Struct logos::Lexer

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pub struct Lexer<'source, Token: Logos<'source>> {
    pub extras: Token::Extras,
    /* private fields */
}
Expand description

Lexer is the main struct of the crate that allows you to read through a Source and produce tokens for enums implementing the Logos trait.

Fields§

§extras: Token::Extras

Extras associated with the Token.

Implementations§

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impl<'source, Token: Logos<'source>> Lexer<'source, Token>

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pub fn new(source: &'source Token::Source) -> Self
where Token::Extras: Default,

Create a new Lexer.

Due to type inference, it might be more ergonomic to construct it by calling Token::lexer on any Token with derived Logos.

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pub fn with_extras( source: &'source Token::Source, extras: Token::Extras, ) -> Self

Create a new Lexer with the provided Extras.

Due to type inference, it might be more ergonomic to construct it by calling Token::lexer_with_extras on any Token with derived Logos.

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pub fn source(&self) -> &'source Token::Source

Source from which this Lexer is reading tokens.

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pub fn spanned(self) -> SpannedIter<'source, Token>

Wrap the Lexer in an Iterator that produces tuples of (Token, Span).

§Example
use logos::Logos;

#[derive(Debug, PartialEq, Clone, Default)]
enum LexingError {
    NumberParseError,
    #[default]
    Other
}

impl From<std::num::ParseIntError> for LexingError {
   fn from(_: std::num::ParseIntError) -> Self {
      LexingError::NumberParseError
  }
}

impl From<std::num::ParseFloatError> for LexingError {
  fn from(_: std::num::ParseFloatError) -> Self {
     LexingError::NumberParseError
  }
}

#[derive(Logos, Debug, PartialEq)]
#[logos(error = LexingError)]
enum Example {
    #[regex(r"[ \n\t\f]+", logos::skip)]
    Ignored,

    #[regex("-?[0-9]+", |lex| lex.slice().parse())]
    Integer(i64),

    #[regex("-?[0-9]+\\.[0-9]+", |lex| lex.slice().parse())]
    Float(f64),
}

let tokens: Vec<_> = Example::lexer("42 3.14 -5 f").spanned().collect();

assert_eq!(
    tokens,
    &[
        (Ok(Example::Integer(42)), 0..2),
        (Ok(Example::Float(3.14)), 3..7),
        (Ok(Example::Integer(-5)), 8..10),
        (Err(LexingError::Other), 11..12), // 'f' is not a recognized token
    ],
);
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pub fn span(&self) -> Span

Get the range for the current token in Source.

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pub fn slice(&self) -> <Token::Source as Source>::Slice<'source>

Get a string slice of the current token.

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pub fn remainder(&self) -> <Token::Source as Source>::Slice<'source>

Get a slice of remaining source, starting at the end of current token.

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pub fn morph<Token2>(self) -> Lexer<'source, Token2>
where Token2: Logos<'source, Source = Token::Source>, Token::Extras: Into<Token2::Extras>,

Turn this lexer into a lexer for a new token type.

The new lexer continues to point at the same span as the current lexer, and the current token becomes the error token of the new token type.

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pub fn bump(&mut self, n: usize)

Bumps the end of currently lexed token by n bytes.

§Panics

Panics if adding n to current offset would place the Lexer beyond the last byte, or in the middle of an UTF-8 code point (does not apply when lexing raw &[u8]).

