Add --no-syntax option

When using plain output, calls to `highlight_regions_for_line()`
 may cause a lot of overhead for little gain.

 So add a new option `--no-syntax` that skips syntax highlighting.
 It only has effect for plain output.

 This change is made in a way that preserves backwards compatibility and
 doesn't break any tests.

 Here is a test-case.

 Without `--no-syntax`

 ```
 Benchmark 1: seq 10000000 | ./target/release/bat -pf
  Time (mean ± σ):      7.899 s ±  0.195 s    [User: 7.962 s, System: 0.076 s]
  Range (min … max):    7.587 s …  8.095 s    10 runs
 ```

 With `--no-syntax`

 ```
 Benchmark 1: seq 10000000 | ./target/release/bat -pf --no-syntax
  Time (mean ± σ):     636.7 ms ±  42.9 ms    [User: 696.8 ms, System: 41.2 ms]
  Range (min … max):   603.5 ms … 715.5 ms    10 runs
 ```

Signed-off-by: Mohammad AlSaleh <CE.Mohammad.AlSaleh@gmail.com>

CHANGELOG.md

@@ -45,6 +45,7 @@
 - Support 'statically linked binary' for aarch64 in 'Release' page, see #2992 (@tzq0301)
 - Update options in shell completions and the man page of `bat`, see #2995 (@akinomyoga)
 - Significantly improve performance by using a buffered writer, see #3101 (@MoSal)
+- Add --no-syntax option, see #3102 (@MoSal)
 
 ## Syntaxes
 

doc/long-help.txt

@@ -87,6 +87,9 @@ Options:
           Alias for '--decorations=always --color=always'. This is useful if the output of bat is
           piped to another program, but you want to keep the colorization/decorations.
 
+      --no-syntax
+          Don't pass text to the syntax highlighter in plain mode.
+
       --paging <when>
           Specify when to use the pager. To disable the pager, use --paging=never' or its
           alias,'-P'. To disable the pager permanently, set BAT_PAGING to 'never'. To control which

src/bin/bat/app.rs

@@ -417,6 +417,11 @@ impl App {
             )),
         };
 
+        // Add syntax.
+        if !self.matches.get_flag("no-syntax") {
+            styled_components.0.insert(StyleComponent::Syntax);
+        }
+
         // If `grid` is set, remove `rule` as it is a subset of `grid`, and print a warning.
         if styled_components.grid() && styled_components.0.remove(&StyleComponent::Rule) {
             bat_warning!("Style 'rule' is a subset of style 'grid', 'rule' will not be visible.");

src/bin/bat/clap_app.rs

@@ -301,6 +301,14 @@ pub fn build_app(interactive_output: bool) -> Command {
                         if the output of bat is piped to another program, but you want \
                         to keep the colorization/decorations.")
         )
+        .arg(
+            Arg::new("no-syntax")
+                .long("no-syntax")
+                .action(ArgAction::SetTrue)
+                .overrides_with("no-syntax")
+                .hide_short_help(true)
+                .long_help("Don't pass text to the syntax highlighter in plain mode.")
+        )
         .arg(
             Arg::new("paging")
                 .long("paging")

src/printer.rs

@@ -639,6 +639,10 @@ impl<'a, W: io::Write> Printer<W> for InteractivePrinter<'a> {
             line
         };
 
+        if self.config.style_components.plain() && !self.config.style_components.syntax() {
+            return write!(handle, "{line}");
+        }
+
         let regions = self.highlight_regions_for_line(&line)?;
         if out_of_range {
             return Ok(());

