Struct http::header::HeaderValue

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pub struct HeaderValue { /* private fields */ }
Expand description

Represents an HTTP header field value.

In practice, HTTP header field values are usually valid ASCII. However, the HTTP spec allows for a header value to contain opaque bytes as well. In this case, the header field value is not able to be represented as a string.

To handle this, the HeaderValue is useable as a type and can be compared with strings and implements Debug. A to_str fn is provided that returns an Err if the header value contains non visible ascii characters.

Implementations§

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impl HeaderValue

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pub const fn from_static(src: &'static str) -> HeaderValue

Convert a static string to a HeaderValue.

This function will not perform any copying, however the string is checked to ensure that no invalid characters are present. Only visible ASCII characters (32-127) are permitted.

§Panics

This function panics if the argument contains invalid header value characters.

Until Allow panicking in constants makes its way into stable, the panic message at compile-time is going to look cryptic, but should at least point at your header value:

error: any use of this value will cause an error
  --> http/src/header/value.rs:67:17
   |
67 |                 ([] as [u8; 0])[0]; // Invalid header value
   |                 ^^^^^^^^^^^^^^^^^^
   |                 |
   |                 index out of bounds: the length is 0 but the index is 0
   |                 inside `HeaderValue::from_static` at http/src/header/value.rs:67:17
   |                 inside `INVALID_HEADER` at src/main.rs:73:33
   |
  ::: src/main.rs:73:1
   |
73 | const INVALID_HEADER: HeaderValue = HeaderValue::from_static("жsome value");
   | ----------------------------------------------------------------------------
§Examples
let val = HeaderValue::from_static("hello");
assert_eq!(val, "hello");
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pub fn from_str(src: &str) -> Result<HeaderValue, InvalidHeaderValue>

Attempt to convert a string to a HeaderValue.

If the argument contains invalid header value characters, an error is returned. Only visible ASCII characters (32-127) are permitted. Use from_bytes to create a HeaderValue that includes opaque octets (128-255).

This function is intended to be replaced in the future by a TryFrom implementation once the trait is stabilized in std.

§Examples
let val = HeaderValue::from_str("hello").unwrap();
assert_eq!(val, "hello");

An invalid value

let val = HeaderValue::from_str("\n");
assert!(val.is_err());
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pub fn from_name(name: HeaderName) -> HeaderValue

Converts a HeaderName into a HeaderValue

Since every valid HeaderName is a valid HeaderValue this is done infallibly.

§Examples
let val = HeaderValue::from_name(ACCEPT);
assert_eq!(val, HeaderValue::from_bytes(b"accept").unwrap());
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pub fn from_bytes(src: &[u8]) -> Result<HeaderValue, InvalidHeaderValue>

Attempt to convert a byte slice to a HeaderValue.

If the argument contains invalid header value bytes, an error is returned. Only byte values between 32 and 255 (inclusive) are permitted, excluding byte 127 (DEL).

This function is intended to be replaced in the future by a TryFrom implementation once the trait is stabilized in std.

§Examples
let val = HeaderValue::from_bytes(b"hello\xfa").unwrap();
assert_eq!(val, &b"hello\xfa"[..]);

An invalid value

let val = HeaderValue::from_bytes(b"\n");
assert!(val.is_err());
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pub fn from_maybe_shared<T>(src: T) -> Result<HeaderValue, InvalidHeaderValue>
where T: AsRef<[u8]> + 'static,

Attempt to convert a Bytes buffer to a HeaderValue.

This will try to prevent a copy if the type passed is the type used internally, and will copy the data if it is not.

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pub unsafe fn from_maybe_shared_unchecked<T>(src: T) -> HeaderValue
where T: AsRef<[u8]> + 'static,

Convert a Bytes directly into a HeaderValue without validating.

This function does NOT validate that illegal bytes are not contained within the buffer.

§Panics

In a debug build this will panic if src is not valid UTF-8.

§Safety

src must contain valid UTF-8. In a release build it is undefined behaviour to call this with src that is not valid UTF-8.

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pub fn to_str(&self) -> Result<&str, ToStrError>

Yields a &str slice if the HeaderValue only contains visible ASCII chars.

This function will perform a scan of the header value, checking all the characters.

§Examples
let val = HeaderValue::from_static("hello");
assert_eq!(val.to_str().unwrap(), "hello");
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pub fn len(&self) -> usize

Returns the length of self.

