colors: add highlight type support for matching lines

This lets users highlight non-matching text in matching lines.

Closes #3024, Closes #3107

crates/printer/src/color.rs

@@ -51,13 +51,13 @@ impl std::fmt::Display for ColorError {
             ColorError::UnrecognizedOutType(ref name) => write!(
                 f,
                 "unrecognized output type '{}'. Choose from: \
-                 path, line, column, match.",
+                 path, line, column, match, highlight.",
                 name,
             ),
             ColorError::UnrecognizedSpecType(ref name) => write!(
                 f,
                 "unrecognized spec type '{}'. Choose from: \
-                fg, bg, style, none.",
+                 fg, bg, style, none.",
                 name,
             ),
             ColorError::UnrecognizedColor(_, ref msg) => write!(f, "{}", msg),
@@ -70,8 +70,8 @@ impl std::fmt::Display for ColorError {
             ),
             ColorError::InvalidFormat(ref original) => write!(
                 f,
-                "invalid color spec format: '{}'. Valid format \
-                 is '(path|line|column|match):(fg|bg|style):(value)'.",
+                "invalid color spec format: '{}'. Valid format is \
+                 '(path|line|column|match|highlight):(fg|bg|style):(value)'.",
                 original,
             ),
         }
@@ -90,6 +90,7 @@ pub struct ColorSpecs {
     line: ColorSpec,
     column: ColorSpec,
     matched: ColorSpec,
+    highlight: ColorSpec,
 }
 
 /// A single color specification provided by the user.
@@ -99,7 +100,7 @@ pub struct ColorSpecs {
 /// The format of a `Spec` is a triple: `{type}:{attribute}:{value}`. Each
 /// component is defined as follows:
 ///
-/// * `{type}` can be one of `path`, `line`, `column` or `match`.
+/// * `{type}` can be one of `path`, `line`, `column`, `match` or `highlight`.
 /// * `{attribute}` can be one of `fg`, `bg` or `style`. `{attribute}` may also
 ///   be the special value `none`, in which case, `{value}` can be omitted.
 /// * `{value}` is either a color name (for `fg`/`bg`) or a style instruction.
@@ -181,6 +182,7 @@ enum OutType {
     Line,
     Column,
     Match,
+    Highlight,
 }
 
 /// The specification type.
@@ -216,6 +218,7 @@ impl ColorSpecs {
                 OutType::Line => spec.merge_into(&mut merged.line),
                 OutType::Column => spec.merge_into(&mut merged.column),
                 OutType::Match => spec.merge_into(&mut merged.matched),
+                OutType::Highlight => spec.merge_into(&mut merged.highlight),
             }
         }
         merged
@@ -249,6 +252,12 @@ impl ColorSpecs {
     pub fn matched(&self) -> &ColorSpec {
         &self.matched
     }
+
+    /// Return the color specification for coloring entire line if there is a
+    /// matched text.
+    pub fn highlight(&self) -> &ColorSpec {
+        &self.highlight
+    }
 }
 
 impl UserColorSpec {
@@ -348,6 +357,7 @@ impl std::str::FromStr for OutType {
             "line" => Ok(OutType::Line),
             "column" => Ok(OutType::Column),
             "match" => Ok(OutType::Match),
+            "highlight" => Ok(OutType::Highlight),
             _ => Err(ColorError::UnrecognizedOutType(s.to_string())),
         }
     }

crates/printer/src/standard.rs

@@ -1320,6 +1320,7 @@ impl<'a, M: Matcher, W: WriteColor> StandardImpl<'a, M, W> {
             self.write(&bytes[line])?;
             return Ok(());
         }
+        self.start_line_highlight()?;
         while !line.is_empty() {
             if matches[*match_index].end() <= line.start() {
                 if *match_index + 1 < matches.len() {
@@ -1346,6 +1347,7 @@ impl<'a, M: Matcher, W: WriteColor> StandardImpl<'a, M, W> {
             }
         }
         self.end_color_match()?;
+        self.end_line_highlight()?;
         Ok(())
     }
 
@@ -1547,11 +1549,37 @@ impl<'a, M: Matcher, W: WriteColor> StandardImpl<'a, M, W> {
         if !self.in_color_match.get() {
             return Ok(());
         }
-        self.wtr().borrow_mut().reset()?;
+        if self.highlight_on() {
+            self.wtr()
+                .borrow_mut()
+                .set_color(self.config().colors.highlight())?;
+        } else {
+            self.wtr().borrow_mut().reset()?;
+        }
         self.in_color_match.set(false);
         Ok(())
     }
 
+    fn highlight_on(&self) -> bool {
+        !self.config().colors.highlight().is_none() && !self.is_context()
+    }
+
+    fn start_line_highlight(&self) -> io::Result<()> {
+        if self.highlight_on() {
+            self.wtr()
+                .borrow_mut()
+                .set_color(self.config().colors.highlight())?;
+        }
+        Ok(())
+    }
+
+    fn end_line_highlight(&self) -> io::Result<()> {
+        if self.highlight_on() {
+            self.wtr().borrow_mut().reset()?;
+        }
+        Ok(())
+    }
+
     fn write(&self, buf: &[u8]) -> io::Result<()> {
         self.wtr().borrow_mut().write_all(buf)
     }