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Diffstat (limited to 'vendor/smol_str/src/lib.rs')
| -rw-r--r-- | vendor/smol_str/src/lib.rs | 516 |
1 files changed, 516 insertions, 0 deletions
diff --git a/vendor/smol_str/src/lib.rs b/vendor/smol_str/src/lib.rs new file mode 100644 index 000000000..8c92e51e1 --- /dev/null +++ b/vendor/smol_str/src/lib.rs @@ -0,0 +1,516 @@ +#![no_std] +extern crate alloc; + +use alloc::{ + string::{String, ToString}, + sync::Arc, +}; +use core::{ + borrow::Borrow, + cmp::{self, Ordering}, + convert::Infallible, + fmt, hash, iter, + ops::Deref, + str::FromStr, +}; + +/// A `SmolStr` is a string type that has the following properties: +/// +/// * `size_of::<SmolStr>() == size_of::<String>()` +/// * `Clone` is `O(1)` +/// * Strings are stack-allocated if they are: +/// * Up to 22 bytes long +/// * Longer than 22 bytes, but substrings of `WS` (see below). Such strings consist +/// solely of consecutive newlines, followed by consecutive spaces +/// * If a string does not satisfy the aforementioned conditions, it is heap-allocated +/// +/// Unlike `String`, however, `SmolStr` is immutable. The primary use case for +/// `SmolStr` is a good enough default storage for tokens of typical programming +/// languages. Strings consisting of a series of newlines, followed by a series of +/// whitespace are a typical pattern in computer programs because of indentation. +/// Note that a specialized interner might be a better solution for some use cases. +/// +/// `WS`: A string of 32 newlines followed by 128 spaces. +#[derive(Clone)] +pub struct SmolStr(Repr); + +impl SmolStr { + #[deprecated = "Use `new_inline` instead"] + pub const fn new_inline_from_ascii(len: usize, bytes: &[u8]) -> SmolStr { + let _len_is_short = [(); INLINE_CAP + 1][len]; + + const ZEROS: &[u8] = &[0; INLINE_CAP]; + + let mut buf = [0; INLINE_CAP]; + macro_rules! s { + ($($idx:literal),*) => ( $(s!(set $idx);)* ); + (set $idx:literal) => ({ + let src: &[u8] = [ZEROS, bytes][($idx < len) as usize]; + let byte = src[$idx]; + let _is_ascii = [(); 128][byte as usize]; + buf[$idx] = byte + }); + } + s!(0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21); + SmolStr(Repr::Inline { + len: len as u8, + buf, + }) + } + + /// Constructs inline variant of `SmolStr`. + /// + /// Panics if `text.len() > 22`. + #[inline] + pub const fn new_inline(text: &str) -> SmolStr { + let mut buf = [0; INLINE_CAP]; + let mut i = 0; + while i < text.len() { + buf[i] = text.as_bytes()[i]; + i += 1 + } + SmolStr(Repr::Inline { + len: text.len() as u8, + buf, + }) + } + + pub fn new<T>(text: T) -> SmolStr + where + T: AsRef<str>, + { + SmolStr(Repr::new(text)) + } + + #[inline(always)] + pub fn as_str(&self) -> &str { + self.0.as_str() + } + + #[inline(always)] + pub fn to_string(&self) -> String { + self.as_str().to_string() + } + + #[inline(always)] + pub fn len(&self) -> usize { + self.0.len() + } + + #[inline(always)] + pub fn is_empty(&self) -> bool { + self.0.is_empty() + } + + #[inline(always)] + pub fn is_heap_allocated(&self) -> bool { + match self.0 { + Repr::Heap(..) => true, + _ => false, + } + } + + fn from_char_iter<I: iter::Iterator<Item = char>>(mut iter: I) -> SmolStr { + let (min_size, _) = iter.size_hint(); + if min_size > INLINE_CAP { + let heap: String = iter.collect(); + return SmolStr(Repr::Heap(heap.into_boxed_str().into())); + } + let mut len = 0; + let mut buf = [0u8; INLINE_CAP]; + while let Some(ch) = iter.next() { + let size = ch.len_utf8(); + if size + len > INLINE_CAP { + let (min_remaining, _) = iter.size_hint(); + let mut heap = String::with_capacity(size + len + min_remaining); + heap.push_str(core::str::from_utf8(&buf[..len]).unwrap()); + heap.push(ch); + heap.extend(iter); + return SmolStr(Repr::Heap(heap.into_boxed_str().into())); + } + ch.encode_utf8(&mut buf[len..]); + len += size; + } + SmolStr(Repr::Inline { + len: len as u8, + buf, + }) + } +} + +impl Default for SmolStr { + fn default() -> SmolStr { + SmolStr::new("") + } +} + +impl