bytes.rs - source
Description: Source of the Rust file `library/std/src/sys/os_str/bytes.rs`.

#
std/sys/os_str/
bytes.rs

    1//! The underlying OsString/OsStr implementation on Unix and many other
    2//! systems: just a `Vec<u8>`/`[u8]`.
    3
    4use core::clone::CloneToUninit;
    5
    6use crate::borrow::Cow;
    7use crate::collections::TryReserveError;
    8use crate::fmt::Write;
    9use crate::rc::Rc;
    10use crate::sync::Arc;
    11use crate::sys::{AsInner, FromInner, IntoInner};
    12use crate::{fmt, mem, str};
    13
    14#[cfg(test)]
    15mod tests;
    16
    17#[derive(Hash)]
    18#[repr(transparent)]
    19pub struct Buf {
    20    pub inner: Vec<u8>,
    21}
    22
    23#[repr(transparent)]
    24pub struct Slice {
    25    pub inner: [u8],
    26}
    27
    28impl IntoInner<Vec<u8>> for Buf {
    29    fn into_inner(self) -> Vec<u8> {
    30        self.inner
    31    }
    32}
    33
    34impl FromInner<Vec<u8>> for Buf {
    35    fn from_inner(inner: Vec<u8>) -> Self {
    36        Buf { inner }
    37    }
    38}
    39
    40impl AsInner<[u8]> for Buf {
    41    #[inline]
    42    fn as_inner(&self) -> &[u8] {
    43        &self.inner
    44    }
    45}
    46
    47impl fmt::Debug for Buf {
    48    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
    49        fmt::Debug::fmt(self.as_slice(), f)
    50    }
    51}
    52
    53impl fmt::Display for Buf {
    54    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
    55        fmt::Display::fmt(self.as_slice(), f)
    56    }
    57}
    58
    59impl fmt::Debug for Slice {
    60    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
    61        fmt::Debug::fmt(&self.inner.utf8_chunks().debug(), f)
    62    }
    63}
    64
    65impl fmt::Display for Slice {
    66    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
    67        // If we're the empty string then our iterator won't actually yield
    68        // anything, so perform the formatting manually
    69        if self.inner.is_empty() {
    70            return "".fmt(f);
    71        }
    72
    73        for chunk in self.inner.utf8_chunks() {
    74            let valid = chunk.valid();
    75            // If we successfully decoded the whole chunk as a valid string then
    76            // we can return a direct formatting of the string which will also
    77            // respect various formatting flags if possible.
    78            if chunk.invalid().is_empty() {
    79                return valid.fmt(f);
    80            }
    81
    82            f.write_str(valid)?;
    83            f.write_char(char::REPLACEMENT_CHARACTER)?;
    84        }
    85        Ok(())
    86    }
    87}
    88
    89impl Clone for Buf {
    90    #[inline]
    91    fn clone(&self) -> Self {
    92        Buf { inner: self.inner.clone() }
    93    }
    94
    95    #[inline]
    96    fn clone_from(&mut self, source: &Self) {
    97        self.inner.clone_from(&source.inner)
    98    }
    99}
    100
    101impl Buf {
    102    #[inline]
    103    pub fn into_encoded_bytes(self) -> Vec<u8> {
    104        self.inner
    105    }
    106
    107    #[inline]
    108    pub unsafe fn from_encoded_bytes_unchecked(s: Vec<u8>) -> Self {
    109        Self { inner: s }
    110    }
    111
    112    #[inline]
    113    pub fn into_string(self) -> Result<String, Buf> {
    114        String::from_utf8(self.inner).map_err(|p| Buf { inner: p.into_bytes() })
    115    }
    116
    117    #[inline]
    118    pub const fn from_string(s: String) -> Buf {
    119        Buf { inner: s.into_bytes() }
    120    }
    121
    122    #[inline]
    123    pub fn with_capacity(capacity: usize) -> Buf {
    124        Buf { inner: Vec::with_capacity(capacity) }
    125    }
    126
    127    #[inline]
    128    pub fn clear(&mut self) {
    129        self.inner.clear()
    130    }
    131
    132    #[inline]
    133    pub fn capacity(&self) -> usize {
    134        self.inner.capacity()
    135    }
    136
    137    #[inline]
    138    pub fn push_slice(&mut self, s: &Slice) {
    139        self.inner.extend_from_slice(&s.inner)
    140    }
    141
    142    #[inline]
    143    pub fn push_str(&mut self, s: &str) {
    144        self.inner.extend_from_slice(s.as_bytes());
