| //! Implementation of [the WTF-8 encoding](https://simonsapin.github.io/wtf-8/). |
| //! |
| //! This library uses Rust’s type system to maintain |
| //! [well-formedness](https://simonsapin.github.io/wtf-8/#well-formed), |
| //! like the `String` and `&str` types do for UTF-8. |
| //! |
| //! Since [WTF-8 must not be used |
| //! for interchange](https://simonsapin.github.io/wtf-8/#intended-audience), |
| //! this library deliberately does not provide access to the underlying bytes |
| //! of WTF-8 strings, |
| //! nor can it decode WTF-8 from arbitrary bytes. |
| //! WTF-8 strings can be obtained from UTF-8, UTF-16, or code points. |
| |
| // this module is imported from @SimonSapin's repo and has tons of dead code on |
| // unix (it's mostly used on windows), so don't worry about dead code here. |
| #![allow(dead_code)] |
| |
| #[cfg(test)] |
| mod tests; |
| |
| use core::char::{encode_utf16_raw, encode_utf8_raw}; |
| use core::str::next_code_point; |
| |
| use crate::borrow::Cow; |
| use crate::collections::TryReserveError; |
| use crate::hash::{Hash, Hasher}; |
| use crate::iter::FusedIterator; |
| use crate::rc::Rc; |
| use crate::sync::Arc; |
| use crate::sys_common::AsInner; |
| use crate::{fmt, mem, ops, slice, str}; |
| |
| const UTF8_REPLACEMENT_CHARACTER: &str = "\u{FFFD}"; |
| |
| /// A Unicode code point: from U+0000 to U+10FFFF. |
| /// |
| /// Compares with the `char` type, |
| /// which represents a Unicode scalar value: |
| /// a code point that is not a surrogate (U+D800 to U+DFFF). |
| #[derive(Eq, PartialEq, Ord, PartialOrd, Clone, Copy)] |
| pub struct CodePoint { |
| value: u32, |
| } |
| |
| /// Format the code point as `U+` followed by four to six hexadecimal digits. |
| /// Example: `U+1F4A9` |
| impl fmt::Debug for CodePoint { |
| #[inline] |
| fn fmt(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result { |
| write!(formatter, "U+{:04X}", self.value) |
| } |
| } |
| |
| impl CodePoint { |
| /// Unsafely creates a new `CodePoint` without checking the value. |
| /// |
| /// Only use when `value` is known to be less than or equal to 0x10FFFF. |
| #[inline] |
| pub unsafe fn from_u32_unchecked(value: u32) -> CodePoint { |
| CodePoint { value } |
| } |
| |
| /// Creates a new `CodePoint` if the value is a valid code point. |
| /// |
| /// Returns `None` if `value` is above 0x10FFFF. |
| #[inline] |
| pub fn from_u32(value: u32) -> Option<CodePoint> { |
| match value { |
| 0..=0x10FFFF => Some(CodePoint { value }), |
| _ => None, |
| } |
| } |
| |
| /// Creates a new `CodePoint` from a `char`. |
| /// |
| /// Since all Unicode scalar values are code points, this always succeeds. |
| #[inline] |
| pub fn from_char(value: char) -> CodePoint { |
| CodePoint { value: value as u32 } |
| } |
| |
| /// Returns the numeric value of the code point. |
| #[inline] |
| pub fn to_u32(&self) -> u32 { |
| self.value |
| } |
| |
| /// Returns the numeric value of the code point if it is a leading surrogate. |
| #[inline] |
| pub fn to_lead_surrogate(&self) -> Option<u16> { |
| match self.value { |
| lead @ 0xD800..=0xDBFF => Some(lead as u16), |
| _ => None, |
| } |
| } |
| |
| /// Returns the numeric value of the code point if it is a trailing surrogate. |
| #[inline] |
| pub fn to_trail_surrogate(&self) -> Option<u16> { |
| match self.value { |
| trail @ 0xDC00..=0xDFFF => Some(trail as u16), |
| _ => None, |
| } |
| } |
| |
| /// Optionally returns a Unicode scalar value for the code point. |
| /// |
| /// Returns `None` if the code point is a surrogate (from U+D800 to U+DFFF). |
| #[inline] |
| pub fn to_char(&self) -> Option<char> { |
| match self.value { |
| 0xD800..=0xDFFF => None, |
| _ => Some(unsafe { char::from_u32_unchecked(self.value) }), |
| } |
| } |
| |
| /// Returns a Unicode scalar value for the code point. |
| /// |
| /// Returns `'\u{FFFD}'` (the replacement character “�”) |
| /// if the code point is a surrogate (from U+D800 to U+DFFF). |
| #[inline] |
| pub fn to_char_lossy(&self) -> char { |
| self.to_char().unwrap_or('\u{FFFD}') |
| } |
| } |
| |
| /// An owned, growable string of well-formed WTF-8 data. |
| /// |
