Struct tower_grpc::metadata::MetadataValue

#[repr(transparent)]
pub struct MetadataValue<VE: ValueEncoding> { /* fields omitted */ }

Represents a custom metadata field value.

MetadataValue is used as the [MetadataMap] value.

Methods

impl<VE: ValueEncoding> MetadataValue<VE>

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

Convert a static string to a MetadataValue.

This function will not perform any copying, however the string is checked to ensure that no invalid characters are present.

For Ascii values, only visible ASCII characters (32-127) are permitted. For Binary values, the string must be valid base64.

Panics

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

Examples

let val = AsciiMetadataValue::from_static("hello");
assert_eq!(val, "hello");

let val = BinaryMetadataValue::from_static("SGVsbG8hIQ==");
assert_eq!(val, "Hello!!");

pub fn try_from_bytes(src: &[u8]) -> Result<Self, InvalidMetadataValueBytes>

Attempt to convert a byte slice to a MetadataValue.

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

For Binary metadata values this method cannot fail. See also the Binary only version of this method from_bytes.

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

Examples

let val = AsciiMetadataValue::try_from_bytes(b"hello\xfa").unwrap();
assert_eq!(val, &b"hello\xfa"[..]);

An invalid value

let val = AsciiMetadataValue::try_from_bytes(b"\n");
assert!(val.is_err());

pub fn from_shared(src: Bytes) -> Result<Self, InvalidMetadataValueBytes>

Attempt to convert a Bytes buffer to a MetadataValue.

For MetadataValue<Ascii>, if the argument contains invalid metadata value bytes, an error is returned. Only byte values between 32 and 255 (inclusive) are permitted, excluding byte 127 (DEL).

For MetadataValue<Binary>, if the argument is not valid base64, an error is returned. In use cases where the input is not base64 encoded, use from_bytes; if the value has to be encoded it's not possible to share the memory anyways.

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

pub unsafe fn from_shared_unchecked(src: Bytes) -> Self

Convert a Bytes directly into a MetadataValue without validating. For MetadataValue the provided parameter must be base64 encoded without padding bytes at the end.

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

pub fn is_empty(&self) -> bool

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

Examples

let val = AsciiMetadataValue::from_static("");
assert!(val.is_empty());

let val = AsciiMetadataValue::from_static("hello");
assert!(!val.is_empty());

pub fn to_bytes(&self) -> Result<Bytes, InvalidMetadataValueBytes>

Converts a MetadataValue to a Bytes buffer. This method cannot fail for Ascii values. For Ascii values, as_bytes is more convenient to use.

Examples

let val = AsciiMetadataValue::from_static("hello");
assert_eq!(val.to_bytes().unwrap().as_ref(), b"hello");

let val = BinaryMetadataValue::from_bytes(b"hello");
assert_eq!(val.to_bytes().unwrap().as_ref(), b"hello");

pub fn set_sensitive(&mut self, val: bool)

Mark that the metadata value represents sensitive information.

Examples

let mut val = AsciiMetadataValue::from_static("my secret");

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

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

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. This setting can be used by components like caches to avoid storing the value. HPACK encoders must set the metadata field to never index when is_sensitive returns true.

Note that sensitivity is not factored into equality or ordering.

Examples

let mut val = AsciiMetadataValue::from_static("my secret");

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

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

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

Converts a MetadataValue to a byte slice. For Binary values, the return value is base64 encoded.

Examples

let val = AsciiMetadataValue::from_static("hello");
assert_eq!(val.as_encoded_bytes(), b"hello");

let val = BinaryMetadataValue::from_bytes(b"Hello!");
assert_eq!(val.as_encoded_bytes(), b"SGVsbG8h");

impl MetadataValue<Ascii>

pub fn from_str(src: &str) -> Result<Self, InvalidMetadataValue>

Attempt to convert a string to a MetadataValue<Ascii>.

If the argument contains invalid metadata value characters, an error is returned. Only visible ASCII characters (32-127) are permitted. Use from_bytes to create a MetadataValue 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 = AsciiMetadataValue::from_str("hello").unwrap();
assert_eq!(val, "hello");

An invalid value

let val = AsciiMetadataValue::from_str("\n");
assert!(val.is_err());

pub fn from_key<KeyVE: ValueEncoding>(key: MetadataKey<KeyVE>) -> Self

Converts a MetadataKey into a MetadataValue.

