Struct std::string::DerefString
[−]
[src]
pub struct DerefString<'a> { // some fields omitted }
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
: needs investigation to see if to_string() can match perf
Creates a new string buffer from the given string.
Examples
#![feature(collections, core)] 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(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 aVec<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)] 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
: 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)] 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)] 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)] 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)] 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)] 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)] 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)] 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)] 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>
: 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)] 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, "");