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|
use shell_words::ParseError;
use std::env;
/// If we use a pager, this enum tells us from where we were told to use it.
#[derive(Debug, PartialEq)]
pub(crate) enum PagerSource {
/// From --config
Config,
/// From the env var BAT_PAGER
EnvVarBatPager,
/// From the env var PAGER
EnvVarPager,
/// No pager was specified, default is used
Default,
}
/// We know about some pagers, for example 'less'. This is a list of all pagers we know about
#[derive(Debug, PartialEq)]
pub(crate) enum PagerKind {
/// bat
Bat,
/// less
Less,
/// more
More,
/// most
Most,
/// A pager we don't know about
Unknown,
}
impl PagerKind {
fn from_bin(bin: &str) -> PagerKind {
use std::path::Path;
match Path::new(bin)
.file_stem()
.map(|s| s.to_string_lossy())
.as_deref()
{
Some("bat") => PagerKind::Bat,
Some("less") => PagerKind::Less,
Some("more") => PagerKind::More,
Some("most") => PagerKind::Most,
_ => PagerKind::Unknown,
}
}
}
/// A pager such as 'less', and from where we got it.
#[derive(Debug)]
pub(crate) struct Pager {
/// The pager binary
pub bin: String,
/// The pager binary arguments (that we might tweak)
pub args: Vec<String>,
/// What pager this is
pub kind: PagerKind,
/// From where this pager comes
pub source: PagerSource,
}
impl Pager {
fn new(bin: &str, args: &[String], kind: PagerKind, source: PagerSource) -> Pager {
Pager {
bin: String::from(bin),
args: args.to_vec(),
kind,
source,
}
}
}
/// Returns what pager to use, after looking at both config and environment variables.
pub(crate) fn get_pager(config_pager: Option<&str>) -> Result<Option<Pager>, ParseError> {
let bat_pager = env::var("BAT_PAGER");
let pager = env::var("PAGER");
let (cmd, source) = match (config_pager, &bat_pager, &pager) {
(Some(config_pager), _, _) => (config_pager, PagerSource::Config),
(_, Ok(bat_pager), _) => (bat_pager.as_str(), PagerSource::EnvVarBatPager),
(_, _, Ok(pager)) => (pager.as_str(), PagerSource::EnvVarPager),
_ => ("less", PagerSource::Default),
};
let parts = shell_words::split(cmd)?;
match parts.split_first() {
Some((bin, args)) => {
let kind = PagerKind::from_bin(bin);
let use_less_instead = if source == PagerSource::EnvVarPager {
// 'more' and 'most' do not supports colors; automatically use
// 'less' instead if the problematic pager came from the
// generic PAGER env var.
// If PAGER=bat, silently use 'less' instead to prevent
// recursion.
// Never silently use 'less' if BAT_PAGER or --pager has been
// specified.
matches!(kind, PagerKind::More | PagerKind::Most | PagerKind::Bat)
} else {
false
};
Ok(Some(if use_less_instead {
let no_args = vec![];
Pager::new("less", &no_args, PagerKind::Less, PagerSource::EnvVarPager)
} else {
Pager::new(bin, args, kind, source)
}))
}
None => Ok(None),
}
}
|
