Struct frame_support::storage::PrefixIterator

source · 
pub struct PrefixIterator<T, OnRemoval = ()> { /* private fields */ }
Expand description

Iterate or drain over a prefix and decode raw_key and raw_value into T.

If any decoding fails it skips it and continues to the next key.

If draining, then the hook OnRemoval::on_removal is called after each removal.

Implementations§

Converts to the same iterator but with the different ‘OnRemoval’ type

Creates a new PrefixIterator, iterating after previous_key and filtering out keys that are not prefixed with prefix.

A decode_fn function must also be supplied, and it takes in two &[u8] parameters, returning a Result containing the decoded type T if successful, and a codec::Error on failure. The first &[u8] argument represents the raw, undecoded key without the prefix of the current item, while the second &[u8] argument denotes the corresponding raw, undecoded value.

Get the last key that has been iterated upon and return it.

Get the prefix that is being iterated upon for this iterator and return it.

Set the key that the iterator should start iterating after.

Mutate this iterator into a draining iterator; items iterated are removed from storage.

Trait Implementations§

The type of the elements being iterated over.
Advances the iterator and returns the next value. Read more
🔬This is a nightly-only experimental API. (iter_next_chunk)
Advances the iterator and returns an array containing the next N values. Read more
Returns the bounds on the remaining length of the iterator. Read more
Consumes the iterator, counting the number of iterations and returning it. Read more
Consumes the iterator, returning the last element. Read more
🔬This is a nightly-only experimental API. (iter_advance_by)
Advances the iterator by n elements. Read more
Returns the nth element of the iterator. Read more
Creates an iterator starting at the same point, but stepping by the given amount at each iteration. Read more
Takes two iterators and creates a new iterator over both in sequence. Read more
‘Zips up’ two iterators into a single iterator of pairs. Read more
🔬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. Read more
Takes a closure and creates an iterator which calls that closure on each element. Read more
Calls a closure on each element of an iterator. Read more
Creates an iterator which uses a closure to determine if an element should be yielded. Read more
Creates an iterator that both filters and maps. Read more
Creates an iterator which gives the current iteration count as well as the next value. Read more
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. Read more
Creates an iterator that skips elements based on a predicate. Read more
Creates an iterator that yields elements based on a predicate. Read more
Creates an iterator that both yields elements based on a predicate and maps. Read more
Creates an iterator that skips the first n elements. Read more
Creates an iterator that yields the first n elements, or fewer if the underlying iterator ends sooner. Read more
An iterator adapter similar to fold that holds internal state and produces a new iterator. Read more
Creates an iterator that works like map, but flattens nested structure. Read more
Creates an iterator which ends after the first None. Read more
Does something with each element of an iterator, passing the value on. Read more
Borrows an iterator, rather than consuming it. Read more
Transforms an iterator into a collection. Read more
🔬This is a nightly-only experimental API. (iter_collect_into)
Collects all the items from an iterator into a collection. Read more
Consumes an iterator, creating two collections from it. Read more
🔬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. Read more
An iterator method that applies a function as long as it returns successfully, producing a single, final value. Read more
An iterator method that applies a fallible function to each item in the iterator, stopping at the first error and returning that error. Read more
Folds every element into an accumulator by applying an operation, returning the final result. Read more
Reduces the elements to a single one, by repeatedly applying a reducing operation. Read more
🔬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. Read more
Tests if every element of the iterator matches a predicate. Read more
Tests if any element of the iterator matches a predicate. Read more
Searches for an element of an iterator that satisfies a predicate. Read more
Applies function to the elements of iterator and returns the first non-none result. Read more
🔬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. Read more
Searches for an element in an iterator, returning its index. Read more
Returns the element that gives the maximum value from the specified function. Read more
Returns the element that gives the maximum value with respect to the specified comparison function. Read more
Returns the element that gives the minimum value from the specified function. Read more
Returns the element that gives the minimum value with respect to the specified comparison function. Read more
Converts an iterator of pairs into a pair of containers. Read more
Creates an iterator which copies all of its elements. Read more
Creates an iterator which clones all of its elements. Read more
🔬This is a nightly-only experimental API. (iter_array_chunks)
Returns an iterator over N elements of the iterator at a time. Read more
Sums the elements of an iterator. Read more
Iterates over the entire iterator, multiplying all the elements Read more
🔬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. Read more
Lexicographically compares the elements of this Iterator with those of another. Read more
🔬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. Read more
Determines if the elements of this Iterator are equal to those of another. Read more
🔬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. Read more
Determines if the elements of this Iterator are unequal to those of another. Read more
Determines if the elements of this Iterator are lexicographically less than those of another. Read more
Determines if the elements of this Iterator are lexicographically less or equal to those of another. Read more
Determines if the elements of this Iterator are lexicographically greater than those of another. Read more
Determines if the elements of this Iterator are lexicographically greater than or equal to those of another. Read more
🔬This is a nightly-only experimental API. (is_sorted)
Checks if the elements of this iterator are sorted using the given comparator function. Read more
🔬This is a nightly-only experimental API. (is_sorted)
Checks if the elements of this iterator are sorted using the given key extraction function. Read more