| /// Similar to `String`, but can additionally contain surrogate code points |
| /// if they’re not in a surrogate pair. |
| #[derive(Eq, PartialEq, Ord, PartialOrd, Clone)] |
| pub struct Wtf8Buf { |
| bytes: Vec<u8>, |
| |
| /// Do we know that `bytes` holds a valid UTF-8 encoding? We can easily |
| /// know this if we're constructed from a `String` or `&str`. |
| /// |
| /// It is possible for `bytes` to have valid UTF-8 without this being |
| /// set, such as when we're concatenating `&Wtf8`'s and surrogates become |
| /// paired, as we don't bother to rescan the entire string. |
| is_known_utf8: bool, |
| } |
| |
| impl ops::Deref for Wtf8Buf { |
| type Target = Wtf8; |
| |
| fn deref(&self) -> &Wtf8 { |
| self.as_slice() |
| } |
| } |
| |
| impl ops::DerefMut for Wtf8Buf { |
| fn deref_mut(&mut self) -> &mut Wtf8 { |
| self.as_mut_slice() |
| } |
| } |
| |
| /// Format the string with double quotes, |
| /// and surrogates as `\u` followed by four hexadecimal digits. |
| /// Example: `"a\u{D800}"` for a string with code points [U+0061, U+D800] |
| impl fmt::Debug for Wtf8Buf { |
| #[inline] |
| fn fmt(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result { |
| fmt::Debug::fmt(&**self, formatter) |
| } |
| } |
| |
| impl Wtf8Buf { |
| /// Creates a new, empty WTF-8 string. |
| #[inline] |
| pub fn new() -> Wtf8Buf { |
| Wtf8Buf { bytes: Vec::new(), is_known_utf8: true } |
| } |
| |
| /// Creates a new, empty WTF-8 string with pre-allocated capacity for `capacity` bytes. |
| #[inline] |
| pub fn with_capacity(capacity: usize) -> Wtf8Buf { |
| Wtf8Buf { bytes: Vec::with_capacity(capacity), is_known_utf8: true } |
| } |
| |
| /// Creates a WTF-8 string from a WTF-8 byte vec. |
| /// |
| /// Since the byte vec is not checked for valid WTF-8, this functions is |
| /// marked unsafe. |
| #[inline] |
| pub unsafe fn from_bytes_unchecked(value: Vec<u8>) -> Wtf8Buf { |
| Wtf8Buf { bytes: value, is_known_utf8: false } |
| } |
| |
| /// Creates a WTF-8 string from a UTF-8 `String`. |
| /// |
| /// This takes ownership of the `String` and does not copy. |
| /// |
| /// Since WTF-8 is a superset of UTF-8, this always succeeds. |
| #[inline] |
| pub fn from_string(string: String) -> Wtf8Buf { |
| Wtf8Buf { bytes: string.into_bytes(), is_known_utf8: true } |
| } |
| |
| /// Creates a WTF-8 string from a UTF-8 `&str` slice. |
| /// |
| /// This copies the content of the slice. |
| /// |
| /// Since WTF-8 is a superset of UTF-8, this always succeeds. |
| #[inline] |
| pub fn from_str(str: &str) -> Wtf8Buf { |
| Wtf8Buf { bytes: <[_]>::to_vec(str.as_bytes()), is_known_utf8: true } |
| } |
| |
| pub fn clear(&mut self) { |
| self.bytes.clear(); |
| self.is_known_utf8 = true; |
| } |
| |
| /// Creates a WTF-8 string from a potentially ill-formed UTF-16 slice of 16-bit code units. |
| /// |
| /// This is lossless: calling `.encode_wide()` on the resulting string |
| /// will always return the original code units. |
| pub fn from_wide(v: &[u16]) -> Wtf8Buf { |
| let mut string = Wtf8Buf::with_capacity(v.len()); |
| for item in char::decode_utf16(v.iter().cloned()) { |
| match item { |
| Ok(ch) => string.push_char(ch), |
| Err(surrogate) => { |
| let surrogate = surrogate.unpaired_surrogate(); |
| // Surrogates are known to be in the code point range. |
| let code_point = unsafe { CodePoint::from_u32_unchecked(surrogate as u32) }; |
| // The string will now contain an unpaired surrogate. |
| string.is_known_utf8 = false; |
| // Skip the WTF-8 concatenation check, |
| // surrogate pairs are already decoded by decode_utf16 |
| string.push_code_point_unchecked(code_point); |
| } |
| } |
| } |
| string |
| } |
| |
| /// Copied from String::push |
| /// This does **not** include the WTF-8 concatenation check or `is_known_utf8` check. |
| fn push_code_point_unchecked(&mut self, code_point: CodePoint) { |
| let mut bytes = [0; 4]; |
| let bytes = encode_utf8_raw(code_point.value, &mut bytes); |
| self.bytes.extend_from_slice(bytes) |
| } |
| |
| #[inline] |
| pub fn as_slice(&self) -> &Wtf8 { |
| unsafe { Wtf8::from_bytes_unchecked(&self.bytes) } |
| } |
| |
| #[inline] |
| pub fn as_mut_slice(&mut self) -> &mut Wtf8 { |
