Struct syn::parse::StepCursor [−][src]
Cursor state associated with speculative parsing.
This type is the input of the closure provided to ParseStream::step
.
Example
use proc_macro2::TokenTree; use syn::Result; use syn::parse::ParseStream; // This function advances the stream past the next occurrence of `@`. If // no `@` is present in the stream, the stream position is unchanged and // an error is returned. fn skip_past_next_at(input: ParseStream) -> Result<()> { input.step(|cursor| { let mut rest = *cursor; while let Some((tt, next)) = rest.token_tree() { match &tt { TokenTree::Punct(punct) if punct.as_char() == '@' => { return Ok(((), next)); } _ => rest = next, } } Err(cursor.error("no `@` was found after this point")) }) }
Implementations
impl<'c, 'a> StepCursor<'c, 'a>
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pub fn error<T: Display>(self, message: T) -> Error
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Triggers an error at the current position of the parse stream.
The ParseStream::step
invocation will return this same error without
advancing the stream state.
Methods from Deref<Target = Cursor<'c>>
Trait Implementations
impl<'c, 'a> Clone for StepCursor<'c, 'a>
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fn clone(&self) -> Self
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pub fn clone_from(&mut self, source: &Self)
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impl<'c, 'a> Copy for StepCursor<'c, 'a>
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impl<'c, 'a> Deref for StepCursor<'c, 'a>
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Auto Trait Implementations
impl<'c, 'a> RefUnwindSafe for StepCursor<'c, 'a>
impl<'c, 'a> !Send for StepCursor<'c, 'a>
impl<'c, 'a> !Sync for StepCursor<'c, 'a>
impl<'c, 'a> Unpin for StepCursor<'c, 'a>
impl<'c, 'a> UnwindSafe for StepCursor<'c, 'a>
Blanket Implementations
impl<T> Any for T where
T: 'static + ?Sized,
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T: 'static + ?Sized,
impl<T> Borrow<T> for T where
T: ?Sized,
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T: ?Sized,
impl<T> BorrowMut<T> for T where
T: ?Sized,
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T: ?Sized,
pub fn borrow_mut(&mut self) -> &mut T
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impl<T> From<T> for T
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impl<T, U> Into<U> for T where
U: From<T>,
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U: From<T>,
impl<T> ToOwned for T where
T: Clone,
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T: Clone,
type Owned = T
The resulting type after obtaining ownership.
pub fn to_owned(&self) -> T
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pub fn clone_into(&self, target: &mut T)
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impl<T, U> TryFrom<U> for T where
U: Into<T>,
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U: Into<T>,
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>
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impl<T, U> TryInto<U> for T where
U: TryFrom<T>,
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U: TryFrom<T>,