Auto Trait Implementations§

Blanket Implementations§

Gets the TypeId of self. Read more
Immutably borrows from an owned value. Read more
Mutably borrows from an owned value. Read more
Convert from a value of T into an equivalent instance of Option<Self>. Read more
Consume self to return Some equivalent value of Option<T>. Read more
Converts self into T using Into<T>. Read more
Convert Box<dyn Trait> (where Trait: Downcast) to Box<dyn Any>. Box<dyn Any> can then be further downcast into Box<ConcreteType> where ConcreteType implements Trait. Read more
Convert Rc<Trait> (where Trait: Downcast) to Rc<Any>. Rc<Any> can then be further downcast into Rc<ConcreteType> where ConcreteType implements Trait. Read more
Convert &Trait (where Trait: Downcast) to &Any. This is needed since Rust cannot generate &Any’s vtable from &Trait’s. Read more
Convert &mut Trait (where Trait: Downcast) to &Any. This is needed since Rust cannot generate &mut Any’s vtable from &mut Trait’s. Read more
Convert Arc<Trait> (where Trait: Downcast) to Arc<Any>. Arc<Any> can then be further downcast into Arc<ConcreteType> where ConcreteType implements Trait. Read more
Causes self to use its Binary implementation when Debug-formatted. Read more
Causes self to use its Display implementation when Debug-formatted. Read more
Causes self to use its LowerExp implementation when Debug-formatted. Read more
Causes self to use its LowerHex implementation when Debug-formatted. Read more
Causes self to use its Octal implementation when Debug-formatted. Read more
Causes self to use its Pointer implementation when Debug-formatted. Read more
Causes self to use its UpperExp implementation when Debug-formatted. Read more
Causes self to use its UpperHex implementation when Debug-formatted. Read more
Formats each item in a sequence. Read more

Returns the argument unchanged.

Instruments this type with the provided Span, returning an Instrumented wrapper. Read more
Instruments this type with the current Span, returning an Instrumented wrapper. Read more

Calls U::from(self).

That is, this conversion is whatever the implementation of From<T> for U chooses to do.

The type of the elements being iterated over.
Which kind of iterator are we turning this into?
Creates an iterator from a value. Read more

Get a reference to the inner from the outer.

Get a mutable reference to the inner from the outer.

