Struct egg::Symbol

pub struct Symbol(_);

An interned string.

This is provided by the symbol_table crate.

Internally, egg frequently compares Vars and elements of Languages. To keep comparisons fast, egg provides Symbol a simple wrapper providing interned strings.

You may wish to use Symbol in your own Languages to increase performance and keep enode sizes down (a Symbol is only 4 bytes, compared to 24 for a String.)

A Symbol is simply a wrapper around an integer. When creating a Symbol from a string, egg looks up it up in a global table, returning the index (inserting it if not found). That integer is used to cheaply implement Copy, Clone, PartialEq, Eq, PartialOrd, Ord, and Hash.

The internal symbol cache leaks the strings, which should be fine if you only put in things like variable names and identifiers.

Example

use egg::Symbol;

assert_eq!(Symbol::from("foo"), Symbol::from("foo"));
assert_eq!(Symbol::from("foo"), "foo".parse().unwrap());

assert_ne!(Symbol::from("foo"), Symbol::from("bar"));

A interned string in the global symbol table.

This requires the global feature on the crate.

GlobalSymbol is a wrapper around Symbol that knows to refer to a built-in, global SymbolTable. Strings into the global table are never freed.

This enables a lot of convience methods and trait implementations over GlobalSymbol (see below). In particular, you can convert it to &'static str, convert From and Into a &str, and de/serialize using serde if the serde feature is enabled.

Implementations

impl GlobalSymbol

pub fn new(s: impl AsRef<str>) -> GlobalSymbol

Intern a string into the global symbol table.

pub fn as_str(&self) -> &'static str

Convert this symbol into the string in the static, global symbol table.

Trait Implementations

impl Clone for GlobalSymbol

fn clone(&self) -> GlobalSymbol

Returns a copy of the value.

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

Performs copy-assignment from source.

impl Debug for GlobalSymbol

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

Formats the value using the given formatter.

impl<'de> Deserialize<'de> for GlobalSymbol

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

Deserialize this value from the given Serde deserializer.

impl Display for GlobalSymbol

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

Formats the value using the given formatter.

impl From<&String> for GlobalSymbol

fn from(s: &String) -> GlobalSymbol

Converts to this type from the input type.

impl From<&str> for GlobalSymbol

fn from(s: &str) -> GlobalSymbol

Converts to this type from the input type.

impl From<GlobalSymbol> for &'static str

fn from(sym: GlobalSymbol) -> &'static str

Converts to this type from the input type.

impl From<String> for GlobalSymbol

fn from(s: String) -> GlobalSymbol

Converts to this type from the input type.

impl FromStr for GlobalSymbol

type Err = Infallible

The associated error which can be returned from parsing.

fn from_str(s: &str) -> Result<GlobalSymbol, <GlobalSymbol as FromStr>::Err>

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

impl Hash for GlobalSymbol

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 GlobalSymbol

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

This method returns an Ordering between self and other.

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

Compares and returns the maximum of two values.

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

Compares and returns the minimum of two values.

fn clamp(self, min: Self, max: Self) -> Selfwhere
    Self: Sized + PartialOrd<Self>,

Restrict a value to a certain interval.

impl PartialEq<GlobalSymbol> for GlobalSymbol

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

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

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

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

impl PartialOrd<GlobalSymbol> for GlobalSymbol

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

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

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

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

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

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

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

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

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 Serialize for GlobalSymbol

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 Copy for GlobalSymbol

impl Eq for GlobalSymbol

impl StructuralEq for GlobalSymbol

impl StructuralPartialEq for GlobalSymbol