unicode_normalization_alignments/
quick_check.rs

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
use lookups::canonical_combining_class;
use stream_safe;
use tables;
use UnicodeNormalization;

/// The QuickCheck algorithm can quickly determine if a text is or isn't
/// normalized without any allocations in many cases, but it has to be able to
/// return `Maybe` when a full decomposition and recomposition is necessary.
#[derive(Debug, Eq, PartialEq)]
pub enum IsNormalized {
    /// The text is definitely normalized.
    Yes,
    /// The text is definitely not normalized.
    No,
    /// The text may be normalized.
    Maybe,
}

// https://unicode.org/reports/tr15/#Detecting_Normalization_Forms
#[inline]
fn quick_check<F, I>(s: I, is_allowed: F, stream_safe: bool) -> IsNormalized
where
    I: Iterator<Item = char>,
    F: Fn(char) -> IsNormalized,
{
    let mut last_cc = 0u8;
    let mut nonstarter_count = 0;
    let mut result = IsNormalized::Yes;
    for ch in s {
        // For ASCII we know it's always allowed and a starter
        if ch <= '\x7f' {
            last_cc = 0;
            nonstarter_count = 0;
            continue;
        }

        // Otherwise, lookup the combining class and QC property
        let cc = canonical_combining_class(ch);
        if last_cc > cc && cc != 0 {
            return IsNormalized::No;
        }
        match is_allowed(ch) {
            IsNormalized::Yes => (),
            IsNormalized::No => return IsNormalized::No,
            IsNormalized::Maybe => {
                result = IsNormalized::Maybe;
            }
        }
        if stream_safe {
            let decomp = stream_safe::classify_nonstarters(ch);

            // If we're above `MAX_NONSTARTERS`, we're definitely *not*
            // stream-safe normalized.
            if nonstarter_count + decomp.leading_nonstarters > stream_safe::MAX_NONSTARTERS {
                return IsNormalized::No;
            }
            if decomp.leading_nonstarters == decomp.decomposition_len {
                nonstarter_count += decomp.decomposition_len;
            } else {
                nonstarter_count = decomp.trailing_nonstarters;
            }
        }
        last_cc = cc;
    }
    result
}

/// Quickly check if a string is in NFC, potentially returning
/// `IsNormalized::Maybe` if further checks are necessary.  In this case a check
/// like `s.chars().nfc().eq(s.chars())` should suffice.
#[inline]
pub fn is_nfc_quick<I: Iterator<Item = char>>(s: I) -> IsNormalized {
    quick_check(s, tables::qc_nfc, false)
}

/// Quickly check if a string is in NFKC.
#[inline]
pub fn is_nfkc_quick<I: Iterator<Item = char>>(s: I) -> IsNormalized {
    quick_check(s, tables::qc_nfkc, false)
}

/// Quickly check if a string is in NFD.
#[inline]
pub fn is_nfd_quick<I: Iterator<Item = char>>(s: I) -> IsNormalized {
    quick_check(s, tables::qc_nfd, false)
}

/// Quickly check if a string is in NFKD.
#[inline]
pub fn is_nfkd_quick<I: Iterator<Item = char>>(s: I) -> IsNormalized {
    quick_check(s, tables::qc_nfkd, false)
}

/// Quickly check if a string is Stream-Safe NFC.
#[inline]
pub fn is_nfc_stream_safe_quick<I: Iterator<Item = char>>(s: I) -> IsNormalized {
    quick_check(s, tables::qc_nfc, true)
}

/// Quickly check if a string is Stream-Safe NFD.
#[inline]
pub fn is_nfd_stream_safe_quick<I: Iterator<Item = char>>(s: I) -> IsNormalized {
    quick_check(s, tables::qc_nfd, true)
}

/// Authoritatively check if a string is in NFC.
#[inline]
pub fn is_nfc(s: &str) -> bool {
    match is_nfc_quick(s.chars()) {
        IsNormalized::Yes => true,
        IsNormalized::No => false,
        IsNormalized::Maybe => s.chars().eq(s.chars().nfc().map(|c| c.0)),
    }
}

/// Authoritatively check if a string is in NFKC.
#[inline]
pub fn is_nfkc(s: &str) -> bool {
    match is_nfkc_quick(s.chars()) {
        IsNormalized::Yes => true,
        IsNormalized::No => false,
        IsNormalized::Maybe => s.chars().eq(s.chars().nfkc().map(|c| c.0)),
    }
}

