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 core::borrow::Borrow;
6use core::iter::FromIterator;
7use litemap::LiteMap;
8
9use super::Key;
10use super::Value;
11
12/// A list of [`Key`]-[`Value`] pairs representing functional information
13/// about content transformations.
14///
15/// Here are examples of fields used in Unicode:
16/// - `s0`, `d0` - Transform source/destination
17/// - `t0` - Machine Translation
18/// - `h0` - Hybrid Locale Identifiers
19///
20/// You can find the full list in [`Unicode BCP 47 T Extension`] section of LDML.
21///
22/// [`Unicode BCP 47 T Extension`]: https://unicode.org/reports/tr35/tr35.html#BCP47_T_Extension
23///
24/// # Examples
25///
26/// ```
27/// use icu::locid::extensions::transform::{key, Fields, Value};
28///
29/// let value = "hybrid".parse::<Value>().expect("Failed to parse a Value.");
30/// let fields = [(key!("h0"), value)].into_iter().collect::<Fields>();
31///
32/// assert_eq!(&fields.to_string(), "h0-hybrid");
33/// ```
34#[derive(Clone, PartialEq, Eq, Debug, Default, Hash, PartialOrd, Ord)]
35pub struct Fields(LiteMap<Key, Value>);
36
37impl Fields {
38 /// Returns a new empty list of key-value pairs. Same as [`default()`](Default::default()), but is `const`.
39 ///
40 /// # Examples
41 ///
42 /// ```
43 /// use icu::locid::extensions::transform::Fields;
44 ///
45 /// assert_eq!(Fields::new(), Fields::default());
46 /// ```
47 #[inline]
48 pub const fn new() -> Self {
49 Self(LiteMap::new())
50 }
51
52 /// Returns `true` if there are no fields.
53 ///
54 /// # Examples
55 ///
56 /// ```
57 /// use icu::locid::locale;
58 /// use icu::locid::Locale;
59 ///
60 /// let loc1 = Locale::try_from_bytes(b"und-t-h0-hybrid").unwrap();
61 /// let loc2 = locale!("und-u-ca-buddhist");
62 ///
63 /// assert!(!loc1.extensions.transform.fields.is_empty());
64 /// assert!(loc2.extensions.transform.fields.is_empty());
65 /// ```
66 pub fn is_empty(&self) -> bool {
67 self.0.is_empty()
68 }
69
70 /// Empties the [`Fields`] list.
71 ///
72 /// Returns the old list.
73 ///
74 /// # Examples
75 ///
76 /// ```
77 /// use icu::locid::extensions::transform::{key, Fields, Value};
78 ///
79 /// let value = "hybrid".parse::<Value>().expect("Failed to parse a Value.");
80 /// let mut fields = [(key!("h0"), value)].into_iter().collect::<Fields>();
81 ///
82 /// assert_eq!(&fields.to_string(), "h0-hybrid");
83 ///
84 /// fields.clear();
85 ///
86 /// assert_eq!(fields, Fields::new());
87 /// ```
88 pub fn clear(&mut self) -> Self {
89 core::mem::take(self)
90 }
91
92 /// Returns `true` if the list contains a [`Value`] for the specified [`Key`].
93 ///
94 ///
95 /// # Examples
96 ///
97 /// ```
98 /// use icu::locid::extensions::transform::{Fields, Key, Value};
99 ///
100 /// let key: Key = "h0".parse().expect("Failed to parse a Key.");
101 /// let value: Value = "hybrid".parse().expect("Failed to parse a Value.");
102 /// let mut fields = [(key, value)].into_iter().collect::<Fields>();
103 ///
104 /// let key: Key = "h0".parse().expect("Failed to parse a Key.");
105 /// assert!(&fields.contains_key(&key));
106 /// ```
107 pub fn contains_key<Q>(&self, key: &Q) -> bool
108 where
109 Key: Borrow<Q>,
110 Q: Ord,
111 {
112 self.0.contains_key(key)
113 }
114
115 /// Returns a reference to the [`Value`] corresponding to the [`Key`].