| // Safety: `Wtf8` doesn't expose any way to mutate the bytes that would |
| // cause them to change from well-formed UTF-8 to ill-formed UTF-8, |
| // which would break the assumptions of the `is_known_utf8` field. |
| unsafe { Wtf8::from_mut_bytes_unchecked(&mut self.bytes) } |
| } |
| |
| /// Reserves capacity for at least `additional` more bytes to be inserted |
| /// in the given `Wtf8Buf`. |
| /// The collection may reserve more space to avoid frequent reallocations. |
| /// |
| /// # Panics |
| /// |
| /// Panics if the new capacity overflows `usize`. |
| #[inline] |
| pub fn reserve(&mut self, additional: usize) { |
| self.bytes.reserve(additional) |
| } |
| |
| /// Tries to reserve capacity for at least `additional` more length units |
| /// in the given `Wtf8Buf`. The `Wtf8Buf` may reserve more space to avoid |
| /// frequent reallocations. After calling `try_reserve`, capacity will be |
| /// greater than or equal to `self.len() + additional`. Does nothing if |
| /// capacity is already sufficient. This method preserves the contents even |
| /// if an error occurs. |
| /// |
| /// # Errors |
| /// |
| /// If the capacity overflows, or the allocator reports a failure, then an error |
| /// is returned. |
| #[inline] |
| pub fn try_reserve(&mut self, additional: usize) -> Result<(), TryReserveError> { |
| self.bytes.try_reserve(additional) |
| } |
| |
| #[inline] |
| pub fn reserve_exact(&mut self, additional: usize) { |
| self.bytes.reserve_exact(additional) |
| } |
| |
| /// Tries to reserve the minimum capacity for exactly `additional` |
| /// length units in the given `Wtf8Buf`. After calling |
| /// `try_reserve_exact`, capacity will be greater than or equal to |
| /// `self.len() + additional` if it returns `Ok(())`. |
| /// Does nothing if the capacity is already sufficient. |
| /// |
| /// Note that the allocator may give the `Wtf8Buf` more space than it |
| /// requests. Therefore, capacity can not be relied upon to be precisely |
| /// minimal. Prefer [`try_reserve`] if future insertions are expected. |
| /// |
| /// [`try_reserve`]: Wtf8Buf::try_reserve |
| /// |
| /// # Errors |
| /// |
| /// If the capacity overflows, or the allocator reports a failure, then an error |
| /// is returned. |
| #[inline] |
| pub fn try_reserve_exact(&mut self, additional: usize) -> Result<(), TryReserveError> { |
| self.bytes.try_reserve_exact(additional) |
| } |
| |
| #[inline] |
| pub fn shrink_to_fit(&mut self) { |
| self.bytes.shrink_to_fit() |
| } |
| |
| #[inline] |
| pub fn shrink_to(&mut self, min_capacity: usize) { |
| self.bytes.shrink_to(min_capacity) |
| } |
| |
| #[inline] |
| pub fn leak<'a>(self) -> &'a mut Wtf8 { |
| unsafe { Wtf8::from_mut_bytes_unchecked(self.bytes.leak()) } |
| } |
| |
| /// Returns the number of bytes that this string buffer can hold without reallocating. |
| #[inline] |
| pub fn capacity(&self) -> usize { |
| self.bytes.capacity() |
| } |
| |
| /// Append a UTF-8 slice at the end of the string. |
| #[inline] |
| pub fn push_str(&mut self, other: &str) { |
| self.bytes.extend_from_slice(other.as_bytes()) |
| } |
| |
| /// Append a WTF-8 slice at the end of the string. |
| /// |
| /// This replaces newly paired surrogates at the boundary |
| /// with a supplementary code point, |
| /// like concatenating ill-formed UTF-16 strings effectively would. |
| #[inline] |
| pub fn push_wtf8(&mut self, other: &Wtf8) { |
| match ((&*self).final_lead_surrogate(), other.initial_trail_surrogate()) { |
| // Replace newly paired surrogates by a supplementary code point. |
| (Some(lead), Some(trail)) => { |
| let len_without_lead_surrogate = self.len() - 3; |
| self.bytes.truncate(len_without_lead_surrogate); |
| let other_without_trail_surrogate = &other.bytes[3..]; |
| // 4 bytes for the supplementary code point |
| self.bytes.reserve(4 + other_without_trail_surrogate.len()); |
| self.push_char(decode_surrogate_pair(lead, trail)); |
| self.bytes.extend_from_slice(other_without_trail_surrogate); |
| } |
| _ => { |
| // If we'll be pushing a string containing a surrogate, we may |
| // no longer have UTF-8. |
| if other.next_surrogate(0).is_some() { |
| self.is_known_utf8 = false; |
| } |
| |
