Struct syn::Ident

pub struct Ident { /* fields omitted */ }

A word of Rust code, which may be a keyword or legal variable name.

An identifier consists of at least one Unicode code point, the first of which has the XID_Start property and the rest of which have the XID_Continue property. An underscore may be used as the first character as long as it is not the only character.

• The empty string is not an identifier. Use Option<Ident>.
• An underscore by itself is not an identifier. Use Token![_] instead.
• A lifetime is not an identifier. Use syn::Lifetime instead.

An identifier constructed with Ident::new is permitted to be a Rust keyword, though parsing one through its Synom implementation rejects Rust keywords. Use call!(Ident::parse_any) when parsing to match the behaviour of Ident::new.

Examples

A new ident can be created from a string using the Ident::from function. Idents produced by Ident::from are set to resolve at the procedural macro def site by default. A different span can be provided explicitly by using Ident::new.

extern crate syn;
extern crate proc_macro2;

use syn::Ident;
use proc_macro2::Span;

fn main() {
    let def_ident = Ident::from("definitely");
    let call_ident = Ident::new("calligraphy", Span::call_site());

    println!("{} {}", def_ident, call_ident);
}

An ident can be interpolated into a token stream using the quote! macro.

#[macro_use]
extern crate quote;

extern crate syn;
use syn::Ident;

fn main() {
    let ident = Ident::from("demo");

    // Create a variable binding whose name is this ident.
    let expanded = quote! { let #ident = 10; };

    // Create a variable binding with a slightly different name.
    let temp_ident = Ident::from(format!("new_{}", ident));
    let expanded = quote! { let #temp_ident = 10; };
}

A string representation of the ident is available through the as_ref() and to_string() methods.

// Examine the ident as a &str.
let ident_str = ident.as_ref();
if ident_str.len() > 60 {
    println!("Very long identifier: {}", ident_str)
}

// Create a String from the ident.
let ident_string = ident.to_string();
give_away(ident_string);

fn give_away(s: String) { /* ... */ }

Methods

impl Ident

pub fn parse_any(input: Cursor) -> PResult<Self>

Parses any identifier

This is useful when parsing a DSL which allows Rust keywords as identifiers.

impl Ident

pub fn new(s: &str, span: Span) -> Self

Creates an ident with the given string representation.

Panics

Panics if the input string is neither a keyword nor a legal variable name.

pub fn span(&self) -> Span

pub fn set_span(&mut self, span: Span)

Trait Implementations

impl Synom for Ident

fn parse(input: Cursor) -> PResult<Self>

fn description() -> Option<&'static str>

A short name of the type being parsed.

impl Eq for Ident

impl Clone for Ident

fn clone(&self) -> Ident

Returns a copy of the value.

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

Performs copy-assignment from source.

impl AsRef<str> for Ident

fn as_ref(&self) -> &str

Performs the conversion.

impl PartialOrd<Ident> for Ident

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

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

#[must_use] fn lt(&self, other: &Rhs) -> bool

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

#[must_use] fn le(&self, other: &Rhs) -> bool

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

#[must_use] fn gt(&self, other: &Rhs) -> bool

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

#[must_use] 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<T: ?Sized> PartialEq<T> for Ident where
    T: AsRef<str>, 

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

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

#[must_use] fn ne(&self, other: &Rhs) -> bool

This method tests for !=.

impl Ord for Ident

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

This method returns an Ordering between self and other.

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

Compares and returns the maximum of two values.

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

Compares and returns the minimum of two values.

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

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

Restrict a value to a certain interval.

impl From<Ident> for Meta

fn from(e: Ident) -> Meta

Performs the conversion.

impl From<Ident> for TypeParam

fn from(ident: Ident) -> Self

Performs the conversion.

impl<'a> From<&'a str> for Ident

fn from(s: &str) -> Self

Performs the conversion.

impl From<Self_> for Ident

fn from(tok: Self_) -> Self

Performs the conversion.

impl From<CapSelf> for Ident

fn from(tok: CapSelf) -> Self

Performs the conversion.

impl From<Super> for Ident

fn from(tok: Super) -> Self

Performs the conversion.

impl From<Crate> for Ident

fn from(tok: Crate) -> Self

Performs the conversion.

impl<'a> From<Cow<'a, str>> for Ident

fn from(s: Cow<'a, str>) -> Self

Performs the conversion.

impl From<String> for Ident

fn from(s: String) -> Self

Performs the conversion.

impl Copy for Ident

impl Hash for Ident

fn hash<H: Hasher>(&self, h: &mut H)

Feeds this value into the given [Hasher].

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

Feeds a slice of this type into the given [Hasher].

impl Debug for Ident

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

Formats the value using the given formatter.

impl Display for Ident

fn fmt(&self, formatter: &mut Formatter) -> Result

Formats the value using the given formatter.

impl ToTokens for Ident

fn to_tokens(&self, tokens: &mut Tokens)

Write self to the given Tokens.

fn into_tokens(self) -> Tokens

Convert self directly into a Tokens object.