    145    }
    146
    147    #[inline]
    148    pub fn reserve(&mut self, additional: usize) {
    149        self.inner.reserve(additional)
    150    }
    151
    152    #[inline]
    153    pub fn try_reserve(&mut self, additional: usize) -> Result<(), TryReserveError> {
    154        self.inner.try_reserve(additional)
    155    }
    156
    157    #[inline]
    158    pub fn reserve_exact(&mut self, additional: usize) {
    159        self.inner.reserve_exact(additional)
    160    }
    161
    162    #[inline]
    163    pub fn try_reserve_exact(&mut self, additional: usize) -> Result<(), TryReserveError> {
    164        self.inner.try_reserve_exact(additional)
    165    }
    166
    167    #[inline]
    168    pub fn shrink_to_fit(&mut self) {
    169        self.inner.shrink_to_fit()
    170    }
    171
    172    #[inline]
    173    pub fn shrink_to(&mut self, min_capacity: usize) {
    174        self.inner.shrink_to(min_capacity)
    175    }
    176
    177    #[inline]
    178    pub fn as_slice(&self) -> &Slice {
    179        // SAFETY: Slice is just a wrapper for [u8],
    180        // and self.inner.as_slice() returns &[u8].
    181        // Therefore, transmuting &[u8] to &Slice is safe.
    182        unsafe { mem::transmute(self.inner.as_slice()) }
    183    }
    184
    185    #[inline]
    186    pub fn as_mut_slice(&mut self) -> &mut Slice {
    187        // SAFETY: Slice is just a wrapper for [u8],
    188        // and self.inner.as_mut_slice() returns &mut [u8].
    189        // Therefore, transmuting &mut [u8] to &mut Slice is safe.
    190        unsafe { mem::transmute(self.inner.as_mut_slice()) }
    191    }
    192
    193    #[inline]
    194    pub fn leak<'a>(self) -> &'a mut Slice {
    195        unsafe { mem::transmute(self.inner.leak()) }
    196    }
    197
    198    #[inline]
    199    pub fn into_box(self) -> Box<Slice> {
    200        unsafe { mem::transmute(self.inner.into_boxed_slice()) }
    201    }
    202
    203    #[inline]
    204    pub fn from_box(boxed: Box<Slice>) -> Buf {
    205        let inner: Box<[u8]> = unsafe { mem::transmute(boxed) };
    206        Buf { inner: inner.into_vec() }
    207    }
    208
    209    #[inline]
    210    pub fn into_arc(&self) -> Arc<Slice> {
    211        self.as_slice().into_arc()
    212    }
    213
    214    #[inline]
    215    pub fn into_rc(&self) -> Rc<Slice> {
    216        self.as_slice().into_rc()
    217    }
    218
    219    /// Provides plumbing to `Vec::truncate` without giving full mutable access
    220    /// to the `Vec`.
    221    ///
    222    /// # Safety
    223    ///
    224    /// The length must be at an `OsStr` boundary, according to
    225    /// `Slice::check_public_boundary`.
    226    #[inline]
    227    pub unsafe fn truncate_unchecked(&mut self, len: usize) {
    228        self.inner.truncate(len);
    229    }
    230
    231    /// Provides plumbing to `Vec::extend_from_slice` without giving full
    232    /// mutable access to the `Vec`.
    233    ///
    234    /// # Safety
    235    ///
    236    /// The slice must be valid for the platform encoding (as described in
    237    /// `OsStr::from_encoded_bytes_unchecked`). This encoding has no safety
    238    /// requirements.
    239    #[inline]
    240    pub unsafe fn extend_from_slice_unchecked(&mut self, other: &[u8]) {
    241        self.inner.extend_from_slice(other);
    242    }
    243}
    244
    245impl Slice {
    246    #[inline]
    247    pub fn as_encoded_bytes(&self) -> &[u8] {
    248        &self.inner
    249    }
    250
    251    #[inline]
    252    pub unsafe fn from_encoded_bytes_unchecked(s: &[u8]) -> &Slice {
    253        unsafe { mem::transmute(s) }
    254    }
    255
    256    #[track_caller]
    257    #[inline]
    258    pub fn check_public_boundary(&self, index: usize) {
    259        if index == 0 || index == self.inner.len() {
    260            return;
    261        }
    262        if index < self.inner.len()
    263            && (self.inner[index - 1].is_ascii() || self.inner[index].is_ascii())
    264        {
    265            return;
    266        }
    267
    268        slow_path(&self.inner, index);
    269
    270        /// We're betting that typical splits will involve an ASCII character.
