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Saturday, 16 October, 2021

Rust For Iter Index

author
Christina Perez
• Saturday, 09 January, 2021
• 16 min read

Returns the bounds on the remaining length of the iterator. The second half of the tuple that is returned is an Option < size >.

(Source: www.freesion.com)

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It is not enforced that an iterator implementation yields the declared number of elements. Size_hint() is primarily intended to be used for optimizations such as reserving space for the elements of the iterator, but must not be trusted to e.g., omit bounds checks in unsafe code.

An incorrect implementation of size_hint() should not lead to memory safety violations. That said, the implementation should provide a correct estimation, because otherwise it would be a violation of the trait's protocol.

The default implementation returns (0, None) which is correct for any iterator. This method will call next repeatedly until None is encountered, returning the number of times it saw Some.

Note that next has to be called at least once even if the iterator does not have any elements. The method does no guarding against overflows, so counting elements of an iterator with more than size::MAX elements either produces the wrong result or panics.

If debug assertions are enabled, a panic is guaranteed. This function might panic if the iterator has more than size::MAX elements.

This method will eagerly skip n elements by calling next up to n times until None is encountered. Advance_by(n) will return Ok(()) if the iterator successfully advances by n elements, or Err(k) if None is encountered, where k is the number of elements the iterator is advanced by before running out of elements (i.e. the length of the iterator).

Calling advance_by(0) does not consume any elements and always returns Ok(()). That means that the preceding elements will be discarded, and also that calling nth(0) multiple times on the same iterator will return different elements.

Note 1: The first element of the iterator will always be returned, regardless of the step given. Note 2: The time at which ignored elements are pulled is not fixed.

Step behaves like the sequence next(), nth(step-1), nth(step-1), … , but is also free to behave like the sequence advance_n_and_return_first(step), advance_n_and_return_first(step), … Which way is used may change for some iterators for performance reasons. The second way will advance the iterator earlier and may consume more items.

In other words, it links two iterators together, in a chain. Once is commonly used to adapt a single value into a chain of other kinds of iteration.

This works because the finite iterator will eventually return None, ending the zipper. Map() transforms one iterator into another, by means of its argument: something that implements Input.

If you are good at thinking in types, you can think of map() like this: If you have an iterator that gives you elements of some type A, and you want an iterator of some other type B, you can use map(), passing a closure that takes an A and returns a B. If you're doing some sort of looping for a side effect, it's considered more idiomatic to use than map().

This is equivalent to using a loop on the iterator, although break and continue are not possible from a closure. It's generally more idiomatic to use a for loop, but for_each may be more legible when processing items at the end of longer iterator chains.

Creates an iterator which uses a closure to determine if an element should be yielded. Given an element the closure must return true or false.

Because the closure passed to filter() takes a reference, and many iterators iterate over references, this leads to a possibly confusing situation, where the type of the closure is a double reference: Creates an iterator that both filters and maps.

Filter_map can be used to make chains of filter and map more concise. The example below shows how a map().filter().map() can be shortened to a single call to filter_map.

The method does no guarding against overflows, so enumerating more than size::MAX elements either produces the wrong result or panics. If debug assertions are enabled, a panic is guaranteed.

The returned iterator might panic if the to-be-returned index would overflow an size. Adds a peek method to an iterator.

Note that the underlying iterator is still advanced when peek is called for the first time: In order to retrieve the next element, next is called on the underlying iterator, hence any side effects (i.e. anything other than fetching the next value) of the next method will occur. Creates an iterator that skip s elements based on a predicate.

Creates an iterator that yields elements based on a predicate. After false is returned, take_while()'s job is over, and the rest of the elements are ignored.

If less than n elements are available, take will limit itself to the size of the underlying iterator: Scan() takes two arguments: an initial value which seeds the internal state, and a closure with two arguments, the first being a mutable reference to the internal state and the second an iterator element.

Creates an iterator that works like map, but flattens nested structure. The map adapter is very useful, but only when the closure argument produces values.

If it produces an iterator instead, there's an extra layer of indirection. Another way of thinking about flat_map() : map's closure returns one item for each element, and flat_map()'s closure returns an iterator for each element.

After an iterator returns None, future calls may or may not yield Some(T) again. Fuse() adapts an iterator, ensuring that after a None is given, it will always return None forever.

Does something with each element of an iterator, passing the value on. While working on such code, you might want to check out what's happening at various parts in the pipeline.

It's more common for inspect() to be used as a debugging tool than to exist in your final code, but applications may find it useful in certain situations when errors need to be logged before being discarded. This is one of the more powerful methods in the standard library, used in a variety of contexts.

