Struct headers::util::entity::EntityTag

pub(crate) struct EntityTag<T = HeaderValue>(T);

An entity tag, defined in RFC7232

An entity tag consists of a string enclosed by two literal double quotes. Preceding the first double quote is an optional weakness indicator, which always looks like W/. Examples for valid tags are "xyzzy" and W/"xyzzy".

ABNF

entity-tag = [ weak ] opaque-tag
weak       = %x57.2F ; "W/", case-sensitive
opaque-tag = DQUOTE *etagc DQUOTE
etagc      = %x21 / %x23-7E / obs-text
           ; VCHAR except double quotes, plus obs-text

Comparison

To check if two entity tags are equivalent in an application always use the strong_eq or weak_eq methods based on the context of the Tag. Only use == to check if two tags are identical.

The example below shows the results for a set of entity-tag pairs and both the weak and strong comparison function results:

ETag 1	ETag 2	Strong Comparison	Weak Comparison
W/"1"	W/"1"	no match	match
W/"1"	W/"2"	no match	no match
W/"1"	"1"	no match	match
"1"	"1"	match	match

Tuple Fields

0: T

Implementations

impl<T: AsRef<[u8]>> EntityTag<T>

pub(crate) fn tag(&self) -> &[u8]

Get the tag.

pub(crate) fn is_weak(&self) -> bool

Return if this is a “weak” tag.

pub(crate) fn strong_eq<R>(&self, other: &EntityTag<R>) -> bool

where R: AsRef<[u8]>,

For strong comparison two entity-tags are equivalent if both are not weak and their opaque-tags match character-by-character.

pub(crate) fn weak_eq<R>(&self, other: &EntityTag<R>) -> bool

where R: AsRef<[u8]>,

For weak comparison two entity-tags are equivalent if their opaque-tags match character-by-character, regardless of either or both being tagged as “weak”.

pub(crate) fn parse(src: T) -> Option<Self>

impl EntityTag

pub(crate) fn from_owned(val: HeaderValue) -> Option<EntityTag>

pub(crate) fn from_val(val: &HeaderValue) -> Option<EntityTag>

Trait Implementations

impl<T: Clone> Clone for EntityTag<T>

fn clone(&self) -> EntityTag<T>

Returns a copy of the value.

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

Performs copy-assignment from source.

impl<T: Debug> Debug for EntityTag<T>

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

Formats the value using the given formatter.

impl<'a> From<&'a EntityTag> for HeaderValue

fn from(tag: &'a EntityTag) -> HeaderValue

Converts to this type from the input type.

impl From<EntityTag> for HeaderValue

fn from(tag: EntityTag) -> HeaderValue

Converts to this type from the input type.

impl<T: PartialEq> PartialEq for EntityTag<T>

fn eq(&self, other: &EntityTag<T>) -> bool

Tests for self and other values to be equal, and is used by ==.

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

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl TryFromValues for EntityTag

fn try_from_values<'i, I>(values: &mut I) -> Result<Self, Error>

where I: Iterator<Item = &'i HeaderValue>,

Try to convert from the values into an instance of Self.

impl<T: Eq> Eq for EntityTag<T>

impl<T> StructuralPartialEq for EntityTag<T>