Repository: sharkdp/bat
File: src/output.rs (Rust)

Code before:
use std::process::{Child, Command, Stdio};

use shell_words;

use app::PagingMode;
use errors::*;

pub enum OutputType {
    Pager(Child),
    Stdout(io::Stdout),
}

impl OutputType {
    pub fn from_mode(mode: PagingMode, pager: Option<&str>) -> Result<Self> {
        use self::PagingMode::*;
        Ok(match mode {
            Always => OutputType::try_pager(false, pager)?,
            QuitIfOneScreen => OutputType::try_pager(true, pager)?,
            _ => OutputType::stdout(),
        })
    }

    /// Try to launch the pager. Fall back to stdout in case of errors.
    fn try_pager(quit_if_one_screen: bool, pager_from_config: Option<&str>) -> Result<Self> {
        let pager_from_env =
            env::var("BAT_PAGER").or_else(|_| env::var("PAGER").map(add_default_flags_to_less));

        let pager = pager_from_config
            .map(|p| p.to_string())
            .or(pager_from_env.ok())
            .unwrap_or(String::from("less"));

        let pagerflags = shell_words::split(&pager)
            .chain_err(|| "Could not parse (BAT_)PAGER environment variable.")?;

        match pagerflags.split_first() {
            Some((pager_name, mut args)) => {
                let mut pager_path = PathBuf::from(pager_name);

                if pager_path.file_stem() == Some(&OsString::from("bat")) {
                    pager_path = PathBuf::from("less");
                    args = &[];
                }

                let is_less = pager_path.file_stem() == Some(&OsString::from("less"));

                let mut process = if is_less {
                    let mut p = Command::new(&pager_path);
                    if args.is_empty() {
                        p.args(vec!["--RAW-CONTROL-CHARS", "--no-init"]);
                        if quit_if_one_screen {

Review comment (suggestion):
The whole point of this was to have a different handling of `PAGER` and `BAT_PAGER`.  We do not want to modify anything for `BAT_PAGER`.

Code after:
use std::process::{Child, Command, Stdio};

use shell_words;

use app::PagingMode;
use errors::*;

pub enum OutputType {
    Pager(Child),
    Stdout(io::Stdout),
}

impl OutputType {
    pub fn from_mode(mode: PagingMode, pager: Option<&str>) -> Result<Self> {
        use self::PagingMode::*;
        Ok(match mode {
            Always => OutputType::try_pager(false, pager)?,
            QuitIfOneScreen => OutputType::try_pager(true, pager)?,
            _ => OutputType::stdout(),
        })
    }

    /// Try to launch the pager. Fall back to stdout in case of errors.
    fn try_pager(quit_if_one_screen: bool, pager_from_config: Option<&str>) -> Result<Self> {
        let mut replace_arguments_to_less = false;

        let pager_from_env = match (env::var("BAT_PAGER"), env::var("PAGER")) {
            (Ok(bat_pager), _) => Some(bat_pager),
            (_, Ok(pager)) => {
                // 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.
                replace_arguments_to_less = true;
                Some(pager)
            }
            _ => None,
        };

        let pager = pager_from_config
            .map(|p| p.to_string())
            .or(pager_from_env)
            .unwrap_or(String::from("less"));

        let pagerflags =
            shell_words::split(&pager).chain_err(|| "Could not parse pager command.")?;

        match pagerflags.split_first() {
            Some((pager_name, args)) => {