mirror of https://github.com/sharkdp/bat.git
121 lines
3.2 KiB
Rust
121 lines
3.2 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 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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BatPagerEnvVar,
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/// From the env var PAGER
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PagerEnvVar,
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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 enum PagerKind {
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/// The pager is ourselves
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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::ffi::OsStr;
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use std::path::Path;
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let stem = Path::new(bin)
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.file_stem()
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.unwrap_or_else(|| OsStr::new("unknown"));
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if stem == OsStr::new("bat") {
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PagerKind::Bat
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} else if stem == OsStr::new("less") {
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PagerKind::Less
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} else if stem == OsStr::new("more") {
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PagerKind::More
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} else if stem == OsStr::new("most") {
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PagerKind::Most
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} else {
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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 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 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::BatPagerEnvVar),
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(_, _, Ok(pager)) => (pager.as_str(), PagerSource::PagerEnvVar),
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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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// 'more' and 'most' does not supports colors; automatically use 'less' instead
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// if the problematic pager came from the generic PAGER env var
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let no_color_support = kind == PagerKind::More || kind == PagerKind::Most;
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let use_less_instead = no_color_support && source == PagerSource::PagerEnvVar;
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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::PagerEnvVar)
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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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