Struct proc_macro2::Ident
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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 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::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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pub fn new(string: &str, span: Span) -> 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.
pub fn span(&self) -> Span
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Returns the span of this Ident
.
pub fn set_span(&mut self, span: Span)
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Configures the span of this Ident
, possibly changing its hygiene
context.
Trait Implementations
impl From<Ident> for TokenTree
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impl Clone for Ident
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fn clone(&self) -> Ident
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Returns a copy of the value. Read more
fn clone_from(&mut self, source: &Self)
1.0.0[src]
Performs copy-assignment from source
. Read more
impl PartialEq for Ident
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fn eq(&self, other: &Ident) -> bool
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This method tests for self
and other
values to be equal, and is used by ==
. Read more
fn ne(&self, other: &Rhs) -> bool
1.0.0[src]
This method tests for !=
.
impl<T: ?Sized> PartialEq<T> for Ident where
T: AsRef<str>,
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T: AsRef<str>,
fn eq(&self, other: &T) -> bool
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This method tests for self
and other
values to be equal, and is used by ==
. Read more
fn ne(&self, other: &Rhs) -> bool
1.0.0[src]
This method tests for !=
.
impl Eq for Ident
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impl PartialOrd for Ident
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fn partial_cmp(&self, other: &Ident) -> Option<Ordering>
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This method returns an ordering between self
and other
values if one exists. Read more
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
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
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
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 Ord for Ident
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fn cmp(&self, other: &Ident) -> Ordering
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This method returns an Ordering
between self
and other
. Read more
fn max(self, other: Self) -> Self
1.21.0[src]
Compares and returns the maximum of two values. Read more
fn min(self, other: Self) -> Self
1.21.0[src]
Compares and returns the minimum of two values. Read more
impl Hash for Ident
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fn hash<H: Hasher>(&self, hasher: &mut H)
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Feeds this value into the given [Hasher
]. Read more
fn hash_slice<H>(data: &[Self], state: &mut H) where
H: Hasher,
1.3.0[src]
H: Hasher,
Feeds a slice of this type into the given [Hasher
]. 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.
fn fmt(&self, f: &mut Formatter) -> Result
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Formats the value using the given formatter. Read more