Choose one element at random from the iterator. Read more
Choose one element at random from the iterator. Read more
Collects values at random from the iterator into a supplied buffer until that buffer is filled. Read more
Collects amount values at random from the iterator into a vector. Read more
Choose one element at random from the iterator. Read more
Collects values at random from the iterator into a supplied buffer until that buffer is filled. Read more
Collects amount values at random from the iterator into a vector. Read more
Alternate elements from two iterators until both have run out. Read more
Alternate elements from two iterators until at least one of them has run out. Read more
An iterator adaptor to insert a particular value between each element of the adapted iterator. Read more
An iterator adaptor to insert a particular value created by a function between each element of the adapted iterator. Read more
Create an iterator which iterates over both this and the specified iterator simultaneously, yielding pairs of two optional elements. Read more
Create an iterator which iterates over both this and the specified iterator simultaneously, yielding pairs of elements. Read more
A “meta iterator adaptor”. Its closure receives a reference to the iterator and may pick off as many elements as it likes, to produce the next iterator element. Read more
Return an iterable that can group iterator elements. Consecutive elements that map to the same key (“runs”), are assigned to the same group. Read more
Return an iterable that can chunk the iterator. Read more
Return an iterator over all contiguous windows producing tuples of a specific size (up to 12). Read more
Return an iterator over all windows, wrapping back to the first elements when the window would otherwise exceed the length of the iterator, producing tuples of a specific size (up to 12). Read more
Return an iterator that groups the items in tuples of a specific size (up to 12). Read more
Split into an iterator pair that both yield all elements from the original iterator. Read more
👎Deprecated since 0.8.0: Use std .step_by() instead
Return an iterator adaptor that steps n elements in the base iterator for each iteration. Read more
Convert each item of the iterator using the Into trait. Read more
👎Deprecated since 0.10.0: Use .map_ok() instead
See .map_ok().
Return an iterator adaptor that applies the provided closure to every Result::Ok value. Result::Err values are unchanged. Read more
Return an iterator adaptor that filters every Result::Ok value with the provided closure. Result::Err values are unchanged. Read more
Return an iterator adaptor that filters and transforms every Result::Ok value with the provided closure. Result::Err values are unchanged. Read more
Return an iterator adaptor that flattens every Result::Ok value into a series of Result::Ok values. Result::Err values are unchanged. Read more
Return an iterator adaptor that merges the two base iterators in ascending order. If both base iterators are sorted (ascending), the result is sorted. Read more
Return an iterator adaptor that merges the two base iterators in order. This is much like .merge() but allows for a custom ordering. Read more
Create an iterator that merges items from both this and the specified iterator in ascending order. Read more
Return an iterator adaptor that flattens an iterator of iterators by merging them in ascending order. Read more
Return an iterator adaptor that flattens an iterator of iterators by merging them according to the given closure. Read more
Return an iterator adaptor that iterates over the cartesian product of the element sets of two iterators self and J. Read more
Return an iterator adaptor that iterates over the cartesian product of all subiterators returned by meta-iterator self. Read more
Return an iterator adaptor that uses the passed-in closure to optionally merge together consecutive elements. Read more
Remove duplicates from sections of consecutive identical elements. If the iterator is sorted, all elements will be unique. Read more
Remove duplicates from sections of consecutive identical elements, determining equality using a comparison function. If the iterator is sorted, all elements will be unique. Read more
Remove duplicates from sections of consecutive identical elements, while keeping a count of how many repeated elements were present. If the iterator is sorted, all elements will be unique. Read more
Remove duplicates from sections of consecutive identical elements, while keeping a count of how many repeated elements were present. This will determine equality using a comparison function. If the iterator is sorted, all elements will be unique. Read more
Return an iterator adaptor that produces elements that appear more than once during the iteration. Duplicates are detected using hash and equality. Read more
Return an iterator adaptor that produces elements that appear more than once during the iteration. Duplicates are detected using hash and equality. Read more
Return an iterator adaptor that filters out elements that have already been produced once during the iteration. Duplicates are detected using hash and equality. Read more
Return an iterator adaptor that filters out elements that have already been produced once during the iteration. Read more
Return an iterator adaptor that borrows from this iterator and takes items while the closure accept returns true. Read more
Return an iterator adaptor that borrows from a Clone-able iterator to only pick off elements while the predicate accept returns true. Read more
Return an iterator adaptor that filters Option<A> iterator elements and produces A. Stops on the first None encountered. Read more
Return an iterator adaptor that iterates over the combinations of the elements from an iterator. Read more
