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use std::fmt::{self, Display, Formatter};
use std::str;
#[derive(Debug, PartialEq)]
pub enum MarkupDisplay<T>
where
T: Display,
{
Safe(T),
Unsafe(T),
}
impl<T> MarkupDisplay<T>
where
T: Display,
{
pub fn mark_safe(self) -> MarkupDisplay<T> {
match self {
MarkupDisplay::Unsafe(t) => MarkupDisplay::Safe(t),
_ => self,
}
}
}
impl<T> From<T> for MarkupDisplay<T>
where
T: Display,
{
fn from(t: T) -> MarkupDisplay<T> {
MarkupDisplay::Unsafe(t)
}
}
impl<T> Display for MarkupDisplay<T>
where
T: Display,
{
fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result {
match *self {
MarkupDisplay::Unsafe(ref t) => escape(&t.to_string()).fmt(f),
MarkupDisplay::Safe(ref t) => t.fmt(f),
}
}
}
pub fn escape(s: &str) -> Escaped<'_> {
Escaped {
bytes: s.as_bytes(),
}
}
macro_rules! escaping_body {
($start:ident, $i:ident, $fmt:ident, $_self:ident, $quote:expr) => {{
if $start < $i {
$fmt.write_str(unsafe { str::from_utf8_unchecked(&$_self.bytes[$start..$i]) })?;
}
$fmt.write_str($quote)?;
$start = $i + 1;
}};
}
pub struct Escaped<'a> {
bytes: &'a [u8],
}
impl<'a> ::std::fmt::Display for Escaped<'a> {
fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
let mut start = 0;
for (i, b) in self.bytes.iter().enumerate() {
if b.wrapping_sub(b'"') <= FLAG {
match *b {
b'<' => escaping_body!(start, i, fmt, self, "<"),
b'>' => escaping_body!(start, i, fmt, self, ">"),
b'&' => escaping_body!(start, i, fmt, self, "&"),
b'"' => escaping_body!(start, i, fmt, self, """),
b'\'' => escaping_body!(start, i, fmt, self, "'"),
b'/' => escaping_body!(start, i, fmt, self, "/"),
_ => (),
}
}
}
fmt.write_str(unsafe { str::from_utf8_unchecked(&self.bytes[start..]) })?;
Ok(())
}
}
const FLAG: u8 = b'>' - b'"';
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn test_escape() {
assert_eq!(escape("").to_string(), "");
assert_eq!(escape("<&>").to_string(), "<&>");
assert_eq!(escape("bla&").to_string(), "bla&");
assert_eq!(escape("<foo").to_string(), "<foo");
assert_eq!(escape("bla&h").to_string(), "bla&h");
}
}
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