#[macro_use]
extern crate uucore;
use clap::{crate_version, App, Arg};
use std::io::{self, Write};
use std::iter::Peekable;
use std::str::Chars;
const NAME: &str = "echo";
const SUMMARY: &str = "display a line of text";
const USAGE: &str = "[OPTIONS]... [STRING]...";
const AFTER_HELP: &str = r#"
Echo the STRING(s) to standard output.
If -e is in effect, the following sequences are recognized:
\\\\ backslash
\\a alert (BEL)
\\b backspace
\\c produce no further output
\\e escape
\\f form feed
\\n new line
\\r carriage return
\\t horizontal tab
\\v vertical tab
\\0NNN byte with octal value NNN (1 to 3 digits)
\\xHH byte with hexadecimal value HH (1 to 2 digits)
"#;
mod options {
pub const STRING: &str = "STRING";
pub const NO_NEWLINE: &str = "no_newline";
pub const ENABLE_BACKSLASH_ESCAPE: &str = "enable_backslash_escape";
pub const DISABLE_BACKSLASH_ESCAPE: &str = "disable_backslash_escape";
}
fn parse_code(
input: &mut Peekable<Chars>,
base: u32,
max_digits: u32,
bits_per_digit: u32,
) -> Option<char> {
let mut ret = 0x8000_0000;
for _ in 0..max_digits {
match input.peek().and_then(|c| c.to_digit(base)) {
Some(n) => ret = (ret << bits_per_digit) | n,
None => break,
}
input.next();
}
std::char::from_u32(ret)
}
fn print_escaped(input: &str, mut output: impl Write) -> io::Result<bool> {
let mut should_stop = false;
let mut buffer = ['\\'; 2];
let mut iter = input.chars().peekable();
while let Some(mut c) = iter.next() {
let mut start = 1;
if c == '\\' {
if let Some(next) = iter.next() {
c = match next {
'\\' => '\\',
'a' => '\x07',
'b' => '\x08',
'c' => {
should_stop = true;
break;
}
'e' => '\x1b',
'f' => '\x0c',
'n' => '\n',
'r' => '\r',
't' => '\t',
'v' => '\x0b',
'x' => parse_code(&mut iter, 16, 2, 4).unwrap_or_else(|| {
start = 0;
next
}),
'0' => parse_code(&mut iter, 8, 3, 3).unwrap_or_else(|| {
start = 0;
next
}),
_ => {
start = 0;
next
}
};
}
}
buffer[1] = c;
for ch in &buffer[start..] {
write!(output, "{}", ch)?;
}
}
Ok(should_stop)
}
pub fn uumain(args: impl uucore::Args) -> i32 {
let matches = App::new(executable!())
.name(NAME)
.setting(clap::AppSettings::TrailingVarArg)
.setting(clap::AppSettings::AllowLeadingHyphen)
.version(crate_version!())
.about(SUMMARY)
.after_help(AFTER_HELP)
.usage(USAGE)
.arg(
Arg::with_name(options::NO_NEWLINE)
.short("n")
.help("do not output the trailing newline")
.takes_value(false)
.display_order(1),
)
.arg(
Arg::with_name(options::ENABLE_BACKSLASH_ESCAPE)
.short("e")
.help("enable interpretation of backslash escapes")
.takes_value(false)
.display_order(2),
)
.arg(
Arg::with_name(options::DISABLE_BACKSLASH_ESCAPE)
.short("E")
.help("disable interpretation of backslash escapes (default)")
.takes_value(false)
.display_order(3),
)
.arg(
Arg::with_name(options::STRING)
.multiple(true)
.allow_hyphen_values(true),
)
.get_matches_from(args);
let no_newline = matches.is_present(options::NO_NEWLINE);
let escaped = matches.is_present(options::ENABLE_BACKSLASH_ESCAPE);
let values: Vec<String> = match matches.values_of(options::STRING) {
Some(s) => s.map(|s| s.to_string()).collect(),
None => vec!["".to_string()],
};
match execute(no_newline, escaped, values) {
Ok(_) => 0,
Err(f) => {
show_error!("{}", f);
1
}
}
}
fn execute(no_newline: bool, escaped: bool, free: Vec<String>) -> io::Result<()> {
let stdout = io::stdout();
let mut output = stdout.lock();
for (i, input) in free.iter().enumerate() {
if i > 0 {
write!(output, " ")?;
}
if escaped {
let should_stop = print_escaped(&input, &mut output)?;
if should_stop {
break;
}
} else {
write!(output, "{}", input)?;
}
}
if !no_newline {
writeln!(output)?;
}
Ok(())
}