git.iko.soy/bat
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bat/src/output.rs
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1use std::io::{self, Write};
2#[cfg(feature = "paging")]
3use std::process::Child;
5#[cfg(feature = "paging")]
6use crate::config::PagingMode;
7use crate::errors::*;
8#[cfg(feature = "paging")]
9use crate::less::retrieve_less_version;
11#[derive(Debug)]
12pub enum OutputType {
13 #[cfg(feature = "paging")]
14 Pager(Child),
15 Stdout(io::Stdout),
18impl OutputType {
19 #[cfg(feature = "paging")]
20 pub fn from_mode(mode: PagingMode, pager: Option<&str>) -> Result<Self> {
21 use self::PagingMode::*;
22 Ok(match mode {
23 Always => OutputType::try_pager(false, pager)?,
24 QuitIfOneScreen => OutputType::try_pager(true, pager)?,
25 _ => OutputType::stdout(),
26 })
27 }
29 /// Try to launch the pager. Fall back to stdout in case of errors.
30 #[cfg(feature = "paging")]
31 fn try_pager(quit_if_one_screen: bool, pager_from_config: Option<&str>) -> Result<Self> {
32 use std::env;
33 use std::ffi::OsString;
34 use std::path::PathBuf;
35 use std::process::{Command, Stdio};
37 let mut replace_arguments_to_less = false;
39 let pager_from_env = match (env::var("BAT_PAGER"), env::var("PAGER")) {
40 (Ok(bat_pager), _) => Some(bat_pager),
41 (_, Ok(pager)) => {
42 // less needs to be called with the '-R' option in order to properly interpret the
43 // ANSI color sequences printed by bat. If someone has set PAGER="less -F", we
44 // therefore need to overwrite the arguments and add '-R'.
45 //
46 // We only do this for PAGER (as it is not specific to 'bat'), not for BAT_PAGER
47 // or bats '--pager' command line option.
48 replace_arguments_to_less = true;
49 Some(pager)
50 }
51 _ => None,
52 };
54 let pager_from_config = pager_from_config.map(|p| p.to_string());
56 if pager_from_config.is_some() {
57 replace_arguments_to_less = false;
58 }
60 let pager = pager_from_config
61 .or(pager_from_env)
62 .unwrap_or_else(|| String::from("less"));
64 let pagerflags =
65 shell_words::split(&pager).chain_err(|| "Could not parse pager command.")?;
67 match pagerflags.split_first() {
68 Some((pager_name, args)) => {
69 let mut pager_path = PathBuf::from(pager_name);
71 if pager_path.file_stem() == Some(&OsString::from("bat")) {
72 pager_path = PathBuf::from("less");
73 }
75 let is_less = pager_path.file_stem() == Some(&OsString::from("less"));
77 let mut process = if is_less {
78 let mut p = Command::new(&pager_path);
79 if args.is_empty() || replace_arguments_to_less {
80 p.arg("--RAW-CONTROL-CHARS");
81 if quit_if_one_screen {
82 p.arg("--quit-if-one-screen");
83 }
85 let less_version = retrieve_less_version();
87 // Passing '--no-init' fixes a bug with '--quit-if-one-screen' in older
88 // versions of 'less'. Unfortunately, it also breaks mouse-wheel support.
89 //
90 // See: http://www.greenwoodsoftware.com/less/news.530.html
91 match less_version {
92 None => {
93 p.arg("--no-init");
94 }
95 Some(version) if version < 530 => {
96 p.arg("--no-init");
97 }
98 _ => {}
99 }
101 // Passing '--mouse' allows mouse scrolling in terminals which do not
102 // support "fake scrolling", see https://github.com/sharkdp/bat/issues/904
103 // The '--mouse' argument is only supported in less 551 or higher.
104 match less_version {
105 Some(version) if version >= 551 => {
106 p.arg("--mouse");
107 }
108 _ => {}
109 }
110 } else {
111 p.args(args);
112 }
113 p.env("LESSCHARSET", "UTF-8");
114 p
115 } else {
116 let mut p = Command::new(&pager_path);
117 p.args(args);
118 p
119 };
121 Ok(process
122 .stdin(Stdio::piped())
123 .spawn()
124 .map(OutputType::Pager)
125 .unwrap_or_else(|_| OutputType::stdout()))
126 }
127 None => Ok(OutputType::stdout()),
128 }
129 }
131 pub(crate) fn stdout() -> Self {
132 OutputType::Stdout(io::stdout())
133 }
135 pub fn handle(&mut self) -> Result<&mut dyn Write> {
136 Ok(match *self {
137 #[cfg(feature = "paging")]
138 OutputType::Pager(ref mut command) => command
139 .stdin
140 .as_mut()
141 .chain_err(|| "Could not open stdin for pager")?,
142 OutputType::Stdout(ref mut handle) => handle,
143 })
144 }
147#[cfg(feature = "paging")]
148impl Drop for OutputType {
149 fn drop(&mut self) {
150 if let OutputType::Pager(ref mut command) = *self {
151 let _ = command.wait();
152 }
153 }