Deref for SmolStr { + type Target = str; + + fn deref(&self) -> &str { + self.as_str() + } +} + +impl PartialEq<SmolStr> for SmolStr { + fn eq(&self, other: &SmolStr) -> bool { + self.as_str() == other.as_str() + } +} + +impl Eq for SmolStr {} + +impl PartialEq<str> for SmolStr { + fn eq(&self, other: &str) -> bool { + self.as_str() == other + } +} + +impl PartialEq<SmolStr> for str { + fn eq(&self, other: &SmolStr) -> bool { + other == self + } +} + +impl<'a> PartialEq<&'a str> for SmolStr { + fn eq(&self, other: &&'a str) -> bool { + self == *other + } +} + +impl<'a> PartialEq<SmolStr> for &'a str { + fn eq(&self, other: &SmolStr) -> bool { + *self == other + } +} + +impl PartialEq<String> for SmolStr { + fn eq(&self, other: &String) -> bool { + self.as_str() == other + } +} + +impl PartialEq<SmolStr> for String { + fn eq(&self, other: &SmolStr) -> bool { + other == self + } +} + +impl<'a> PartialEq<&'a String> for SmolStr { + fn eq(&self, other: &&'a String) -> bool { + self == *other + } +} + +impl<'a> PartialEq<SmolStr> for &'a String { + fn eq(&self, other: &SmolStr) -> bool { + *self == other + } +} + +impl Ord for SmolStr { + fn cmp(&self, other: &SmolStr) -> Ordering { + self.as_str().cmp(other.as_str()) + } +} + +impl PartialOrd for SmolStr { + fn partial_cmp(&self, other: &SmolStr) -> Option<Ordering> { + Some(self.cmp(other)) + } +} + +impl hash::Hash for SmolStr { + fn hash<H: hash::Hasher>(&self, hasher: &mut H) { + self.as_str().hash(hasher) + } +} + +impl fmt::Debug for SmolStr { + fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { + fmt::Debug::fmt(self.as_str(), f) + } +} + +impl fmt::Display for SmolStr { + fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { + fmt::Display::fmt(self.as_str(), f) + } +} + +impl iter::FromIterator<char> for SmolStr { + fn from_iter<I: iter::IntoIterator<Item = char>>(iter: I) -> SmolStr { + let iter = iter.into_iter(); + Self::from_char_iter(iter) + } +} + +fn build_from_str_iter<T>(mut iter: impl Iterator<Item = T>) -> SmolStr +where + T: AsRef<str>, + String: iter::Extend<T>, +{ + let mut len = 0; + let mut buf = [0u8; INLINE_CAP]; + while let Some(slice) = iter.next() { + let slice = slice.as_ref(); + let size = slice.len(); + if size + len > INLINE_CAP { + let mut heap = String::with_capacity(size + len); + heap.push_str(core::str::from_utf8(&buf[..len]).unwrap()); + heap.push_str(&slice); + heap.extend(iter); + return SmolStr(Repr::Heap(heap.into_boxed_str().into())); + } + (&mut buf[len..][..size]).copy_from_slice(slice.as_bytes()); + len += size; + } + SmolStr(Repr::Inline { + len: len as u8, + buf, + }) +} + +impl iter::FromIterator<String> for SmolStr { + fn from_iter<I: iter::IntoIterator<Item = String>>(iter: I) -> SmolStr { + build_from_str_iter(iter.into_iter()) + } +} + +impl<'a> iter::FromIterator<&'a String> for SmolStr { + fn from_iter<I: iter::IntoIterator<Item = &'a String>>(iter: I) -> SmolStr { + SmolStr::from_iter(iter.into_iter().map(|x| x.as_str())) + } +} + +impl<'a> iter::FromIterator<&'a str> for SmolStr { + fn from_iter<I: iter::IntoIterator<Item = &'a str>>(iter: I) -> SmolStr { + build_from_str_iter(iter.into_iter()) + } +} + +impl<T> From<T> for SmolStr +where + T: AsRef<str>, +{ + fn from(text: T) -> Self { + Self::new(text) + } +} + +impl From<SmolStr> for String { + fn from(text: SmolStr) -> Self { + text.as_str().into() + } +} + +impl Borrow<str> for SmolStr { + fn borrow(&self) -> &str { + self.as_str() + } +} + +impl FromStr for SmolStr { + type Err = Infallible; + + #[inline] + fn from_str(s: &str) -> Result<SmolStr, Self::Err> { + Ok(SmolStr::from(s)) + } +} + +#[cfg(feature = "arbitrary")] +impl<'a> arbitrary::Arbitrary<'a> for SmolStr { + fn arbitrary(u: &mut arbitrary::Unstructured<'a>) -> Result<Self, arbitrary::Error> { + let s = <&str>::arbitrary(u)?; + Ok(SmolStr::new(s)) + } +} + +const INLINE_CAP: usize = 22; +const N_NEWLINES: usize = 32; +const N_SPACES: usize = 128; +const WS: &str = + "\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n "; + +#[derive(Clone, Debug)] +enum Repr { + Heap(Arc<str>), + Inline { len: u8, buf: [u8; INLINE_CAP] }, + Substring { newlines: usize, spaces: usize }, +} + +impl Repr { + fn new<T>(text: T) -> Self + where + T: AsRef<str>, + { + { + let text = text.as_ref(); + + let len = text.len(); + if len <= INLINE_CAP { + let mut buf = [0; INLINE_CAP]; + buf[..len].copy_from_slice(text.as_bytes()); + return Repr::Inline { + len: len as u8, + buf, + }; + } + + if len <= N_NEWLINES + N_SPACES { + let bytes = text.as_bytes(); + let possible_newline_count = cmp::min(len, N_NEWLINES); + let newlines = bytes[..possible_newline_count] + .iter() + .take_while(|&&b| b == b'\n') + .count(); + let possible_space_count = len - newlines; + if possible_space_count <= N_SPACES && bytes[newlines..].iter().all(|&b| b == b' ') + { + let spaces = possible_space_count; + return Repr::Substring { newlines, spaces }; + } + } + } + + Repr::Heap(text.as_ref().into()) + } + + #[inline(always)] + fn len(&self) -> usize { + match self { + Repr::Heap(data) => data.len(), + Repr::Inline { len, .. } => *len as usize, + Repr::Substring { newlines, spaces } => *newlines + *spaces, + } + } + + #[inline(always)] + fn is_empty(&self) -> bool { + match self { + Repr::Heap(data) => data.is_empty(), + Repr::Inline { len, .. } => *len == 0, + // A substring isn't created for an empty string. + Repr::Substring { .. } => false, + } + } + + #[inline] + fn as_str(&self) -> &str { + match self { + Repr::Heap(data) => &*data, + Repr::Inline { len, buf } => { + let len = *len as usize; + let buf = &buf[..len]; + unsafe { ::core::str::from_utf8_unchecked(buf) } + } + Repr::Substring { newlines, spaces } => { + let newlines = *newlines; + let spaces = *spaces; + assert!(newlines <= N_NEWLINES && spaces <= N_SPACES); + &WS[N_NEWLINES - newlines..N_NEWLINES + spaces] + } + } + } +} + +#[cfg(feature = "serde")] +mod serde { + use alloc::{string::String, vec::Vec}; + use core::fmt; + + use serde::de::{Deserializer, Error, Unexpected, Visitor}; + + use crate::SmolStr; + + // https://github.com/serde-rs/serde/blob/629802f2abfd1a54a6072992888fea7ca5bc209f/serde/src/private/de.rs#L56-L125 + fn smol_str<'de: 'a, 'a, D>(deserializer: D) -> Result<SmolStr, D::Error> + where + D: Deserializer<'de>, + { + struct SmolStrVisitor; + + impl<'a> Visitor<'a> for SmolStrVisitor { + type Value = SmolStr; + + fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result { + formatter.write_str("a string") + } + + fn visit_str<E>(self, v: &str) -> Result<Self::Value, E> + where + E: Error, + { + Ok(SmolStr::from(v)) + } + + fn visit_borrowed_str<E>(self, v: &'a str) -> Result<Self::Value, E> + where + E: Error, + { + Ok(SmolStr::from(v)) + } + + fn visit_string<E>(self, v: String) -> Result<Self::Value, E> + where + E: Error, + { + Ok(SmolStr::from(v)) + } + + fn visit_bytes<E>(self, v: &[u8]) -> Result<Self::Value, E> + where + E: Error, + { + match core::str::from_utf8(v) { + Ok(s) => Ok(SmolStr::from(s)), + Err(_) => Err(Error::invalid_value(Unexpected::Bytes(v), &self)), + } + } + + fn visit_borrowed_bytes<E>(self, v: &'a [u8]) -> Result<Self::Value, E> + where + E: Error, + { + match core::str::from_utf8(v) { + Ok(s) => Ok(SmolStr::from(s)), + Err(_) => Err(Error::invalid_value(Unexpected::Bytes(v), &self)), + } + } + + fn visit_byte_buf<E>(self, v: Vec<u8>) -> Result<Self::Value, E> + where + E: Error, + { + match String::from_utf8(v) { + Ok(s) => Ok(SmolStr::from(s)), + Err(e) => Err(Error::invalid_value( + Unexpected::Bytes(&e.into_bytes()), + &self, + )), + } + } + } + + deserializer.deserialize_str(SmolStrVisitor) + } + + impl serde::Serialize for SmolStr { + fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error> + where + S: serde::Serializer, + { + self.as_str().serialize(serializer) + } + } + + impl<'de> serde::Deserialize<'de> for SmolStr { + fn deserialize<D>(deserializer: D) -> Result<Self, D::Error> + where + D: serde::Deserializer<'de>, + { + smol_str(deserializer) + } + } +} |