# Struct syn::Ident [−] [src]

    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.

    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.

    use proc_macro2::{Ident, Span};
    use quote::quote;

    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)
    }

## Implementations

### `impl Ident` [src]

#### `pub fn new(string: &str, span: Span) -> Ident` [src]

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. If you are not sure whether the string contains an identifier and need to handle an error case, use `syn::parse_str` `::<Ident>` rather than `Ident::new`.

#### `pub fn span(&self) -> Span` [src]

Returns the span of this `Ident`.

#### `pub fn set_span(&mut self, span: Span)` [src]

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

## Trait Implementations

### `impl Clone for Ident` [src]

#### `pub fn clone(&self) -> Ident` [src]

Returns a copy of the value. Read more

#### `pub fn clone_from(&mut self, source: &Self)`1.0.0 [src]

Performs copy-assignment from `source`. Read more

### `impl Debug for Ident` [src]

#### `pub fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error>` [src]

Formats the value using the given formatter. Read more

### `impl Display for Ident` [src]

Prints the identifier as a string that should be losslessly convertible back into the same identifier.

#### `pub fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error>` [src]

Formats the value using the given formatter. Read more

### `impl Eq for Ident` [src]

### `impl From<Crate> for Ident` [src]

#### `fn from(token: Crate) -> Ident` [src]

Performs the conversion.

### `impl From<Extern> for Ident` [src]

#### `fn from(token: Extern) -> Ident` [src]

Performs the conversion.

### `impl From<Ident> for TokenTree` [src]

#### `pub fn from(g: Ident) -> TokenTree` [src]

Performs the conversion.

### `impl From<Ident> for TypeParam` [src]

#### `fn from(ident: Ident) -> Self` [src]

Performs the conversion.

### `impl From<SelfType> for Ident` [src]

#### `fn from(token: SelfType) -> Ident` [src]

Performs the conversion.

### `impl From<SelfValue> for Ident` [src]

#### `fn from(token: SelfValue) -> Ident` [src]

Performs the conversion.

### `impl From<Super> for Ident` [src]

#### `fn from(token: Super) -> Ident` [src]

Performs the conversion.

### `impl From<Underscore> for Ident` [src]

#### `fn from(token: Underscore) -> Ident` [src]

Performs the conversion.

### `impl Hash for Ident` [src]

#### `pub fn hash<H>(&self, hasher: &mut H) where
H: Hasher,` [src]

Feeds this value into the given `Hasher`. Read more

#### `pub fn hash_slice<H>(data: &[Self], state: &mut H) where
H: Hasher,` 1.3.0 [src]

Feeds a slice of this type into the given `Hasher`. Read more

### `impl IdentExt for Ident` [src]

#### `fn parse_any(input: ParseStream<'_>) -> Result<Self>` [src]

Parses any identifier including keywords. Read more

#### `fn unraw(&self) -> Ident` [src]

Strips the raw marker `r#`, if any, from the beginning of an ident. Read more

#### `const peek_any: PeekFn` [src]

Peeks any identifier including keywords. Usage: `input.peek(Ident::peek_any)` Read more

### `impl IdentFragment for Ident` [src]

#### `pub fn span(&self) -> Option<Span>` [src]

Span associated with this `IdentFragment`. Read more

#### `pub fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error>` [src]

Format this value as an identifier fragment.

### `impl Ord for Ident` [src]

#### `pub fn cmp(&self, other: &Ident) -> Ordering` [src]

This method returns an `Ordering` between `self` and `other`. Read more

#### `#[must_use]pub fn max(self, other: Self) -> Self` 1.21.0 [src]

Compares and returns the maximum of two values. Read more

#### `#[must_use]pub fn min(self, other: Self) -> Self` 1.21.0 [src]

Compares and returns the minimum of two values. Read more

#### `#[must_use]pub fn clamp(self, min: Self, max: Self) -> Self` 1.50.0 [src]

Restrict a value to a certain interval. Read more

### `impl Parse for Ident` [src]

#### `fn parse(input: ParseStream<'_>) -> Result<Self>` [src]

### `impl PartialEq<Ident> for Ident` [src]

#### `pub fn eq(&self, other: &Ident) -> bool` [src]

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

#### `#[must_use]pub fn ne(&self, other: &Rhs) -> bool` 1.0.0 [src]

This method tests for `!=`.