Since every valid MetadataKey is a valid MetadataValue this is done infallibly.

Examples

let val = AsciiMetadataValue::from_key::<Ascii>("accept".parse().unwrap());
assert_eq!(val, AsciiMetadataValue::try_from_bytes(b"accept").unwrap());

pub fn len(&self) -> usize

Returns the length of self, in bytes.

This method is not available for MetadataValue because that cannot be implemented in constant time, which most people would probably expect. To get the length of MetadataValue, convert it to a Bytes value and measure its length.

Examples

let val = AsciiMetadataValue::from_static("hello");
assert_eq!(val.len(), 5);

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

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

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

Examples

let val = AsciiMetadataValue::from_static("hello");
assert_eq!(val.to_str().unwrap(), "hello");

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

Converts a MetadataValue to a byte slice. For Binary values, use to_bytes.

Examples

let val = AsciiMetadataValue::from_static("hello");
assert_eq!(val.as_bytes(), b"hello");

impl MetadataValue<Binary>

pub fn from_bytes(src: &[u8]) -> Self

Convert a byte slice to a MetadataValue<Binary>.

Examples

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

Trait Implementations

impl<KeyVE: ValueEncoding> From<MetadataKey<KeyVE>> for MetadataValue<Ascii>

fn from(h: MetadataKey<KeyVE>) -> MetadataValue<Ascii>

Performs the conversion.

impl From<u16> for MetadataValue<Ascii>

fn from(num: u16) -> MetadataValue<Ascii>

Performs the conversion.

impl From<i16> for MetadataValue<Ascii>

fn from(num: i16) -> MetadataValue<Ascii>

Performs the conversion.

impl From<u32> for MetadataValue<Ascii>

fn from(num: u32) -> MetadataValue<Ascii>

Performs the conversion.

impl From<i32> for MetadataValue<Ascii>

fn from(num: i32) -> MetadataValue<Ascii>

Performs the conversion.

impl From<u64> for MetadataValue<Ascii>

fn from(num: u64) -> MetadataValue<Ascii>

Performs the conversion.

impl From<i64> for MetadataValue<Ascii>

fn from(num: i64) -> MetadataValue<Ascii>

Performs the conversion.

impl From<usize> for MetadataValue<Ascii>

fn from(num: usize) -> MetadataValue<Ascii>

Performs the conversion.

impl From<isize> for MetadataValue<Ascii>

fn from(num: isize) -> MetadataValue<Ascii>

Performs the conversion.

impl<VE: ValueEncoding> From<MetadataValue<VE>> for Bytes

fn from(value: MetadataValue<VE>) -> Bytes

Performs the conversion.

impl<'a, VE: ValueEncoding> From<&'a MetadataValue<VE>> for MetadataValue<VE>

fn from(t: &'a MetadataValue<VE>) -> Self

Performs the conversion.

impl<VE: ValueEncoding> AsRef<[u8]> for MetadataValue<VE>

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

Performs the conversion.

impl<VE: ValueEncoding> Ord for MetadataValue<VE>

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

This method returns an Ordering between self and other.

fn max(self, other: Self) -> Self

Compares and returns the maximum of two values.

fn min(self, other: Self) -> Self

Compares and returns the minimum of two values.

fn clamp(self, min: Self, max: Self) -> Self

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

Restrict a value to a certain interval.

impl<VE: ValueEncoding> PartialOrd<MetadataValue<VE>> for MetadataValue<VE>

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

This method returns an ordering between self and other values if one exists.

#[must_use] fn lt(&self, other: &Rhs) -> bool

This method tests less than (for self and other) and is used by the < operator.

#[must_use] fn le(&self, other: &Rhs) -> bool

This method tests less than or equal to (for self and other) and is used by the <= operator.

#[must_use] fn gt(&self, other: &Rhs) -> bool

This method tests greater than (for self and other) and is used by the > operator.

#[must_use] fn ge(&self, other: &Rhs) -> bool

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

impl<VE: ValueEncoding> PartialOrd<str> for MetadataValue<VE>

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

This method returns an ordering between self and other values if one exists.

#[must_use] fn lt(&self, other: &Rhs) -> bool

This method tests less than (for self and other) and is used by the < operator.

