ResizableArray.md

ResizableArray

This class serves as a wrapper around T[], implementing ICollection and IReadOnlyList<T>. It is intended to be used when direct access to the underlying array is required; unlike List<T>, the actual, underlying T[] may be safely and directly accessed in user code (without reflection or hacks) via ResizableArray<T>.Array that forms this part of the contract.

ResizableArray is a lower-level data structure, it does not abstract away the Count of the underlying array (i.e. there is no distinction between Count and Capacity). Its benefit over a plain T[] is the incorporation of various static functions found in the System.Array namespace as direct methods of this object-oriented container.

If and when Microsoft's APIs all move over to Span<T>, this will cease to have any purpose. Until then, ResizableArray comes in handy to avoid deduplication when dealing with various Microsoft-provided APIs that require a plain T[] parameter as a buffer into which the result of an operation is stored.

ResizableArray<T>()

Creates a new ResizableArray<T> with zero size.

ResizableArray<T>(int initialSize)

Creates a new ResizableArray<T> with ResizableArray<T>.Array initialized to new T[initialSize].

ResizableArray<T>(IReadOnlyList<T> values)

Efficiently creates a new ResizableArray<T> containing the data found within the indexable values.

ResizableArray<T>(IEnumerable<T> values)

Efficiently creates a new ResizableArray<T> from the contents of values without iterating over the IEnumerable<T> more than once, even when the length of values is not known or is inaccessible.

ResizableArray<T>.Append(T[] array)

Appends the values in array to the end of the ResizableArray, resizing appropriately. After the call is completed, ResizableArray.Count is equal to the previous Count plus array.Count.

ResizableArray<T>.Append(T[] array, int start, int count)

Appends count values from array beginning with array[start] to the end of the ResizableArray, resizing appropriately. After the call is completed, ResizableArray.Count is equal to the previous Count plus count.

ResizableArray<T>.Resize(int newSize)

Increases or reduces the size of internal array to the value specified by newSize. The array is truncated if the value is less than the current value of ResizableArray<T>.Count. Depending on memory layout and fragmentation, this operation may complete without copying any data (i.e. in constant time).

ResizableArray<T>.Array

Directly exposes the underlying T[] array, for use with functions that mandate a T[] parameter. Use should be avoided otherwise.