| self.bytes.extend_from_slice(&other.bytes); |
| } |
| } |
| } |
| |
| /// Append a Unicode scalar value at the end of the string. |
| #[inline] |
| pub fn push_char(&mut self, c: char) { |
| self.push_code_point_unchecked(CodePoint::from_char(c)) |
| } |
| |
| /// Append a code point at the end of the string. |
| /// |
| /// This replaces newly paired surrogates at the boundary |
| /// with a supplementary code point, |
| /// like concatenating ill-formed UTF-16 strings effectively would. |
| #[inline] |
| pub fn push(&mut self, code_point: CodePoint) { |
| if let Some(trail) = code_point.to_trail_surrogate() { |
| if let Some(lead) = (&*self).final_lead_surrogate() { |
| let len_without_lead_surrogate = self.len() - 3; |
| self.bytes.truncate(len_without_lead_surrogate); |
| self.push_char(decode_surrogate_pair(lead, trail)); |
| return; |
| } |
| |
| // We're pushing a trailing surrogate. |
| self.is_known_utf8 = false; |
| } else if code_point.to_lead_surrogate().is_some() { |
| // We're pushing a leading surrogate. |
| self.is_known_utf8 = false; |
| } |
| |
| // No newly paired surrogates at the boundary. |
| self.push_code_point_unchecked(code_point) |
| } |
| |
| /// Shortens a string to the specified length. |
| /// |
| /// # Panics |
| /// |
| /// Panics if `new_len` > current length, |
| /// or if `new_len` is not a code point boundary. |
| #[inline] |
| pub fn truncate(&mut self, new_len: usize) { |
| assert!(is_code_point_boundary(self, new_len)); |
| self.bytes.truncate(new_len) |
| } |
| |
| /// Consumes the WTF-8 string and tries to convert it to a vec of bytes. |
| #[inline] |
| pub fn into_bytes(self) -> Vec<u8> { |
| self.bytes |
| } |
| |
| /// Consumes the WTF-8 string and tries to convert it to UTF-8. |
| /// |
| /// This does not copy the data. |
| /// |
| /// If the contents are not well-formed UTF-8 |
| /// (that is, if the string contains surrogates), |
| /// the original WTF-8 string is returned instead. |
| pub fn into_string(self) -> Result<String, Wtf8Buf> { |
| if self.is_known_utf8 || self.next_surrogate(0).is_none() { |
| Ok(unsafe { String::from_utf8_unchecked(self.bytes) }) |
| } else { |
| Err(self) |
| } |
| } |
| |
| /// Consumes the WTF-8 string and converts it lossily to UTF-8. |
| /// |
| /// This does not copy the data (but may overwrite parts of it in place). |
| /// |
| /// Surrogates are replaced with `"\u{FFFD}"` (the replacement character “�”) |
| pub fn into_string_lossy(mut self) -> String { |
| // Fast path: If we already have UTF-8, we can return it immediately. |
| if self.is_known_utf8 { |
| return unsafe { String::from_utf8_unchecked(self.bytes) }; |
| } |
| |
| let mut pos = 0; |
| loop { |
| match self.next_surrogate(pos) { |
| Some((surrogate_pos, _)) => { |
| pos = surrogate_pos + 3; |
| self.bytes[surrogate_pos..pos] |
| .copy_from_slice(UTF8_REPLACEMENT_CHARACTER.as_bytes()); |
| } |
| None => return unsafe { String::from_utf8_unchecked(self.bytes) }, |
| } |
| } |
| } |
| |
| /// Converts this `Wtf8Buf` into a boxed `Wtf8`. |
| #[inline] |
| pub fn into_box(self) -> Box<Wtf8> { |
| // SAFETY: relies on `Wtf8` being `repr(transparent)`. |
| unsafe { mem::transmute(self.bytes.into_boxed_slice()) } |
| } |
| |
| /// Converts a `Box<Wtf8>` into a `Wtf8Buf`. |
| pub fn from_box(boxed: Box<Wtf8>) -> Wtf8Buf { |
| let bytes: Box<[u8]> = unsafe { mem::transmute(boxed) }; |
| Wtf8Buf { bytes: bytes.into_vec(), is_known_utf8: false } |
| } |
| |
| /// Provides plumbing to core `Vec::extend_from_slice`. |
| /// More well behaving alternative to allowing outer types |
| /// full mutable access to the core `Vec`. |
| #[inline] |
| pub(crate) fn extend_from_slice(&mut self, other: &[u8]) { |
| self.bytes.extend_from_slice(other); |
| self.is_known_utf8 = false; |
| } |
| } |
| |
| /// Creates a new WTF-8 string from an iterator of code points. |
| /// |
| /// This replaces surrogate code point pairs with supplementary code points, |
| /// like concatenating ill-formed UTF-16 strings effectively would. |
| impl FromIterator<CodePoint> for Wtf8Buf { |
| fn from_iter<T: IntoIterator<Item = CodePoint>>(iter: T) -> Wtf8Buf { |
| let mut string = Wtf8Buf::new(); |