Trait Implementations§

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impl<'source, Token> Clone for Lexer<'source, Token>
where Token: Logos<'source> + Clone, Token::Extras: Clone,

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fn clone(&self) -> Self

Returns a copy of the value. Read more
1.0.0 · source§

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

Performs copy-assignment from source. Read more
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impl<'source, Token> Debug for Lexer<'source, Token>
where Token: Logos<'source>, Token::Source: Debug, Token::Extras: Debug,

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fn fmt(&self, fmt: &mut Formatter<'_>) -> Result

Formats the value using the given formatter. Read more
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impl<'source, Token> Iterator for Lexer<'source, Token>
where Token: Logos<'source>,

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type Item = Result<Token, <Token as Logos<'source>>::Error>

The type of the elements being iterated over.
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fn next(&mut self) -> Option<Result<Token, Token::Error>>

Advances the iterator and returns the next value. Read more
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fn next_chunk<const N: usize>( &mut self, ) -> Result<[Self::Item; N], IntoIter<Self::Item, N>>
where Self: Sized,

🔬This is a nightly-only experimental API. (iter_next_chunk)
Advances the iterator and returns an array containing the next N values. Read more
1.0.0 · source§

fn size_hint(&self) -> (usize, Option<usize>)

Returns the bounds on the remaining length of the iterator. Read more
1.0.0 · source§

fn count(self) -> usize
where Self: Sized,

Consumes the iterator, counting the number of iterations and returning it. Read more
1.0.0 · source§

fn last(self) -> Option<Self::Item>
where Self: Sized,

Consumes the iterator, returning the last element. Read more
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fn advance_by(&mut self, n: usize) -> Result<(), NonZero<usize>>

🔬This is a nightly-only experimental API. (iter_advance_by)
Advances the iterator by n elements. Read more
1.0.0 · source§

fn nth(&mut self, n: usize) -> Option<Self::Item>

Returns the nth element of the iterator. Read more
1.28.0 · source§

fn step_by(self, step: usize) -> StepBy<Self>
where Self: Sized,

Creates an iterator starting at the same point, but stepping by the given amount at each iteration. Read more
1.0.0 · source§

fn chain<U>(self, other: U) -> Chain<Self, <U as IntoIterator>::IntoIter>
where Self: Sized, U: IntoIterator<Item = Self::Item>,

Takes two iterators and creates a new iterator over both in sequence. Read more
1.0.0 · source§

fn zip<U>(self, other: U) -> Zip<Self, <U as IntoIterator>::IntoIter>
where Self: Sized, U: IntoIterator,

‘Zips up’ two iterators into a single iterator of pairs. Read more
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fn intersperse_with<G>(self, separator: G) -> IntersperseWith<Self, G>
where Self: Sized, G: FnMut() -> Self::Item,

🔬This is a nightly-only experimental API. (iter_intersperse)
Creates a new iterator which places an item generated by separator between adjacent items of the original iterator. Read more
1.0.0 · source§

fn map<B, F>(self, f: F) -> Map<Self, F>
where Self: Sized, F: FnMut(Self::Item) -> B,

Takes a closure and creates an iterator which calls that closure on each element. Read more
1.21.0 · source§

fn for_each<F>(self, f: F)
where Self: Sized, F: FnMut(Self::Item),

Calls a closure on each element of an iterator. Read more
1.0.0 · source§

fn filter<P>(self, predicate: P) -> Filter<Self, P>
where Self: Sized, P: FnMut(&Self::Item) -> bool,

Creates an iterator which uses a closure to determine if an element should be yielded. Read more
1.0.0 · source§

fn filter_map<B, F>(self, f: F) -> FilterMap<Self, F>
where Self: Sized, F: FnMut(Self::Item) -> Option<B>,

Creates an iterator that both filters and maps. Read more
1.0.0 · source§

fn enumerate(self) -> Enumerate<Self>
where Self: Sized,

Creates an iterator which gives the current iteration count as well as the next value. Read more
1.0.0 · source§

fn peekable(self) -> Peekable<Self>
where Self: Sized,

Creates an iterator which can use the peek and peek_mut methods to look at the next element of the iterator without consuming it. See their documentation for more information. Read more
1.0.0 · source§

fn skip_while<P>(self, predicate: P) -> SkipWhile<Self, P>
where Self: Sized, P: FnMut(&Self::Item) -> bool,

