Struct serde_json::de::StreamDeserializer

[+] Show declaration

pub struct StreamDeserializer<'de, R, T> { /* fields omitted */ }

[−] Expand description

Iterator that deserializes a stream into multiple JSON values.

A stream deserializer can be created from any JSON deserializer using the Deserializer::into_iter method.

The data can consist of any JSON value. Values need to be a self-delineating value e.g. arrays, objects, or strings, or be followed by whitespace or a self-delineating value.

use serde_json::{Deserializer, Value};

fn main() {
    let data = "{\"k\": 3}1\"cool\"\"stuff\" 3{}  [0, 1, 2]";

    let stream = Deserializer::from_str(data).into_iter::<Value>();

    for value in stream {
        println!("{}", value.unwrap());
    }
}

Methods

impl<'de, R, T> StreamDeserializer<'de, R, T> where
    R: Read<'de>,
    T: Deserialize<'de>, [−]

pub fn new(read: R) -> Self[−]

Create a JSON stream deserializer from one of the possible serde_json input sources.

Typically it is more convenient to use one of these methods instead:

• Deserializer::from_str(...).into_iter()
• Deserializer::from_bytes(...).into_iter()
• Deserializer::from_reader(...).into_iter()

pub fn byte_offset(&self) -> usize[−]

Returns the number of bytes so far deserialized into a successful T.

If a stream deserializer returns an EOF error, new data can be joined to old_data[stream.byte_offset()..] to try again.

let data = b"[0] [1] [";

let de = serde_json::Deserializer::from_slice(data);
let mut stream = de.into_iter::<Vec<i32>>();
assert_eq!(0, stream.byte_offset());

println!("{:?}", stream.next()); // [0]
assert_eq!(3, stream.byte_offset());

println!("{:?}", stream.next()); // [1]
assert_eq!(7, stream.byte_offset());

println!("{:?}", stream.next()); // error
assert_eq!(8, stream.byte_offset());

// If err.is_eof(), can join the remaining data to new data and continue.
let remaining = &data[stream.byte_offset()..];

Note: In the future this method may be changed to return the number of bytes so far deserialized into a successful T or syntactically valid JSON skipped over due to a type error. See serde-rs/json#70 for an example illustrating this.

Trait Implementations

impl<'de, R, T> Iterator for StreamDeserializer<'de, R, T> where
    R: Read<'de>,
    T: Deserialize<'de>, [+]

[+] Show hidden undocumented items

type Item = Result<T>

The type of the elements being iterated over.

fn next(&mut self) -> Option<Result<T>>[−]

Advances the iterator and returns the next value.

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

Returns the bounds on the remaining length of the iterator.

fn count(self) -> usize[−]

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

fn last(self) -> Option<Self::Item>[−]

Consumes the iterator, returning the last element.

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

Returns the nth element of the iterator.

fn step_by(self, step: usize) -> StepBy<Self>[−]

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
    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
    U: IntoIterator, [−]

'Zips up' two iterators into a single iterator of pairs.

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

Calls a closure on each element of an iterator.

fn filter<P>(self, predicate: P) -> Filter<Self, P> where
    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
    F: FnMut(Self::Item) -> Option<B>, [−]

Creates an iterator that both filters and maps.

fn enumerate(self) -> Enumerate<Self>[−]

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

fn peekable(self) -> Peekable<Self>[−]

Creates an iterator which can use peek to look at the next element of the iterator without consuming it.

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

Creates an iterator that [skip]s elements based on a predicate.

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

Creates an iterator that yields elements based on a predicate.

fn skip(self, n: usize) -> Skip<Self>[−]

Creates an iterator that skips the first n elements.

fn take(self, n: usize) -> Take<Self>[−]

Creates an iterator that yields its first n elements.

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

An iterator adaptor 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
    F: FnMut(Self::Item) -> U,
    U: IntoIterator, [−]

Creates an iterator that works like map, but flattens nested structure.

fn flatten(self) -> Flatten<Self> where
    Self::Item: IntoIterator, [−]

Creates an iterator that flattens nested structure.

fn fuse(self) -> Fuse<Self>[−]

Creates an iterator which ends after the first [None].

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

Do something with each element of an iterator, passing the value on.

fn by_ref(&mut self) -> &mut Self[−]

Borrows an iterator, rather than consuming it.

[+] Expand attributes

#[must_use = "if you really need to exhaust the iterator, consider `.for_each(drop)` instead"]

fn collect<B>(self) -> B where
    B: FromIterator<Self::Item>, [−]

Transforms an iterator into a collection.

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

Consumes an iterator, creating two collections from it.

fn try_fold<B, F, R>(&mut self, init: B, f: F) -> R where
    F: FnMut(B, Self::Item) -> R,
    R: Try<Ok = 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) -> R where
    F: FnMut(Self::Item) -> R,
    R: Try<Ok = ()>, [−]

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) -> B where
    F: FnMut(B, Self::Item) -> B, [−]

An iterator method that applies a function, producing a single, final value.

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

Tests if every element of the iterator matches a predicate.

fn any<F>(&mut self, f: F) -> bool where
    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
    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
    F: FnMut(Self::Item) -> Option<B>, [−]

Applies function to the elements of iterator and returns the first non-none result.

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

Searches for an element in an iterator, returning its index.

fn rposition<P>(&mut self, predicate: P) -> Option<usize> where
    P: FnMut(Self::Item) -> bool,
    Self: ExactSizeIterator + DoubleEndedIterator, [−]

Searches for an element in an iterator from the right, returning its index.

fn max(self) -> Option<Self::Item> where
    Self::Item: Ord, [−]

Returns the maximum element of an iterator.

fn min(self) -> Option<Self::Item> where
    Self::Item: Ord, [−]

Returns the minimum element of an iterator.

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

Returns the element that gives the minimum value with respect to the specified comparison function.

fn rev(self) -> Rev<Self> where
    Self: DoubleEndedIterator, [−]

Reverses an iterator's direction.

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

Converts an iterator of pairs into a pair of containers.

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

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

Creates an iterator which copies all of its elements.

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

Creates an iterator which [clone]s all of its elements.

fn cycle(self) -> Cycle<Self> where
    Self: Clone, [−]

Repeats an iterator endlessly.

fn sum<S>(self) -> S where
    S: Sum<Self::Item>, [−]

Sums the elements of an iterator.

fn product<P>(self) -> P where
    P: Product<Self::Item>, [−]

Iterates over the entire iterator, multiplying all the elements

fn cmp<I>(self, other: I) -> Ordering where
    I: IntoIterator<Item = Self::Item>,
    Self::Item: Ord, [−]

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

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

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

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

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

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

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

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

Determines if the elements of this Iterator are lexicographically less than those of another.

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

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

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

Determines if the elements of this Iterator are lexicographically greater than those of another.

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

Determines if the elements of this Iterator are lexicographically greater than or equal to those of another.