| string.extend(iter); |
| string |
| } |
| } |
| |
| /// Append code points from an iterator to the string. |
| /// |
| /// This replaces surrogate code point pairs with supplementary code points, |
| /// like concatenating ill-formed UTF-16 strings effectively would. |
| impl Extend<CodePoint> for Wtf8Buf { |
| fn extend<T: IntoIterator<Item = CodePoint>>(&mut self, iter: T) { |
| let iterator = iter.into_iter(); |
| let (low, _high) = iterator.size_hint(); |
| // Lower bound of one byte per code point (ASCII only) |
| self.bytes.reserve(low); |
| iterator.for_each(move |code_point| self.push(code_point)); |
| } |
| |
| #[inline] |
| fn extend_one(&mut self, code_point: CodePoint) { |
| self.push(code_point); |
| } |
| |
| #[inline] |
| fn extend_reserve(&mut self, additional: usize) { |
| // Lower bound of one byte per code point (ASCII only) |
| self.bytes.reserve(additional); |
| } |
| } |
| |
| /// A borrowed slice of well-formed WTF-8 data. |
| /// |
| /// Similar to `&str`, but can additionally contain surrogate code points |
| /// if they’re not in a surrogate pair. |
| #[derive(Eq, Ord, PartialEq, PartialOrd)] |
| #[repr(transparent)] |
| pub struct Wtf8 { |
| bytes: [u8], |
| } |
| |
| impl AsInner<[u8]> for Wtf8 { |
| #[inline] |
| fn as_inner(&self) -> &[u8] { |
| &self.bytes |
| } |
| } |
| |
| /// Format the slice with double quotes, |
| /// and surrogates as `\u` followed by four hexadecimal digits. |
| /// Example: `"a\u{D800}"` for a slice with code points [U+0061, U+D800] |
| impl fmt::Debug for Wtf8 { |
| fn fmt(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result { |
| fn write_str_escaped(f: &mut fmt::Formatter<'_>, s: &str) -> fmt::Result { |
| use crate::fmt::Write; |
| for c in s.chars().flat_map(|c| c.escape_debug()) { |
| f.write_char(c)? |
| } |
| Ok(()) |
| } |
| |
| formatter.write_str("\"")?; |
| let mut pos = 0; |
| while let Some((surrogate_pos, surrogate)) = self.next_surrogate(pos) { |
| write_str_escaped(formatter, unsafe { |
| str::from_utf8_unchecked(&self.bytes[pos..surrogate_pos]) |
| })?; |
| write!(formatter, "\\u{{{:x}}}", surrogate)?; |
| pos = surrogate_pos + 3; |
| } |
| write_str_escaped(formatter, unsafe { str::from_utf8_unchecked(&self.bytes[pos..]) })?; |
| formatter.write_str("\"") |
| } |
| } |
| |
| impl fmt::Display for Wtf8 { |
| fn fmt(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result { |
| let wtf8_bytes = &self.bytes; |
| let mut pos = 0; |
| loop { |
| match self.next_surrogate(pos) { |
| Some((surrogate_pos, _)) => { |
| formatter.write_str(unsafe { |
| str::from_utf8_unchecked(&wtf8_bytes[pos..surrogate_pos]) |
| })?; |
| formatter.write_str(UTF8_REPLACEMENT_CHARACTER)?; |
| pos = surrogate_pos + 3; |
| } |
| None => { |
| let s = unsafe { str::from_utf8_unchecked(&wtf8_bytes[pos..]) }; |
| if pos == 0 { return s.fmt(formatter) } else { return formatter.write_str(s) } |
| } |
| } |
| } |
| } |
| } |
| |
| impl Wtf8 { |
| /// Creates a WTF-8 slice from a UTF-8 `&str` slice. |
| /// |
| /// Since WTF-8 is a superset of UTF-8, this always succeeds. |
| #[inline] |
| pub fn from_str(value: &str) -> &Wtf8 { |
| unsafe { Wtf8::from_bytes_unchecked(value.as_bytes()) } |
| } |
| |
| /// Creates a WTF-8 slice from a WTF-8 byte slice. |
| /// |
| /// Since the byte slice is not checked for valid WTF-8, this functions is |
| /// marked unsafe. |
| #[inline] |
| pub unsafe fn from_bytes_unchecked(value: &[u8]) -> &Wtf8 { |
| // SAFETY: start with &[u8], end with fancy &[u8] |
| unsafe { &*(value as *const [u8] as *const Wtf8) } |
| } |
| |
| /// Creates a mutable WTF-8 slice from a mutable WTF-8 byte slice. |
| /// |
| /// Since the byte slice is not checked for valid WTF-8, this functions is |
| /// marked unsafe. |
| #[inline] |
| unsafe fn from_mut_bytes_unchecked(value: &mut [u8]) -> &mut Wtf8 { |
| // SAFETY: start with &mut [u8], end with fancy &mut [u8] |
| unsafe { &mut *(value as *mut [u8] as *mut Wtf8) } |
| } |
| |
| /// Returns the length, in WTF-8 bytes. |
| #[inline] |
| pub fn len(&self) -> usize { |
| self.bytes.len() |
| } |
| |
| #[inline] |
| pub fn is_empty(&self) -> bool { |
| self.bytes.is_empty() |
