xml/
escape.rs

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1//! Contains functions for performing XML special characters escaping.
2
3use std::borrow::Cow;
4
5enum Value {
6    Char(char),
7    Str(&'static str)
8}
9
10impl Value {
11    fn dispatch_for_attribute(c: char) -> Value {
12        match c {
13            '<'  => Value::Str("&lt;"),
14            '>'  => Value::Str("&gt;"),
15            '"'  => Value::Str("&quot;"),
16            '\'' => Value::Str("&apos;"),
17            '&'  => Value::Str("&amp;"),
18            '\n' => Value::Str("&#xA;"),
19            '\r' => Value::Str("&#xD;"),
20            _    => Value::Char(c)
21        }
22    }
23
24    fn dispatch_for_pcdata(c: char) -> Value {
25        match c {
26            '<'  => Value::Str("&lt;"),
27            '&'  => Value::Str("&amp;"),
28            _    => Value::Char(c)
29        }
30    }
31}
32
33enum Process<'a> {
34    Borrowed(&'a str),
35    Owned(String)
36}
37
38impl<'a> Process<'a> {
39    fn process(&mut self, (i, next): (usize, Value)) {
40        match next {
41            Value::Str(s) => match *self {
42                Process::Owned(ref mut o) => o.push_str(s),
43                Process::Borrowed(b) => {
44                    let mut r = String::with_capacity(b.len() + s.len());
45                    r.push_str(&b[..i]);
46                    r.push_str(s);
47                    *self = Process::Owned(r);
48                }
49            },
50            Value::Char(c) => match *self {
51                Process::Borrowed(_) => {}
52                Process::Owned(ref mut o) => o.push(c)
53            }
54        }
55    }
56
57    fn into_result(self) -> Cow<'a, str> {
58        match self {
59            Process::Borrowed(b) => Cow::Borrowed(b),
60            Process::Owned(o) => Cow::Owned(o)
61        }
62    }
63}
64
65impl<'a> Extend<(usize, Value)> for Process<'a> {
66    fn extend<I: IntoIterator<Item=(usize, Value)>>(&mut self, it: I) {
67        for v in it.into_iter() {
68            self.process(v);
69        }
70    }
71}
72
73fn escape_str(s: &str, dispatch: fn(char) -> Value) -> Cow<str> {
74    let mut p = Process::Borrowed(s);
75    p.extend(s.char_indices().map(|(ind, c)| (ind, dispatch(c))));
76    p.into_result()
77}
78
79/// Performs escaping of common XML characters inside an attribute value.
80///
81/// This function replaces several important markup characters with their
82/// entity equivalents:
83///
84/// * `<` → `&lt;`
85/// * `>` → `&gt;`
86/// * `"` → `&quot;`
87/// * `'` → `&apos;`
88/// * `&` → `&amp;`
89///
90/// The resulting string is safe to use inside XML attribute values or in PCDATA sections.
91///
92/// Does not perform allocations if the given string does not contain escapable characters.
93#[inline]
94pub fn escape_str_attribute(s: &str) -> Cow<str> {
95    escape_str(s, Value::dispatch_for_attribute)
96}
97
98/// Performs escaping of common XML characters inside PCDATA.
99///
100/// This function replaces several important markup characters with their
101/// entity equivalents:
102///
103/// * `<` → `&lt;`
104/// * `&` → `&amp;`
105///
106/// The resulting string is safe to use inside PCDATA sections but NOT inside attribute values.
107///
108/// Does not perform allocations if the given string does not contain escapable characters.
109#[inline]
110pub fn escape_str_pcdata(s: &str) -> Cow<str> {
111    escape_str(s, Value::dispatch_for_pcdata)
112}
113
114#[cfg(test)]
115mod tests {
116    use super::{escape_str_pcdata, escape_str_attribute};
117
118    // TODO: add more tests
119
120    #[test]
121    fn test_escape_multibyte_code_points() {
122        assert_eq!(escape_str_attribute("☃<"), "☃&lt;");
123        assert_eq!(escape_str_pcdata("☃<"), "☃&lt;");
124    }
125}
126
xml/escape.rs

xml/
escape.rs
