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use std::fmt::Write;
/// Expand tabs like an ANSI-enabled expand(1).
pub fn expand_tabs(mut text: &str, width: usize, cursor: &mut usize) -> String {
let mut buffer = String::with_capacity(text.len() * 2);
while let Some(index) = text.find('\t') {
// Add previous text.
if index > 0 {
*cursor += index;
buffer.push_str(&text[0..index]);
}
// Add tab.
let spaces = width - (*cursor % width);
*cursor += spaces;
buffer.push_str(&*" ".repeat(spaces));
// Next.
text = &text[index + 1..text.len()];
}
*cursor += text.len();
buffer.push_str(text);
buffer
}
fn try_parse_utf8_char(input: &[u8]) -> Option<(char, usize)> {
let str_from_utf8 = |seq| std::str::from_utf8(seq).ok();
let decoded = input
.get(0..1)
.and_then(str_from_utf8)
.map(|c| (c, 1))
.or_else(|| input.get(0..2).and_then(str_from_utf8).map(|c| (c, 2)))
.or_else(|| input.get(0..3).and_then(str_from_utf8).map(|c| (c, 3)))
.or_else(|| input.get(0..4).and_then(str_from_utf8).map(|c| (c, 4)));
decoded.map(|(seq, n)| (seq.chars().next().unwrap(), n))
}
pub fn replace_nonprintable(input: &[u8], tab_width: usize) -> String {
let mut output = String::new();
let tab_width = if tab_width == 0 { 4 } else { tab_width };
let mut idx = 0;
let mut line_idx = 0;
let len = input.len();
while idx < len {
if let Some((chr, skip_ahead)) = try_parse_utf8_char(&input[idx..]) {
idx += skip_ahead;
line_idx += 1;
match chr {
// space
' ' => output.push('·'),
// tab
'\t' => {
let tab_stop = tab_width - ((line_idx - 1) % tab_width);
line_idx = 0;
if tab_stop == 1 {
output.push('↹');
} else {
output.push('├');
output.push_str(&"─".repeat(tab_stop - 2));
output.push('┤');
}
}
// line feed
'\x0A' => {
output.push_str("␊\x0A");
line_idx = 0;
}
// carriage return
'\x0D' => output.push('␍'),
// null
'\x00' => output.push('␀'),
// bell
'\x07' => output.push('␇'),
// backspace
'\x08' => output.push('␈'),
// escape
'\x1B' => output.push('␛'),
// printable ASCII
c if c.is_ascii_alphanumeric()
|| c.is_ascii_punctuation()
|| c.is_ascii_graphic() =>
{
output.push(c)
}
// everything else
c => output.push_str(&c.escape_unicode().collect::<String>()),
}
} else {
write!(output, "\\x{:02X}", input[idx]).ok();
idx += 1;
}
}
output
}
#[test]
fn test_try_parse_utf8_char() {
assert_eq!(try_parse_utf8_char(&[0x20]), Some((' ', 1)));
assert_eq!(try_parse_utf8_char(&[0x20, 0x20]), Some((' ', 1)));
assert_eq!(try_parse_utf8_char(&[0x20, 0xef]), Some((' ', 1)));
assert_eq!(try_parse_utf8_char(&[0x00]), Some(('\x00', 1)));
assert_eq!(try_parse_utf8_char(&[0x1b]), Some(('\x1b', 1)));
assert_eq!(try_parse_utf8_char(&[0xc3, 0xa4]), Some(('ä', 2)));
assert_eq!(try_parse_utf8_char(&[0xc3, 0xa4, 0xef]), Some(('ä', 2)));
assert_eq!(try_parse_utf8_char(&[0xc3, 0xa4, 0x20]), Some(('ä', 2)));
assert_eq!(try_parse_utf8_char(&[0xe2, 0x82, 0xac]), Some(('€', 3)));
assert_eq!(
try_parse_utf8_char(&[0xe2, 0x82, 0xac, 0xef]),
Some(('€', 3))
);
assert_eq!(
try_parse_utf8_char(&[0xe2, 0x82, 0xac, 0x20]),
Some(('€', 3))
);
assert_eq!(try_parse_utf8_char(&[0xe2, 0x88, 0xb0]), Some(('∰', 3)));
assert_eq!(
try_parse_utf8_char(&[0xf0, 0x9f, 0x8c, 0x82]),
Some(('🌂', 4))
);
assert_eq!(
try_parse_utf8_char(&[0xf0, 0x9f, 0x8c, 0x82, 0xef]),
Some(('🌂', 4))
);
assert_eq!(
try_parse_utf8_char(&[0xf0, 0x9f, 0x8c, 0x82, 0x20]),
Some(('🌂', 4))
);
assert_eq!(try_parse_utf8_char(&[]), None);
assert_eq!(try_parse_utf8_char(&[0xef]), None);
assert_eq!(try_parse_utf8_char(&[0xef, 0x20]), None);
assert_eq!(try_parse_utf8_char(&[0xf0, 0xf0]), None);
}
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