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