Creates an iterator that skips elements based on a predicate. Read more
1.0.0 · source§

fn take_while<P>(self, predicate: P) -> TakeWhile<Self, P>
where Self: Sized, P: FnMut(&Self::Item) -> bool,

Creates an iterator that yields elements based on a predicate. Read more
1.57.0 · source§

fn map_while<B, P>(self, predicate: P) -> MapWhile<Self, P>
where Self: Sized, P: FnMut(Self::Item) -> Option<B>,

Creates an iterator that both yields elements based on a predicate and maps. Read more
1.0.0 · source§

fn skip(self, n: usize) -> Skip<Self>
where Self: Sized,

Creates an iterator that skips the first n elements. Read more
1.0.0 · source§

fn take(self, n: usize) -> Take<Self>
where Self: Sized,

Creates an iterator that yields the first n elements, or fewer if the underlying iterator ends sooner. Read more
1.0.0 · source§

fn scan<St, B, F>(self, initial_state: St, f: F) -> Scan<Self, St, F>
where Self: Sized, F: FnMut(&mut St, Self::Item) -> Option<B>,

An iterator adapter which, like fold, holds internal state, but unlike fold, produces a new iterator. Read more
1.0.0 · source§

fn flat_map<U, F>(self, f: F) -> FlatMap<Self, U, F>
where Self: Sized, U: IntoIterator, F: FnMut(Self::Item) -> U,

Creates an iterator that works like map, but flattens nested structure. Read more
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fn map_windows<F, R, const N: usize>(self, f: F) -> MapWindows<Self, F, N>
where Self: Sized, F: FnMut(&[Self::Item; N]) -> R,

🔬This is a nightly-only experimental API. (iter_map_windows)
Calls the given function f for each contiguous window of size N over self and returns an iterator over the outputs of f. Like slice::windows(), the windows during mapping overlap as well. Read more
1.0.0 · source§

fn fuse(self) -> Fuse<Self>
where Self: Sized,

Creates an iterator which ends after the first None. Read more
1.0.0 · source§

fn inspect<F>(self, f: F) -> Inspect<Self, F>
where Self: Sized, F: FnMut(&Self::Item),

Does something with each element of an iterator, passing the value on. Read more
1.0.0 · source§

fn by_ref(&mut self) -> &mut Self
where Self: Sized,

Borrows an iterator, rather than consuming it. Read more
1.0.0 · source§

fn collect<B>(self) -> B
where B: FromIterator<Self::Item>, Self: Sized,

Transforms an iterator into a collection. Read more
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fn collect_into<E>(self, collection: &mut E) -> &mut E
where E: Extend<Self::Item>, Self: Sized,

🔬This is a nightly-only experimental API. (iter_collect_into)
Collects all the items from an iterator into a collection. Read more
1.0.0 · source§

fn partition<B, F>(self, f: F) -> (B, B)
where Self: Sized, B: Default + Extend<Self::Item>, F: FnMut(&Self::Item) -> bool,

Consumes an iterator, creating two collections from it. Read more
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fn is_partitioned<P>(self, predicate: P) -> bool
where Self: Sized, P: FnMut(Self::Item) -> bool,

🔬This is a nightly-only experimental API. (iter_is_partitioned)
Checks if the elements of this iterator are partitioned according to the given predicate, such that all those that return true precede all those that return false. Read more
1.27.0 · source§

fn try_fold<B, F, R>(&mut self, init: B, f: F) -> R
where Self: Sized, F: FnMut(B, Self::Item) -> R, R: Try<Output = B>,

An iterator method that applies a function as long as it returns successfully, producing a single, final value. Read more
1.27.0 · source§

fn try_for_each<F, R>(&mut self, f: F) -> R
where Self: Sized, F: FnMut(Self::Item) -> R, R: Try<Output = ()>,

An iterator method that applies a fallible function to each item in the iterator, stopping at the first error and returning that error. Read more
1.0.0 · source§

fn fold<B, F>(self, init: B, f: F) -> B
where Self: Sized, F: FnMut(B, Self::Item) -> B,

