Struct Keyword 

pub struct Keyword(/* private fields */);

A keyword is a symbol, optionally with a namespace, that prints with a leading colon. This concept is imported from Clojure, as it features in EDN and the query syntax that we use.

Clojure’s constraints are looser than ours, allowing empty namespaces or names:

user=> (keyword "" "")
:/
user=> (keyword "foo" "")
:foo/
user=> (keyword "" "bar")
:/bar

We think that’s nonsense, so we only allow keywords like :bar and :foo/bar, with both namespace and main parts containing no whitespace and no colon or slash:

let bar     = Keyword::plain("bar");                         // :bar
let foo_bar = Keyword::namespaced("foo", "bar");        // :foo/bar
assert_eq!("bar", bar.name());
assert_eq!(None, bar.namespace());
assert_eq!("bar", foo_bar.name());
assert_eq!(Some("foo"), foo_bar.namespace());

If you’re not sure whether your input is well-formed, you should use a parser or a reader function first to validate. TODO: implement read.

Callers are expected to follow these rules: http://www.clojure.org/reference/reader#_symbols

Future: fast equality (interning?) for keywords.

Implementations

impl Keyword

pub fn plain<T>(name: T) -> Keyword

where T: Into<String>,

impl Keyword

pub fn namespaced<N, T>(namespace: N, name: T) -> Keyword

where N: AsRef<str>, T: AsRef<str>,

Creates a new Keyword.

Examples

let keyword = Keyword::namespaced("foo", "bar");
assert_eq!(keyword.to_string(), ":foo/bar");

See also the kw! macro in the main mentat crate.

pub fn name(&self) -> &str

pub fn namespace(&self) -> Option<&str>

pub fn components(&self) -> (&str, &str)

pub fn is_backward(&self) -> bool

Whether this Keyword should be interpreted in reverse order. For example, the two following snippets are identical:

[?y :person/friend ?x]
[?x :person/hired ?y]

[?y :person/friend ?x]
[?y :person/_hired ?x]

Examples

assert!(!Keyword::namespaced("foo", "bar").is_backward());
assert!(Keyword::namespaced("foo", "_bar").is_backward());

pub fn is_forward(&self) -> bool

Whether this Keyword should be interpreted in forward order. See symbols::Keyword::is_backward.

Examples

assert!(Keyword::namespaced("foo", "bar").is_forward());
assert!(!Keyword::namespaced("foo", "_bar").is_forward());

pub fn is_namespaced(&self) -> bool

pub fn to_reversed(&self) -> Keyword

Returns a Keyword with the same namespace and a ‘backward’ name. See symbols::Keyword::is_backward.

Returns a forward name if passed a reversed keyword; i.e., this function is its own inverse.

Examples

let nsk = Keyword::namespaced("foo", "bar");
assert!(!nsk.is_backward());
assert_eq!(":foo/bar", nsk.to_string());

let reversed = nsk.to_reversed();
assert!(reversed.is_backward());
assert_eq!(":foo/_bar", reversed.to_string());

pub fn unreversed(&self) -> Option<Keyword>

If this Keyword is ‘backward’ (see symbols::Keyword::is_backward), return Some('forward name'); otherwise, return None.

Examples

let nsk = Keyword::namespaced("foo", "bar");
assert_eq!(None, nsk.unreversed());

let reversed = nsk.to_reversed();
assert_eq!(Some(nsk), reversed.unreversed());

Trait Implementations

impl Clone for Keyword

fn clone(&self) -> Keyword

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for Keyword

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

Formats the value using the given formatter.

impl<'de> Deserialize<'de> for Keyword

fn deserialize<__D>( __deserializer: __D, ) -> Result<Keyword, <__D as Deserializer<'de>>::Error>

where __D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl Display for Keyword

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

Print the keyword in EDN format.

Examples

assert_eq!(":baz", Keyword::plain("baz").to_string());
assert_eq!(":bar/baz", Keyword::namespaced("bar", "baz").to_string());
assert_eq!(":bar/_baz", Keyword::namespaced("bar", "baz").to_reversed().to_string());
assert_eq!(":bar/baz", Keyword::namespaced("bar", "baz").to_reversed().to_reversed().to_string());

impl Eq for Keyword

impl From<Keyword> for TypedValue

fn from(value: Keyword) -> TypedValue

Converts to this type from the input type.

impl Hash for Keyword

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

where __H: Hasher,

Feeds this value into the given Hasher.

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

where H: Hasher, Self: Sized,

Feeds a slice of this type into the given Hasher.

impl Ord for Keyword

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

This method returns an Ordering between self and other.

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

where Self: Sized,

Compares and returns the maximum of two values.

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

where Self: Sized,

Compares and returns the minimum of two values.

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

where Self: Sized,

Restrict a value to a certain interval.

fn clamp_to<R>(self, range: R) -> Self

where Self: Sized, R: ClampBounds<Self>,

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

Restrict a value to a certain range.

impl PartialEq for Keyword

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

Equality operator ==.

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

Inequality operator !=.

impl PartialOrd for Keyword

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

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

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

Tests less than (for self and other) and is used by the < operator.

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

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

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

Tests greater than (for self and other) and is used by the > operator.

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

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

impl Serialize for Keyword

fn serialize<__S>( &self, __serializer: __S, ) -> Result<<__S as Serializer>::Ok, <__S as Serializer>::Error>

where __S: Serializer,

Serialize this value into the given Serde serializer.

impl StructuralPartialEq for Keyword