| } |
| |
| /// Returns the code point at `position` if it is in the ASCII range, |
| /// or `b'\xFF'` otherwise. |
| /// |
| /// # Panics |
| /// |
| /// Panics if `position` is beyond the end of the string. |
| #[inline] |
| pub fn ascii_byte_at(&self, position: usize) -> u8 { |
| match self.bytes[position] { |
| ascii_byte @ 0x00..=0x7F => ascii_byte, |
| _ => 0xFF, |
| } |
| } |
| |
| /// Returns an iterator for the string’s code points. |
| #[inline] |
| pub fn code_points(&self) -> Wtf8CodePoints<'_> { |
| Wtf8CodePoints { bytes: self.bytes.iter() } |
| } |
| |
| /// Access raw bytes of WTF-8 data |
| #[inline] |
| pub fn as_bytes(&self) -> &[u8] { |
| &self.bytes |
| } |
| |
| /// Tries to convert the string to UTF-8 and return a `&str` slice. |
| /// |
| /// Returns `None` if the string contains surrogates. |
| /// |
| /// This does not copy the data. |
| #[inline] |
| pub fn as_str(&self) -> Result<&str, str::Utf8Error> { |
| str::from_utf8(&self.bytes) |
| } |
| |
| /// Creates an owned `Wtf8Buf` from a borrowed `Wtf8`. |
| pub fn to_owned(&self) -> Wtf8Buf { |
| Wtf8Buf { bytes: self.bytes.to_vec(), is_known_utf8: false } |
| } |
| |
| /// Lossily converts the string to UTF-8. |
| /// Returns a UTF-8 `&str` slice if the contents are well-formed in UTF-8. |
| /// |
| /// Surrogates are replaced with `"\u{FFFD}"` (the replacement character “�”). |
| /// |
| /// This only copies the data if necessary (if it contains any surrogate). |
| pub fn to_string_lossy(&self) -> Cow<'_, str> { |
| let surrogate_pos = match self.next_surrogate(0) { |
| None => return Cow::Borrowed(unsafe { str::from_utf8_unchecked(&self.bytes) }), |
| Some((pos, _)) => pos, |
| }; |
| let wtf8_bytes = &self.bytes; |
| let mut utf8_bytes = Vec::with_capacity(self.len()); |
| utf8_bytes.extend_from_slice(&wtf8_bytes[..surrogate_pos]); |
| utf8_bytes.extend_from_slice(UTF8_REPLACEMENT_CHARACTER.as_bytes()); |
| let mut pos = surrogate_pos + 3; |
| loop { |
| match self.next_surrogate(pos) { |
| Some((surrogate_pos, _)) => { |
| utf8_bytes.extend_from_slice(&wtf8_bytes[pos..surrogate_pos]); |
| utf8_bytes.extend_from_slice(UTF8_REPLACEMENT_CHARACTER.as_bytes()); |
| pos = surrogate_pos + 3; |
| } |
| None => { |
| utf8_bytes.extend_from_slice(&wtf8_bytes[pos..]); |
| return Cow::Owned(unsafe { String::from_utf8_unchecked(utf8_bytes) }); |
| } |
| } |
| } |
| } |
| |
| /// Converts the WTF-8 string to potentially ill-formed UTF-16 |
| /// and return an iterator of 16-bit code units. |
| /// |
| /// This is lossless: |
| /// calling `Wtf8Buf::from_ill_formed_utf16` on the resulting code units |
| /// would always return the original WTF-8 string. |
| #[inline] |
| pub fn encode_wide(&self) -> EncodeWide<'_> { |
| EncodeWide { code_points: self.code_points(), extra: 0 } |
| } |
| |
| #[inline] |
| fn next_surrogate(&self, mut pos: usize) -> Option<(usize, u16)> { |
| let mut iter = self.bytes[pos..].iter(); |
| loop { |
| let b = *iter.next()?; |
| if b < 0x80 { |
| pos += 1; |
| } else if b < 0xE0 { |
| iter.next(); |
| pos += 2; |
| } else if b == 0xED { |
| match (iter.next(), iter.next()) { |
| (Some(&b2), Some(&b3)) if b2 >= 0xA0 => { |
| return Some((pos, decode_surrogate(b2, b3))); |
| } |
| _ => pos += 3, |
| } |
| } else if b < 0xF0 { |
| iter.next(); |
| iter.next(); |
| pos += 3; |
| } else { |
| iter.next(); |
| iter.next(); |
| iter.next(); |
| pos += 4; |
| } |
| } |
| } |
| |
| #[inline] |
| fn final_lead_surrogate(&self) -> Option<u16> { |
| match self.bytes { |
| [.., 0xED, b2 @ 0xA0..=0xAF, b3] => Some(decode_surrogate(b2, b3)), |
| _ => None, |
| } |
| } |
| |
| #[inline] |
| fn initial_trail_surrogate(&self) -> Option<u16> { |
| match self.bytes { |
| [0xED, b2 @ 0xB0..=0xBF, b3, ..] => Some(decode_surrogate(b2, b3)), |
| _ => None, |
| } |
| } |
| |
| pub fn clone_into(&self, buf: &mut Wtf8Buf) { |
| buf.is_known_utf8 = false; |
| self.bytes.clone_into(&mut buf.bytes); |
| } |
| |
| /// Boxes this `Wtf8`. |
| #[inline] |
| pub fn into_box(&self) -> Box<Wtf8> { |
| let boxed: Box<[u8]> = self.bytes.into(); |
| unsafe { mem::transmute(boxed) } |
| } |
| |
| /// Creates a boxed, empty `Wtf8`. |
