mirror of https://github.com/boa-dev/boa.git
Haled Odat
1 year ago
6 changed files with 358 additions and 203 deletions
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use crate::{builtins::string::is_trimmable_whitespace, JsString}; |
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use super::{is_ascii, JsStr, JsStrVariant}; |
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#[derive(Debug, Clone, Copy)] |
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pub enum JsStringSliceVariant<'a> { |
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U8Ascii(&'a str), |
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U8NonAscii(&'a str, usize), |
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U16Ascii(&'a [u16]), |
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U16NonAscii(&'a [u16]), |
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} |
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#[derive(Debug, Clone, Copy)] |
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pub struct JsStringSlice<'a> { |
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inner: JsStringSliceVariant<'a>, |
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} |
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impl<'a> JsStringSlice<'a> { |
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pub(crate) unsafe fn u8_ascii_unchecked(value: &'a str) -> Self { |
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debug_assert!(value.is_ascii(), "string must be ascii"); |
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Self { |
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inner: JsStringSliceVariant::U8Ascii(value), |
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} |
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} |
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pub(crate) unsafe fn u16_ascii_unchecked(value: &'a [u16]) -> Self { |
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debug_assert!(is_ascii(value), "string must be ascii"); |
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Self { |
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inner: JsStringSliceVariant::U16Ascii(value), |
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} |
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} |
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pub(crate) unsafe fn u8_non_ascii_unchecked(value: &'a str) -> Self { |
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debug_assert!(!value.is_ascii(), "string must not be ascii"); |
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let len = value.encode_utf16().count(); |
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Self { |
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inner: JsStringSliceVariant::U8NonAscii(value, len), |
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} |
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} |
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pub(crate) unsafe fn u16_non_ascii_unchecked(value: &'a [u16]) -> Self { |
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debug_assert!(!is_ascii(value), "string must not be ascii"); |
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Self { |
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inner: JsStringSliceVariant::U16NonAscii(value), |
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} |
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} |
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pub(crate) fn variant(self) -> JsStringSliceVariant<'a> { |
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self.inner |
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} |
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pub fn len(&self) -> usize { |
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match self.variant() { |
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JsStringSliceVariant::U8Ascii(s) => s.len(), |
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JsStringSliceVariant::U8NonAscii(_, len) => len, |
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JsStringSliceVariant::U16NonAscii(s) | JsStringSliceVariant::U16Ascii(s) => s.len(), |
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} |
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} |
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pub fn is_ascii(&self) -> bool { |
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matches!( |
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self.variant(), |
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JsStringSliceVariant::U8Ascii(_) | JsStringSliceVariant::U16Ascii(_) |
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) |
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} |
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/// Trims both leading and trailing space.
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#[inline] |
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#[must_use] |
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pub fn trim(&self) -> Self { |
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self.trim_start().trim_end() |
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} |
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/// Trims all leading space.
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#[inline] |
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#[must_use] |
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pub fn trim_start(&self) -> JsStringSlice<'a> { |
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match self.variant() { |
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JsStringSliceVariant::U8Ascii(s) => { |
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// SAFETY: Calling `trim_start()` on ASCII string always returns ASCII string, so this is safe.
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unsafe { JsStringSlice::u8_ascii_unchecked(s.trim_start()) } |
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} |
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JsStringSliceVariant::U8NonAscii(s, _) => JsStringSlice::from(s.trim_start()), |
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JsStringSliceVariant::U16Ascii(s) => { |
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let value = if let Some(left) = s.iter().copied().position(|r| { |
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!char::from_u32(u32::from(r)) |
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.map(is_trimmable_whitespace) |
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.unwrap_or_default() |
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}) { |
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&s[left..] |
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} else { |
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// SAFETY: An empty string is valid ASCII, so this is safe.
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return unsafe { JsStringSlice::u8_ascii_unchecked("") }; |
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}; |
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// SAFETY: Calling `trim_start()` on ASCII string always returns ASCII string, so this is safe.
