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#![cfg_attr(not(any(feature = "json", test)), no_std)]
#![deny(elided_lifetimes_in_paths)]
#![deny(unreachable_pub)]
use core::fmt::{self, Display, Formatter, Write};
use core::str;
#[derive(Debug)]
pub struct MarkupDisplay<E, T>
where
E: Escaper,
T: Display,
{
value: DisplayValue<T>,
escaper: E,
}
impl<E, T> MarkupDisplay<E, T>
where
E: Escaper,
T: Display,
{
pub fn new_unsafe(value: T, escaper: E) -> Self {
Self {
value: DisplayValue::Unsafe(value),
escaper,
}
}
pub fn new_safe(value: T, escaper: E) -> Self {
Self {
value: DisplayValue::Safe(value),
escaper,
}
}
#[must_use]
pub fn mark_safe(mut self) -> MarkupDisplay<E, T> {
self.value = match self.value {
DisplayValue::Unsafe(t) => DisplayValue::Safe(t),
_ => self.value,
};
self
}
}
impl<E, T> Display for MarkupDisplay<E, T>
where
E: Escaper,
T: Display,
{
fn fmt(&self, fmt: &mut Formatter<'_>) -> fmt::Result {
match self.value {
DisplayValue::Unsafe(ref t) => write!(
EscapeWriter {
fmt,
escaper: &self.escaper
},
"{t}"
),
DisplayValue::Safe(ref t) => t.fmt(fmt),
}
}
}
#[derive(Debug)]
pub struct EscapeWriter<'a, E, W> {
fmt: W,
escaper: &'a E,
}
impl<E, W> Write for EscapeWriter<'_, E, W>
where
W: Write,
E: Escaper,
{
fn write_str(&mut self, s: &str) -> fmt::Result {
self.escaper.write_escaped(&mut self.fmt, s)
}
}
pub fn escape<E>(string: &str, escaper: E) -> Escaped<'_, E>
where
E: Escaper,
{
Escaped { string, escaper }
}
#[derive(Debug)]
pub struct Escaped<'a, E>
where
E: Escaper,
{
string: &'a str,
escaper: E,
}
impl<E> Display for Escaped<'_, E>
where
E: Escaper,
{
fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
self.escaper.write_escaped(fmt, self.string)
}
}
pub struct Html;
impl Escaper for Html {
fn write_escaped<W>(&self, mut fmt: W, string: &str) -> fmt::Result
where
W: Write,
{
let mut last = 0;
for (index, byte) in string.bytes().enumerate() {
const MIN_CHAR: u8 = b'"';
const MAX_CHAR: u8 = b'>';
const TABLE: [Option<&&str>; (MAX_CHAR - MIN_CHAR + 1) as usize] = {
let mut table = [None; (MAX_CHAR - MIN_CHAR + 1) as usize];
table[(b'<' - MIN_CHAR) as usize] = Some(&"<");
table[(b'>' - MIN_CHAR) as usize] = Some(&">");
table[(b'&' - MIN_CHAR) as usize] = Some(&"&");
table[(b'"' - MIN_CHAR) as usize] = Some(&""");
table[(b'\'' - MIN_CHAR) as usize] = Some(&"'");
table
};
let escaped = match byte {
MIN_CHAR..=MAX_CHAR => TABLE[(byte - MIN_CHAR) as usize],
_ => None,
};
if let Some(escaped) = escaped {
fmt.write_str(&string[last..index])?;
fmt.write_str(escaped)?;
last = index + 1;
}
}
fmt.write_str(&string[last..])
}
}
pub struct Text;
impl Escaper for Text {
fn write_escaped<W>(&self, mut fmt: W, string: &str) -> fmt::Result
where
W: Write,
{
fmt.write_str(string)
}
}
#[derive(Debug, PartialEq)]
enum DisplayValue<T>
where
T: Display,
{
Safe(T),
Unsafe(T),
}
pub trait Escaper {
fn write_escaped<W>(&self, fmt: W, string: &str) -> fmt::Result
where
W: Write;
}
/// Escape chevrons, ampersand and apostrophes for use in JSON
#[cfg(feature = "json")]
#[derive(Debug, Clone, Default)]
pub struct JsonEscapeBuffer(Vec<u8>);
#[cfg(feature = "json")]
impl JsonEscapeBuffer {
pub fn new() -> Self {
Self(Vec::new())
}
pub fn finish(self) -> String {
unsafe { String::from_utf8_unchecked(self.0) }
}
}
#[cfg(feature = "json")]
impl std::io::Write for JsonEscapeBuffer {
fn write(&mut self, bytes: &[u8]) -> std::io::Result<usize> {
let mut last = 0;
for (index, byte) in bytes.iter().enumerate() {
let escaped = match byte {
b'&' => Some(br#"\u0026"#),
b'\'' => Some(br#"\u0027"#),
b'<' => Some(br#"\u003c"#),
b'>' => Some(br#"\u003e"#),
_ => None,
};
if let Some(escaped) = escaped {
self.0.extend(&bytes[last..index]);
self.0.extend(escaped);
last = index + 1;
}
}
self.0.extend(&bytes[last..]);
Ok(bytes.len())
}
fn flush(&mut self) -> std::io::Result<()> {
Ok(())
}
}
#[cfg(test)]
mod tests {
use super::*;
use std::string::ToString;
#[test]
fn test_escape() {
assert_eq!(escape("", Html).to_string(), "");
assert_eq!(escape("<&>", Html).to_string(), "<&>");
assert_eq!(escape("bla&", Html).to_string(), "bla&");
assert_eq!(escape("<foo", Html).to_string(), "<foo");
assert_eq!(escape("bla&h", Html).to_string(), "bla&h");
}
}
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