| pub fn empty_box() -> Box<Wtf8> { |
| let boxed: Box<[u8]> = Default::default(); |
| unsafe { mem::transmute(boxed) } |
| } |
| |
| #[inline] |
| pub fn into_arc(&self) -> Arc<Wtf8> { |
| let arc: Arc<[u8]> = Arc::from(&self.bytes); |
| unsafe { Arc::from_raw(Arc::into_raw(arc) as *const Wtf8) } |
| } |
| |
| #[inline] |
| pub fn into_rc(&self) -> Rc<Wtf8> { |
| let rc: Rc<[u8]> = Rc::from(&self.bytes); |
| unsafe { Rc::from_raw(Rc::into_raw(rc) as *const Wtf8) } |
| } |
| |
| #[inline] |
| pub fn make_ascii_lowercase(&mut self) { |
| self.bytes.make_ascii_lowercase() |
| } |
| |
| #[inline] |
| pub fn make_ascii_uppercase(&mut self) { |
| self.bytes.make_ascii_uppercase() |
| } |
| |
| #[inline] |
| pub fn to_ascii_lowercase(&self) -> Wtf8Buf { |
| Wtf8Buf { bytes: self.bytes.to_ascii_lowercase(), is_known_utf8: false } |
| } |
| |
| #[inline] |
| pub fn to_ascii_uppercase(&self) -> Wtf8Buf { |
| Wtf8Buf { bytes: self.bytes.to_ascii_uppercase(), is_known_utf8: false } |
| } |
| |
| #[inline] |
| pub fn is_ascii(&self) -> bool { |
| self.bytes.is_ascii() |
| } |
| |
| #[inline] |
| pub fn eq_ignore_ascii_case(&self, other: &Self) -> bool { |
| self.bytes.eq_ignore_ascii_case(&other.bytes) |
| } |
| } |
| |
| /// Returns a slice of the given string for the byte range \[`begin`..`end`). |
| /// |
| /// # Panics |
| /// |
| /// Panics when `begin` and `end` do not point to code point boundaries, |
| /// or point beyond the end of the string. |
| impl ops::Index<ops::Range<usize>> for Wtf8 { |
| type Output = Wtf8; |
| |
| #[inline] |
| fn index(&self, range: ops::Range<usize>) -> &Wtf8 { |
| // is_code_point_boundary checks that the index is in [0, .len()] |
| if range.start <= range.end |
| && is_code_point_boundary(self, range.start) |
| && is_code_point_boundary(self, range.end) |
| { |
| unsafe { slice_unchecked(self, range.start, range.end) } |
| } else { |
| slice_error_fail(self, range.start, range.end) |
| } |
| } |
| } |
| |
| /// Returns a slice of the given string from byte `begin` to its end. |
| /// |
| /// # Panics |
| /// |
| /// Panics when `begin` is not at a code point boundary, |
| /// or is beyond the end of the string. |
| impl ops::Index<ops::RangeFrom<usize>> for Wtf8 { |
| type Output = Wtf8; |
| |
| #[inline] |
| fn index(&self, range: ops::RangeFrom<usize>) -> &Wtf8 { |
| // is_code_point_boundary checks that the index is in [0, .len()] |
| if is_code_point_boundary(self, range.start) { |
| unsafe { slice_unchecked(self, range.start, self.len()) } |
| } else { |
| slice_error_fail(self, range.start, self.len()) |
| } |
| } |
| } |
| |
| /// Returns a slice of the given string from its beginning to byte `end`. |
| /// |
| /// # Panics |
| /// |
| /// Panics when `end` is not at a code point boundary, |
| /// or is beyond the end of the string. |
| impl ops::Index<ops::RangeTo<usize>> for Wtf8 { |
| type Output = Wtf8; |
| |
| #[inline] |
| fn index(&self, range: ops::RangeTo<usize>) -> &Wtf8 { |
| // is_code_point_boundary checks that the index is in [0, .len()] |
| if is_code_point_boundary(self, range.end) { |
| unsafe { slice_unchecked(self, 0, range.end) } |
| } else { |
| slice_error_fail(self, 0, range.end) |
| } |
| } |
| } |
| |
| impl ops::Index<ops::RangeFull> for Wtf8 { |
| type Output = Wtf8; |
| |
| #[inline] |
| fn index(&self, _range: ops::RangeFull) -> &Wtf8 { |
| self |
| } |
| } |
| |
| #[inline] |
| fn decode_surrogate(second_byte: u8, third_byte: u8) -> u16 { |
| // The first byte is assumed to be 0xED |
| 0xD800 | (second_byte as u16 & 0x3F) << 6 | third_byte as u16 & 0x3F |
| } |
| |
| #[inline] |
| fn decode_surrogate_pair(lead: u16, trail: u16) -> char { |
| let code_point = 0x10000 + ((((lead - 0xD800) as u32) << 10) | (trail - 0xDC00) as u32); |
| unsafe { char::from_u32_unchecked(code_point) } |
| } |
| |
| /// Copied from str::is_char_boundary |
| #[inline] |
| pub fn is_code_point_boundary(slice: &Wtf8, index: usize) -> bool { |
| if index == 0 { |
| return true; |
| } |
| match slice.bytes.get(index) { |
| None => index == slice.len(), |
| Some(&b) => (b as i8) >= -0x40, |
| } |
| } |
| |
| /// Verify that `index` is at the edge of either a valid UTF-8 codepoint |
