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

Represents a custom metadata field value.

MetadataValue is used as the MetadataMap value.

Implementations§

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!!");
👎Deprecated: Use TryFrom instead

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.

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());
👎Deprecated: Use TryFrom instead

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.

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

Safety

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

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());

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");

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());

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());

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");
👎Deprecated: Use TryFrom or FromStr instead

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).

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());

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(b"accept").unwrap());

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);

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");

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");

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§

Converts this type into a shared reference of the (usually inferred) input type.
Returns a copy of the value. Read more
Performs copy-assignment from source. Read more
Formats the value using the given formatter. Read more
Converts to this type from the input type.
Converts to this type from the input type.
Converts to this type from the input type.
Converts to this type from the input type.
Converts to this type from the input type.
Converts to this type from the input type.
Converts to this type from the input type.
Converts to this type from the input type.
Converts to this type from the input type.
Converts to this type from the input type.
Converts to this type from the input type.
The associated error which can be returned from parsing.
Parses a string s to return a value of this type. Read more
Feeds this value into the given Hasher. Read more
Feeds a slice of this type into the given Hasher. Read more
Feeds this value into the given Hasher. Read more
Feeds a slice of this type into the given Hasher. Read more
This method returns an Ordering between self and other. Read more
Compares and returns the maximum of two values. Read more
Compares and returns the minimum of two values. Read more
Restrict a value to a certain interval. Read more
This method tests for self and other values to be equal, and is used by ==. Read more
This method tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason. Read more
This method tests for self and other values to be equal, and is used by ==. Read more
This method tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason. Read more
This method tests for self and other values to be equal, and is used by ==. Read more
This method tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason. Read more
This method tests for self and other values to be equal, and is used by ==. Read more
This method tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason. Read more
This method tests for self and other values to be equal, and is used by ==. Read more
This method tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason. Read more
This method tests for self and other values to be equal, and is used by ==. Read more
This method tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason. Read more
This method tests for self and other values to be equal, and is used by ==. Read more
This method tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason. Read more
This method tests for self and other values to be equal, and is used by ==. Read more
This method tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason. Read more
This method tests for self and other values to be equal, and is used by ==. Read more
This method tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason. Read more
This method tests for self and other values to be equal, and is used by ==. Read more
This method tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason. Read more
This method returns an ordering between self and other values if one exists. Read more
This method tests less than (for self and other) and is used by the < operator. Read more
This method tests less than or equal to (for self and other) and is used by the <= operator. Read more
This method tests greater than (for self and other) and is used by the > operator. Read more
This method tests greater than or equal to (for self and other) and is used by the >= operator. Read more
This method returns an ordering between self and other values if one exists. Read more
This method tests less than (for self and other) and is used by the < operator. Read more
This method tests less than or equal to (for self and other) and is used by the <= operator. Read more
This method tests greater than (for self and other) and is used by the > operator. Read more
This method tests greater than or equal to (for self and other) and is used by the >= operator. Read more
This method returns an ordering between self and other values if one exists. Read more
This method tests less than (for self and other) and is used by the < operator. Read more
This method tests less than or equal to (for self and other) and is used by the <= operator. Read more
This method tests greater than (for self and other) and is used by the > operator. Read more
This method tests greater than or equal to (for self and other) and is used by the >= operator. Read more
This method returns an ordering between self and other values if one exists. Read more
This method tests less than (for self and other) and is used by the < operator. Read more
This method tests less than or equal to (for self and other) and is used by the <= operator. Read more
This method tests greater than (for self and other) and is used by the > operator. Read more
This method tests greater than or equal to (for self and other) and is used by the >= operator. Read more
This method returns an ordering between self and other values if one exists. Read more
This method tests less than (for self and other) and is used by the < operator. Read more
This method tests less than or equal to (for self and other) and is used by the <= operator. Read more
This method tests greater than (for self and other) and is used by the > operator. Read more
This method tests greater than or equal to (for self and other) and is used by the >= operator. Read more
This method returns an ordering between self and other values if one exists. Read more
This method tests less than (for self and other) and is used by the < operator. Read more
This method tests less than or equal to (for self and other) and is used by the <= operator. Read more
This method tests greater than (for self and other) and is used by the > operator. Read more
This method tests greater than or equal to (for self and other) and is used by the >= operator. Read more
This method returns an ordering between self and other values if one exists. Read more
This method tests less than (for self and other) and is used by the < operator. Read more
This method tests less than or equal to (for self and other) and is used by the <= operator. Read more
This method tests greater than (for self and other) and is used by the > operator. Read more
This method tests greater than or equal to (for self and other) and is used by the >= operator. Read more
This method returns an ordering between self and other values if one exists. Read more
This method tests less than (for self and other) and is used by the < operator. Read more
This method tests less than or equal to (for self and other) and is used by the <= operator. Read more
This method tests greater than (for self and other) and is used by the > operator. Read more
This method tests greater than or equal to (for self and other) and is used by the >= operator. Read more
This method returns an ordering between self and other values if one exists. Read more
This method tests less than (for self and other) and is used by the < operator. Read more
This method tests less than or equal to (for self and other) and is used by the <= operator. Read more
This method tests greater than (for self and other) and is used by the > operator. Read more
This method tests greater than or equal to (for self and other) and is used by the >= operator. Read more
This method returns an ordering between self and other values if one exists. Read more
This method tests less than (for self and other) and is used by the < operator. Read more
This method tests less than or equal to (for self and other) and is used by the <= operator. Read more
This method tests greater than (for self and other) and is used by the > operator. Read more
This method tests greater than or equal to (for self and other) and is used by the >= operator. Read more

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.

Examples

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

An invalid value

let val = AsciiMetadataValue::try_from(b"\n");
assert!(val.is_err());
The type returned in the event of a conversion error.
Performs the conversion.

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.

Examples

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

An invalid value

let val = AsciiMetadataValue::try_from(b"\n");
assert!(val.is_err());
The type returned in the event of a conversion error.
Performs the conversion.

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).

The type returned in the event of a conversion error.
Performs the conversion.

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).

The type returned in the event of a conversion error.
Performs the conversion.

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.

The type returned in the event of a conversion error.
Performs the conversion.

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).

The type returned in the event of a conversion error.
Performs the conversion.

Attempt to convert a Vec of bytes 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.

The type returned in the event of a conversion error.
Performs the conversion.

Auto Trait Implementations§

Blanket Implementations§

Gets the TypeId of self. Read more
Immutably borrows from an owned value. Read more
Mutably borrows from an owned value. Read more
Compare self to key and return true if they are equal.

Returns the argument unchanged.

Converts to this type from a reference to the input type.
Instruments this type with the provided Span, returning an Instrumented wrapper. Read more
Instruments this type with the current Span, returning an Instrumented wrapper. Read more
Instruments this type with the provided Span, returning an Instrumented wrapper. Read more
Instruments this type with the current Span, returning an Instrumented wrapper. Read more

Calls U::from(self).

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

The resulting type after obtaining ownership.
Creates owned data from borrowed data, usually by cloning. Read more
Uses borrowed data to replace owned data, usually by cloning. Read more
The type returned in the event of a conversion error.
Performs the conversion.
The type returned in the event of a conversion error.
Performs the conversion.
Attaches the provided Subscriber to this type, returning a WithDispatch wrapper. Read more
Attaches the current default Subscriber to this type, returning a WithDispatch wrapper. Read more
Attaches the provided Subscriber to this type, returning a WithDispatch wrapper. Read more
Attaches the current default Subscriber to this type, returning a WithDispatch wrapper. Read more