/// Authoritatively check if a string is in NFD.
#[inline]
pub fn is_nfd(s: &str) -> bool {
    match is_nfd_quick(s.chars()) {
        IsNormalized::Yes => true,
        IsNormalized::No => false,
        IsNormalized::Maybe => s.chars().eq(s.chars().nfd().map(|c| c.0)),
    }
}

/// Authoritatively check if a string is in NFKD.
#[inline]
pub fn is_nfkd(s: &str) -> bool {
    match is_nfkd_quick(s.chars()) {
        IsNormalized::Yes => true,
        IsNormalized::No => false,
        IsNormalized::Maybe => s.chars().eq(s.chars().nfkd().map(|c| c.0)),
    }
}

/// Authoritatively check if a string is Stream-Safe NFC.
#[inline]
pub fn is_nfc_stream_safe(s: &str) -> bool {
    match is_nfc_stream_safe_quick(s.chars()) {
        IsNormalized::Yes => true,
        IsNormalized::No => false,
        IsNormalized::Maybe => s.chars().eq(s.chars().stream_safe().nfc().map(|c| c.0)),
    }
}

/// Authoritatively check if a string is Stream-Safe NFD.
#[inline]
pub fn is_nfd_stream_safe(s: &str) -> bool {
    match is_nfd_stream_safe_quick(s.chars()) {
        IsNormalized::Yes => true,
        IsNormalized::No => false,
        IsNormalized::Maybe => s.chars().eq(s.chars().stream_safe().nfd().map(|c| c.0)),
    }
}

#[cfg(test)]
mod tests {
    use super::{is_nfc_stream_safe_quick, is_nfd_stream_safe_quick, IsNormalized};

    #[test]
    fn test_stream_safe_nfd() {
        let okay = "Da\u{031b}\u{0316}\u{0317}\u{0318}\u{0319}\u{031c}\u{031d}\u{0300}\u{0301}\u{0302}\u{0303}\u{0304}\u{0305}\u{0306}\u{0307}\u{0308}\u{0309}\u{030a}\u{030b}\u{030c}\u{030d}\u{030e}\u{030f}\u{0310}\u{0311}\u{0312}\u{0313}\u{0314}\u{0315}\u{031a}ngerzone";
        assert_eq!(is_nfd_stream_safe_quick(okay.chars()), IsNormalized::Yes);

        let too_much = "Da\u{031b}\u{0316}\u{0317}\u{0318}\u{0319}\u{031c}\u{031d}\u{031e}\u{0300}\u{0301}\u{0302}\u{0303}\u{0304}\u{0305}\u{0306}\u{0307}\u{0308}\u{0309}\u{030a}\u{030b}\u{030c}\u{030d}\u{030e}\u{030f}\u{0310}\u{0311}\u{0312}\u{0313}\u{0314}\u{0315}\u{031a}ngerzone";
        assert_eq!(is_nfd_stream_safe_quick(too_much.chars()), IsNormalized::No);
    }

    #[test]
    fn test_stream_safe_nfc() {
        let okay = "ok\u{e0}\u{031b}\u{0316}\u{0317}\u{0318}\u{0319}\u{031c}\u{031d}\u{0301}\u{0302}\u{0303}\u{0304}\u{0305}\u{0306}\u{0307}\u{0308}\u{0309}\u{030a}\u{030b}\u{030c}\u{030d}\u{030e}\u{030f}\u{0310}\u{0311}\u{0312}\u{0313}\u{0314}\u{0315}\u{031a}y";
        assert_eq!(is_nfc_stream_safe_quick(okay.chars()), IsNormalized::Maybe);

        let too_much = "not ok\u{e0}\u{031b}\u{0316}\u{0317}\u{0318}\u{0319}\u{031c}\u{031d}\u{031e}\u{0301}\u{0302}\u{0303}\u{0304}\u{0305}\u{0306}\u{0307}\u{0308}\u{0309}\u{030a}\u{030b}\u{030c}\u{030d}\u{030e}\u{030f}\u{0310}\u{0311}\u{0312}\u{0313}\u{0314}\u{0315}\u{031a}y";
        assert_eq!(is_nfc_stream_safe_quick(too_much.chars()), IsNormalized::No);
    }
}