Folds every element into an accumulator by applying an operation, returning the final result. Read more
1.51.0 · source§

fn reduce<F>(self, f: F) -> Option<Self::Item>
where Self: Sized, F: FnMut(Self::Item, Self::Item) -> Self::Item,

Reduces the elements to a single one, by repeatedly applying a reducing operation. Read more
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fn try_reduce<F, R>( &mut self, f: F, ) -> <<R as Try>::Residual as Residual<Option<<R as Try>::Output>>>::TryType
where Self: Sized, F: FnMut(Self::Item, Self::Item) -> R, R: Try<Output = Self::Item>, <R as Try>::Residual: Residual<Option<Self::Item>>,

🔬This is a nightly-only experimental API. (iterator_try_reduce)
Reduces the elements to a single one by repeatedly applying a reducing operation. If the closure returns a failure, the failure is propagated back to the caller immediately. Read more
1.0.0 · source§

fn all<F>(&mut self, f: F) -> bool
where Self: Sized, F: FnMut(Self::Item) -> bool,

Tests if every element of the iterator matches a predicate. Read more
1.0.0 · source§

fn any<F>(&mut self, f: F) -> bool
where Self: Sized, F: FnMut(Self::Item) -> bool,

Tests if any element of the iterator matches a predicate. Read more
1.0.0 · source§

fn find<P>(&mut self, predicate: P) -> Option<Self::Item>
where Self: Sized, P: FnMut(&Self::Item) -> bool,

Searches for an element of an iterator that satisfies a predicate. Read more
1.30.0 · source§

fn find_map<B, F>(&mut self, f: F) -> Option<B>
where Self: Sized, F: FnMut(Self::Item) -> Option<B>,

Applies function to the elements of iterator and returns the first non-none result. Read more
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fn try_find<F, R>( &mut self, f: F, ) -> <<R as Try>::Residual as Residual<Option<Self::Item>>>::TryType
where Self: Sized, F: FnMut(&Self::Item) -> R, R: Try<Output = bool>, <R as Try>::Residual: Residual<Option<Self::Item>>,

🔬This is a nightly-only experimental API. (try_find)
Applies function to the elements of iterator and returns the first true result or the first error. Read more
1.0.0 · source§

fn position<P>(&mut self, predicate: P) -> Option<usize>
where Self: Sized, P: FnMut(Self::Item) -> bool,

Searches for an element in an iterator, returning its index. Read more
1.6.0 · source§

fn max_by_key<B, F>(self, f: F) -> Option<Self::Item>
where B: Ord, Self: Sized, F: FnMut(&Self::Item) -> B,

Returns the element that gives the maximum value from the specified function. Read more
1.15.0 · source§

fn max_by<F>(self, compare: F) -> Option<Self::Item>
where Self: Sized, F: FnMut(&Self::Item, &Self::Item) -> Ordering,

Returns the element that gives the maximum value with respect to the specified comparison function. Read more
1.6.0 · source§

fn min_by_key<B, F>(self, f: F) -> Option<Self::Item>
where B: Ord, Self: Sized, F: FnMut(&Self::Item) -> B,

Returns the element that gives the minimum value from the specified function. Read more
1.15.0 · source§

fn min_by<F>(self, compare: F) -> Option<Self::Item>
where Self: Sized, F: FnMut(&Self::Item, &Self::Item) -> Ordering,

Returns the element that gives the minimum value with respect to the specified comparison function. Read more
1.0.0 · source§

fn unzip<A, B, FromA, FromB>(self) -> (FromA, FromB)
where FromA: Default + Extend<A>, FromB: Default + Extend<B>, Self: Sized + Iterator<Item = (A, B)>,

Converts an iterator of pairs into a pair of containers. Read more
1.36.0 · source§

fn copied<'a, T>(self) -> Copied<Self>
where T: 'a + Copy, Self: Sized + Iterator<Item = &'a T>,

