Merge pull request #1473 from RReverser/chars

Add JsString <-> char conversions
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Alex Crichton 2019-04-24 09:49:56 -07:00 committed by GitHub
commit cc89109004
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2 changed files with 48 additions and 0 deletions

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@ -3641,6 +3641,36 @@ impl JsString {
) -> impl ExactSizeIterator<Item = u16> + DoubleEndedIterator<Item = u16> + 'a {
(0..self.length()).map(move |i| self.char_code_at(i) as u16)
}
/// If this string consists of a single Unicode code point, then this method
/// converts it into a Rust `char` without doing any allocations.
///
/// If this JS value is not a valid UTF-8 or consists of more than a single
/// codepoint, then this returns `None`.
///
/// Note that a single Unicode code point might be represented as more than
/// one code unit on the JavaScript side. For example, a JavaScript string
/// `"\uD801\uDC37"` is actually a single Unicode code point U+10437 which
/// corresponds to a character '𐐷'.
pub fn as_char(&self) -> Option<char> {
let len = self.length();
if len == 0 || len > 2 {
return None;
}
// This will be simplified when definitions are fixed:
// https://github.com/rustwasm/wasm-bindgen/issues/1362
let cp = self.code_point_at(0).as_f64().unwrap_throw() as u32;
let c = std::char::from_u32(cp)?;
if c.len_utf16() as u32 == len {
Some(c)
} else {
None
}
}
}
impl PartialEq<str> for JsString {
@ -3679,6 +3709,13 @@ impl From<String> for JsString {
}
}
impl From<char> for JsString {
#[inline]
fn from(c: char) -> Self {
JsString::from_code_point1(c as u32).unwrap_throw()
}
}
impl<'a> From<&'a JsString> for String {
fn from(s: &'a JsString) -> Self {
s.obj.as_string().unwrap_throw()

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@ -553,3 +553,14 @@ fn is_valid_utf16() {
assert!(!JsString::from_char_code1(0xd800).is_valid_utf16());
assert!(!JsString::from_char_code1(0xdc00).is_valid_utf16());
}
#[wasm_bindgen_test]
fn as_char() {
assert_eq!(JsString::from('a').as_char(), Some('a'));
assert_eq!(JsString::from('🥑').as_char(), Some('🥑'));
assert_eq!(JsString::from("").as_char(), None);
assert_eq!(JsString::from("ab").as_char(), None);
assert_eq!(JsString::from_char_code1(0xd800).as_char(), None);
assert_eq!(JsString::from_char_code1(0xdc00).as_char(), None);
assert_eq!(JsString::from_char_code1(0xdfff).as_char(), None);
}