| /// (i.e. a codepoint that's not a surrogate) or of the whole string. |
| /// |
| /// These are the cases currently permitted by `OsStr::slice_encoded_bytes`. |
| /// Splitting between surrogates is valid as far as WTF-8 is concerned, but |
| /// we do not permit it in the public API because WTF-8 is considered an |
| /// implementation detail. |
| #[track_caller] |
| #[inline] |
| pub fn check_utf8_boundary(slice: &Wtf8, index: usize) { |
| if index == 0 { |
| return; |
| } |
| match slice.bytes.get(index) { |
| Some(0xED) => (), // Might be a surrogate |
| Some(&b) if (b as i8) >= -0x40 => return, |
| Some(_) => panic!("byte index {index} is not a codepoint boundary"), |
| None if index == slice.len() => return, |
| None => panic!("byte index {index} is out of bounds"), |
| } |
| if slice.bytes[index + 1] >= 0xA0 { |
| // There's a surrogate after index. Now check before index. |
| if index >= 3 && slice.bytes[index - 3] == 0xED && slice.bytes[index - 2] >= 0xA0 { |
| panic!("byte index {index} lies between surrogate codepoints"); |
| } |
| } |
| } |
| |
| /// Copied from core::str::raw::slice_unchecked |
| #[inline] |
| pub unsafe fn slice_unchecked(s: &Wtf8, begin: usize, end: usize) -> &Wtf8 { |
| // SAFETY: memory layout of a &[u8] and &Wtf8 are the same |
| unsafe { |
| let len = end - begin; |
| let start = s.as_bytes().as_ptr().add(begin); |
| Wtf8::from_bytes_unchecked(slice::from_raw_parts(start, len)) |
| } |
| } |
| |
| /// Copied from core::str::raw::slice_error_fail |
| #[inline(never)] |
| pub fn slice_error_fail(s: &Wtf8, begin: usize, end: usize) -> ! { |
| assert!(begin <= end); |
| panic!("index {begin} and/or {end} in `{s:?}` do not lie on character boundary"); |
| } |
| |
| /// Iterator for the code points of a WTF-8 string. |
| /// |
| /// Created with the method `.code_points()`. |
| #[derive(Clone)] |
| pub struct Wtf8CodePoints<'a> { |
| bytes: slice::Iter<'a, u8>, |
| } |
| |
| impl<'a> Iterator for Wtf8CodePoints<'a> { |
| type Item = CodePoint; |
| |
| #[inline] |
| fn next(&mut self) -> Option<CodePoint> { |
| // SAFETY: `self.bytes` has been created from a WTF-8 string |
| unsafe { next_code_point(&mut self.bytes).map(|c| CodePoint { value: c }) } |
| } |
| |
| #[inline] |
| fn size_hint(&self) -> (usize, Option<usize>) { |
| let len = self.bytes.len(); |
| (len.saturating_add(3) / 4, Some(len)) |
| } |
| } |
| |
| /// Generates a wide character sequence for potentially ill-formed UTF-16. |
| #[stable(feature = "rust1", since = "1.0.0")] |
| #[derive(Clone)] |
| pub struct EncodeWide<'a> { |
| code_points: Wtf8CodePoints<'a>, |
| extra: u16, |
| } |
| |
| // Copied from libunicode/u_str.rs |
| #[stable(feature = "rust1", since = "1.0.0")] |
| impl<'a> Iterator for EncodeWide<'a> { |
| type Item = u16; |
| |
| #[inline] |
| fn next(&mut self) -> Option<u16> { |
| if self.extra != 0 { |
| let tmp = self.extra; |
| self.extra = 0; |
| return Some(tmp); |
| } |
| |
| let mut buf = [0; 2]; |
| self.code_points.next().map(|code_point| { |
| let n = encode_utf16_raw(code_point.value, &mut buf).len(); |
| if n == 2 { |
| self.extra = buf[1]; |
| } |
| buf[0] |
| }) |
| } |
| |
| #[inline] |
| fn size_hint(&self) -> (usize, Option<usize>) { |
| let (low, high) = self.code_points.size_hint(); |
| let ext = (self.extra != 0) as usize; |
| // every code point gets either one u16 or two u16, |
| // so this iterator is between 1 or 2 times as |
| // long as the underlying iterator. |
| (low + ext, high.and_then(|n| n.checked_mul(2)).and_then(|n| n.checked_add(ext))) |
| } |
| } |
| |
| #[stable(feature = "encode_wide_fused_iterator", since = "1.62.0")] |
| impl FusedIterator for EncodeWide<'_> {} |
| |
| impl Hash for CodePoint { |
| #[inline] |
| fn hash<H: Hasher>(&self, state: &mut H) { |
| self.value.hash(state) |
| } |
| } |
| |
| impl Hash for Wtf8Buf { |
| #[inline] |
| fn hash<H: Hasher>(&self, state: &mut H) { |
| state.write(&self.bytes); |
| 0xfeu8.hash(state) |
| } |
| } |
| |
| impl Hash for Wtf8 { |
| #[inline] |
| fn hash<H: Hasher>(&self, state: &mut H) { |
| state.write(&self.bytes); |
| 0xfeu8.hash(state) |
| } |
| } |