#[must_use] fn le(&self, other: &Rhs) -> bool

This method tests less than or equal to (for self and other) and is used by the <= operator.

#[must_use] fn gt(&self, other: &Rhs) -> bool

This method tests greater than (for self and other) and is used by the > operator.

#[must_use] fn ge(&self, other: &Rhs) -> bool

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

impl<VE: ValueEncoding> PartialOrd<[u8]> for MetadataValue<VE>

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

This method returns an ordering between self and other values if one exists.

#[must_use] fn lt(&self, other: &Rhs) -> bool

This method tests less than (for self and other) and is used by the < operator.

#[must_use] fn le(&self, other: &Rhs) -> bool

This method tests less than or equal to (for self and other) and is used by the <= operator.

#[must_use] fn gt(&self, other: &Rhs) -> bool

This method tests greater than (for self and other) and is used by the > operator.

#[must_use] fn ge(&self, other: &Rhs) -> bool

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

impl<VE: ValueEncoding> PartialOrd<MetadataValue<VE>> for str

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

This method returns an ordering between self and other values if one exists.

#[must_use] fn lt(&self, other: &Rhs) -> bool

This method tests less than (for self and other) and is used by the < operator.

#[must_use] fn le(&self, other: &Rhs) -> bool

This method tests less than or equal to (for self and other) and is used by the <= operator.

#[must_use] fn gt(&self, other: &Rhs) -> bool

This method tests greater than (for self and other) and is used by the > operator.

#[must_use] fn ge(&self, other: &Rhs) -> bool

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

impl<VE: ValueEncoding> PartialOrd<MetadataValue<VE>> for [u8]

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

This method returns an ordering between self and other values if one exists.

#[must_use] fn lt(&self, other: &Rhs) -> bool

This method tests less than (for self and other) and is used by the < operator.

#[must_use] fn le(&self, other: &Rhs) -> bool

This method tests less than or equal to (for self and other) and is used by the <= operator.

#[must_use] fn gt(&self, other: &Rhs) -> bool

This method tests greater than (for self and other) and is used by the > operator.

#[must_use] fn ge(&self, other: &Rhs) -> bool

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

impl<VE: ValueEncoding> PartialOrd<String> for MetadataValue<VE>

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

This method returns an ordering between self and other values if one exists.

#[must_use] fn lt(&self, other: &Rhs) -> bool

This method tests less than (for self and other) and is used by the < operator.

#[must_use] fn le(&self, other: &Rhs) -> bool

This method tests less than or equal to (for self and other) and is used by the <= operator.

#[must_use] fn gt(&self, other: &Rhs) -> bool

This method tests greater than (for self and other) and is used by the > operator.

#[must_use] fn ge(&self, other: &Rhs) -> bool

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

impl<VE: ValueEncoding> PartialOrd<MetadataValue<VE>> for String

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

This method returns an ordering between self and other values if one exists.

#[must_use] fn lt(&self, other: &Rhs) -> bool

This method tests less than (for self and other) and is used by the < operator.

#[must_use] fn le(&self, other: &Rhs) -> bool

This method tests less than or equal to (for self and other) and is used by the <= operator.

#[must_use] fn gt(&self, other: &Rhs) -> bool

This method tests greater than (for self and other) and is used by the > operator.

#[must_use] fn ge(&self, other: &Rhs) -> bool

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

impl<'a, VE: ValueEncoding> PartialOrd<MetadataValue<VE>> for &'a MetadataValue<VE>

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

This method returns an ordering between self and other values if one exists.

#[must_use] fn lt(&self, other: &Rhs) -> bool

This method tests less than (for self and other) and is used by the < operator.

#[must_use] fn le(&self, other: &Rhs) -> bool

This method tests less than or equal to (for self and other) and is used by the <= operator.

#[must_use] fn gt(&self, other: &Rhs) -> bool

This method tests greater than (for self and other) and is used by the > operator.

#[must_use] fn ge(&self, other: &Rhs) -> bool

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

impl<'a, VE: ValueEncoding, T: ?Sized> PartialOrd<&'a T> for MetadataValue<VE> where
    MetadataValue<VE>: PartialOrd<T>, 

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

This method returns an ordering between self and other values if one exists.

#[must_use] fn lt(&self, other: &Rhs) -> bool

This method tests less than (for self and other) and is used by the < operator.

