handlebars/
support.rs

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1pub mod str {
2    use std::io::{Result, Write};
3
4    use crate::Output;
5
6    #[derive(Debug)]
7    pub struct StringWriter {
8        buf: Vec<u8>,
9    }
10
11    impl Default for StringWriter {
12        fn default() -> Self {
13            Self::new()
14        }
15    }
16
17    impl StringWriter {
18        pub fn new() -> StringWriter {
19            StringWriter {
20                buf: Vec::with_capacity(8 * 1024),
21            }
22        }
23
24        pub fn into_string(self) -> String {
25            String::from_utf8(self.buf).unwrap_or_default()
26        }
27    }
28
29    impl Write for StringWriter {
30        fn write(&mut self, buf: &[u8]) -> Result<usize> {
31            self.buf.extend_from_slice(buf);
32            Ok(buf.len())
33        }
34
35        fn flush(&mut self) -> Result<()> {
36            Ok(())
37        }
38    }
39
40    /// See https://github.com/handlebars-lang/handlebars.js/blob/37411901da42200ced8e1a7fc2f67bf83526b497/lib/handlebars/utils.js#L1
41    pub fn escape_html(s: &str) -> String {
42        let mut output = String::new();
43        for c in s.chars() {
44            match c {
45                '<' => output.push_str("&lt;"),
46                '>' => output.push_str("&gt;"),
47                '"' => output.push_str("&quot;"),
48                '&' => output.push_str("&amp;"),
49                '\'' => output.push_str("&#x27;"),
50                '`' => output.push_str("&#x60;"),
51                '=' => output.push_str("&#x3D;"),
52                _ => output.push(c),
53            }
54        }
55        output
56    }
57
58    /// add indent for lines but last
59    pub fn with_indent(s: &str, indent: &str) -> String {
60        let mut output = String::new();
61
62        let mut it = s.chars().peekable();
63        while let Some(c) = it.next() {
64            output.push(c);
65            // check if c is not the last character, we don't append
66            // indent for last line break
67            if c == '\n' && it.peek().is_some() {
68                output.push_str(indent);
69            }
70        }
71
72        output
73    }
74
75    /// like `with_indent`, but writing straight into the output
76    pub fn write_indented(s: &str, indent: &str, w: &mut dyn Output) -> std::io::Result<()> {
77        let mut i = 0;
78        let len = s.len();
79        loop {
80            let Some(next_newline) = s[i..].find('\n') else {
81                w.write(&s[i..])?;
82                return Ok(());
83            };
84            w.write(&s[i..i + next_newline + 1])?;
85            i += next_newline + 1;
86            if i == len {
87                return Ok(());
88            }
89            w.write(indent)?;
90        }
91    }
92
93    #[inline]
94    pub(crate) fn whitespace_matcher(c: char) -> bool {
95        c == ' ' || c == '\t'
96    }
97
98    #[inline]
99    pub(crate) fn newline_matcher(c: char) -> bool {
100        c == '\n' || c == '\r'
101    }
102
103    #[inline]
104    pub(crate) fn strip_first_newline(s: &str) -> &str {
105        if let Some(s) = s.strip_prefix("\r\n") {
106            s
107        } else if let Some(s) = s.strip_prefix('\n') {
108            s
109        } else {
110            s
111        }
112    }
113
114    pub(crate) fn find_trailing_whitespace_chars(s: &str) -> Option<&str> {
115        let trimmed = s.trim_end_matches(whitespace_matcher);
116        if trimmed.len() == s.len() {
117            None
118        } else {
119            Some(&s[trimmed.len()..])
120        }
121    }
122
123    pub(crate) fn ends_with_empty_line(text: &str) -> bool {
124        let s = text.trim_end_matches(whitespace_matcher);
125        // also matches when text is just whitespaces
126        s.ends_with(newline_matcher) || s.is_empty()
127    }
128
129    pub(crate) fn starts_with_empty_line(text: &str) -> bool {
130        text.trim_start_matches(whitespace_matcher)
131            .starts_with(newline_matcher)
132    }
133
134    #[cfg(test)]
135    mod test {
136        use crate::support::str::StringWriter;
137        use std::io::Write;
138
139        #[test]
140        fn test_string_writer() {
141            let mut sw = StringWriter::new();
142
143            let _ = sw.write("hello".to_owned().into_bytes().as_ref());
144            let _ = sw.write("world".to_owned().into_bytes().as_ref());
145
146            let s = sw.into_string();
147            assert_eq!(s, "helloworld".to_string());
148        }
149    }
150}
handlebars/support.rs

handlebars/
support.rs
