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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),
}
}
}
fn escapable(b: u8) -> bool {
match b {
b'<' | b'>' | b'&' | b'"' | b'\'' | b'/' => true,
_ => false,
}
}
pub fn escape(s: String) -> String {
let mut found = Vec::new();
for (i, b) in s.as_bytes().iter().enumerate() {
if escapable(*b) {
found.push(i);
}
}
if found.is_empty() {
return s;
}
let bytes = s.as_bytes();
let max_len = bytes.len() + found.len() * 5;
let mut res = Vec::<u8>::with_capacity(max_len);
let mut start = 0;
for idx in &found {
if start < *idx {
res.extend(&bytes[start..*idx]);
}
start = *idx + 1;
match bytes[*idx] {
b'<' => { res.extend(b"<"); },
b'>' => { res.extend(b">"); },
b'&' => { res.extend(b"&"); },
b'"' => { res.extend(b"""); },
b'\'' => { res.extend(b"'"); },
b'/' => { res.extend(b"/"); },
_ => panic!("incorrect indexing"),
}
}
if start < bytes.len() - 1 {
res.extend(&bytes[start..]);
}
String::from_utf8(res).unwrap()
}
#[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");
}
}
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