bat/src/output.rs

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Rust
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use std::io::{self, Write};
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#[cfg(feature = "paging")]
use std::process::Child;
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use crate::error::*;
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#[cfg(feature = "paging")]
use crate::less::{retrieve_less_version, LessVersion};
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#[cfg(feature = "paging")]
use crate::paging::PagingMode;
#[cfg(feature = "paging")]
use crate::wrapping::WrappingMode;
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#[cfg(feature = "paging")]
#[derive(Debug, PartialEq)]
enum SingleScreenAction {
Quit,
Nothing,
}
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#[derive(Debug)]
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pub enum OutputType {
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#[cfg(feature = "paging")]
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Pager(Child),
Stdout(io::Stdout),
}
impl OutputType {
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#[cfg(feature = "paging")]
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pub fn from_mode(
paging_mode: PagingMode,
wrapping_mode: WrappingMode,
pager: Option<&str>,
) -> Result<Self> {
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use self::PagingMode::*;
Ok(match paging_mode {
Always => OutputType::try_pager(SingleScreenAction::Nothing, wrapping_mode, pager)?,
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QuitIfOneScreen => {
OutputType::try_pager(SingleScreenAction::Quit, wrapping_mode, pager)?
}
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_ => OutputType::stdout(),
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})
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}
/// Try to launch the pager. Fall back to stdout in case of errors.
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#[cfg(feature = "paging")]
fn try_pager(
single_screen_action: SingleScreenAction,
wrapping_mode: WrappingMode,
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pager_from_config: Option<&str>,
) -> Result<Self> {
use crate::pager::{self, PagerKind, PagerSource};
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use std::process::{Command, Stdio};
let pager_opt =
pager::get_pager(pager_from_config).map_err(|_| "Could not parse pager command.")?;
let pager = match pager_opt {
Some(pager) => pager,
None => return Ok(OutputType::stdout()),
};
if pager.kind == PagerKind::Bat {
return Err(Error::InvalidPagerValueBat);
}
let resolved_path = match grep_cli::resolve_binary(&pager.bin) {
Ok(path) => path,
Err(_) => {
return Ok(OutputType::stdout());
}
};
let mut p = Command::new(resolved_path);
let args = pager.args;
if pager.kind == PagerKind::Less {
// less needs to be called with the '-R' option in order to properly interpret the
// ANSI color sequences printed by bat. If someone has set PAGER="less -F", we
// therefore need to overwrite the arguments and add '-R'.
//
// We only do this for PAGER (as it is not specific to 'bat'), not for BAT_PAGER
// or bats '--pager' command line option.
let replace_arguments_to_less = pager.source == PagerSource::EnvVarPager;
if args.is_empty() || replace_arguments_to_less {
p.arg("-R"); // Short version of --RAW-CONTROL-CHARS for maximum compatibility
if single_screen_action == SingleScreenAction::Quit {
p.arg("-F"); // Short version of --quit-if-one-screen for compatibility
}
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if wrapping_mode == WrappingMode::NoWrapping(true) {
p.arg("-S"); // Short version of --chop-long-lines for compatibility
}
// Passing '--no-init' fixes a bug with '--quit-if-one-screen' in older
// versions of 'less'. Unfortunately, it also breaks mouse-wheel support.
//
// See: http://www.greenwoodsoftware.com/less/news.530.html
//
// For newer versions (530 or 558 on Windows), we omit '--no-init' as it
// is not needed anymore.
match retrieve_less_version(&pager.bin) {
None => {
p.arg("--no-init");
}
Some(LessVersion::Less(version))
if (version < 530 || (cfg!(windows) && version < 558)) =>
{
p.arg("--no-init");
}
_ => {}
}
} else {
p.args(args);
}
p.env("LESSCHARSET", "UTF-8");
} else {
p.args(args);
};
Ok(p.stdin(Stdio::piped())
.spawn()
.map(OutputType::Pager)
.unwrap_or_else(|_| OutputType::stdout()))
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}
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pub(crate) fn stdout() -> Self {
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OutputType::Stdout(io::stdout())
}
#[cfg(feature = "paging")]
pub(crate) fn is_pager(&self) -> bool {
matches!(self, OutputType::Pager(_))
}
#[cfg(not(feature = "paging"))]
pub(crate) fn is_pager(&self) -> bool {
false
}
pub fn handle(&mut self) -> Result<&mut dyn Write> {
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Ok(match *self {
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#[cfg(feature = "paging")]
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OutputType::Pager(ref mut command) => command
.stdin
.as_mut()
.ok_or("Could not open stdin for pager")?,
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OutputType::Stdout(ref mut handle) => handle,
})
}
}
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#[cfg(feature = "paging")]
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impl Drop for OutputType {
fn drop(&mut self) {
if let OutputType::Pager(ref mut command) = *self {
let _ = command.wait();
}
}
}