icu_locid/extensions/transform/
value.rs

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1// This file is part of ICU4X. For terms of use, please see the file
2// called LICENSE at the top level of the ICU4X source tree
3// (online at: https://github.com/unicode-org/icu4x/blob/main/LICENSE ).
4
5use crate::parser::{ParserError, SubtagIterator};
6use crate::shortvec::ShortBoxSlice;
7use core::ops::RangeInclusive;
8use core::str::FromStr;
9use tinystr::TinyAsciiStr;
10
11/// A value used in a list of [`Fields`](super::Fields).
12///
13/// The value has to be a sequence of one or more alphanumerical strings
14/// separated by `-`.
15/// Each part of the sequence has to be no shorter than three characters and no
16/// longer than 8.
17///
18/// # Examples
19///
20/// ```
21/// use icu::locid::extensions::transform::Value;
22///
23/// "hybrid".parse::<Value>().expect("Valid Value.");
24///
25/// "hybrid-foobar".parse::<Value>().expect("Valid Value.");
26///
27/// "no".parse::<Value>().expect_err("Invalid Value.");
28/// ```
29#[derive(Debug, PartialEq, Eq, Clone, Hash, PartialOrd, Ord, Default)]
30pub struct Value(ShortBoxSlice<TinyAsciiStr<{ *TYPE_LENGTH.end() }>>);
31
32const TYPE_LENGTH: RangeInclusive<usize> = 3..=8;
33const TRUE_TVALUE: TinyAsciiStr<8> = tinystr::tinystr!(8, "true");
34
35impl Value {
36    /// A constructor which takes a utf8 slice, parses it and
37    /// produces a well-formed [`Value`].
38    ///
39    /// # Examples
40    ///
41    /// ```
42    /// use icu::locid::extensions::transform::Value;
43    ///
44    /// let value = Value::try_from_bytes(b"hybrid").expect("Parsing failed.");
45    /// ```
46    pub fn try_from_bytes(input: &[u8]) -> Result<Self, ParserError> {
47        let mut v = ShortBoxSlice::default();
48        let mut has_value = false;
49
50        for subtag in SubtagIterator::new(input) {
51            if !Self::is_type_subtag(subtag) {
52                return Err(ParserError::InvalidExtension);
53            }
54            has_value = true;
55            let val =
56                TinyAsciiStr::from_bytes(subtag).map_err(|_| ParserError::InvalidExtension)?;
57            if val != TRUE_TVALUE {
58                v.push(val);
59            }
60        }
61
62        if !has_value {
63            return Err(ParserError::InvalidExtension);
64        }
65        Ok(Self(v))
66    }
67
68    pub(crate) fn from_short_slice_unchecked(
69        input: ShortBoxSlice<TinyAsciiStr<{ *TYPE_LENGTH.end() }>>,
70    ) -> Self {
71        Self(input)
72    }
73
74    pub(crate) fn is_type_subtag(t: &[u8]) -> bool {
75        TYPE_LENGTH.contains(&t.len()) && t.iter().all(u8::is_ascii_alphanumeric)
76    }
77
78    pub(crate) fn parse_subtag(
79        t: &[u8],
80    ) -> Result<Option<TinyAsciiStr<{ *TYPE_LENGTH.end() }>>, ParserError> {
81        let s = TinyAsciiStr::from_bytes(t).map_err(|_| ParserError::InvalidSubtag)?;
82        if !TYPE_LENGTH.contains(&t.len()) || !s.is_ascii_alphanumeric() {
83            return Err(ParserError::InvalidExtension);
84        }
85
86        let s = s.to_ascii_lowercase();
87
88        if s == TRUE_TVALUE {
89            Ok(None)
90        } else {
91            Ok(Some(s))
92        }
93    }
94
95    pub(crate) fn for_each_subtag_str<E, F>(&self, f: &mut F) -> Result<(), E>
96    where
97        F: FnMut(&str) -> Result<(), E>,
98    {
99        if self.0.is_empty() {
100            f("true")?;
101        } else {
102            self.0.iter().map(TinyAsciiStr::as_str).try_for_each(f)?;
103        }
104        Ok(())
105    }
106}
107
108impl FromStr for Value {
109    type Err = ParserError;
110
111    fn from_str(source: &str) -> Result<Self, Self::Err> {
112        Self::try_from_bytes(source.as_bytes())
113    }
114}
115
116impl_writeable_for_each_subtag_str_no_test!(Value, selff, selff.0.is_empty() => alloc::borrow::Cow::Borrowed("true"));
117
118#[test]
119fn test_writeable() {
120    use writeable::assert_writeable_eq;
121
122    let hybrid = "hybrid".parse().unwrap();
123    let foobar = "foobar".parse().unwrap();
124
125    assert_writeable_eq!(Value::default(), "true");
126    assert_writeable_eq!(
127        Value::from_short_slice_unchecked(vec![hybrid].into()),
128        "hybrid"
129    );
130    assert_writeable_eq!(
131        Value::from_short_slice_unchecked(vec![hybrid, foobar].into()),
132        "hybrid-foobar"
133    );
134}
icu_locid/extensions/transform/value.rs

icu_locid/extensions/transform/
value.rs
