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 [`Keywords`](super::Keywords).
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///
19/// # Examples
20///
21/// ```
22/// use icu::locid::extensions::unicode::{value, Value};
23/// use writeable::assert_writeable_eq;
24///
25/// assert_writeable_eq!(value!("gregory"), "gregory");
26/// assert_writeable_eq!(
27/// "islamic-civil".parse::<Value>().unwrap(),
28/// "islamic-civil"
29/// );
30///
31/// // The value "true" has the special, empty string representation
32/// assert_eq!(value!("true").to_string(), "");
33/// ```
34#[derive(Debug, PartialEq, Eq, Clone, Hash, PartialOrd, Ord, Default)]
35pub struct Value(ShortBoxSlice<TinyAsciiStr<{ *VALUE_LENGTH.end() }>>);
36
37const VALUE_LENGTH: RangeInclusive<usize> = 3..=8;
38const TRUE_VALUE: TinyAsciiStr<8> = tinystr::tinystr!(8, "true");
39
40impl Value {
41 /// A constructor which takes a utf8 slice, parses it and
42 /// produces a well-formed [`Value`].
43 ///
44 /// # Examples
45 ///
46 /// ```
47 /// use icu::locid::extensions::unicode::Value;
48 ///
49 /// Value::try_from_bytes(b"buddhist").expect("Parsing failed.");
50 /// ```
51 pub fn try_from_bytes(input: &[u8]) -> Result<Self, ParserError> {
52 let mut v = ShortBoxSlice::new();
53
54 if !input.is_empty() {
55 for subtag in SubtagIterator::new(input) {
56 let val = Self::subtag_from_bytes(subtag)?;
57 if let Some(val) = val {
58 v.push(val);
59 }
60 }
61 }
62 Ok(Self(v))
63 }
64
65 /// Const constructor for when the value contains only a single subtag.
66 ///
67 /// # Examples
68 ///
69 /// ```
70 /// use icu::locid::extensions::unicode::Value;
71 ///
72 /// Value::try_from_single_subtag(b"buddhist").expect("valid subtag");
73 /// Value::try_from_single_subtag(b"#####").expect_err("invalid subtag");
74 /// Value::try_from_single_subtag(b"foo-bar").expect_err("not a single subtag");
75 /// ```
76 pub const fn try_from_single_subtag(subtag: &[u8]) -> Result<Self, ParserError> {
77 match Self::subtag_from_bytes(subtag) {
78 Err(_) => Err(ParserError::InvalidExtension),
79 Ok(option) => Ok(Self::from_tinystr(option)),
80 }
81 }
82
83 #[doc(hidden)]
84 pub fn as_tinystr_slice(&self) -> &[TinyAsciiStr<8>] {
85 &self.0
86 }
87
88 #[doc(hidden)]
89 pub const fn as_single_subtag(&self) -> Option<&TinyAsciiStr<8>> {
90 self.0.single()
91 }
92
93 #[doc(hidden)]
94 pub const fn from_tinystr(subtag: Option<TinyAsciiStr<8>>) -> Self {
95 match subtag {
96 None => Self(ShortBoxSlice::new()),
97 Some(val) => {
98 debug_assert!(val.is_ascii_alphanumeric());
99 debug_assert!(!matches!(val, TRUE_VALUE));
100 Self(ShortBoxSlice::new_single(val))
101 }
102 }
103 }
104
105 pub(crate) fn from_short_slice_unchecked(input: ShortBoxSlice<TinyAsciiStr<8>>) -> Self {
106 Self(input)
107 }
108
109 #[doc(hidden)]
110 pub const fn subtag_from_bytes(bytes: &[u8]) -> Result<Option<TinyAsciiStr<8>>, ParserError> {
111 Self::parse_subtag_from_bytes_manual_slice(bytes, 0, bytes.len())
112 }
113
114 pub(crate) fn parse_subtag(t: &[u8]) -> Result<Option<TinyAsciiStr<8>>, ParserError> {
115 Self::parse_subtag_from_bytes_manual_slice(t, 0, t.len())
116 }
117
118 pub(crate) const fn parse_subtag_from_bytes_manual_slice(
119 bytes: &[u8],
120 start: usize,
121 end: usize,
122 ) -> Result<Option<TinyAsciiStr<8>>, ParserError> {
123 let slice_len = end - start;
124 if slice_len > *VALUE_LENGTH.end() || slice_len < *VALUE_LENGTH.start() {
125 return Err(ParserError::InvalidExtension);
126 }
127
128 match TinyAsciiStr::from_bytes_manual_slice(bytes, start, end) {
129 Ok(TRUE_VALUE) => Ok(None),
130 Ok(s) if s.is_ascii_alphanumeric() => Ok(Some(s.to_ascii_lowercase())),
131 Ok(_) => Err(ParserError::InvalidExtension),
132 Err(_) => Err(ParserError::InvalidSubtag),
133 }
134 }
135
136 pub(crate) fn for_each_subtag_str<E, F>(&self, f: &mut F) -> Result<(), E>
137 where
138 F: FnMut(&str) -> Result<(), E>,
139 {
140 self.0.iter().map(TinyAsciiStr::as_str).try_for_each(f)
141 }
142}
143
144impl FromStr for Value {
145 type Err = ParserError;
146
147 fn from_str(source: &str) -> Result<Self, Self::Err> {
148 Self::try_from_bytes(input:source.as_bytes())
149 }
150}
151
152impl_writeable_for_subtag_list!(Value, "islamic", "civil");
153
154/// A macro allowing for compile-time construction of valid Unicode [`Value`] subtag.
155///
156/// The macro only supports single-subtag values.
157///
158/// # Examples
159///
160/// ```
161/// use icu::locid::extensions::unicode::{key, value};
162/// use icu::locid::Locale;
163///
164/// let loc: Locale = "de-u-ca-buddhist".parse().unwrap();
165///
166/// assert_eq!(
167/// loc.extensions.unicode.keywords.get(&key!("ca")),
168/// Some(&value!("buddhist"))
169/// );
170/// ```
171///
172/// [`Value`]: crate::extensions::unicode::Value
173#[macro_export]
174#[doc(hidden)]
175macro_rules! extensions_unicode_value {
176 ($value:literal) => {{
177 // What we want:
178 // const R: $crate::extensions::unicode::Value =
179 // match $crate::extensions::unicode::Value::try_from_single_subtag($value.as_bytes()) {
180 // Ok(r) => r,
181 // #[allow(clippy::panic)] // const context
182 // _ => panic!(concat!("Invalid Unicode extension value: ", $value)),
183 // };
184 // Workaround until https://github.com/rust-lang/rust/issues/73255 lands:
185 const R: $crate::extensions::unicode::Value =
186 $crate::extensions::unicode::Value::from_tinystr(
187 match $crate::extensions::unicode::Value::subtag_from_bytes($value.as_bytes()) {
188 Ok(r) => r,
189 _ => panic!(concat!("Invalid Unicode extension value: ", $value)),
190 },
191 );
192 R
193 }};
194}
195#[doc(inline)]
196pub use extensions_unicode_value as value;
197