    271        ///
    272        /// Putting the expensive checks in a separate function generates notably
    273        /// better assembly.
    274        #[track_caller]
    275        #[inline(never)]
    276        fn slow_path(bytes: &[u8], index: usize) {
    277            let (before, after) = bytes.split_at(index);
    278
    279            // UTF-8 takes at most 4 bytes per codepoint, so we don't
    280            // need to check more than that.
    281            let after = after.get(..4).unwrap_or(after);
    282            match str::from_utf8(after) {
    283                Ok(_) => return,
    284                Err(err) if err.valid_up_to() != 0 => return,
    285                Err(_) => (),
    286            }
    287
    288            for len in 2..=4.min(index) {
    289                let before = &before[index - len..];
    290                if str::from_utf8(before).is_ok() {
    291                    return;
    292                }
    293            }
    294
    295            panic!("byte index {index} is not an OsStr boundary");
    296        }
    297    }
    298
    299    #[inline]
    300    pub fn from_str(s: &str) -> &Slice {
    301        unsafe { Slice::from_encoded_bytes_unchecked(s.as_bytes()) }
    302    }
    303
    304    #[inline]
    305    pub fn to_str(&self) -> Result<&str, crate::str::Utf8Error> {
    306        str::from_utf8(&self.inner)
    307    }
    308
    309    #[inline]
    310    pub fn to_string_lossy(&self) -> Cow<'_, str> {
    311        String::from_utf8_lossy(&self.inner)
    312    }
    313
    314    #[inline]
    315    pub fn to_owned(&self) -> Buf {
    316        Buf { inner: self.inner.to_vec() }
    317    }
    318
    319    #[inline]
    320    pub fn clone_into(&self, buf: &mut Buf) {
    321        self.inner.clone_into(&mut buf.inner)
    322    }
    323
    324    #[inline]
    325    pub fn empty_box() -> Box<Slice> {
    326        let boxed: Box<[u8]> = Default::default();
    327        unsafe { mem::transmute(boxed) }
    328    }
    329
    330    #[inline]
    331    pub fn into_arc(&self) -> Arc<Slice> {
    332        let arc: Arc<[u8]> = Arc::from(&self.inner);
    333        unsafe { Arc::from_raw(Arc::into_raw(arc) as *const Slice) }
    334    }
    335
    336    #[inline]
    337    pub fn into_rc(&self) -> Rc<Slice> {
    338        let rc: Rc<[u8]> = Rc::from(&self.inner);
    339        unsafe { Rc::from_raw(Rc::into_raw(rc) as *const Slice) }
    340    }
    341
    342    #[inline]
    343    pub fn make_ascii_lowercase(&mut self) {
    344        self.inner.make_ascii_lowercase()
    345    }
    346
    347    #[inline]
    348    pub fn make_ascii_uppercase(&mut self) {
    349        self.inner.make_ascii_uppercase()
    350    }
    351
    352    #[inline]
    353    pub fn to_ascii_lowercase(&self) -> Buf {
    354        Buf { inner: self.inner.to_ascii_lowercase() }
    355    }
    356
    357    #[inline]
    358    pub fn to_ascii_uppercase(&self) -> Buf {
    359        Buf { inner: self.inner.to_ascii_uppercase() }
    360    }
    361
    362    #[inline]
    363    pub fn is_ascii(&self) -> bool {
    364        self.inner.is_ascii()
    365    }
    366
    367    #[inline]
    368    pub fn eq_ignore_ascii_case(&self, other: &Self) -> bool {
    369        self.inner.eq_ignore_ascii_case(&other.inner)
    370    }
    371}
    372
    373#[unstable(feature = "clone_to_uninit", issue = "126799")]
    374unsafe impl CloneToUninit for Slice {
    375    #[inline]
    376    #[cfg_attr(debug_assertions, track_caller)]
    377    unsafe fn clone_to_uninit(&self, dst: *mut u8) {
    378        // SAFETY: we're just a transparent wrapper around [u8]
    379        unsafe { self.inner.clone_to_uninit(dst) }
    380    }
    381}