syntect/
escape.rs

1// Copyright 2013 The Rust Project Developers. See the COPYRIGHT
2// file at the top-level directory of this distribution and at
3// http://rust-lang.org/COPYRIGHT.
4//
5// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
6// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
7// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
8// option. This file may not be copied, modified, or distributed
9// except according to those terms.
10
11//! HTML Escaping
12//!
13//! This module contains one unit-struct which can be used to HTML-escape a
14//! string of text (for use in a format string).
15
16use std::fmt;
17
18/// Wrapper struct which will emit the HTML-escaped version of the contained
19/// string when passed to a format string.
20pub struct Escape<'a>(pub &'a str);
21
22impl<'a> fmt::Display for Escape<'a> {
23    fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
24        // Because the internet is always right, turns out there's not that many
25        // characters to escape: http://stackoverflow.com/questions/7381974
26        let Escape(s) = *self;
27        let pile_o_bits = s;
28        let mut last = 0;
29        for (i, ch) in s.bytes().enumerate() {
30            match ch as char {
31                '<' | '>' | '&' | '\'' | '"' => {
32                    fmt.write_str(&pile_o_bits[last..i])?;
33                    let s = match ch as char {
34                        '>' => "&gt;",
35                        '<' => "&lt;",
36                        '&' => "&amp;",
37                        '\'' => "&#39;",
38                        '"' => "&quot;",
39                        _ => unreachable!(),
40                    };
41                    fmt.write_str(s)?;
42                    last = i + 1;
43                }
44                _ => {}
45            }
46        }
47
48        if last < s.len() {
49            fmt.write_str(&pile_o_bits[last..])?;
50        }
51        Ok(())
52    }
53}