Add a "builtin" pager using the Minus crate

Cargo.lock

@@ -135,6 +135,7 @@ dependencies = [
  "indexmap",
  "itertools 0.13.0",
  "itertools 0.14.0",
+ "minus",
  "nix",
  "nu-ansi-term",
  "once_cell",
@@ -339,6 +340,15 @@ dependencies = [
  "cfg-if",
 ]
 
+[[package]]
+name = "crossbeam-channel"
+version = "0.5.15"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "82b8f8f868b36967f9606790d1903570de9ceaf870a7bf9fbbd3016d636a2cb2"
+dependencies = [
+ "crossbeam-utils",
+]
+
 [[package]]
 name = "crossbeam-deque"
 version = "0.8.6"
@@ -364,6 +374,31 @@ version = "0.8.21"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "d0a5c400df2834b80a4c3327b3aad3a4c4cd4de0629063962b03235697506a28"
 
+[[package]]
+name = "crossterm"
+version = "0.27.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f476fe445d41c9e991fd07515a6f463074b782242ccf4a5b7b1d1012e70824df"
+dependencies = [
+ "bitflags 2.6.0",
+ "crossterm_winapi",
+ "libc",
+ "mio 0.8.11",
+ "parking_lot",
+ "signal-hook",
+ "signal-hook-mio",
+ "winapi",
+]
+
+[[package]]
+name = "crossterm_winapi"
+version = "0.9.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "acdd7c62a3665c7f6830a51635d9ac9b23ed385797f70a83bb8bafe9c572ab2b"
+dependencies = [
+ "winapi",
+]
+
 [[package]]
 name = "darling"
 version = "0.20.10"
@@ -983,6 +1018,33 @@ dependencies = [
  "adler2",
 ]
 
+[[package]]
+name = "minus"
+version = "5.6.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "093bd0520d2a37943566a73750e6d44094dac75d66a978d1f0d97ffc78686832"
+dependencies = [
+ "crossbeam-channel",
+ "crossterm",
+ "once_cell",
+ "parking_lot",
+ "regex",
+ "textwrap",
+ "thiserror 1.0.69",
+]
+
+[[package]]
+name = "mio"
+version = "0.8.11"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a4a650543ca06a924e8b371db273b2756685faae30f8487da1b56505a8f78b0c"
+dependencies = [
+ "libc",
+ "log",
+ "wasi 0.11.0+wasi-snapshot-preview1",
+ "windows-sys 0.48.0",
+]
+
 [[package]]
 name = "mio"
 version = "1.0.3"
@@ -1050,6 +1112,9 @@ name = "once_cell"
 version = "1.20.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "1261fe7e33c73b354eab43b1273a57c8f967d0391e80353e51f764ac02cf6775"
+dependencies = [
+ "parking_lot_core",
+]
 
 [[package]]
 name = "onig"
@@ -1428,6 +1493,36 @@ version = "1.3.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "0fda2ff0d084019ba4d7c6f371c95d8fd75ce3524c3cb8fb653a3023f6323e64"
 
+[[package]]
+name = "signal-hook"
+version = "0.3.18"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d881a16cf4426aa584979d30bd82cb33429027e42122b169753d6ef1085ed6e2"
+dependencies = [
+ "libc",
+ "signal-hook-registry",
+]
+
+[[package]]
+name = "signal-hook-mio"
+version = "0.2.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "34db1a06d485c9142248b7a054f034b349b212551f3dfd19c94d45a754a217cd"
+dependencies = [
+ "libc",
+ "mio 0.8.11",
+ "signal-hook",
+]
+
+[[package]]
+name = "signal-hook-registry"
+version = "1.4.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b2a4719bff48cee6b39d12c020eeb490953ad2443b7055bd0b21fca26bd8c28b"
+dependencies = [
+ "libc",
+]
+
 [[package]]
 name = "smallvec"
 version = "1.13.2"
@@ -1543,7 +1638,7 @@ dependencies = [
  "cfg-if",
  "libc",
  "memchr",
- "mio",
+ "mio 1.0.3",
  "terminal-trx",
  "windows-sys 0.59.0",
  "xterm-color",
@@ -1576,6 +1671,15 @@ version = "0.5.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "8f50febec83f5ee1df3015341d8bd429f2d1cc62bcba7ea2076759d315084683"
 
+[[package]]
+name = "textwrap"
+version = "0.16.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "c13547615a44dc9c452a8a534638acdf07120d4b6847c8178705da06306a3057"
+dependencies = [
+ "unicode-width",
+]
+
 [[package]]
 name = "thiserror"
 version = "1.0.69"
@@ -1932,6 +2036,15 @@ dependencies = [
  "windows-targets 0.52.6",
 ]
 