Creates an iterator which copies all of its elements. Read more
1.0.0 · source§

fn cloned<'a, T>(self) -> Cloned<Self>
where T: 'a + Clone, Self: Sized + Iterator<Item = &'a T>,

Creates an iterator which clones all of its elements. Read more
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fn array_chunks<const N: usize>(self) -> ArrayChunks<Self, N>
where Self: Sized,

🔬This is a nightly-only experimental API. (iter_array_chunks)
Returns an iterator over N elements of the iterator at a time. Read more
1.11.0 · source§

fn sum<S>(self) -> S
where Self: Sized, S: Sum<Self::Item>,

Sums the elements of an iterator. Read more
1.11.0 · source§

fn product<P>(self) -> P
where Self: Sized, P: Product<Self::Item>,

Iterates over the entire iterator, multiplying all the elements Read more
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fn cmp_by<I, F>(self, other: I, cmp: F) -> Ordering
where Self: Sized, I: IntoIterator, F: FnMut(Self::Item, <I as IntoIterator>::Item) -> Ordering,

🔬This is a nightly-only experimental API. (iter_order_by)
Lexicographically compares the elements of this Iterator with those of another with respect to the specified comparison function. Read more
1.5.0 · source§

fn partial_cmp<I>(self, other: I) -> Option<Ordering>
where I: IntoIterator, Self::Item: PartialOrd<<I as IntoIterator>::Item>, Self: Sized,

Lexicographically compares the PartialOrd elements of this Iterator with those of another. The comparison works like short-circuit evaluation, returning a result without comparing the remaining elements. As soon as an order can be determined, the evaluation stops and a result is returned. Read more
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fn partial_cmp_by<I, F>(self, other: I, partial_cmp: F) -> Option<Ordering>
where Self: Sized, I: IntoIterator, F: FnMut(Self::Item, <I as IntoIterator>::Item) -> Option<Ordering>,

🔬This is a nightly-only experimental API. (iter_order_by)
Lexicographically compares the elements of this Iterator with those of another with respect to the specified comparison function. Read more
1.5.0 · source§

fn eq<I>(self, other: I) -> bool
where I: IntoIterator, Self::Item: PartialEq<<I as IntoIterator>::Item>, Self: Sized,

Determines if the elements of this Iterator are equal to those of another. Read more
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fn eq_by<I, F>(self, other: I, eq: F) -> bool
where Self: Sized, I: IntoIterator, F: FnMut(Self::Item, <I as IntoIterator>::Item) -> bool,

🔬This is a nightly-only experimental API. (iter_order_by)
Determines if the elements of this Iterator are equal to those of another with respect to the specified equality function. Read more
1.5.0 · source§

fn ne<I>(self, other: I) -> bool
where I: IntoIterator, Self::Item: PartialEq<<I as IntoIterator>::Item>, Self: Sized,

Determines if the elements of this Iterator are not equal to those of another. Read more
1.5.0 · source§

fn lt<I>(self, other: I) -> bool
where I: IntoIterator, Self::Item: PartialOrd<<I as IntoIterator>::Item>, Self: Sized,

Determines if the elements of this Iterator are lexicographically less than those of another. Read more
1.5.0 · source§

fn le<I>(self, other: I) -> bool
where I: IntoIterator, Self::Item: PartialOrd<<I as IntoIterator>::Item>, Self: Sized,

Determines if the elements of this Iterator are lexicographically less or equal to those of another. Read more
1.5.0 · source§

fn gt<I>(self, other: I) -> bool
where I: IntoIterator, Self::Item: PartialOrd<<I as IntoIterator>::Item>, Self: Sized,

Determines if the elements of this Iterator are lexicographically greater than those of another. Read more
1.5.0 · source§

fn ge<I>(self, other: I) -> bool
where I: IntoIterator, Self::Item: PartialOrd<<I as IntoIterator>::Item>, Self: Sized,

