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use std::fmt::{self, Display, Formatter};
#[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,
}
}
pub fn unsafe_string(&self) -> String {
match *self {
MarkupDisplay::Safe(ref t) | MarkupDisplay::Unsafe(ref t) => format!("{}", t),
}
}
}
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(_) => write!(f, "{}", escape(self.unsafe_string())),
MarkupDisplay::Safe(ref t) => t.fmt(f),
}
}
}
const FLAG: u8 = b'>' - b'"';
pub fn escape(s: String) -> String {
let mut found = None;
for (i, b) in s.as_bytes().iter().enumerate() {
if b.wrapping_sub(b'"') <= FLAG {
match *b {
b'<' | b'>' | b'&' | b'"' | b'\'' | b'/' => {
found = Some(i);
break;
}
_ => (),
};
}
}
if let Some(found) = found {
let bytes = s.as_bytes();
let mut res = Vec::with_capacity(s.len() + 6);
res.extend(&bytes[0..found]);
for c in bytes[found..].iter() {
match *c {
b'<' => {
res.extend(b"<");
}
b'>' => {
res.extend(b">");
}
b'&' => {
res.extend(b"&");
}
b'"' => {
res.extend(b""");
}
b'\'' => {
res.extend(b"'");
}
b'/' => {
res.extend(b"/");
}
_ => res.push(*c),
}
}
String::from_utf8(res).unwrap()
} else {
s
}
}
#[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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