diff options
| author | Laurenz <laurmaedje@gmail.com> | 2022-06-13 23:16:40 +0200 |
|---|---|---|
| committer | Laurenz <laurmaedje@gmail.com> | 2022-06-14 13:53:02 +0200 |
| commit | c81e2a5f56eb262663f292578c683fba7f18251f (patch) | |
| tree | 6c045a8dcbec5e75e01a15f970ef8cee6ff042d0 /src/util/eco_string.rs | |
| parent | 891af17260a6750a74a102388a05e59cf1ffc3c1 (diff) | |
Many fixes
Diffstat (limited to 'src/util/eco_string.rs')
| -rw-r--r-- | src/util/eco_string.rs | 488 |
1 files changed, 0 insertions, 488 deletions
diff --git a/src/util/eco_string.rs b/src/util/eco_string.rs deleted file mode 100644 index e3c8fc8a..00000000 --- a/src/util/eco_string.rs +++ /dev/null @@ -1,488 +0,0 @@ -use std::borrow::Borrow; -use std::cmp::Ordering; -use std::fmt::{self, Debug, Display, Formatter, Write}; -use std::hash::{Hash, Hasher}; -use std::ops::{Add, AddAssign, Deref}; -use std::sync::Arc; - -use super::ArcExt; - -/// Create a new [`EcoString`] from a format string. -macro_rules! format_eco { - ($($tts:tt)*) => {{ - use std::fmt::Write; - let mut s = $crate::util::EcoString::new(); - write!(s, $($tts)*).unwrap(); - s - }}; -} - -/// An economical string with inline storage and clone-on-write semantics. -#[derive(Clone)] -pub struct EcoString(Repr); - -/// The internal representation. Either: -/// - inline when below a certain number of bytes, -/// - or reference-counted on the heap with COW semantics. -#[derive(Clone)] -enum Repr { - Small { buf: [u8; LIMIT], len: u8 }, - Large(Arc<String>), -} - -/// The maximum number of bytes that can be stored inline. -/// -/// The value is chosen such that an `EcoString` fits exactly into 16 bytes -/// (which are needed anyway due to the `Arc`s alignment, at least on 64-bit -/// platforms). -/// -/// Must be at least 4 to hold any char. -const LIMIT: usize = 14; - -impl EcoString { - /// Create a new, empty string. - pub fn new() -> Self { - Self(Repr::Small { buf: [0; LIMIT], len: 0 }) - } - - /// Create a new, empty string with the given `capacity`. - pub fn with_capacity(capacity: usize) -> Self { - if capacity <= LIMIT { - Self::new() - } else { - Self(Repr::Large(Arc::new(String::with_capacity(capacity)))) - } - } - - /// Create an instance from an existing string-like type. - pub fn from_str<S>(s: S) -> Self - where - S: AsRef<str> + Into<String>, - { - let slice = s.as_ref(); - let len = slice.len(); - Self(if len <= LIMIT { - let mut buf = [0; LIMIT]; - buf[.. len].copy_from_slice(slice.as_bytes()); - Repr::Small { buf, len: len as u8 } - } else { - Repr::Large(Arc::new(s.into())) - }) - } - - /// Whether the string is empty. - pub fn is_empty(&self) -> bool { - self.len() == 0 - } - - /// The length of the string in bytes. - pub fn len(&self) -> usize { - match &self.0 { - Repr::Small { len, .. } => usize::from(*len), - Repr::Large(string) => string.len(), - } - } - - /// A string slice containing the entire string. - pub fn as_str(&self) -> &str { - self - } - - /// Append the given character at the end. - pub fn push(&mut self, c: char) { - match &mut self.0 { - Repr::Small { buf, len } => { - let prev = usize::from(*len); - if c.len_utf8() == 1 && prev < LIMIT { - buf[prev] = c as u8; - *len += 1; - } else { - self.push_str(c.encode_utf8(&mut [0; 4])); - } - } - Repr::Large(rc) => Arc::make_mut(rc).push(c), - } - } - - /// Append the given string slice at the end. - pub fn push_str(&mut self, string: &str) { - match &mut self.0 { - Repr::Small { buf, len } => { - let prev = usize::from(*len); - let new = prev + string.len(); - if new <= LIMIT { - buf[prev .. new].copy_from_slice(string.as_bytes()); - *len = new as u8; - } else { - let mut spilled = String::with_capacity(new); - spilled.push_str(self); - spilled.push_str(string); - self.0 = Repr::Large(Arc::new(spilled)); - } - } - Repr::Large(rc) => Arc::make_mut(rc).push_str(string), - } - } - - /// Remove