Struct reqwest::header::UserAgent

pub struct UserAgent(pub String);

User-Agent header, defined in RFC7231

The User-Agent header field contains information about the user agent originating the request, which is often used by servers to help identify the scope of reported interoperability problems, to work around or tailor responses to avoid particular user agent limitations, and for analytics regarding browser or operating system use. A user agent SHOULD send a User-Agent field in each request unless specifically configured not to do so.

ABNF

User-Agent = product *( RWS ( product / comment ) )
product         = token ["/" product-version]
product-version = token

Example values

• CERN-LineMode/2.15 libwww/2.17b3
• Bunnies

Notes

• The parser does not split the value

Example

use hyper::header::{Headers, UserAgent};

let mut headers = Headers::new();
headers.set(UserAgent("hyper/0.5.2".to_owned()));

Methods from Deref<Target = String>

pub fn as_str(&self) -> &str

Extracts a string slice containing the entire string.

Examples

Basic usage:

let s = String::from("foo");

assert_eq!("foo", s.as_str());

pub fn as_mut_str(&mut self) -> &mut str

Converts a String into a mutable string slice.

Examples

Basic usage:

let mut s = String::from("foobar");
let s_mut_str = s.as_mut_str();

s_mut_str.make_ascii_uppercase();

assert_eq!("FOOBAR", s_mut_str);

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

Appends a given string slice onto the end of this String.

Examples

Basic usage:

let mut s = String::from("foo");

s.push_str("bar");

assert_eq!("foobar", s);

pub fn capacity(&self) -> usize

Returns this String's capacity, in bytes.

Examples

Basic usage:

let s = String::with_capacity(10);

assert!(s.capacity() >= 10);

pub fn reserve(&mut self, additional: usize)

Ensures that this String's capacity is at least additional bytes larger than its length.

The capacity may be increased by more than additional bytes if it chooses, to prevent frequent reallocations.

If you do not want this "at least" behavior, see the reserve_exact method.

Panics

Panics if the new capacity overflows usize.

Examples

Basic usage:

let mut s = String::new();

s.reserve(10);

assert!(s.capacity() >= 10);

This may not actually increase the capacity:

let mut s = String::with_capacity(10);
s.push('a');
s.push('b');

// s now has a length of 2 and a capacity of 10
assert_eq!(2, s.len());
assert_eq!(10, s.capacity());

// Since we already have an extra 8 capacity, calling this...
s.reserve(8);

// ... doesn't actually increase.
assert_eq!(10, s.capacity());

pub fn reserve_exact(&mut self, additional: usize)

Ensures that this String's capacity is additional bytes larger than its length.

Consider using the reserve method unless you absolutely know better than the allocator.

Panics

Panics if the new capacity overflows usize.

Examples

Basic usage:

let mut s = String::new();

s.reserve_exact(10);

assert!(s.capacity() >= 10);

This may not actually increase the capacity:

let mut s = String::with_capacity(10);
s.push('a');
s.push('b');

// s now has a length of 2 and a capacity of 10
assert_eq!(2, s.len());
assert_eq!(10, s.capacity());

// Since we already have an extra 8 capacity, calling this...
s.reserve_exact(8);

// ... doesn't actually increase.
assert_eq!(10, s.capacity());

pub fn shrink_to_fit(&mut self)

Shrinks the capacity of this String to match its length.

Examples

Basic usage:

let mut s = String::from("foo");

s.reserve(100);
assert!(s.capacity() >= 100);

s.shrink_to_fit();
assert_eq!(3, s.capacity());

pub fn push(&mut self, ch: char)

Appends the given char to the end of this String.

Examples

Basic usage:

let mut s = String::from("abc");

s.push('1');
s.push('2');
s.push('3');

assert_eq!("abc123", s);

Important traits for &'a [u8]

impl<'a> Read for &'a [u8]impl<'a> Write for &'a mut [u8]

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

Returns a byte slice of this String's contents.

The inverse of this method is from_utf8.

Examples

Basic usage:

let s = String::from("hello");

assert_eq!(&[104, 101, 108, 108, 111], s.as_bytes());

pub fn truncate(&mut self, new_len: usize)

Shortens this String to the specified length.

If new_len is greater than the string's current length, this has no effect.

Note that this method has no effect on the allocated capacity of the string

Panics

Panics if new_len does not lie on a char boundary.

Examples

Basic usage:

let mut s = String::from("hello");

s.truncate(2);

assert_eq!("he", s);

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

Removes the last character from the string buffer and returns it.

Returns None if this String is empty.

Examples

Basic usage:

let mut s = String::from("foo");

assert_eq!(s.pop(), Some('o'));
assert_eq!(s.pop(), Some('o'));
assert_eq!(s.pop(), Some('f'));

assert_eq!(s.pop(), None);

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

Removes a char from this String at a byte position and returns it.

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

Panics

Panics if idx is larger than or equal to the String's length, or if it does not lie on a char boundary.

Examples

Basic usage:

let mut s = String::from("foo");

assert_eq!(s.remove(0), 'f');
assert_eq!(s.remove(1), 'o');
assert_eq!(s.remove(0), 'o');

pub fn retain<F>(&mut self, f: F) where
    F: FnMut(char) -> bool, 

🔬 This is a nightly-only experimental API. (string_retain)

Retains only the characters specified by the predicate.

