(lines_have_homolog),
         state,
         Left,
         background_color_extends_to_terminal_width,
@@ -286,6 +298,7 @@ fn paint_right_panel_plus_line<'a>(
     line_index: Option<usize>,
     syntax_style_sections: &[LineSections<'a, SyntectStyle>],
     diff_style_sections: &[LineSections<'a, Style>],
+    lines_have_homolog: &[bool],
     state: &'a State,
     line_numbers_data: &mut Option<&mut line_numbers::LineNumbersData>,
     background_color_extends_to_terminal_width: BgShouldFill,
@@ -306,6 +319,7 @@ fn paint_right_panel_plus_line<'a>(
         panel_line_is_empty,
         line_index,
         diff_style_sections,
+        Some(lines_have_homolog),
         state,
         Right,
         background_color_extends_to_terminal_width,
@@ -320,6 +334,7 @@ fn get_right_fill_style_for_panel<'a>(
     line_is_empty: bool,
     line_index: Option<usize>,
     diff_style_sections: &[LineSections<'a, Style>],
+    lines_have_homolog: Option<&[bool]>,
     state: &State,
     panel_side: PanelSide,
     background_color_extends_to_terminal_width: BgShouldFill,
@@ -339,6 +354,7 @@ fn get_right_fill_style_for_panel<'a>(
             let (bg_fill_mode, fill_style) =
                 Painter::get_should_right_fill_background_color_and_fill_style(
                     &diff_style_sections[index],
+                    lines_have_homolog.map(|h| h[index]),
                     state,
                     background_color_extends_to_terminal_width,
                     config,
@@ -435,6 +451,7 @@ fn pad_panel_line_to_width<'a>(
     panel_line_is_empty: bool,
     line_index: Option<usize>,
     diff_style_sections: &[LineSections<'a, Style>],
+    lines_have_homolog: Option<&[bool]>,
     state: &State,
     panel_side: PanelSide,
     background_color_extends_to_terminal_width: BgShouldFill,
@@ -472,6 +489,7 @@ fn pad_panel_line_to_width<'a>(
         panel_line_is_empty,
         line_index,
         diff_style_sections,
+        lines_have_homolog,
         state,
         panel_side,
         background_color_extends_to_terminal_width,
diff --git a/src/paint.rs b/src/paint.rs
index ef1bb005..a4253133 100644
--- a/src/paint.rs
+++ b/src/paint.rs
@@ -190,6 +190,7 @@ impl<'p> Painter<'p> {
                 lines,
                 syntax_style_sections,
                 diff_style_sections,
+                lines_have_homolog,
                 line_alignment,
                 &mut self.line_numbers_data,
                 &mut self.output_buffer,
@@ -202,6 +203,7 @@ impl<'p> Painter<'p> {
                     lines[Minus],
                     &syntax_style_sections[Minus],
                     &diff_style_sections[Minus],
+                    &lines_have_homolog[Minus],
                     &mut self.output_buffer,
                     self.config,
                     &mut self.line_numbers_data.as_mut(),
@@ -219,6 +221,7 @@ impl<'p> Painter<'p> {
                     lines[Plus],
                     &syntax_style_sections[Plus],
                     &diff_style_sections[Plus],
+                    &lines_have_homolog[Plus],
                     &mut self.output_buffer,
                     self.config,
                     &mut self.line_numbers_data.as_mut(),
@@ -270,6 +273,7 @@ impl<'p> Painter<'p> {
                 &lines,
                 &syntax_style_sections,
                 &[diff_style_sections],
+                &[false],
                 &mut self.output_buffer,
                 self.config,
                 &mut self.line_numbers_data.as_mut(),
@@ -287,6 +291,7 @@ impl<'p> Painter<'p> {
         lines: &'a [(String, State)],
         syntax_style_sections: &[LineSections<'a, SyntectStyle>],
         diff_style_sections: &[LineSections<'a, Style>],
+        lines_have_homolog: &[bool],
         output_buffer: &mut String,
         config: &config::Config,
         line_numbers_data: &mut Option<&mut line_numbers::LineNumbersData>,
@@ -301,10 +306,11 @@ impl<'p> Painter<'p> {
         // 2. We must ensure that we fill rightwards with the appropriate
         //    non-emph background color. In that case we don't use the last
         //    style of the line, because this might be emph.
-        for (((_, state), syntax_sections), diff_sections) in lines
+        for ((((_, state), syntax_sections), diff_sections), &line_has_homolog) in lines
             .iter()
             .zip_eq(syntax_style_sections)
             .zip_eq(diff_style_sections)
+            .zip_eq(lines_have_homolog)
         {
             let (mut line, line_is_empty) = Painter::paint_line(
                 syntax_sections,
@@ -318,6 +324,7 @@ impl<'p> Painter<'p> {
             let (bg_fill_mode, fill_style) =
                 Painter::get_should_right_fill_background_color_and_fill_style(
                     diff_sections,
+                    Some(line_has_homolog),
                     state,
                     background_color_extends_to_terminal_width,
                     config,
@@ -372,6 +379,7 @@ impl<'p> Painter<'p> {
             &lines,
             &syntax_style_sections,
             &diff_style_sections,
+            &[false],
             &mut self.output_buffer,
             self.config,
             &mut None,
@@ -385,14 +393,27 @@ impl<'p> Painter<'p> {
     /// the style for doing so.
     pub fn get_should_right_fill_background_color_and_fill_style(
         diff_sections: &[(Style, &str)],
+        line_has_homolog: Option<bool>,
         state: &State,
         background_color_extends_to_terminal_width: BgShouldFill,
         config: &config::Config,
     ) -> (Option<BgFillMethod>, Style) {
-        let non_emph_style = match state {
-            State::HunkMinus(None) | State::HunkMinusWrapped => config.minus_non_emph_style,
+        let fill_style = match state {
+            State::HunkMinus(None) | State::HunkMinusWrapped => {
+                if let Some(true) = line_has_homolog {
+                    config.minus_non_emph_style
+                } else {
+                    config.minus_style
+                }
+            }
             State::HunkZero | State::HunkZeroWrapped => config.zero_style,
-            State::HunkPlus(None) | State::HunkPlusWrapped => config.plus_non_emph_style,
+            State::HunkPlus(None) | State::HunkPlusWrapped => {
+                if let Some(true) = line_has_homolog {
+                    config.plus_non_emph_style
+                } else {
+                    config.plus_style
+                }
+            }
             State::HunkMinus(Some(_)) | State::HunkPlus(Some(_)) => {
                 if !diff_sections.is_empty() {
                     diff_sections[diff_sections.len() - 1].0
@@ -403,7 +424,6 @@ impl<'p> Painter<'p> {
             State::Blame(_, _) => diff_sections[0].0,
             _ => config.null_style,
         };
-        let fill_style = non_emph_style;
 
         match (
             fill_style.get_background_color().is_some(),
diff --git a/src/tests/ansi_test_utils.rs b/src/tests/ansi_test_utils.rs
index e2b637f5..04555b51 100644
--- a/src/tests/ansi_test_utils.rs
+++ b/src/tests/ansi_test_utils.rs
@@ -146,6 +146,7 @@ pub mod ansi_test_utils {
             &lines,
             &syntax_style_sections,
             &diff_style_sections,
+            &[false],
             &mut output_buffer,
             config,
             &mut None,