This length is in bytes.

§Examples
let val = HeaderValue::from_static("hello");
assert_eq!(val.len(), 5);
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pub fn is_empty(&self) -> bool

Returns true if the HeaderValue has a length of zero bytes.

§Examples
let val = HeaderValue::from_static("");
assert!(val.is_empty());

let val = HeaderValue::from_static("hello");
assert!(!val.is_empty());
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pub fn as_bytes(&self) -> &[u8]

Converts a HeaderValue to a byte slice.

§Examples
let val = HeaderValue::from_static("hello");
assert_eq!(val.as_bytes(), b"hello");
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pub fn set_sensitive(&mut self, val: bool)

Mark that the header value represents sensitive information.

§Examples
let mut val = HeaderValue::from_static("my secret");

val.set_sensitive(true);
assert!(val.is_sensitive());

val.set_sensitive(false);
assert!(!val.is_sensitive());
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pub fn is_sensitive(&self) -> bool

Returns true if the value represents sensitive data.

Sensitive data could represent passwords or other data that should not be stored on disk or in memory. By marking header values as sensitive, components using this crate can be instructed to treat them with special care for security reasons. For example, caches can avoid storing sensitive values, and HPACK encoders used by HTTP/2.0 implementations can choose not to compress them.

Additionally, sensitive values will be masked by the Debug implementation of HeaderValue.

Note that sensitivity is not factored into equality or ordering.

§Examples
let mut val = HeaderValue::from_static("my secret");

val.set_sensitive(true);
assert!(val.is_sensitive());

val.set_sensitive(false);
assert!(!val.is_sensitive());

Trait Implementations§

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impl AsRef<[u8]> for HeaderValue

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

Converts this type into a shared reference of the (usually inferred) input type.
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impl Clone for HeaderValue

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fn clone(&self) -> HeaderValue

Returns a copy of the value. Read more
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fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source. Read more
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impl Debug for HeaderValue

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

Formats the value using the given formatter. Read more
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impl<'a> From<&'a HeaderValue> for HeaderValue

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fn from(t: &'a HeaderValue) -> Self

Converts to this type from the input type.
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impl From<HeaderName> for HeaderValue

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fn from(h: HeaderName) -> HeaderValue

Converts to this type from the input type.
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impl From<i16> for HeaderValue

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fn from(num: i16) -> HeaderValue

Converts to this type from the input type.
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impl From<i32> for HeaderValue

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fn from(num: i32) -> HeaderValue

Converts to this type from the input type.
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impl From<i64> for HeaderValue

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fn from(num: i64) -> HeaderValue

Converts to this type from the input type.
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impl From<isize> for HeaderValue

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fn from(num: isize) -> HeaderValue

Converts to this type from the input type.
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impl From<u16> for HeaderValue

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fn from(num: u16) -> HeaderValue

Converts to this type from the input type.
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impl From<u32> for HeaderValue

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fn from(num: u32) -> HeaderValue

Converts to this type from the input type.
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impl From<u64> for HeaderValue

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fn from(num: u64) -> HeaderValue

Converts to this type from the input type.
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impl From<usize> for HeaderValue

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fn from(num: usize) -> HeaderValue

Converts to this type from the input type.
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impl FromStr for HeaderValue

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type Err = InvalidHeaderValue

The associated error which can be returned from parsing.
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fn from_str(s: &str) -> Result<HeaderValue, Self::Err>

Parses a string s to return a value of this type. Read more
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impl Hash for HeaderValue

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fn hash<H: Hasher>(&self, state: &mut H)

Feeds this value into the given Hasher. Read more
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fn hash_slice<H>(data: &[Self], state: &mut H)
where H: Hasher, Self: Sized,

Feeds a slice of this type into the given Hasher. Read more
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impl Ord for HeaderValue

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fn cmp(&self, other: &Self) -> Ordering

This method returns an Ordering between self and other. Read more
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fn max(self, other: Self) -> Self
where Self: Sized,

Compares and returns the maximum of two values. Read more
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fn min(self, other: Self) -> Self
where Self: Sized,

Compares and returns the minimum of two values. Read more
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fn clamp(self, min: Self, max: Self) -> Self
where Self: Sized + PartialOrd,

