Struct collections::string::DerefString [] [src]

pub struct DerefString<'a> {
    // some fields omitted
}
Unstable

Wrapper type providing a &String`&Stringreference via` reference via Deref`Deref`.

Methods from Deref<Target=String>

fn new() -> String

Creates a new string buffer initialized with the empty string.

Examples

fn main() { let mut s = String::new(); }
let mut s = String::new();

fn with_capacity(capacity: usize) -> String

Creates a new string buffer with the given capacity. The string will be able to hold exactly capacity`capacitybytes without reallocating. If` bytes without reallocating. If capacity`capacity` is 0, the string will not allocate.

Examples

fn main() { let mut s = String::with_capacity(10); }
let mut s = String::with_capacity(10);

fn from_str(string: &str) -> String

Unstable

: needs investigation to see if to_string() can match perf

Creates a new string buffer from the given string.

Examples

#![feature(collections, core)] extern crate collections; fn main() { let s = String::from_str("hello"); assert_eq!(&s[..], "hello"); }
let s = String::from_str("hello");
assert_eq!(&s[..], "hello");

fn from_utf8(vec: Vec<u8>) -> Result<String, FromUtf8Error>

Returns the vector as a string buffer, if possible, taking care not to copy it.

Failure

If the given vector is not valid UTF-8, then the original vector and the corresponding error is returned.

Examples

#![feature(core)] fn main() { use std::str::Utf8Error; let hello_vec = vec![104, 101, 108, 108, 111]; let s = String::from_utf8(hello_vec).unwrap(); assert_eq!(s, "hello"); let invalid_vec = vec![240, 144, 128]; let s = String::from_utf8(invalid_vec).err().unwrap(); let err = s.utf8_error(); assert_eq!(s.into_bytes(), [240, 144, 128]); }
use std::str::Utf8Error;

let hello_vec = vec![104, 101, 108, 108, 111];
let s = String::from_utf8(hello_vec).unwrap();
assert_eq!(s, "hello");

let invalid_vec = vec![240, 144, 128];
let s = String::from_utf8(invalid_vec).err().unwrap();
let err = s.utf8_error();
assert_eq!(s.into_bytes(), [240, 144, 128]);

fn from_utf8_lossy<'a>(v: &'a [u8]) -> Cow<'a, str>

Converts a vector of bytes to a new UTF-8 string. Any invalid UTF-8 sequences are replaced with U+FFFD REPLACEMENT CHARACTER.

Examples

fn main() { let input = b"Hello \xF0\x90\x80World"; let output = String::from_utf8_lossy(input); assert_eq!(output, "Hello \u{FFFD}World"); }
let input = b"Hello \xF0\x90\x80World";
let output = String::from_utf8_lossy(input);
assert_eq!(output, "Hello \u{FFFD}World");

fn from_utf16(v: &[u16]) -> Result<String, FromUtf16Error>

Decode a UTF-16 encoded vector v`vinto a` into a String`String, returning`, returning None`Noneif` if v`v` contains any invalid data.

Examples

fn main() { // 𝄞music let mut v = &mut [0xD834, 0xDD1E, 0x006d, 0x0075, 0x0073, 0x0069, 0x0063]; assert_eq!(String::from_utf16(v).unwrap(), "𝄞music".to_string()); // 𝄞mu<invalid>ic v[4] = 0xD800; assert!(String::from_utf16(v).is_err()); }
// 𝄞music
let mut v = &mut [0xD834, 0xDD1E, 0x006d, 0x0075,
                  0x0073, 0x0069, 0x0063];
assert_eq!(String::from_utf16(v).unwrap(),
           "𝄞music".to_string());

// 𝄞mu<invalid>ic
v[4] = 0xD800;
assert!(String::from_utf16(v).is_err());

fn from_utf16_lossy(v: &[u16]) -> String

Decode a UTF-16 encoded vector v`v` into a string, replacing invalid data with the replacement character (U+FFFD).

Examples

fn main() { // 𝄞mus<invalid>ic<invalid> let v = &[0xD834, 0xDD1E, 0x006d, 0x0075, 0x0073, 0xDD1E, 0x0069, 0x0063, 0xD834]; assert_eq!(String::from_utf16_lossy(v), "𝄞mus\u{FFFD}ic\u{FFFD}".to_string()); }
// 𝄞mus<invalid>ic<invalid>
let v = &[0xD834, 0xDD1E, 0x006d, 0x0075,
          0x0073, 0xDD1E, 0x0069, 0x0063,
          0xD834];

assert_eq!(String::from_utf16_lossy(v),
           "𝄞mus\u{FFFD}ic\u{FFFD}".to_string());

unsafe fn from_raw_parts(buf: *mut u8, length: usize, capacity: usize) -> String

Creates a new String`String` from a length, capacity, and pointer.