+[[package]]
+name = "windows-sys"
+version = "0.48.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "677d2418bec65e3338edb076e806bc1ec15693c5d0104683f2efe857f61056a9"
+dependencies = [
+ "windows-targets 0.48.5",
+]
+
 [[package]]
 name = "windows-sys"
 version = "0.52.0"
@@ -1959,6 +2072,21 @@ dependencies = [
  "windows-targets 0.53.2",
 ]
 
+[[package]]
+name = "windows-targets"
+version = "0.48.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9a2fa6e2155d7247be68c096456083145c183cbbbc2764150dda45a87197940c"
+dependencies = [
+ "windows_aarch64_gnullvm 0.48.5",
+ "windows_aarch64_msvc 0.48.5",
+ "windows_i686_gnu 0.48.5",
+ "windows_i686_msvc 0.48.5",
+ "windows_x86_64_gnu 0.48.5",
+ "windows_x86_64_gnullvm 0.48.5",
+ "windows_x86_64_msvc 0.48.5",
+]
+
 [[package]]
 name = "windows-targets"
 version = "0.52.6"
@@ -1991,6 +2119,12 @@ dependencies = [
  "windows_x86_64_msvc 0.53.0",
 ]
 
+[[package]]
+name = "windows_aarch64_gnullvm"
+version = "0.48.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "2b38e32f0abccf9987a4e3079dfb67dcd799fb61361e53e2882c3cbaf0d905d8"
+
 [[package]]
 name = "windows_aarch64_gnullvm"
 version = "0.52.6"
@@ -2003,6 +2137,12 @@ version = "0.53.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "86b8d5f90ddd19cb4a147a5fa63ca848db3df085e25fee3cc10b39b6eebae764"
 
+[[package]]
+name = "windows_aarch64_msvc"
+version = "0.48.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "dc35310971f3b2dbbf3f0690a219f40e2d9afcf64f9ab7cc1be722937c26b4bc"
+
 [[package]]
 name = "windows_aarch64_msvc"
 version = "0.52.6"
@@ -2015,6 +2155,12 @@ version = "0.53.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "c7651a1f62a11b8cbd5e0d42526e55f2c99886c77e007179efff86c2b137e66c"
 
+[[package]]
+name = "windows_i686_gnu"
+version = "0.48.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a75915e7def60c94dcef72200b9a8e58e5091744960da64ec734a6c6e9b3743e"
+
 [[package]]
 name = "windows_i686_gnu"
 version = "0.52.6"
@@ -2039,6 +2185,12 @@ version = "0.53.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "9ce6ccbdedbf6d6354471319e781c0dfef054c81fbc7cf83f338a4296c0cae11"
 
+[[package]]
+name = "windows_i686_msvc"
+version = "0.48.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "8f55c233f70c4b27f66c523580f78f1004e8b5a8b659e05a4eb49d4166cca406"
+
 [[package]]
 name = "windows_i686_msvc"
 version = "0.52.6"
@@ -2051,6 +2203,12 @@ version = "0.53.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "581fee95406bb13382d2f65cd4a908ca7b1e4c2f1917f143ba16efe98a589b5d"
 
+[[package]]
+name = "windows_x86_64_gnu"
+version = "0.48.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "53d40abd2583d23e4718fddf1ebec84dbff8381c07cae67ff7768bbf19c6718e"
+
 [[package]]
 name = "windows_x86_64_gnu"
 version = "0.52.6"
@@ -2063,6 +2221,12 @@ version = "0.53.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "2e55b5ac9ea33f2fc1716d1742db15574fd6fc8dadc51caab1c16a3d3b4190ba"
 
+[[package]]
+name = "windows_x86_64_gnullvm"
+version = "0.48.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "0b7b52767868a23d5bab768e390dc5f5c55825b6d30b86c844ff2dc7414044cc"
+
 [[package]]
 name = "windows_x86_64_gnullvm"
 version = "0.52.6"
@@ -2075,6 +2239,12 @@ version = "0.53.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "0a6e035dd0599267ce1ee132e51c27dd29437f63325753051e71dd9e42406c57"
 
+[[package]]
+name = "windows_x86_64_msvc"
+version = "0.48.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ed94fce61571a4006852b7389a063ab983c02eb1bb37b47f8272ce92d06d9538"
+
 [[package]]
 name = "windows_x86_64_msvc"
 version = "0.52.6"

