[][src]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.

  • The empty string is not an identifier. Use Option<Ident>.
  • 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 Parse implementation rejects Rust keywords. Use input.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::new function. A span must be provided explicitly which governs the name resolution behavior of the resulting identifier.

extern crate proc_macro2;

use proc_macro2::{Ident, Span};

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

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

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

#[macro_use]
extern crate quote;

extern crate proc_macro2;

use proc_macro2::{Ident, Span};

fn main() {
    let ident = Ident::new("demo", Span::call_site());

    // 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::new(&format!("new_{}", ident), Span::call_site());
    let expanded = quote! { let #temp_ident = 10; };
}

A string representation of the ident is available through the to_string() method.

// Examine the ident as a string.
let ident_string = ident.to_string();
if ident_string.len() > 60 {
    println!("Very long identifier: {}", ident_string)
}

Methods

impl Ident
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Creates a new Ident with the given string as well as the specified span.

The string argument must be a valid identifier permitted by the language, otherwise the function will panic.

Note that span, currently in rustc, configures the hygiene information for this identifier.

As of this time Span::call_site() explicitly opts-in to "call-site" hygiene meaning that identifiers created with this span will be resolved as if they were written directly at the location of the macro call, and other code at the macro call site will be able to refer to them as well.

Later spans like Span::def_site() will allow to opt-in to "definition-site" hygiene meaning that identifiers created with this span will be resolved at the location of the macro definition and other code at the macro call site will not be able to refer to them.

Due to the current importance of hygiene this constructor, unlike other tokens, requires a Span to be specified at construction.

Panics

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

Returns the span of this Ident.

Configures the span of this Ident, possibly changing its hygiene context.

Trait Implementations

impl Clone for Ident
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Performs copy-assignment from source. Read more

impl Display for Ident
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Prints the identifier as a string that should be losslessly convertible back into the same identifier.

impl Ord for Ident
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Compares and returns the maximum of two values. Read more

Compares and returns the minimum of two values. Read more

impl PartialOrd<Ident> for Ident
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This method tests less than (for self and other) and is used by the < operator. Read more

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

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

This method tests greater than or equal to (for self and other) and is used by the >= operator. Read more

impl From<Ident> for TokenTree
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impl Hash for Ident
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Feeds a slice of this type into the given [Hasher]. Read more

impl Eq for Ident
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impl Debug for Ident
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impl<T> PartialEq<T> for Ident where
    T: AsRef<str> + ?Sized
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This method tests for !=.

impl PartialEq<Ident> for Ident
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This method tests for !=.

impl ToTokens for Ident
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Convert self directly into a TokenStream object. Read more

impl Token for Ident
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impl IdentExt for Ident
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impl Parse for Ident
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impl From<SelfValue> for Ident
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impl From<SelfType> for Ident
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impl From<Super> for Ident
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impl From<Crate> for Ident
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impl From<Extern> for Ident
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impl From<Underscore> for Ident
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impl From<Ident> for Meta
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impl From<Ident> for TypeParam
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Auto Trait Implementations

impl !Send for Ident

impl !Sync for Ident

Blanket Implementations

impl<K> Token for K where
    K: CustomKeyword, 
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impl<T> Spanned for T where
    T: ToTokens
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impl<T> From for T
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impl<T, U> Into for T where
    U: From<T>, 
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impl<T> ToString for T where
    T: Display + ?Sized
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impl<T> ToOwned for T where
    T: Clone
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impl<T, U> TryFrom for T where
    T: From<U>, 
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🔬 This is a nightly-only experimental API. (try_from)

The type returned in the event of a conversion error.

impl<T> Borrow for T where
    T: ?Sized
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impl<T> Any for T where
    T: 'static + ?Sized
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impl<T, U> TryInto for T where
    U: TryFrom<T>, 
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🔬 This is a nightly-only experimental API. (try_from)

The type returned in the event of a conversion error.

impl<T> BorrowMut for T where
    T: ?Sized
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impl<E> SpecializationError for E
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impl<T> Erased for T
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impl<T> Send for T where
    T: ?Sized
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impl<T> Sync for T where
    T: ?Sized
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impl<T> Erased for T