### `impl<T> PartialEq<T> for Ident where
T: AsRef<str> + ?Sized,` [src]

#### `pub fn eq(&self, other: &T) -> bool` [src]

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

#### `#[must_use]pub fn ne(&self, other: &Rhs) -> bool` 1.0.0 [src]

This method tests for `!=`.

### `impl PartialOrd<Ident> for Ident` [src]

#### `pub fn partial_cmp(&self, other: &Ident) -> Option<Ordering>` [src]

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

#### `#[must_use]pub fn lt(&self, other: &Rhs) -> bool` 1.0.0 [src]

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

#### `#[must_use]pub fn le(&self, other: &Rhs) -> bool` 1.0.0 [src]

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

#### `#[must_use]pub fn gt(&self, other: &Rhs) -> bool` 1.0.0 [src]

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

#### `#[must_use]pub fn ge(&self, other: &Rhs) -> bool` 1.0.0 [src]

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

### `impl ToTokens for Ident` [src]

#### `pub fn to_tokens(&self, tokens: &mut TokenStream)` [src]

Write `self` to the given `TokenStream`. Read more

#### `pub fn to_token_stream(&self) -> TokenStream` [src]

Convert `self` directly into a `TokenStream` object. Read more

#### `pub fn into_token_stream(self) -> TokenStream` [src]

Convert `self` directly into a `TokenStream` object. Read more

### `impl Token for Ident` [src]

#### `fn peek(cursor: Cursor<'_>) -> bool` [src]

#### `fn display() -> &'static str` [src]

## Auto Trait Implementations

### `impl RefUnwindSafe for Ident`

### `impl !Send for Ident`

### `impl !Sync for Ident`

### `impl Unpin for Ident`

### `impl UnwindSafe for Ident`

## Blanket Implementations

### `impl<T> Any for T where
T: 'static + ?Sized,` [src]

#### `pub fn type_id(&self) -> TypeId` [src]

Gets the `TypeId` of `self`. Read more

### `impl<T> Borrow<T> for T where
T: ?Sized,` [src]

#### `pub fn borrow(&self) -> &T` [src]

Immutably borrows from an owned value. Read more

### `impl<T> BorrowMut<T> for T where
T: ?Sized,` [src]

#### `pub fn borrow_mut(&mut self) -> &mut T` [src]

Mutably borrows from an owned value. Read more

### `impl<T> From<T> for T` [src]

#### `pub fn from(t: T) -> T` [src]

Performs the conversion.

### `impl<T, U> Into<U> for T where
U: From<T>,` [src]

#### `pub fn into(self) -> U` [src]

Performs the conversion.

### `impl<T> Spanned for T where
T: Spanned + ?Sized,` [src]

#### `pub fn span(&Self) -> Span` [src]

Returns a `Span` covering the complete contents of this syntax tree node, or `Span::call_site()` if this node is empty. Read more

### `impl<T> ToOwned for T where
T: Clone,` [src]

#### `type Owned = T`

The resulting type after obtaining ownership.

#### `pub fn to_owned(&self) -> T` [src]

Creates owned data from borrowed data, usually by cloning. Read more

#### `pub fn clone_into(&self, target: &mut T)` [src]

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

recently added

Uses borrowed data to replace owned data, usually by cloning. Read more

### `impl<T> ToString for T where
T: Display + ?Sized,` [src]

#### `pub default fn to_string(&self) -> String` [src]

Converts the given value to a `String`. Read more

### `impl<T, U> TryFrom<U> for T where
U: Into<T>,` [src]

#### `type Error = Infallible`

The type returned in the event of a conversion error.

#### `pub fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>` [src]

Performs the conversion.

### `impl<T, U> TryInto<U> for T where
U: TryFrom<T>,` [src]

#### `type Error = <U as TryFrom<T>>::Error`

The type returned in the event of a conversion error.

#### `pub fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>` [src]

Performs the conversion.