116 ///
117 ///
118 /// # Examples
119 ///
120 /// ```
121 /// use icu::locid::extensions::transform::{key, Fields, Value};
122 ///
123 /// let value = "hybrid".parse::<Value>().unwrap();
124 /// let fields = [(key!("h0"), value.clone())]
125 /// .into_iter()
126 /// .collect::<Fields>();
127 ///
128 /// assert_eq!(fields.get(&key!("h0")), Some(&value));
129 /// ```
130 pub fn get<Q>(&self, key: &Q) -> Option<&Value>
131 where
132 Key: Borrow<Q>,
133 Q: Ord,
134 {
135 self.0.get(key)
136 }
137
138 /// Sets the specified keyword, returning the old value if it already existed.
139 ///
140 /// # Examples
141 ///
142 /// ```
143 /// use icu::locid::extensions::transform::{key, Value};
144 /// use icu::locid::Locale;
145 ///
146 /// let lower = "lower".parse::<Value>().expect("valid extension subtag");
147 /// let casefold = "casefold".parse::<Value>().expect("valid extension subtag");
148 ///
149 /// let mut loc: Locale = "en-t-hi-d0-casefold"
150 /// .parse()
151 /// .expect("valid BCP-47 identifier");
152 /// let old_value = loc.extensions.transform.fields.set(key!("d0"), lower);
153 ///
154 /// assert_eq!(old_value, Some(casefold));
155 /// assert_eq!(loc, "en-t-hi-d0-lower".parse().unwrap());
156 /// ```
157 pub fn set(&mut self, key: Key, value: Value) -> Option<Value> {
158 self.0.insert(key, value)
159 }
160
161 /// Retains a subset of fields as specified by the predicate function.
162 ///
163 /// # Examples
164 ///
165 /// ```
166 /// use icu::locid::extensions::transform::key;
167 /// use icu::locid::Locale;
168 ///
169 /// let mut loc: Locale = "und-t-h0-hybrid-d0-hex-m0-xml".parse().unwrap();
170 ///
171 /// loc.extensions
172 /// .transform
173 /// .fields
174 /// .retain_by_key(|&k| k == key!("h0"));
175 /// assert_eq!(loc, "und-t-h0-hybrid".parse().unwrap());
176 ///
177 /// loc.extensions
178 /// .transform
179 /// .fields
180 /// .retain_by_key(|&k| k == key!("d0"));
181 /// assert_eq!(loc, Locale::UND);
182 /// ```
183 pub fn retain_by_key<F>(&mut self, mut predicate: F)
184 where
185 F: FnMut(&Key) -> bool,
186 {
187 self.0.retain(|k, _| predicate(k))
188 }
189
190 pub(crate) fn for_each_subtag_str<E, F>(&self, f: &mut F) -> Result<(), E>
191 where
192 F: FnMut(&str) -> Result<(), E>,
193 {
194 for (k, v) in self.0.iter() {
195 f(k.as_str())?;
196 v.for_each_subtag_str(f)?;
197 }
198 Ok(())
199 }
200
201 /// This needs to be its own method to help with type inference in helpers.rs
202 #[cfg(test)]
203 pub(crate) fn from_tuple_vec(v: Vec<(Key, Value)>) -> Self {
204 v.into_iter().collect()
205 }
206}
207
208impl From<LiteMap<Key, Value>> for Fields {
209 fn from(map: LiteMap<Key, Value>) -> Self {
210 Self(map)
211 }
212}
213
214impl FromIterator<(Key, Value)> for Fields {
215 fn from_iter<I: IntoIterator<Item = (Key, Value)>>(iter: I) -> Self {
216 LiteMap::from_iter(iter).into()
217 }
218}
219
220impl_writeable_for_key_value!(Fields, "h0", "hybrid", "m0", "m0-true");
221