Cargo.toml

@@ -33,7 +33,7 @@ minimal-application = [
     "wild",
 ]
 git = ["git2"] # Support indicating git modifications
-paging = ["shell-words", "grep-cli"] # Support applying a pager on the output
+paging = [ "shell-words", "grep-cli", "minus"] # Support applying a pager on the output
 lessopen = ["execute"] # Support $LESSOPEN preprocessor
 build-assets = ["syntect/yaml-load", "syntect/plist-load", "regex", "walkdir"]
 
@@ -52,6 +52,10 @@ thiserror = "2.0"
 wild = { version = "2.2", optional = true }
 content_inspector = "0.2.4"
 shell-words = { version = "1.1.0", optional = true }
+minus = { version = "5.6", optional = true, features = [
+  "dynamic_output",
+  "search",
+] }
 unicode-width = "0.2.1"
 globset = "0.4"
 serde = "1.0"

examples/buffer.rs

@@ -14,7 +14,7 @@ fn main() {
     controller
         .run(
             vec![input.into()],
-            Some(OutputHandle::FmtWrite(&mut buffer)),
+            Some(&mut OutputHandle::FmtWrite(&mut buffer)),
         )
         .unwrap();
 

src/bin/bat/main.rs

@@ -16,7 +16,7 @@ use std::io::{BufReader, Write};
 use std::path::Path;
 use std::process;
 
-use bat::output::{OutputHandle, OutputType};
+use bat::output::OutputType;
 use bat::theme::DetectColorScheme;
 use nu_ansi_term::Color::Green;
 use nu_ansi_term::Style;
@@ -229,10 +229,7 @@ pub fn list_themes(
             )?;
             config.theme = theme.to_string();
             Controller::new(&config, &assets)
-                .run(
+                .run(vec![theme_preview_file()], Some(&mut writer))
-                    vec![theme_preview_file()],
-                    Some(OutputHandle::IoWrite(&mut writer)),
-                )
                 .ok();
             writeln!(writer)?;
         } else if config.loop_through {

src/controller.rs

@@ -36,14 +36,18 @@ impl Controller<'_> {
         }
     }
 
-    pub fn run(&self, inputs: Vec<Input>, output_handle: Option<OutputHandle<'_>>) -> Result<bool> {
+    pub fn run(
+        &self,
+        inputs: Vec<Input>,
+        output_handle: Option<&mut OutputHandle<'_>>,
+    ) -> Result<bool> {
         self.run_with_error_handler(inputs, output_handle, default_error_handler)
     }
 
     pub fn run_with_error_handler(
         &self,
         inputs: Vec<Input>,
-        output_handle: Option<OutputHandle<'_>>,
+        output_handle: Option<&mut OutputHandle<'_>>,
         mut handle_error: impl FnMut(&Error, &mut dyn Write),
     ) -> Result<bool> {
         let mut output_type;
@@ -88,7 +92,7 @@ impl Controller<'_> {
         let mut writer = match output_handle {
             Some(OutputHandle::FmtWrite(w)) => OutputHandle::FmtWrite(w),
             Some(OutputHandle::IoWrite(w)) => OutputHandle::IoWrite(w),
-            None => OutputHandle::IoWrite(output_type.handle()?),
+            None => output_type.handle()?,
         };
         let mut no_errors: bool = true;
         let stderr = io::stderr();

src/error.rs

@@ -28,6 +28,9 @@ pub enum Error {
     InvalidPagerValueBat,
     #[error("{0}")]
     Msg(String),
+    #[cfg(feature = "paging")]
+    #[error(transparent)]
+    MinusError(#[from] ::minus::MinusError),
     #[cfg(feature = "lessopen")]
     #[error(transparent)]
     VarError(#[from] ::std::env::VarError),

src/output.rs

@@ -1,7 +1,9 @@
 use std::fmt;
-use std::io::{self, Write};
+use std::io;
 #[cfg(feature = "paging")]
 use std::process::Child;
+#[cfg(feature = "paging")]
+use std::thread::{spawn, JoinHandle};
 
 use crate::error::*;
 #[cfg(feature = "paging")]
@@ -11,6 +13,36 @@ use crate::paging::PagingMode;
 #[cfg(feature = "paging")]
 use crate::wrapping::WrappingMode;
 
