colors: add highlight type support for matching lines

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

Closes #3024, Closes #3107

CHANGELOG.md

@@ -43,6 +43,8 @@ Feature enhancements:
   When using multithreading, schedule files to search in order given on CLI.
 * [FEATURE #2943](https://github.com/BurntSushi/ripgrep/issues/2943):
   Add `aarch64` release artifacts for Windows.
+* [FEATURE #3024](https://github.com/BurntSushi/ripgrep/issues/3024):
+  Add `highlight` color type, for styling non-matching text in a matching line.
 * [FEATURE #3048](https://github.com/BurntSushi/ripgrep/pull/3048):
   Globs in ripgrep (and the `globset` crate) now support nested alternates.
 

FAQ.md

@@ -285,8 +285,8 @@ As a special case, `--colors '{type}:none'` will clear all colors and styles
 associated with `{type}`, which lets you start with a clean slate (instead of
 building on top of ripgrep's default color settings).
 
-Here's an example that makes highlights the matches with a nice blue background
-with bolded white text:
+Here's an example that highlights the matches with a nice blue background with
+bolded white text:
 
 ```
 $ rg somepattern \

crates/core/flags/complete/rg.zsh

@@ -363,10 +363,11 @@ _rg() {
           'column:specify coloring for column numbers'
           'line:specify coloring for line numbers'
           'match:specify coloring for match text'
+          'highlight:specify coloring for matching lines'
           'path:specify coloring for file names'
         )
         descr='color/style type'
-      elif [[ ${IPREFIX#--*=}$PREFIX == (column|line|match|path):[^:]# ]]; then
+      elif [[ ${IPREFIX#--*=}$PREFIX == (column|line|match|highlight|path):[^:]# ]]; then
         suf=( -qS: )
         tmp=(
           'none:clear color/style for type'

crates/core/flags/defs.rs

@@ -751,7 +751,8 @@ the \flag{colors} flag to manually set all color styles to \fBnone\fP:
     \-\-colors 'path:none' \\
     \-\-colors 'line:none' \\
     \-\-colors 'column:none' \\
-    \-\-colors 'match:none'
+    \-\-colors 'match:none' \\
+    \-\-colors 'highlight:none'
 .EE
 .sp
 "
@@ -829,7 +830,7 @@ impl Flag for Colors {
         "Configure color settings and styles."
     }
     fn doc_long(&self) -> &'static str {
-        r"
+        r#"
 This flag specifies color settings for use in the output. This flag may be
 provided multiple times. Settings are applied iteratively. Pre-existing color
 labels are limited to one of eight choices: \fBred\fP, \fBblue\fP, \fBgreen\fP,
@@ -839,11 +840,11 @@ are limited to \fBnobold\fP, \fBbold\fP, \fBnointense\fP, \fBintense\fP,
 .sp
 The format of the flag is
 \fB{\fP\fItype\fP\fB}:{\fP\fIattribute\fP\fB}:{\fP\fIvalue\fP\fB}\fP.
-\fItype\fP should be one of \fBpath\fP, \fBline\fP, \fBcolumn\fP or
-\fBmatch\fP. \fIattribute\fP can be \fBfg\fP, \fBbg\fP or \fBstyle\fP.
-\fIvalue\fP is either a color (for \fBfg\fP and \fBbg\fP) or a text style. A
-special format, \fB{\fP\fItype\fP\fB}:none\fP, will clear all color settings
-for \fItype\fP.
+\fItype\fP should be one of \fBpath\fP, \fBline\fP, \fBcolumn\fP,
+\fBhighlight\fP or \fBmatch\fP. \fIattribute\fP can be \fBfg\fP, \fBbg\fP or
+\fBstyle\fP. \fIvalue\fP is either a color (for \fBfg\fP and \fBbg\fP) or a
+text style. A special format, \fB{\fP\fItype\fP\fB}:none\fP, will clear all
+color settings for \fItype\fP.
 .sp
 For example, the following command will change the match color to magenta and
 the background color for line numbers to yellow:
@@ -852,6 +853,17 @@ the background color for line numbers to yellow:
     rg \-\-colors 'match:fg:magenta' \-\-colors 'line:bg:yellow'
 .EE
 .sp
+Another example, the following command will "highlight" the non-matching text
+in matching lines:
+.sp
+.EX
+    rg \-\-colors 'highlight:bg:yellow' \-\-colors 'highlight:fg:black'
+.EE
+.sp
+The "highlight" color type is particularly useful for contrasting matching
+lines with surrounding context printed by the \flag{before-context},
+\flag{after-context}, \flag{context} or \flag{passthru} flags.
+.sp
 Extended colors can be used for \fIvalue\fP when the tty supports ANSI color
 sequences. These are specified as either \fIx\fP (256-color) or
 .IB x , x , x
@@ -874,7 +886,7 @@ or, equivalently,
 .sp
 Note that the \fBintense\fP and \fBnointense\fP styles will have no effect when
 used alongside these extended color codes.
-"
+"#
     }
 
     fn update(&self, v: FlagValue, args: &mut LowArgs) -> anyhow::Result<()> {
@@ -908,6 +920,24 @@ fn test_colors() {
             "line:bg:yellow".parse().unwrap()
         ]
     );
+
+    let args = parse_low_raw(["--colors", "highlight:bg:240"]).unwrap();
+    assert_eq!(args.colors, vec!["highlight:bg:240".parse().unwrap()]);
+
+    let args = parse_low_raw([
+        "--colors",
+        "match:fg:magenta",
+        "--colors",
+        "highlight:bg:blue",
+    ])
+    .unwrap();
+    assert_eq!(
+        args.colors,
+        vec![
+            "match:fg:magenta".parse().unwrap(),
+            "highlight:bg:blue".parse().unwrap()
+        ]
+    );
 }
 
 /// --column

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)
     }