This is unsafe because:

  • We call Vec::from_raw_parts`Vec::from_raw_partsto get a` to get a Vec<u8>`Vec`;
  • We assume that the Vec`Vec` contains valid UTF-8.

unsafe fn from_utf8_unchecked(bytes: Vec<u8>) -> String

Converts a vector of bytes to a new String`String` without checking if it contains valid UTF-8. This is unsafe because it assumes that the UTF-8-ness of the vector has already been validated.

fn into_bytes(self) -> Vec<u8>

Returns the underlying byte buffer, encoded as UTF-8.

Examples

#![feature(collections)] extern crate collections; fn main() { let s = String::from_str("hello"); let bytes = s.into_bytes(); assert_eq!(bytes, [104, 101, 108, 108, 111]); }
let s = String::from_str("hello");
let bytes = s.into_bytes();
assert_eq!(bytes, [104, 101, 108, 108, 111]);

fn as_str(&self) -> &str

Unstable

: waiting on RFC revision

Extracts a string slice containing the entire string.

fn push_str(&mut self, string: &str)

Pushes the given string onto this string buffer.

Examples

#![feature(collections)] extern crate collections; fn main() { let mut s = String::from_str("foo"); s.push_str("bar"); assert_eq!(s, "foobar"); }
let mut s = String::from_str("foo");
s.push_str("bar");
assert_eq!(s, "foobar");

fn capacity(&self) -> usize

Returns the number of bytes that this string buffer can hold without reallocating.

Examples

fn main() { let s = String::with_capacity(10); assert!(s.capacity() >= 10); }
let s = String::with_capacity(10);
assert!(s.capacity() >= 10);

fn reserve(&mut self, additional: usize)

Reserves capacity for at least additional`additionalmore bytes to be inserted in the given` more bytes to be inserted in the given String`String`. The collection may reserve more space to avoid frequent reallocations.

Panics

Panics if the new capacity overflows usize`usize`.

Examples

fn main() { let mut s = String::new(); s.reserve(10); assert!(s.capacity() >= 10); }
let mut s = String::new();
s.reserve(10);
assert!(s.capacity() >= 10);

fn reserve_exact(&mut self, additional: usize)

Reserves the minimum capacity for exactly additional`additionalmore bytes to be inserted in the given` more bytes to be inserted in the given String`String`. Does nothing if the capacity is already sufficient.

Note that the allocator may give the collection more space than it requests. Therefore capacity can not be relied upon to be precisely minimal. Prefer reserve`reserve` if future insertions are expected.

Panics

Panics if the new capacity overflows usize`usize`.

Examples

fn main() { let mut s = String::new(); s.reserve(10); assert!(s.capacity() >= 10); }
let mut s = String::new();
s.reserve(10);
assert!(s.capacity() >= 10);

fn shrink_to_fit(&mut self)

Shrinks the capacity of this string buffer to match its length.

Examples

#![feature(collections)] extern crate collections; fn main() { let mut s = String::from_str("foo"); s.reserve(100); assert!(s.capacity() >= 100); s.shrink_to_fit(); assert_eq!(s.capacity(), 3); }
let mut s = String::from_str("foo");
s.reserve(100);
assert!(s.capacity() >= 100);
s.shrink_to_fit();
assert_eq!(s.capacity(), 3);

fn push(&mut self, ch: char)

Adds the given character to the end of the string.

Examples

#![feature(collections)] extern crate collections; fn main() { let mut s = String::from_str("abc"); s.push('1'); s.push('2'); s.push('3'); assert_eq!(s, "abc123"); }
let mut s = String::from_str("abc");
s.push('1');
s.push('2');
s.push('3');
assert_eq!(s, "abc123");

fn as_bytes(&self) -> &[u8]

Works with the underlying buffer as a byte slice.

Examples

#![feature(collections)] extern crate collections; fn main() { let s = String::from_str("hello"); let b: &[_] = &[104, 101, 108, 108, 111]; assert_eq!(s.as_bytes(), b); }
let s = String::from_str("hello");
let b: &[_] = &[104, 101, 108, 108, 111];
assert_eq!(s.as_bytes(), b);

fn truncate(&mut self, new_len: usize)

Shortens a string to the specified length.

Panics

Panics if new_len`new_len> current length, or if` > current length, or if new_len`new_len` is not a character boundary.

