Struct proc_macro2::Ident
source · pub struct Ident { /* private fields */ }
Expand description
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§
source§impl Ident
impl Ident
sourcepub fn new(string: &str, span: Span) -> Self
pub fn new(string: &str, span: Span) -> Self
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
.
sourcepub fn new_raw(string: &str, span: Span) -> Self
pub fn new_raw(string: &str, span: Span) -> Self
Same as Ident::new
, but creates a raw identifier (r#ident
). The
string
argument must be a valid identifier permitted by the language
(including keywords, e.g. fn
). Keywords which are usable in path
segments (e.g. self
, super
) are not supported, and will cause a
panic.
Trait Implementations§
source§impl Display for Ident
impl Display for Ident
Prints the identifier as a string that should be losslessly convertible back into the same identifier.
source§impl Ord for Ident
impl Ord for Ident
source§impl PartialEq for Ident
impl PartialEq for Ident
source§impl PartialOrd for Ident
impl PartialOrd for Ident
1.0.0 · source§fn le(&self, other: &Rhs) -> bool
fn le(&self, other: &Rhs) -> bool
self
and other
) and is used by the <=
operator. Read moreimpl Eq for Ident
Auto Trait Implementations§
impl Freeze for Ident
impl RefUnwindSafe for Ident
impl !Send for Ident
impl !Sync for Ident
impl Unpin for Ident
impl UnwindSafe for Ident
Blanket Implementations§
source§impl<T> BorrowMut<T> for Twhere
T: ?Sized,
impl<T> BorrowMut<T> for Twhere
T: ?Sized,
source§fn borrow_mut(&mut self) -> &mut T
fn borrow_mut(&mut self) -> &mut T
source§impl<T> CloneToUninit for Twhere
T: Clone,
impl<T> CloneToUninit for Twhere
T: Clone,
source§default unsafe fn clone_to_uninit(&self, dst: *mut T)
default unsafe fn clone_to_uninit(&self, dst: *mut T)
clone_to_uninit
)