Struct Symbol 

pub(in attributes) struct Symbol(SymbolIndex);

An interned UTF-8 string.

Internally, a Symbol is implemented as an index, and all operations (including hashing, equality, and ordering) operate on that index. The use of rustc_index::newtype_index! means that Option<Symbol> only takes up 4 bytes, because rustc_index::newtype_index! reserves the last 256 values for tagging purposes.

Note that Symbol cannot directly be a rustc_index::newtype_index! because it implements fmt::Debug, Encodable, and Decodable in special ways.

Tuple Fields

0: SymbolIndex

Implementations

impl Symbol

pub const fn new(n: u32) -> Symbol

Avoid this except for things like deserialization of previously serialized symbols, and testing. Use intern instead.

pub fn intern(str: &str) -> Symbol

Maps a string to its interned representation.

pub fn as_str(&self) -> &str

Access the underlying string. This is a slowish operation because it requires locking the symbol interner.

Note that the lifetime of the return value is a lie. It’s not the same as &self, but actually tied to the lifetime of the underlying interner. Interners are long-lived, and there are very few of them, and this function is typically used for short-lived things, so in practice it works out ok.

pub fn as_u32(self) -> u32

pub fn is_empty(self) -> bool

pub fn to_ident_string(self) -> String

This method is supposed to be used in error messages, so it’s expected to be identical to printing the original identifier token written in source code (token_to_string, Ident::to_string), except that symbols don’t keep the rawness flag or edition, so we have to guess the rawness using the global edition.

impl Symbol

pub fn is_reserved(self, edition: impl Copy + FnOnce() -> Edition) -> bool

pub fn is_weak(self) -> bool

pub fn is_path_segment_keyword(self) -> bool

A keyword or reserved identifier that can be used as a path segment.

pub fn is_bool_lit(self) -> bool

Returns true if the symbol is true or false.

pub fn can_be_raw(self) -> bool

Returns true if this symbol can be a raw identifier.

pub fn is_predefined(index: u32) -> bool

Was this symbol index predefined in the compiler’s symbols! macro? Note: this applies to both Symbols and ByteSymbols, which is why it takes a u32 argument instead of a &self argument. Use with care.

Trait Implementations

impl Clone for Symbol

fn clone(&self) -> Symbol

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for Symbol

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

Formats the value using the given formatter.

impl<D> Decodable<D> for Symbol

where D: SpanDecoder,

fn decode(s: &mut D) -> Symbol

impl Display for Symbol

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

Formats the value using the given formatter.

impl<E> Encodable<E> for Symbol

where E: SpanEncoder,

fn encode(&self, s: &mut E)

impl Hash for Symbol

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<CTX> HashStable<CTX> for Symbol

fn hash_stable(&self, hcx: &mut CTX, hasher: &mut StableHasher<SipHasher128>)

impl IntoDiagArg for Symbol

fn into_diag_arg(self, path: &mut Option<PathBuf>) -> DiagArgValue

Convert Self into a DiagArgValue suitable for rendering in a diagnostic.

impl Ord for Symbol

fn cmp(&self, other: &Symbol) -> 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.

impl PartialEq for Symbol

fn eq(&self, other: &Symbol) -> 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 PartialOrd for Symbol

fn partial_cmp(&self, other: &Symbol) -> 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 PrintAttribute for Symbol

fn should_render(&self) -> bool

Whether or not this will render as something meaningful, or if it’s skipped (which will force the containing struct to also skip printing a comma and the field name).

fn print_attribute(&self, p: &mut Printer)

impl StableCompare for Symbol

const CAN_USE_UNSTABLE_SORT: bool = true

fn stable_cmp(&self, other: &Symbol) -> Ordering

impl<CTX> ToStableHashKey<CTX> for Symbol

type KeyType = String

fn to_stable_hash_key(&self, _: &CTX) -> String

impl Copy for Symbol

impl Eq for Symbol

impl StructuralPartialEq for Symbol

Layout

Note: Most layout information is completely unstable and may even differ between compilations. The only exception is types with certain repr(...) attributes. Please see the Rust Reference's “Type Layout” chapter for details on type layout guarantees.

Size: 4 bytes