For example, a String can be built from char s, and an iterator of Result items can be collected into Result, E>. Because collect() is so general, it can cause problems with type inference.

The relative order of partitioned items is not maintained. 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.

An iterator method that applies a function as long as it returns successfully, producing a single, final value. The closure either returns successfully, with the value that the accumulator should have for the next iteration, or it returns failure, with an error value that is propagated back to the caller immediately (short-circuiting).

If applying the closure succeeded against every element of the iterator, try_fold() returns the final accumulator as success. Folding is useful whenever you have a collection of something, and want to produce a single value from it.

In particular, try to have this call try_fold() on the internal parts from which this iterator is composed. Operator may be convenient for chaining the accumulator value along, but beware any invariants that need to be upheld before those early returns.

This is a smut self method, so iteration needs to be presumable after hitting an error here. An iterator method that applies a fallible function to each item in the iterator, stopping at the first error and returning that error.

This can also be thought of as the fallible form of for_each() or as the stateless version of try_fold(). An iterator method that applies a function, producing a single, final value.

The closure returns the value that the accumulator should have for the next iteration. After applying this closure to every element of the iterator, fold() returns the accumulator.

Folding is useful whenever you have a collection of something, and want to produce a single value from it. Note: fold(), and similar methods that traverse the entire iterator, may not terminate for infinite iterators, even on traits for which a result is determinable in finite time.

In particular, try to have this call fold() on the internal parts from which this iterator is composed. It's common for people who haven't used iterators a lot to use a for loop with a list of things to build up a result.

It applies this closure to each element of the iterator, and if they all return true, then so does all(). An empty iterator returns true.

It applies this closure to each element of the iterator, and if any of them return true, then so does any(). An empty iterator returns false.

Find() is short-circuiting; in other words, it will stop processing as soon as the closure returns true. Applies function to the elements of iterator and returns the first non-none result.

Applies function to the elements of iterator and returns the first true result or the first error. Searches for an element in an iterator, returning its index.

Position() takes a closure that returns true or false. Position() is short-circuiting; in other words, it will stop processing as soon as it finds a true.

The method does no guarding against overflows, so if there are more than size::MAX non-matching elements, it either produces the wrong result or panics. If debug assertions are enabled, a panic is guaranteed.

This function might panic if the iterator has more than size::MAX non-matching elements. Searches for an element in an iterator from the right, returning its index.

Rposition() takes a closure that returns true or false. It applies this closure to each element of the iterator, starting from the end, and if one of them returns true, then position() returns Some(index) .

Rposition() is short-circuiting; in other words, it will stop processing as soon as it finds a true. Returns the maximum element of an iterator.

Returns the minimum element of an iterator. Returns the element that gives the maximum value from the specified function.

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

Returns the element that gives the minimum value with respect to the specified comparison function. Unzip() consumes an entire iterator of pairs, producing two collections: one from the left elements of the pairs, and one from the right elements.

Instead of stopping at None, the iterator will instead start again, from the beginning. Takes each element, adds them together, and returns the result.

An empty iterator returns the zero value of the type. When calling sum() and a primitive integer type is being returned, this method will panic if the computation overflows and debug assertions are enabled.

An empty iterator returns the one value of the type. When calling product() and a primitive integer type is being returned, method will panic if the computation overflows and debug assertions are enabled.

Compares the elements of this Iterator with those of another with respect to the specified comparison function. Compares the elements of this Iterator with those of another with respect to the specified comparison function.

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

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

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

If the iterator yields exactly zero or one element, true is returned. Note that if Self::Item is only Partial, but not ORD, the above definition implies that this function returns false if any two consecutive items are not comparable.

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

Advances the iterator and returns the next value. Individual iterator implementations may choose to resume iteration, and so calling next() again may or may not eventually start returning Some(Item) again at some point.

The method does no guarding against overflows, so enumerating more than size::MAX elements either produces the wrong result or panics. If debug assertions are enabled, a panic is guaranteed.

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Sources
1 www.gamezebo.com - https://www.gamezebo.com/2019/10/30/complete-guide-bitlife-ribbons-achievements-jobs-money/
2 progameguides.com - https://progameguides.com/bitlife/how-to-escape-every-prison-guide/
3 bitlifie.com - https://bitlifie.com/life-expectancy-guide-bitlife/
4 www.getdroidtips.com - https://www.getdroidtips.com/bitlife-health-guide-treat-illnesses/
5 www.mrguider.org - https://www.mrguider.org/cheats/bitlife-life-simulator-guide-tips-cheats-strategies/