src/style.rs

@@ -15,6 +15,7 @@ pub enum StyleComponent {
     HeaderFilename,
     HeaderFilesize,
     LineNumbers,
+    Syntax,
     Snip,
     Full,
     Default,
@@ -39,6 +40,7 @@ impl StyleComponent {
             StyleComponent::HeaderFilename => &[StyleComponent::HeaderFilename],
             StyleComponent::HeaderFilesize => &[StyleComponent::HeaderFilesize],
             StyleComponent::LineNumbers => &[StyleComponent::LineNumbers],
+            StyleComponent::Syntax => &[StyleComponent::Syntax],
             StyleComponent::Snip => &[StyleComponent::Snip],
             StyleComponent::Full => &[
                 #[cfg(feature = "git")]
@@ -47,6 +49,7 @@ impl StyleComponent {
                 StyleComponent::HeaderFilename,
                 StyleComponent::HeaderFilesize,
                 StyleComponent::LineNumbers,
+                StyleComponent::Syntax,
                 StyleComponent::Snip,
             ],
             StyleComponent::Default => &[
@@ -55,6 +58,7 @@ impl StyleComponent {
                 StyleComponent::Grid,
                 StyleComponent::HeaderFilename,
                 StyleComponent::LineNumbers,
+                StyleComponent::Syntax,
                 StyleComponent::Snip,
             ],
             StyleComponent::Plain => &[],
@@ -76,6 +80,7 @@ impl FromStr for StyleComponent {
             "header-filename" => Ok(StyleComponent::HeaderFilename),
             "header-filesize" => Ok(StyleComponent::HeaderFilesize),
             "numbers" => Ok(StyleComponent::LineNumbers),
+            "syntax" => Ok(StyleComponent::Syntax),
             "snip" => Ok(StyleComponent::Snip),
             "full" => Ok(StyleComponent::Full),
             "default" => Ok(StyleComponent::Default),
@@ -122,12 +127,18 @@ impl StyleComponents {
         self.0.contains(&StyleComponent::LineNumbers)
     }
 
+    pub fn syntax(&self) -> bool {
+        self.0.contains(&StyleComponent::Syntax)
+    }
+
     pub fn snip(&self) -> bool {
         self.0.contains(&StyleComponent::Snip)
     }
 
     pub fn plain(&self) -> bool {
-        self.0.iter().all(|c| c == &StyleComponent::Plain)
+        self.0
+            .iter()
+            .all(|c| c == &StyleComponent::Plain || c == &StyleComponent::Syntax)
     }
 
     pub fn insert(&mut self, component: StyleComponent) {
@@ -245,7 +256,7 @@ mod test {
     #[test]
     pub fn style_component_list_parse() {
         assert_eq!(
-            StyleComponentList::from_str("grid,+numbers,snip,-snip,header")
+            StyleComponentList::from_str("grid,+numbers,snip,-snip,header,-syntax")
                 .expect("no error")
                 .0,
             vec![
@@ -254,6 +265,7 @@ mod test {
                 (Override, Snip),
                 (Remove, Snip),
                 (Override, Header),
+                (Remove, Syntax),
             ]
         );
 

tests/integration_tests.rs

@@ -2888,3 +2888,34 @@ fn style_components_will_merge_with_env_var() {
         .stdout("     STDIN\n   1 test\n")
         .stderr("");
 }
+
+#[test]
+fn skip_syntax() {
+    macro_rules! bat {
+        ([$($extra_arg:expr)*], out=$out:expr) => {
+            bat()
+                .arg("--paging=never")
+                .arg("--terminal-width=80")
+                .arg("--decorations=always")
+                .arg("--theme=ansi")
+                .arg("--style=plain")
+                .arg("--highlight-line=1")
+                $(.arg($extra_arg))*
+                .write_stdin("Ansi Underscore Test\nAnother Line")
+                .assert()
+                .success()
+                .stdout($out)
+                .stderr("");
+            };
+    }
+    // without --no-syntax
+    bat! {
+        [],
+        out = "\x1B[4mAnsi Underscore Test\n\x1B[24mAnother Line"
+    };
+    // with --no-syntax
+    bat! {
+        ["--no-syntax"],
+        out = "Ansi Underscore Test\nAnother Line"
+    };
+}