Restrict a value to a certain interval. Read more
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impl<'a, T: ?Sized> PartialEq<&'a T> for HeaderValue

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fn eq(&self, other: &&'a T) -> bool

This method tests for self and other values to be equal, and is used by ==.
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fn ne(&self, other: &Rhs) -> bool

This method tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.
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impl PartialEq<[u8]> for HeaderValue

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fn eq(&self, other: &[u8]) -> bool

This method tests for self and other values to be equal, and is used by ==.
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fn ne(&self, other: &Rhs) -> bool

This method tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.
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impl<'a> PartialEq<HeaderValue> for &'a HeaderValue

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fn eq(&self, other: &HeaderValue) -> bool

This method tests for self and other values to be equal, and is used by ==.
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fn ne(&self, other: &Rhs) -> bool

This method tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.
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impl<'a> PartialEq<HeaderValue> for &'a str

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fn eq(&self, other: &HeaderValue) -> bool

This method tests for self and other values to be equal, and is used by ==.
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fn ne(&self, other: &Rhs) -> bool

This method tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.
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impl PartialEq<HeaderValue> for [u8]

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fn eq(&self, other: &HeaderValue) -> bool

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

fn ne(&self, other: &Rhs) -> bool

This method tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.
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impl PartialEq<HeaderValue> for String

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fn eq(&self, other: &HeaderValue) -> bool

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

fn ne(&self, other: &Rhs) -> bool

This method tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.
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impl PartialEq<HeaderValue> for str

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fn eq(&self, other: &HeaderValue) -> bool

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

fn ne(&self, other: &Rhs) -> bool

This method tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.
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impl PartialEq<String> for HeaderValue

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fn eq(&self, other: &String) -> bool

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

fn ne(&self, other: &Rhs) -> bool

This method tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.
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impl PartialEq<str> for HeaderValue

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fn eq(&self, other: &str) -> bool

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

fn ne(&self, other: &Rhs) -> bool

This method tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.
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impl PartialEq for HeaderValue

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fn eq(&self, other: &HeaderValue) -> bool

This method tests for self and other values to be equal, and is used by ==.
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fn ne(&self, other: &Rhs) -> bool

This method tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.
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impl<'a, T: ?Sized> PartialOrd<&'a T> for HeaderValue

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fn partial_cmp(&self, other: &&'a T) -> Option<Ordering>

This method returns an ordering between self and other values if one exists. Read more
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fn lt(&self, other: &Rhs) -> bool

This method tests less than (for self and other) and is used by the < operator. Read more
1.0.0 · source§

fn le(&self, other: &Rhs) -> bool

This method tests less than or equal to (for self and other) and is used by the <= operator. Read more
1.0.0 · source§

fn gt(&self, other: &Rhs) -> bool

This method tests greater than (for self and other) and is used by the > operator. Read more
1.0.0 · source§

fn ge(&self, other: &Rhs) -> bool

This method tests greater than or equal to (for self and other) and is used by the >= operator. Read more
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impl PartialOrd<[u8]> for HeaderValue

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fn partial_cmp(&self, other: &[u8]) -> Option<Ordering>

This method returns an ordering between self and other values if one exists. Read more
1.0.0 · source§

fn lt(&self, other: &Rhs) -> bool

This method tests less than (for self and other) and is used by the < operator. Read more
1.0.0 · source§

fn le(&self, other: &Rhs) -> bool

This method tests less than or equal to (for self and other) and is used by the <= operator. Read more
1.0.0 · source§

fn gt(&self, other: &Rhs) -> bool

This method tests greater than (for self and other) and is used by the > operator. Read more
1.0.0 · source§

fn ge(&self, other: &Rhs) -> bool

This method tests greater than or equal to (for self and other) and is used by the >= operator. Read more
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impl<'a> PartialOrd<HeaderValue> for &'a HeaderValue

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fn partial_cmp(&self, other: &HeaderValue) -> Option<Ordering>

This method returns an ordering between self and other values if one exists. Read more
1.0.0 · source§

fn lt(&self, other: &Rhs) -> bool

This method tests less than (for self and other) and is used by the < operator. Read more
1.0.0 · source§

fn le(&self, other: &Rhs) -> bool

This method tests less than or equal to (for self and other) and is used by the <= operator. Read more
1.0.0 · source§

fn gt(&self, other: &Rhs) -> bool

This method tests greater than (for self and other) and is used by the > operator. Read more
1.0.0 · source§

fn ge(&self, other: &Rhs) -> bool

This method tests greater than or equal to (for self and other) and is used by the >= operator. Read more
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impl<'a> PartialOrd<HeaderValue> for &'a str

