[][src]Struct syn::parse::StepCursor

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.


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"))


impl<'c, 'a> StepCursor<'c, 'a>[src]

pub fn error<T: Display>(self, message: T) -> Error[src]

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>[src]

impl<'c, 'a> Copy for StepCursor<'c, 'a>[src]

impl<'c, 'a> Deref for StepCursor<'c, 'a>[src]

type Target = Cursor<'c>

The resulting type after dereferencing.

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

impl<T> Borrow<T> for T where
    T: ?Sized

impl<T> BorrowMut<T> for T where
    T: ?Sized

impl<T> From<T> for T[src]

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

impl<T> ToOwned for T where
    T: Clone

type Owned = T

The resulting type after obtaining ownership.

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

type Error = Infallible

The type returned in the event of a conversion error.

impl<T, U> TryInto<U> for T where
    U: TryFrom<T>, 

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

The type returned in the event of a conversion error.