+#[cfg(feature = "paging")]
+pub struct BuiltinPager {
+    pager: minus::Pager,
+    handle: Option<JoinHandle<Result<()>>>,
+}
+
+#[cfg(feature = "paging")]
+impl BuiltinPager {
+    fn new() -> Self {
+        let pager = minus::Pager::new();
+        let handle = {
+            let pager = pager.clone();
+            Some(spawn(move || {
+                minus::dynamic_paging(pager).map_err(Error::from)
+            }))
+        };
+        Self { pager, handle }
+    }
+}
+
+#[cfg(feature = "paging")]
+impl std::fmt::Debug for BuiltinPager {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        f.debug_struct("BuiltinPager")
+            //.field("pager", &self.pager) /// minus::Pager doesn't implement fmt::Debug
+            .field("handle", &self.handle)
+            .finish()
+    }
+}
+
 #[cfg(feature = "paging")]
 #[derive(Debug, PartialEq)]
 enum SingleScreenAction {
@@ -22,6 +54,8 @@ enum SingleScreenAction {
 pub enum OutputType {
     #[cfg(feature = "paging")]
     Pager(Child),
+    #[cfg(feature = "paging")]
+    BuiltinPager(BuiltinPager),
     Stdout(io::Stdout),
 }
 
@@ -64,6 +98,10 @@ impl OutputType {
             return Err(Error::InvalidPagerValueBat);
         }
 
+        if pager.kind == PagerKind::Builtin {
+            return Ok(OutputType::BuiltinPager(BuiltinPager::new()));
+        }
+
         let resolved_path = match grep_cli::resolve_binary(&pager.bin) {
             Ok(path) => path,
             Err(_) => {
@@ -138,7 +176,7 @@ impl OutputType {
 
     #[cfg(feature = "paging")]
     pub(crate) fn is_pager(&self) -> bool {
-        matches!(self, OutputType::Pager(_))
+        matches!(self, OutputType::Pager(_) | OutputType::BuiltinPager(_))
     }
 
     #[cfg(not(feature = "paging"))]
@@ -146,14 +184,18 @@ impl OutputType {
         false
     }
 
-    pub fn handle(&mut self) -> Result<&mut dyn Write> {
+    pub fn handle<'a>(&'a mut self) -> Result<OutputHandle<'a>> {
         Ok(match *self {
             #[cfg(feature = "paging")]
-            OutputType::Pager(ref mut command) => command
+            OutputType::Pager(ref mut command) => OutputHandle::IoWrite(
-                .stdin
+                command
-                .as_mut()
+                    .stdin
-                .ok_or("Could not open stdin for pager")?,
+                    .as_mut()
-            OutputType::Stdout(ref mut handle) => handle,
+                    .ok_or("Could not open stdin for pager")?,
+            ),
+            #[cfg(feature = "paging")]
+            OutputType::BuiltinPager(ref mut pager) => OutputHandle::FmtWrite(&mut pager.pager),
+            OutputType::Stdout(ref mut handle) => OutputHandle::IoWrite(handle),
         })
     }
 }
@@ -161,8 +203,16 @@ impl OutputType {
 #[cfg(feature = "paging")]
 impl Drop for OutputType {
     fn drop(&mut self) {
-        if let OutputType::Pager(ref mut command) = *self {
+        match *self {
-            let _ = command.wait();
+            OutputType::Pager(ref mut command) => {
+                let _ = command.wait();
+            }
+            OutputType::BuiltinPager(ref mut pager) => {
+                if pager.handle.is_some() {
+                    let _ = pager.handle.take().unwrap().join().unwrap();
+                }
+            }
+            OutputType::Stdout(_) => (),
         }
     }
 }

src/pager.rs

@@ -32,6 +32,9 @@ pub(crate) enum PagerKind {
     /// most
     Most,
 
+    /// builtin
+    Builtin,
+
     /// A pager we don't know about
     Unknown,
 }
@@ -40,6 +43,10 @@ impl PagerKind {
     fn from_bin(bin: &str) -> PagerKind {
         use std::path::Path;
 
+        if bin == "builtin" {
+            return PagerKind::Builtin;
+        }
+
         // Set to `less` by default on most Linux distros.
         let pager_bin = Path::new(bin).file_stem();
 

src/pretty_printer.rs

@@ -328,7 +328,7 @@ impl<'a> PrettyPrinter<'a> {
         if let Some(mut w) = writer {
             controller.run(
                 inputs.into_iter().map(|i| i.into()).collect(),
-                Some(OutputHandle::FmtWrite(&mut w)),
+                Some(&mut OutputHandle::FmtWrite(&mut w)),
             )
         } else {
             controller.run(inputs.into_iter().map(|i| i.into()).collect(), None)