the last character from the string. - pub fn pop(&mut self) -> Option<char> { - let c = self.as_str().chars().rev().next()?; - match &mut self.0 { - Repr::Small { len, .. } => { - *len -= c.len_utf8() as u8; - } - Repr::Large(rc) => { - Arc::make_mut(rc).pop(); - } - } - Some(c) - } - - /// Clear the string. - pub fn clear(&mut self) { - match &mut self.0 { - Repr::Small { len, .. } => *len = 0, - Repr::Large(rc) => { - if Arc::strong_count(rc) == 1 { - Arc::make_mut(rc).clear(); - } else { - *self = Self::new(); - } - } - } - } - - /// Convert the string to lowercase. - pub fn to_lowercase(&self) -> Self { - if let Repr::Small { mut buf, len } = self.0 { - if self.is_ascii() { - buf[.. usize::from(len)].make_ascii_lowercase(); - return Self(Repr::Small { buf, len }); - } - } - - self.as_str().to_lowercase().into() - } - - /// Convert the string to uppercase. - pub fn to_uppercase(&self) -> Self { - if let Repr::Small { mut buf, len } = self.0 { - if self.is_ascii() { - buf[.. usize::from(len)].make_ascii_uppercase(); - return Self(Repr::Small { buf, len }); - } - } - - self.as_str().to_uppercase().into() - } - - /// Repeat this string `n` times. - pub fn repeat(&self, n: usize) -> Self { - if n == 0 { - return Self::new(); - } - - if let Repr::Small { buf, len } = self.0 { - let prev = usize::from(len); - let new = prev.saturating_mul(n); - if new <= LIMIT { - let src = &buf[.. prev]; - let mut buf = [0; LIMIT]; - for i in 0 .. n { - buf[prev * i .. prev * (i + 1)].copy_from_slice(src); - } - return Self(Repr::Small { buf, len: new as u8 }); - } - } - - self.as_str().repeat(n).into() - } -} - -impl Deref for EcoString { - type Target = str; - - fn deref(&self) -> &str { - match &self.0 { - // Safety: - // The buffer contents stem from correct UTF-8 sources: - // - Valid ASCII characters - // - Other string slices - // - Chars that were encoded with char::encode_utf8 - // Furthermore, we still do the bounds-check on the len in case - // it gets corrupted somehow. - Repr::Small { buf, len } => unsafe { - std::str::from_utf8_unchecked(&buf[.. usize::from(*len)]) - }, - Repr::Large(string) => string.as_str(), - } - } -} - -impl Default for EcoString { - fn default() -> Self { - Self::new() - } -} - -impl Debug for EcoString { - fn fmt(&self, f: &mut Formatter) -> fmt::Result { - f.write_char('"')?; - for c in self.chars() { - match c { - '\\' => f.write_str(r"\\")?, - '"' => f.write_str(r#"\""#)?, - '\n' => f.write_str(r"\n")?, - '\r' => f.write_str(r"\r")?, - '\t' => f.write_str(r"\t")?, - _ => f.write_char(c)?, - } - } - f.write_char('"') - } -} - -impl Display for EcoString { - fn fmt(&self, f: &mut Formatter) -> fmt::Result { - Display::fmt(self.as_str(), f) - } -} - -impl Eq for EcoString {} - -impl PartialEq for EcoString { - fn eq(&self, other: &Self) -> bool { - self.as_str().eq(other.as_str()) - } -} - -impl PartialEq<str> for EcoString { - fn eq(&self, other: &str) -> bool { - self.as_str().eq(other) - } -} - -impl PartialEq<&str> for EcoString { - fn eq(&self, other: &&str) -> bool { - self.as_str().eq(*other) - } -} - -impl Ord for EcoString { - fn cmp(&self, other: &Self) -> Ordering { - self.as_str().cmp(other.as_str()) - } -} - -impl PartialOrd for EcoString { - fn partial_cmp(&self, other: &Self) -> Option<Ordering> { - self.as_str().partial_cmp(other.as_str()) - } -} - -impl Hash for EcoString { - fn hash<H: Hasher>(&self, state: &mut H) { - self.as_str().hash(state); - } -} - -impl Write for EcoString { - fn write_str(&mut self, s: &str) -> fmt::Result { - self.push_str(s); - Ok(()) - } - - fn write_char(&mut self, c: char) -> fmt::Result { - self.push(c); - Ok(()) - } -} - -impl Add for EcoString { - type Output = Self; - - fn add(mut self, rhs: Self) -> Self::Output { - self += rhs; - self - } -} - -impl