Determines if the elements of this Iterator are lexicographically greater than or equal to those of another. Read more
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fn is_sorted_by<F>(self, compare: F) -> bool
where Self: Sized, F: FnMut(&Self::Item, &Self::Item) -> bool,

🔬This is a nightly-only experimental API. (is_sorted)
Checks if the elements of this iterator are sorted using the given comparator function. Read more
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fn is_sorted_by_key<F, K>(self, f: F) -> bool
where Self: Sized, F: FnMut(Self::Item) -> K, K: PartialOrd,

🔬This is a nightly-only experimental API. (is_sorted)
Checks if the elements of this iterator are sorted using the given key extraction function. Read more

Auto Trait Implementations§

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impl<'source, Token> Freeze for Lexer<'source, Token>
where <Token as Logos<'source>>::Extras: Freeze, Token: Freeze, <Token as Logos<'source>>::Error: Freeze,

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impl<'source, Token> RefUnwindSafe for Lexer<'source, Token>
where <Token as Logos<'source>>::Extras: RefUnwindSafe, <Token as Logos<'source>>::Source: RefUnwindSafe, Token: RefUnwindSafe, <Token as Logos<'source>>::Error: RefUnwindSafe,

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impl<'source, Token> Send for Lexer<'source, Token>
where <Token as Logos<'source>>::Extras: Send, <Token as Logos<'source>>::Source: Sync, Token: Send, <Token as Logos<'source>>::Error: Send,

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impl<'source, Token> Sync for Lexer<'source, Token>
where <Token as Logos<'source>>::Extras: Sync, <Token as Logos<'source>>::Source: Sync, Token: Sync, <Token as Logos<'source>>::Error: Sync,

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impl<'source, Token> Unpin for Lexer<'source, Token>
where <Token as Logos<'source>>::Extras: Unpin, Token: Unpin, <Token as Logos<'source>>::Error: Unpin,

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impl<'source, Token> UnwindSafe for Lexer<'source, Token>
where <Token as Logos<'source>>::Extras: UnwindSafe, <Token as Logos<'source>>::Source: RefUnwindSafe, Token: UnwindSafe, <Token as Logos<'source>>::Error: UnwindSafe,

Blanket Implementations§

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impl<T> Any for T
where T: 'static + ?Sized,

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fn type_id(&self) -> TypeId

Gets the TypeId of self. Read more
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impl<T> Borrow<T> for T
where T: ?Sized,

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fn borrow(&self) -> &T

Immutably borrows from an owned value. Read more
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impl<T> BorrowMut<T> for T
where T: ?Sized,

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fn borrow_mut(&mut self) -> &mut T

Mutably borrows from an owned value. Read more
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impl<T> From<T> for T

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fn from(t: T) -> T

Returns the argument unchanged.

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impl<T, U> Into<U> for T
where U: From<T>,

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fn into(self) -> U

Calls U::from(self).

That is, this conversion is whatever the implementation of From<T> for U chooses to do.

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impl<I> IntoIterator for I
where I: Iterator,

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type Item = <I as Iterator>::Item

The type of the elements being iterated over.
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type IntoIter = I

Which kind of iterator are we turning this into?
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fn into_iter(self) -> I

Creates an iterator from a value. Read more
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impl<T> ToOwned for T
where T: Clone,

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type Owned = T

The resulting type after obtaining ownership.
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fn to_owned(&self) -> T

Creates owned data from borrowed data, usually by cloning. Read more
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fn clone_into(&self, target: &mut T)

Uses borrowed data to replace owned data, usually by cloning. Read more
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impl<T, U> TryFrom<U> for T
where U: Into<T>,

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type Error = Infallible

The type returned in the event of a conversion error.
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fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>

Performs the conversion.
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impl<T, U> TryInto<U> for T
where U: TryFrom<T>,

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

The type returned in the event of a conversion error.
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fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>

Performs the conversion.