In other words, remove all characters c such that f(c) returns false. This method operates in place and preserves the order of the retained characters.

Examples

#![feature(string_retain)]

let mut s = String::from("f_o_ob_ar");

s.retain(|c| c != '_');

assert_eq!(s, "foobar");

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

Inserts a character into this String at a byte position.

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

Panics

Panics if idx is larger than the String's length, or if it does not lie on a char boundary.

Examples

Basic usage:

let mut s = String::with_capacity(3);

s.insert(0, 'f');
s.insert(1, 'o');
s.insert(2, 'o');

assert_eq!("foo", s);

pub fn insert_str(&mut self, idx: usize, string: &str)

Inserts a string slice into this String at a byte position.

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

Panics

Panics if idx is larger than the String's length, or if it does not lie on a char boundary.

Examples

Basic usage:

let mut s = String::from("bar");

s.insert_str(0, "foo");

assert_eq!("foobar", s);

Important traits for Vec<u8>

impl Write for Vec<u8>

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

Returns a mutable reference to the contents of this String.

Safety

This function is unsafe because it does not check that the bytes passed to it are valid UTF-8. If this constraint is violated, it may cause memory unsafety issues with future users of the String, as the rest of the standard library assumes that Strings are valid UTF-8.

Examples

Basic usage:

let mut s = String::from("hello");

unsafe {
    let vec = s.as_mut_vec();
    assert_eq!(&[104, 101, 108, 108, 111][..], &vec[..]);

    vec.reverse();
}
assert_eq!(s, "olleh");

pub fn len(&self) -> usize

Returns the length of this String, in bytes.

Examples

Basic usage:

let a = String::from("foo");

assert_eq!(a.len(), 3);

pub fn is_empty(&self) -> bool

Returns true if this String has a length of zero.

Returns false otherwise.

Examples

Basic usage:

let mut v = String::new();
assert!(v.is_empty());

v.push('a');
assert!(!v.is_empty());

pub fn split_off(&mut self, at: usize) -> String

Splits the string into two at the given index.

Returns a newly allocated String. self contains bytes [0, at), and the returned String contains bytes [at, len). at must be on the boundary of a UTF-8 code point.

Note that the capacity of self does not change.

Panics

Panics if at is not on a UTF-8 code point boundary, or if it is beyond the last code point of the string.

Examples

let mut hello = String::from("Hello, World!");
let world = hello.split_off(7);
assert_eq!(hello, "Hello, ");
assert_eq!(world, "World!");

pub fn clear(&mut self)

Truncates this String, removing all contents.

While this means the String will have a length of zero, it does not touch its capacity.

Examples

Basic usage:

let mut s = String::from("foo");

s.clear();

assert!(s.is_empty());
assert_eq!(0, s.len());
assert_eq!(3, s.capacity());

Important traits for Drain<'a>

impl<'a> Iterator for Drain<'a> type Item = char;

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

Creates a draining iterator that removes the specified range in the string and yields the removed chars.

Note: The element range is removed even if the iterator is not consumed until the end.

Panics

Panics if the starting point or end point do not lie on a char boundary, or if they're out of bounds.

Examples

Basic usage:

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, "");

pub fn splice<R>(&mut self, range: R, replace_with: &str) where
    R: RangeArgument<usize>, 

🔬 This is a nightly-only experimental API. (splice)

recently added

Creates a splicing iterator that removes the specified range in the string, and replaces it with the given string. The given string doesn't need to be the same length as the range.

Note: Unlike Vec::splice, the replacement happens eagerly, and this method does not return the removed chars.

Panics

Panics if the starting point or end point do not lie on a char boundary, or if they're out of bounds.

Examples

Basic usage:

#![feature(splice)]
let mut s = String::from("α is alpha, β is beta");
let beta_offset = s.find('β').unwrap_or(s.len());

// Replace the range up until the β from the string
s.splice(..beta_offset, "Α is capital alpha; ");
assert_eq!(s, "Α is capital alpha; β is beta");

Trait Implementations

impl Display for UserAgent

fn fmt(&self, f: &mut Formatter) -> Result<(), Error>

Formats the value using the given formatter.

impl PartialEq<UserAgent> for UserAgent

fn eq(&self, __arg_0: &UserAgent) -> bool

This method tests for self and other values to be equal, and is used by ==.

fn ne(&self, __arg_0: &UserAgent) -> bool

This method tests for !=.

impl Deref for UserAgent

type Target = String

The resulting type after dereferencing.

fn deref(&self) -> &String

Dereferences the value.

impl DerefMut for UserAgent

fn deref_mut(&mut self) -> &mut String

Mutably dereferences the value.

impl Debug for UserAgent

fn fmt(&self, __arg_0: &mut Formatter) -> Result<(), Error>

Formats the value using the given formatter.

impl Clone for UserAgent

fn clone(&self) -> UserAgent

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl HeaderFormat for UserAgent

fn fmt_header(&self, f: &mut Formatter) -> Result<(), Error>

Format a header to be output into a TcpStream.

impl Header for UserAgent

fn header_name() -> &'static str

Returns the name of the header field this belongs to.

fn parse_header(raw: &[Vec<u8>]) -> Result<UserAgent, Error>

Parse a header from a raw stream of bytes.