Return an iterator adaptor that iterates over the k-length combinations of the elements from an iterator. Read more
Return an iterator that iterates over the k-length combinations of the elements from an iterator, with replacement. Read more
Return an iterator adaptor that iterates over all k-permutations of the elements from an iterator. Read more
Return an iterator that iterates through the powerset of the elements from an iterator. Read more
Return an iterator adaptor that pads the sequence to a minimum length of min by filling missing elements using a closure f. Read more
Return an iterator adaptor that wraps each element in a Position to ease special-case handling of the first or last elements. Read more
Return an iterator adaptor that yields the indices of all elements satisfying a predicate, counted from the start of the iterator. Read more
Return an iterator adaptor that applies a mutating function to each element before yielding it. Read more
Advances the iterator and returns the next items grouped in a tuple of a specific size (up to 12). Read more
Collects all items from the iterator into a tuple of a specific size (up to 12). Read more
Find the position and value of the first element satisfying a predicate. Read more
Find the value of the first element satisfying a predicate or return the last element, if any. Read more
Find the value of the first element satisfying a predicate or return the first element, if any. Read more
Returns true if the given item is present in this iterator. Read more
Check whether all elements compare equal. Read more
Check whether all elements are unique (non equal). Read more
Consume the first n elements from the iterator eagerly, and return the same iterator again. Read more
Consume the last n elements from the iterator eagerly, and return the same iterator again. Read more
👎Deprecated since 0.8.0: Use .for_each() instead
Run the closure f eagerly on each element of the iterator. Read more
Combine all an iterator’s elements into one element by using Extend. Read more
.collect_vec() is simply a type specialization of Iterator::collect, for convenience. Read more
.try_collect() is more convenient way of writing .collect::<Result<_, _>>() Read more
Assign to each reference in self from the from iterator, stopping at the shortest of the two iterators. Read more
Combine all iterator elements into one String, separated by sep. Read more
Format all iterator elements, separated by sep. Read more
Format all iterator elements, separated by sep. Read more
👎Deprecated since 0.10.0: Use .fold_ok() instead
See .fold_ok().
Fold Result values from an iterator. Read more
Fold Option values from an iterator. Read more
👎Deprecated since 0.10.2: Use Iterator::reduce instead
Accumulator of the elements in the iterator. Read more
Accumulate the elements in the iterator in a tree-like manner. Read more
An iterator method that applies a function, producing a single, final value. Read more
Iterate over the entire iterator and add all the elements. Read more
Iterate over the entire iterator and multiply all the elements. Read more
Sort all iterator elements into a new iterator in ascending order. Read more
Sort all iterator elements into a new iterator in ascending order. Read more
Sort all iterator elements into a new iterator in ascending order. Read more
Sort all iterator elements into a new iterator in ascending order. Read more
Sort all iterator elements into a new iterator in ascending order. Read more
Sort all iterator elements into a new iterator in ascending order. Read more
Sort all iterator elements into a new iterator in ascending order. The key function is called exactly once per key. Read more
Sort the k smallest elements into a new iterator, in ascending order. Read more
Collect all iterator elements into one of two partitions. Unlike Iterator::partition, each partition may have a distinct type. Read more
Partition a sequence of Results into one list of all the Ok elements and another list of all the Err elements. Read more
Return a HashMap of keys mapped to Vecs of values. Keys and values are taken from (Key, Value) tuple pairs yielded by the input iterator. Read more
Return an Iterator on a HashMap. Keys mapped to Vecs of values. The key is specified in the closure. Read more
Constructs a GroupingMap to be used later with one of the efficient group-and-fold operations it allows to perform. Read more
Constructs a GroupingMap to be used later with one of the efficient group-and-fold operations it allows to perform. Read more
Return all minimum elements of an iterator. Read more
Return all minimum elements of an iterator, as determined by the specified function. Read more
Return all minimum elements of an iterator, as determined by the specified function. Read more
Return all maximum elements of an iterator. Read more
Return all maximum elements of an iterator, as determined by the specified function. Read more
Return all minimum elements of an iterator, as determined by the specified function. Read more
Return the minimum and maximum elements in the iterator. Read more
Return the minimum and maximum element of an iterator, as determined by the specified function. Read more
Return the minimum and maximum element of an iterator, as determined by the specified comparison function. Read more
Return the position of the maximum element in the iterator. Read more
Return the position of the maximum element in the iterator, as determined by the specified function. Read more
Return the position of the maximum element in the iterator, as determined by the specified comparison function. Read more
Return the position of the minimum element in the iterator. Read more