#[must_use] fn le(&self, other: &Rhs) -> bool

This method tests less than or equal to (for self and other) and is used by the <= operator.

#[must_use] fn gt(&self, other: &Rhs) -> bool

This method tests greater than (for self and other) and is used by the > operator.

#[must_use] fn ge(&self, other: &Rhs) -> bool

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

impl<'a, VE: ValueEncoding> PartialOrd<MetadataValue<VE>> for &'a str

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

This method returns an ordering between self and other values if one exists.

#[must_use] fn lt(&self, other: &Rhs) -> bool

This method tests less than (for self and other) and is used by the < operator.

#[must_use] fn le(&self, other: &Rhs) -> bool

This method tests less than or equal to (for self and other) and is used by the <= operator.

#[must_use] fn gt(&self, other: &Rhs) -> bool

This method tests greater than (for self and other) and is used by the > operator.

#[must_use] fn ge(&self, other: &Rhs) -> bool

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

impl<VE: Clone + ValueEncoding> Clone for MetadataValue<VE>

fn clone(&self) -> MetadataValue<VE>

Returns a copy of the value.

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

Performs copy-assignment from source.

impl<VE: ValueEncoding> PartialEq<MetadataValue<VE>> for MetadataValue<VE>

fn eq(&self, other: &MetadataValue<VE>) -> bool

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

#[must_use] fn ne(&self, other: &Rhs) -> bool

This method tests for !=.

impl<VE: ValueEncoding> PartialEq<str> for MetadataValue<VE>

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

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

#[must_use] fn ne(&self, other: &Rhs) -> bool

This method tests for !=.

impl<VE: ValueEncoding> PartialEq<[u8]> for MetadataValue<VE>

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

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

#[must_use] fn ne(&self, other: &Rhs) -> bool

This method tests for !=.

impl<VE: ValueEncoding> PartialEq<MetadataValue<VE>> for str

fn eq(&self, other: &MetadataValue<VE>) -> bool

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

#[must_use] fn ne(&self, other: &Rhs) -> bool

This method tests for !=.

impl<VE: ValueEncoding> PartialEq<MetadataValue<VE>> for [u8]

fn eq(&self, other: &MetadataValue<VE>) -> bool

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

#[must_use] fn ne(&self, other: &Rhs) -> bool

This method tests for !=.

impl<VE: ValueEncoding> PartialEq<String> for MetadataValue<VE>

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

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

#[must_use] fn ne(&self, other: &Rhs) -> bool

This method tests for !=.

impl<VE: ValueEncoding> PartialEq<MetadataValue<VE>> for String

fn eq(&self, other: &MetadataValue<VE>) -> bool

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

#[must_use] fn ne(&self, other: &Rhs) -> bool

This method tests for !=.

impl<'a, VE: ValueEncoding> PartialEq<MetadataValue<VE>> for &'a MetadataValue<VE>

fn eq(&self, other: &MetadataValue<VE>) -> bool

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

#[must_use] fn ne(&self, other: &Rhs) -> bool

This method tests for !=.

impl<'a, VE: ValueEncoding, T: ?Sized> PartialEq<&'a T> for MetadataValue<VE> where
    MetadataValue<VE>: PartialEq<T>, 

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

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

#[must_use] fn ne(&self, other: &Rhs) -> bool

This method tests for !=.

impl<'a, VE: ValueEncoding> PartialEq<MetadataValue<VE>> for &'a str

fn eq(&self, other: &MetadataValue<VE>) -> bool

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

#[must_use] fn ne(&self, other: &Rhs) -> bool

This method tests for !=.

impl<VE: ValueEncoding> Eq for MetadataValue<VE>

impl<VE: ValueEncoding> Debug for MetadataValue<VE>

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

Formats the value using the given formatter.

impl<VE: Hash + ValueEncoding> Hash for MetadataValue<VE>

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

Feeds this value into the given [Hasher].

fn hash_slice<H>(data: &[Self], state: &mut H) where
    H: Hasher, 

Feeds a slice of this type into the given [Hasher].

impl FromStr for MetadataValue<Ascii>

type Err = InvalidMetadataValue

The associated error which can be returned from parsing.

fn from_str(s: &str) -> Result<MetadataValue<Ascii>, Self::Err>

Parses a string s to return a value of this type.