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fn partial_cmp(&self, other: &HeaderValue) -> Option<Ordering>

This method returns an ordering between self and other values if one exists. Read more
1.0.0 · source§

fn lt(&self, other: &Rhs) -> bool

This method tests less than (for self and other) and is used by the < operator. Read more
1.0.0 · source§

fn le(&self, other: &Rhs) -> bool

This method tests less than or equal to (for self and other) and is used by the <= operator. Read more
1.0.0 · source§

fn gt(&self, other: &Rhs) -> bool

This method tests greater than (for self and other) and is used by the > operator. Read more
1.0.0 · source§

fn ge(&self, other: &Rhs) -> bool

This method tests greater than or equal to (for self and other) and is used by the >= operator. Read more
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impl PartialOrd<HeaderValue> for [u8]

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fn partial_cmp(&self, other: &HeaderValue) -> Option<Ordering>

This method returns an ordering between self and other values if one exists. Read more
1.0.0 · source§

fn lt(&self, other: &Rhs) -> bool

This method tests less than (for self and other) and is used by the < operator. Read more
1.0.0 · source§

fn le(&self, other: &Rhs) -> bool

This method tests less than or equal to (for self and other) and is used by the <= operator. Read more
1.0.0 · source§

fn gt(&self, other: &Rhs) -> bool

This method tests greater than (for self and other) and is used by the > operator. Read more
1.0.0 · source§

fn ge(&self, other: &Rhs) -> bool

This method tests greater than or equal to (for self and other) and is used by the >= operator. Read more
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impl PartialOrd<HeaderValue> for String

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fn partial_cmp(&self, other: &HeaderValue) -> Option<Ordering>

This method returns an ordering between self and other values if one exists. Read more
1.0.0 · source§

fn lt(&self, other: &Rhs) -> bool

This method tests less than (for self and other) and is used by the < operator. Read more
1.0.0 · source§

fn le(&self, other: &Rhs) -> bool

This method tests less than or equal to (for self and other) and is used by the <= operator. Read more
1.0.0 · source§

fn gt(&self, other: &Rhs) -> bool

This method tests greater than (for self and other) and is used by the > operator. Read more
1.0.0 · source§

fn ge(&self, other: &Rhs) -> bool

This method tests greater than or equal to (for self and other) and is used by the >= operator. Read more
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impl PartialOrd<HeaderValue> for str

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fn partial_cmp(&self, other: &HeaderValue) -> Option<Ordering>

This method returns an ordering between self and other values if one exists. Read more
1.0.0 · source§

fn lt(&self, other: &Rhs) -> bool

This method tests less than (for self and other) and is used by the < operator. Read more
1.0.0 · source§

fn le(&self, other: &Rhs) -> bool

This method tests less than or equal to (for self and other) and is used by the <= operator. Read more
1.0.0 · source§

fn gt(&self, other: &Rhs) -> bool

This method tests greater than (for self and other) and is used by the > operator. Read more
1.0.0 · source§

fn ge(&self, other: &Rhs) -> bool

This method tests greater than or equal to (for self and other) and is used by the >= operator. Read more
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impl PartialOrd<String> for HeaderValue

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fn partial_cmp(&self, other: &String) -> Option<Ordering>

This method returns an ordering between self and other values if one exists. Read more
1.0.0 · source§

fn lt(&self, other: &Rhs) -> bool

This method tests less than (for self and other) and is used by the < operator. Read more
1.0.0 · source§

fn le(&self, other: &Rhs) -> bool

This method tests less than or equal to (for self and other) and is used by the <= operator. Read more
1.0.0 · source§

fn gt(&self, other: &Rhs) -> bool

This method tests greater than (for self and other) and is used by the > operator. Read more
1.0.0 · source§

fn ge(&self, other: &Rhs) -> bool

This method tests greater than or equal to (for self and other) and is used by the >= operator. Read more
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impl PartialOrd<str> for HeaderValue

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fn partial_cmp(&self, other: &str) -> Option<Ordering>