Examples

#![feature(collections)] extern crate collections; fn main() { let mut s = String::from_str("hello"); s.truncate(2); assert_eq!(s, "he"); }
let mut s = String::from_str("hello");
s.truncate(2);
assert_eq!(s, "he");

fn pop(&mut self) -> Option<char>

Removes the last character from the string buffer and returns it. Returns None`None` if this string buffer is empty.

Examples

#![feature(collections)] extern crate collections; fn main() { let mut s = String::from_str("foo"); assert_eq!(s.pop(), Some('o')); assert_eq!(s.pop(), Some('o')); assert_eq!(s.pop(), Some('f')); assert_eq!(s.pop(), None); }
let mut s = String::from_str("foo");
assert_eq!(s.pop(), Some('o'));
assert_eq!(s.pop(), Some('o'));
assert_eq!(s.pop(), Some('f'));
assert_eq!(s.pop(), None);

fn remove(&mut self, idx: usize) -> char

Removes the character from the string buffer at byte position idx`idx` and returns it.

Warning

This is an O(n) operation as it requires copying every element in the buffer.

Panics

If idx`idx` does not lie on a character boundary, or if it is out of bounds, then this function will panic.

Examples

#![feature(collections)] extern crate collections; fn main() { let mut s = String::from_str("foo"); assert_eq!(s.remove(0), 'f'); assert_eq!(s.remove(1), 'o'); assert_eq!(s.remove(0), 'o'); }
let mut s = String::from_str("foo");
assert_eq!(s.remove(0), 'f');
assert_eq!(s.remove(1), 'o');
assert_eq!(s.remove(0), 'o');

fn insert(&mut self, idx: usize, ch: char)

Inserts a character into the string buffer at byte position idx`idx`.

Warning

This is an O(n) operation as it requires copying every element in the buffer.

Panics

If idx`idx` does not lie on a character boundary or is out of bounds, then this function will panic.

unsafe fn as_mut_vec(&mut self) -> &mut Vec<u8>

Views the string buffer as a mutable sequence of bytes.

This is unsafe because it does not check to ensure that the resulting string will be valid UTF-8.

Examples

#![feature(collections)] extern crate collections; fn main() { let mut s = String::from_str("hello"); unsafe { let vec = s.as_mut_vec(); assert!(vec == &[104, 101, 108, 108, 111]); vec.reverse(); } assert_eq!(s, "olleh"); }
let mut s = String::from_str("hello");
unsafe {
    let vec = s.as_mut_vec();
    assert!(vec == &[104, 101, 108, 108, 111]);
    vec.reverse();
}
assert_eq!(s, "olleh");

fn len(&self) -> usize

Returns the number of bytes in this string.

Examples

fn main() { let a = "foo".to_string(); assert_eq!(a.len(), 3); }
let a = "foo".to_string();
assert_eq!(a.len(), 3);

fn is_empty(&self) -> bool

Returns true if the string contains no bytes

Examples

fn main() { let mut v = String::new(); assert!(v.is_empty()); v.push('a'); assert!(!v.is_empty()); }
let mut v = String::new();
assert!(v.is_empty());
v.push('a');
assert!(!v.is_empty());

fn clear(&mut self)

Truncates the string, returning it to 0 length.

Examples

fn main() { let mut s = "foo".to_string(); s.clear(); assert!(s.is_empty()); }
let mut s = "foo".to_string();
s.clear();
assert!(s.is_empty());

fn drain<R>(&mut self, range: R) -> Drain where R: RangeArgument<usize>

Unstable

: recently added, matches RFC

Create a draining iterator that removes the specified range in the string and yields the removed chars from start to end. The element range is removed even if the iterator is not consumed until the end.

Panics

Panics if the starting point or end point are not on character boundaries, or if they are out of bounds.

Examples

#![feature(collections_drain)] extern crate collections; fn main() { let mut s = String::from("α is alpha, β is beta"); let beta_offset = s.find('β').unwrap_or(s.len()); // Remove the range up until the β from the string let t: String = s.drain(..beta_offset).collect(); assert_eq!(t, "α is alpha, "); assert_eq!(s, "β is beta"); // A full range clears the string s.drain(..); assert_eq!(s, ""); }

let mut s = String::from("α is alpha, β is beta");
let beta_offset = s.find('β').unwrap_or(s.len());

// Remove the range up until the β from the string
let t: String = s.drain(..beta_offset).collect();
assert_eq!(t, "α is alpha, ");
assert_eq!(s, "β is beta");

// A full range clears the string
s.drain(..);
assert_eq!(s, "");

Trait Implementations

impl<'a> Deref for DerefString<'a>

type Target = String

fn deref<'b>(&'b self) -> &'b String