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unsafe { JsStringSlice::u16_ascii_unchecked(value) } |
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} |
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JsStringSliceVariant::U16NonAscii(s) => { |
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let value = if let Some(left) = s.iter().copied().position(|r| { |
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!char::from_u32(u32::from(r)) |
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.map(is_trimmable_whitespace) |
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.unwrap_or_default() |
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}) { |
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&s[left..] |
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} else { |
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// SAFETY: An empty string is valid ASCII, so this is safe.
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return unsafe { JsStringSlice::u8_ascii_unchecked("") }; |
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}; |
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JsStringSlice::from(value) |
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} |
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} |
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} |
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/// Trims all trailing space.
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#[inline] |
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#[must_use] |
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pub fn trim_end(&self) -> JsStringSlice<'a> { |
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match self.variant() { |
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JsStringSliceVariant::U8Ascii(s) => { |
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// SAFETY: Calling `trim_start()` on ASCII string always returns ASCII string, so this is safe.
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unsafe { JsStringSlice::u8_ascii_unchecked(s.trim_end()) } |
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} |
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JsStringSliceVariant::U8NonAscii(s, _) => JsStringSlice::from(s.trim_end()), |
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JsStringSliceVariant::U16Ascii(s) => { |
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let value = if let Some(right) = s.iter().copied().rposition(|r| { |
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!char::from_u32(u32::from(r)) |
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.map(is_trimmable_whitespace) |
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.unwrap_or_default() |
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}) { |
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&s[..=right] |
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} else { |
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// SAFETY: An empty string is valid ASCII, so this is safe.
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return unsafe { JsStringSlice::u8_ascii_unchecked("") }; |
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}; |
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// SAFETY: Calling `trim_start()` on ASCII string always returns ASCII string, so this is safe.
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unsafe { JsStringSlice::u16_ascii_unchecked(value) } |
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} |
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JsStringSliceVariant::U16NonAscii(s) => { |
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let value = if let Some(right) = s.iter().copied().rposition(|r| { |
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!char::from_u32(u32::from(r)) |
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.map(is_trimmable_whitespace) |
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.unwrap_or_default() |
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}) { |
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&s[..=right] |
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} else { |
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// SAFETY: An empty string is valid ASCII, so this is safe.
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return unsafe { JsStringSlice::u8_ascii_unchecked("") }; |
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}; |
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JsStringSlice::from(value) |
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} |
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} |
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} |
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pub fn iter(self) -> crate::string::Iter<'a> { |
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crate::string::Iter::new(self) |
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} |
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} |
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impl<'a> From<&'a JsString> for JsStringSlice<'a> { |
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fn from(value: &'a JsString) -> Self { |
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Self::from(value.as_str()) |
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} |
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} |
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impl<'a> From<JsStr<'a>> for JsStringSlice<'a> { |
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fn from(value: JsStr<'a>) -> Self { |
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match value.variant() { |
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JsStrVariant::Ascii(s) => { |
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// SAFETY: `JsStrVariant::Ascii` always contains ASCII string, so this safe.
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unsafe { Self::u8_ascii_unchecked(s) } |
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} |
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JsStrVariant::U16(s) => { |
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// SAFETY: `JsStrVariant::Ascii` always contains non-ASCII string, so this safe.
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unsafe { Self::u16_non_ascii_unchecked(s) } |
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} |
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} |
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} |
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} |
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impl<'a> From<&'a str> for JsStringSlice<'a> { |
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fn from(value: &'a str) -> Self { |
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if value.is_ascii() { |
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// SAFETY: Already checked that it's ASCII, so this is safe.
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return unsafe { Self::u8_ascii_unchecked(value) }; |
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} |
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// SAFETY: Already checked that it's non-ASCII, so this is safe.
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unsafe { Self::u8_non_ascii_unchecked(value) } |
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} |
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} |
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impl<'a> From<&'a [u16]> for JsStringSlice<'a> { |
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fn from(s: &'a [u16]) -> Self { |
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if is_ascii(s) { |
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// SAFETY: Already checked that it's ASCII, so this is safe.
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return unsafe { Self::u16_ascii_unchecked(s) }; |
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} |
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// SAFETY: Already checked that it's non-ASCII, so this is safe.
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unsafe { Self::u16_non_ascii_unchecked(s) } |
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} |
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} |
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