This method returns an ordering between self and other values if one exists. Read more
1.0.0 · source§

fn lt(&self, other: &Rhs) -> bool

This method tests less than (for self and other) and is used by the < operator. Read more
1.0.0 · source§

fn le(&self, other: &Rhs) -> bool

This method tests less than or equal to (for self and other) and is used by the <= operator. Read more
1.0.0 · source§

fn gt(&self, other: &Rhs) -> bool

This method tests greater than (for self and other) and is used by the > operator. Read more
1.0.0 · source§

fn ge(&self, other: &Rhs) -> bool

This method tests greater than or equal to (for self and other) and is used by the >= operator. Read more
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impl PartialOrd for HeaderValue

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fn partial_cmp(&self, other: &HeaderValue) -> Option<Ordering>

This method returns an ordering between self and other values if one exists. Read more
1.0.0 · source§

fn lt(&self, other: &Rhs) -> bool

This method tests less than (for self and other) and is used by the < operator. Read more
1.0.0 · source§

fn le(&self, other: &Rhs) -> bool

This method tests less than or equal to (for self and other) and is used by the <= operator. Read more
1.0.0 · source§

fn gt(&self, other: &Rhs) -> bool

This method tests greater than (for self and other) and is used by the > operator. Read more
1.0.0 · source§

fn ge(&self, other: &Rhs) -> bool

This method tests greater than or equal to (for self and other) and is used by the >= operator. Read more
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impl<'a> TryFrom<&'a [u8]> for HeaderValue

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type Error = InvalidHeaderValue

The type returned in the event of a conversion error.
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fn try_from(t: &'a [u8]) -> Result<Self, Self::Error>

Performs the conversion.
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impl<'a> TryFrom<&'a String> for HeaderValue

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type Error = InvalidHeaderValue

The type returned in the event of a conversion error.
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fn try_from(s: &'a String) -> Result<Self, Self::Error>

Performs the conversion.
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impl<'a> TryFrom<&'a str> for HeaderValue

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type Error = InvalidHeaderValue

The type returned in the event of a conversion error.
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fn try_from(t: &'a str) -> Result<Self, Self::Error>

Performs the conversion.
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impl TryFrom<String> for HeaderValue

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type Error = InvalidHeaderValue

The type returned in the event of a conversion error.
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fn try_from(t: String) -> Result<Self, Self::Error>

Performs the conversion.
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impl TryFrom<Vec<u8>> for HeaderValue

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type Error = InvalidHeaderValue

The type returned in the event of a conversion error.
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fn try_from(vec: Vec<u8>) -> Result<Self, Self::Error>

Performs the conversion.
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impl Eq for HeaderValue

Auto Trait Implementations§

Blanket Implementations§

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impl<T> Any for T
where T: 'static + ?Sized,

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fn type_id(&self) -> TypeId

Gets the TypeId of self. Read more
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impl<T> Borrow<T> for T
where T: ?Sized,

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fn borrow(&self) -> &T

Immutably borrows from an owned value. Read more
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impl<T> BorrowMut<T> for T
where T: ?Sized,

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fn borrow_mut(&mut self) -> &mut T

Mutably borrows from an owned value. Read more
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impl<T> CloneToUninit for T
where T: Clone,

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default unsafe fn clone_to_uninit(&self, dst: *mut T)

🔬This is a nightly-only experimental API. (clone_to_uninit)
Performs copy-assignment from self to dst. Read more
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impl<T> From<T> for T

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fn from(t: T) -> T

Returns the argument unchanged.

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impl<T, U> Into<U> for T
where U: From<T>,

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fn into(self) -> U

Calls U::from(self).

That is, this conversion is whatever the implementation of From<T> for U chooses to do.

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impl<T> ToOwned for T
where T: Clone,

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type Owned = T

The resulting type after obtaining ownership.
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fn to_owned(&self) -> T

Creates owned data from borrowed data, usually by cloning. Read more
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fn clone_into(&self, target: &mut T)

Uses borrowed data to replace owned data, usually by cloning. Read more
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impl<T, U> TryFrom<U> for T
where U: Into<T>,

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type Error = Infallible

The type returned in the event of a conversion error.
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fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>

Performs the conversion.
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impl<T, U> TryInto<U> for T
where U: TryFrom<T>,

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type Error = <U as TryFrom<T>>::Error

The type returned in the event of a conversion error.
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fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>

Performs the conversion.