AddAssign for EcoString { - fn add_assign(&mut self, rhs: Self) { - self.push_str(rhs.as_str()); - } -} - -impl AsRef<str> for EcoString { - fn as_ref(&self) -> &str { - self - } -} - -impl Borrow<str> for EcoString { - fn borrow(&self) -> &str { - self - } -} - -impl From<&Self> for EcoString { - fn from(s: &Self) -> Self { - s.clone() - } -} - -impl From<char> for EcoString { - fn from(c: char) -> Self { - let mut buf = [0; LIMIT]; - let len = c.encode_utf8(&mut buf).len(); - Self(Repr::Small { buf, len: len as u8 }) - } -} - -impl From<&str> for EcoString { - fn from(s: &str) -> Self { - Self::from_str(s) - } -} - -impl From<String> for EcoString { - fn from(s: String) -> Self { - Self::from_str(s) - } -} - -impl From<&EcoString> for String { - fn from(s: &EcoString) -> Self { - s.as_str().to_owned() - } -} - -impl From<EcoString> for String { - fn from(s: EcoString) -> Self { - match s.0 { - Repr::Small { .. } => s.as_str().to_owned(), - Repr::Large(rc) => Arc::take(rc), - } - } -} - -impl FromIterator<char> for EcoString { - fn from_iter<T: IntoIterator<Item = char>>(iter: T) -> Self { - let mut s = Self::new(); - for c in iter { - s.push(c); - } - s - } -} - -#[cfg(test)] -mod tests { - use super::*; - - const ALPH: &str = "abcdefghijklmnopqrstuvwxyz"; - - #[test] - fn test_str_new() { - // Test inline strings. - assert_eq!(EcoString::new(), ""); - assert_eq!(EcoString::from('a'), "a"); - assert_eq!(EcoString::from('😀'), "😀"); - assert_eq!(EcoString::from("abc"), "abc"); - - // Test around the inline limit. - assert_eq!(EcoString::from(&ALPH[.. LIMIT - 1]), ALPH[.. LIMIT - 1]); - assert_eq!(EcoString::from(&ALPH[.. LIMIT]), ALPH[.. LIMIT]); - assert_eq!(EcoString::from(&ALPH[.. LIMIT + 1]), ALPH[.. LIMIT + 1]); - - // Test heap string. - assert_eq!(EcoString::from(ALPH), ALPH); - } - - #[test] - fn test_str_push() { - let mut v = EcoString::new(); - v.push('a'); - v.push('b'); - v.push_str("cd😀"); - assert_eq!(v, "abcd😀"); - assert_eq!(v.len(), 8); - - // Test fully filling the inline storage. - v.push_str("efghij"); - assert_eq!(v.len(), LIMIT); - - // Test spilling with `push`. - let mut a = v.clone(); - a.push('k'); - assert_eq!(a, "abcd😀efghijk"); - assert_eq!(a.len(), 15); - - // Test spilling with `push_str`. - let mut b = v.clone(); - b.push_str("klmn"); - assert_eq!(b, "abcd😀efghijklmn"); - assert_eq!(b.len(), 18); - - // v should be unchanged. - assert_eq!(v.len(), LIMIT); - } - - #[test] - fn test_str_pop() { - // Test with inline string. - let mut v = EcoString::from("Hello World!"); - assert_eq!(v.pop(), Some('!')); - assert_eq!(v, "Hello World"); - - // Remove one-by-one. - for _ in 0 .. 10 { - v.pop(); - } - - assert_eq!(v, "H"); - assert_eq!(v.pop(), Some('H')); - assert_eq!(v, ""); - assert!(v.is_empty()); - - // Test with large string. - let mut v = EcoString::from(ALPH); - assert_eq!(v.pop(), Some('z')); - assert_eq!(v.len(), 25); - } - - #[test] - fn test_str_index() { - // Test that we can use the index syntax. - let v = EcoString::from("abc"); - assert_eq!(&v[.. 2], "ab"); - } - - #[test] - fn test_str_case() { - assert_eq!(EcoString::new().to_uppercase(), ""); - assert_eq!(EcoString::from("abc").to_uppercase(), "ABC"); - assert_eq!(EcoString::from("AΣ").to_lowercase(), "aς"); - assert_eq!( - EcoString::from("a").repeat(100).to_uppercase(), - EcoString::from("A").repeat(100) - ); - assert_eq!( - EcoString::from("Ö").repeat(20).to_lowercase(), - EcoString::from("ö").repeat(20) - ); - } - - #[test] - fn test_str_repeat() { - // Test with empty string. - assert_eq!(EcoString::new().repeat(0), ""); - assert_eq!(EcoString::new().repeat(100), ""); - - // Test non-spilling and spilling case. - let v = EcoString::from("abc"); - assert_eq!(v.repeat(0), ""); - assert_eq!(v.repeat(3), "abcabcabc"); - assert_eq!(v.repeat(5), "abcabcabcabcabc"); - } -} |
