Struct syn::parse::StepCursor [−][src]
pub struct StepCursor<'c, 'a> { /* fields omitted */ }
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::parse::{ParseStream, Result}; // 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(ref punct) if punct.as_char() == '@' => { return Ok(((), next)); } _ => rest = next, } } Err(cursor.error("no `@` was found after this point")) }) }
Methods
impl<'c, 'a> StepCursor<'c, 'a>
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impl<'c, 'a> StepCursor<'c, 'a>
pub fn error<T: Display>(self, message: T) -> Error
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pub fn error<T: Display>(self, message: T) -> Error
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> Copy for StepCursor<'c, 'a>
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impl<'c, 'a> Copy for StepCursor<'c, 'a>
impl<'c, 'a> Clone for StepCursor<'c, 'a>
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impl<'c, 'a> Clone for StepCursor<'c, 'a>
fn clone(&self) -> StepCursor<'c, 'a>
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fn clone(&self) -> StepCursor<'c, 'a>
Returns a copy of the value. Read more
fn clone_from(&mut self, source: &Self)
1.0.0[src]
fn clone_from(&mut self, source: &Self)
1.0.0
[src]Performs copy-assignment from source
. Read more
impl<'c, 'a> Deref for StepCursor<'c, 'a>
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impl<'c, 'a> Deref for StepCursor<'c, 'a>
Auto Trait Implementations
impl<'c, 'a> !Send for StepCursor<'c, 'a>
impl<'c, 'a> !Send for StepCursor<'c, 'a>
impl<'c, 'a> !Sync for StepCursor<'c, 'a>
impl<'c, 'a> !Sync for StepCursor<'c, 'a>