Struct ebml_iterable::TagIterator

pub struct TagIterator<R: Read, TSpec>where
    TSpec: EbmlSpecification<TSpec> + EbmlTag<TSpec> + Clone,{ /* private fields */ }

Provides an iterator over EBML files (read from a source implementing the std::io::Read trait). Can be configured to read specific “Master” tags as complete objects rather than just emitting when they start and end.

This is a generic struct that requires a specification implementing EbmlSpecification and EbmlTag. No specifications are included in this crate - you will need to either use another crate providing a spec (such as the Matroska spec implemented in the webm-iterable or write your own spec if you want to iterate over a custom EBML file. The iterator outputs TSpec variants representing the type of tag (defined by the specification) and the accompanying tag data. “Master” tags (defined by the specification) usually will be read as Start and End variants, but the iterator can be configured to buffer Master tags into a Full variant using the tags_to_buffer parameter.

Note: The Self::with_capacity() method can be used to construct a TagIterator with a specified default buffer size. This is only useful as a microoptimization to memory management if you know the maximum tag size of the file you’re reading.

Example

use std::fs::File;
use ebml_iterable::TagIterator;

let file = File::open("my_ebml_file.ebml")?;
let mut my_iterator: TagIterator<_, EmptySpec> = TagIterator::new(file, &[]);
for tag in my_iterator {
  println!("{:?}", tag?);
}

Errors

The Item type for the associated Iterator implementation is a Result<TSpec, TagIteratorError>, meaning each next() call has the potential to fail. This is because the source data is not parsed all at once - it is incrementally parsed as the iterator progresses. If the iterator runs into an error (such as corrupted data or an unexpected end-of-file), it needs to be propagated to the logic trying to read the tags. The different possible error states are enumerated in TagIteratorError.

Panics

The iterator can panic if <TSpec> is an internally inconsistent specification (i.e. it claims that a specific tag id has a specific data type but fails to produce a tag variant using data of that type). This won’t happen if the specification being used was created using the #[ebml_specification] attribute macro.

Implementations

impl<R: Read, TSpec> TagIterator<R, TSpec>where
    TSpec: EbmlSpecification<TSpec> + EbmlTag<TSpec> + Clone,

pub fn new(source: R, tags_to_buffer: &[TSpec]) -> Self

Returns a new TagIterator<TSpec> instance.

The source parameter must implement std::io::Read. The second argument, tags_to_buffer, specifies which “Master” tags should be read as Master::Fulls rather than as Master::Start and Master::Ends. Refer to the documentation on TagIterator for more explanation of how to use the returned instance.

pub fn with_capacity(source: R, tags_to_buffer: &[TSpec], capacity: usize) -> Self

Returns a new TagIterator<TSpec> instance with the specified internal buffer capacity.

This initializes the TagIterator with a specific byte capacity. The iterator will still reallocate if necessary. (Reallocation occurs if the iterator comes across a tag that should be output as a Master::Full and its size in bytes is greater than the iterator’s current buffer capacity.)

Examples found in repository

src/tag_iterator.rs (line 73)

    pub fn new(source: R, tags_to_buffer: &[TSpec]) -> Self {
        TagIterator::with_capacity(source, tags_to_buffer, DEFAULT_BUFFER_LEN)
    }

Trait Implementations

impl<R: Read, TSpec> Iterator for TagIterator<R, TSpec>where
    TSpec: EbmlSpecification<TSpec> + EbmlTag<TSpec> + Clone,

type Item = Result<TSpec, TagIteratorError>

The type of the elements being iterated over.

fn next(&mut self) -> Option<Self::Item>

Advances the iterator and returns the next value.

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.

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

Returns the bounds on the remaining length of the iterator.

fn count(self) -> usizewhere
    Self: Sized,

Consumes the iterator, counting the number of iterations and returning it.

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

Consumes the iterator, returning the last element.

fn advance_by(&mut self, n: usize) -> Result<(), usize>

🔬This is a nightly-only experimental API. (iter_advance_by)

Advances the iterator by n elements.

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

Returns the nth element of the iterator.

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.

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.

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.

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.

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.

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

Calls a closure on each element of an iterator.

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.

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.

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

Creates an iterator which gives the current iteration count as well as the next value.

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.

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.

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.

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.

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

Creates an iterator that skips the first n elements.

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.

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 similar to fold that holds internal state and produces a new iterator.

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.

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

Creates an iterator which ends after the first None.

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.

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

Borrows an iterator, rather than consuming it.

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

Transforms an iterator into a collection.

fn collect_into<E>(self, collection: &mut E) -> &mut Ewhere
    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.

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.

fn is_partitioned<P>(self, predicate: P) -> boolwhere
    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.

fn try_fold<B, F, R>(&mut self, init: B, f: F) -> Rwhere
    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.

fn try_for_each<F, R>(&mut self, f: F) -> Rwhere
    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.

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

Folds every element into an accumulator by applying an operation, returning the final result.

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.

fn try_reduce<F, R>(
    &mut self,
    f: F
) -> <<R as Try>::Residual as Residual<Option<<R as Try>::Output>>>::TryTypewhere
    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.

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

Tests if every element of the iterator matches a predicate.

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

Tests if any element of the iterator matches a predicate.

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.

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.

fn try_find<F, R>(
    &mut self,
    f: F
) -> <<R as Try>::Residual as Residual<Option<Self::Item>>>::TryTypewhere
    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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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

Sums the elements of an iterator.

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

Iterates over the entire iterator, multiplying all the elements

fn cmp_by<I, F>(self, other: I, cmp: F) -> Orderingwhere
    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.

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

Lexicographically compares the elements of this Iterator with those of another.

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.

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

Determines if the elements of this Iterator are equal to those of another.

fn eq_by<I, F>(self, other: I, eq: F) -> boolwhere
    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.

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

Determines if the elements of this Iterator are unequal to those of another.

fn lt<I>(self, other: I) -> boolwhere
    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.

fn le<I>(self, other: I) -> boolwhere
    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.

fn gt<I>(self, other: I) -> boolwhere
    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.

fn ge<I>(self, other: I) -> boolwhere
    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.

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

🔬This is a nightly-only experimental API. (is_sorted)

Checks if the elements of this iterator are sorted using the given comparator function.

fn is_sorted_by_key<F, K>(self, f: F) -> boolwhere
    Self: Sized,
    F: FnMut(Self::Item) -> K,
    K: PartialOrd<K>,

🔬This is a nightly-only experimental API. (is_sorted)

Checks if the elements of this iterator are sorted using the given key extraction function.