indoc/
unindent.rs

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1use std::slice::Split;
2
3pub fn unindent(s: &str) -> String {
4    let preserve_empty_first_line = false;
5    do_unindent(s, preserve_empty_first_line)
6}
7
8// Compute the maximal number of spaces that can be removed from every line, and
9// remove them.
10pub fn unindent_bytes(s: &[u8]) -> Vec<u8> {
11    let preserve_empty_first_line = false;
12    do_unindent_bytes(s, preserve_empty_first_line)
13}
14
15pub(crate) fn do_unindent(s: &str, preserve_empty_first_line: bool) -> String {
16    let bytes = s.as_bytes();
17    let unindented = do_unindent_bytes(bytes, preserve_empty_first_line);
18    String::from_utf8(unindented).unwrap()
19}
20
21fn do_unindent_bytes(s: &[u8], preserve_empty_first_line: bool) -> Vec<u8> {
22    // Document may start either on the same line as opening quote or
23    // on the next line
24    let ignore_first_line =
25        !preserve_empty_first_line && (s.starts_with(b"\n") || s.starts_with(b"\r\n"));
26
27    // Largest number of spaces that can be removed from every
28    // non-whitespace-only line after the first
29    let spaces = s
30        .lines()
31        .skip(1)
32        .filter_map(count_spaces)
33        .min()
34        .unwrap_or(0);
35
36    let mut result = Vec::with_capacity(s.len());
37    for (i, line) in s.lines().enumerate() {
38        if i > 1 || (i == 1 && !ignore_first_line) {
39            result.push(b'\n');
40        }
41        if i == 0 {
42            // Do not un-indent anything on same line as opening quote
43            result.extend_from_slice(line);
44        } else if line.len() > spaces {
45            // Whitespace-only lines may have fewer than the number of spaces
46            // being removed
47            result.extend_from_slice(&line[spaces..]);
48        }
49    }
50    result
51}
52
53pub trait Unindent {
54    type Output;
55
56    fn unindent(&self) -> Self::Output;
57}
58
59impl Unindent for str {
60    type Output = String;
61
62    fn unindent(&self) -> Self::Output {
63        unindent(self)
64    }
65}
66
67impl Unindent for String {
68    type Output = String;
69
70    fn unindent(&self) -> Self::Output {
71        unindent(self)
72    }
73}
74
75impl Unindent for [u8] {
76    type Output = Vec<u8>;
77
78    fn unindent(&self) -> Self::Output {
79        unindent_bytes(self)
80    }
81}
82
83impl<'a, T: ?Sized + Unindent> Unindent for &'a T {
84    type Output = T::Output;
85
86    fn unindent(&self) -> Self::Output {
87        (**self).unindent()
88    }
89}
90
91// Number of leading spaces in the line, or None if the line is entirely spaces.
92fn count_spaces(line: &[u8]) -> Option<usize> {
93    for (i, ch) in line.iter().enumerate() {
94        if *ch != b' ' && *ch != b'\t' {
95            return Some(i);
96        }
97    }
98    None
99}
100
101// Based on core::str::StrExt.
102trait BytesExt {
103    fn lines(&self) -> Split<u8, fn(&u8) -> bool>;
104}
105
106impl BytesExt for [u8] {
107    fn lines(&self) -> Split<u8, fn(&u8) -> bool> {
108        fn is_newline(b: &u8) -> bool {
109            *b == b'\n'
110        }
111        let bytestring = if self.starts_with(b"\r\n") {
112            &self[1..]
113        } else {
114            self
115        };
116        bytestring.split(is_newline as fn(&u8) -> bool)
117    }
118}
indoc/unindent.rs

indoc/
unindent.rs