Return the position of the minimum element in the iterator, as determined by the specified function. Read more
Return the position of the minimum element in the iterator, as determined by the specified comparison function. Read more
Return the positions of the minimum and maximum elements in the iterator. Read more
Return the postions of the minimum and maximum elements of an iterator, as determined by the specified function. Read more
Return the postions of the minimum and maximum elements of an iterator, as determined by the specified comparison function. Read more
If the iterator yields exactly one element, that element will be returned, otherwise an error will be returned containing an iterator that has the same output as the input iterator. Read more
If the iterator yields no elements, Ok(None) will be returned. If the iterator yields exactly one element, that element will be returned, otherwise an error will be returned containing an iterator that has the same output as the input iterator. Read more
An iterator adaptor that allows the user to peek at multiple .next() values without advancing the base iterator. Read more
Collect the items in this iterator and return a HashMap which contains each item that appears in the iterator and the number of times it appears. Read more
Collect the items in this iterator and return a HashMap which contains each item that appears in the iterator and the number of times it appears, determining identity using a keying function. Read more
Converts an iterator of tuples into a tuple of containers. Read more
Unzip this iterator into multiple collections.
Unzip this iterator into multiple collections.
Unzip this iterator into multiple collections.
Unzip this iterator into multiple collections.
Unzip this iterator into multiple collections.
Unzip this iterator into multiple collections.
Unzip this iterator into multiple collections.
Unzip this iterator into multiple collections.
Unzip this iterator into multiple collections.
Unzip this iterator into multiple collections.
Unzip this iterator into multiple collections.
Unzip this iterator into multiple collections.
Unzip this iterator into multiple collections.
Pipes by value. This is generally the method you want to use. Read more
Borrows self and passes that borrow into the pipe function. Read more
Mutably borrows self and passes that borrow into the pipe function. Read more
Borrows self, then passes self.borrow() into the pipe function. Read more
Mutably borrows self, then passes self.borrow_mut() into the pipe function. Read more
Borrows self, then passes self.as_ref() into the pipe function.
Mutably borrows self, then passes self.as_mut() into the pipe function. Read more
Borrows self, then passes self.deref() into the pipe function.
Mutably borrows self, then passes self.deref_mut() into the pipe function. Read more
The alignment of pointer.
The type for initializers.
Initializes a with the given initializer. Read more
Dereferences the given pointer. Read more
Mutably dereferences the given pointer. Read more
Drops the object pointed to by the given pointer. Read more
Should always be Self
Convert from a value of T into an equivalent instance of Self. Read more
Consume self to return an equivalent value of T. Read more
Immutable access to a value. Read more
Mutable access to a value. Read more
Immutable access to the Borrow<B> of a value. Read more
Mutable access to the BorrowMut<B> of a value. Read more
Immutable access to the AsRef<R> view of a value. Read more
Mutable access to the AsMut<R> view of a value. Read more
Immutable access to the Deref::Target of a value. Read more
Mutable access to the Deref::Target of a value. Read more
Calls .tap() only in debug builds, and is erased in release builds.
Calls .tap_mut() only in debug builds, and is erased in release builds. Read more
Calls .tap_borrow() only in debug builds, and is erased in release builds. Read more
Calls .tap_borrow_mut() only in debug builds, and is erased in release builds. Read more
Calls .tap_ref() only in debug builds, and is erased in release builds. Read more
Calls .tap_ref_mut() only in debug builds, and is erased in release builds. Read more
Calls .tap_deref() only in debug builds, and is erased in release builds. Read more
Calls .tap_deref_mut() only in debug builds, and is erased in release builds. Read more
Attempts to convert self into T using TryInto<T>. Read more
The type returned in the event of a conversion error.
Performs the conversion.
The type returned in the event of a conversion error.
Performs the conversion.
The counterpart to unchecked_from.
Returns an iterator over the string in Unicode Normalization Form D (canonical decomposition). Read more
Returns an iterator over the string in Unicode Normalization Form KD (compatibility decomposition). Read more
An Iterator over the string in Unicode Normalization Form C (canonical decomposition followed by canonical composition). Read more
An Iterator over the string in Unicode Normalization Form KC (compatibility decomposition followed by canonical composition). Read more
A transformation which replaces CJK Compatibility Ideograph codepoints with normal forms using Standardized Variation Sequences. This is not part of the canonical or compatibility decomposition algorithms, but performing it before those algorithms produces normalized output which better preserves the intent of the original text. Read more
An Iterator over the string with Conjoining Grapheme Joiner characters inserted according to the Stream-Safe Text Process (UAX15-D4) Read more
Consume self to return an equivalent value of T.
Attaches the provided Subscriber to this type, returning a WithDispatch wrapper. Read more
Attaches the current default Subscriber to this type, returning a WithDispatch wrapper. Read more