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Added indexer to `SafeElementArray`

pull/350/head
David Hall 2022-10-12 09:39:43 -06:00
parent 83346f4794
commit 18cafb3499
1 changed files with 18 additions and 1 deletions
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19
PInvoke/Shared/InteropServices/SafeElementArray.cs
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@ -14,7 +14,7 @@ namespace Vanara.InteropServices
/// <typeparam name="TElem">The type of the array elements.</typeparam>
/// <typeparam name="TPrefix">The type of the value used to represent the number of elements in the array.</typeparam>
/// <typeparam name="TMem">The memory methods to use for allocation.</typeparam>
public class SafeElementArray<TElem, TPrefix, TMem> : SafeMemoryHandle<TMem>, IEnumerable<TElem> where TMem : IMemoryMethods, new() where TElem : struct where TPrefix : IConvertible
public class SafeElementArray<TElem, TPrefix, TMem> : SafeMemoryHandle<TMem>, IReadOnlyList<TElem> where TMem : IMemoryMethods, new() where TElem : struct where TPrefix : IConvertible
{
/// <summary>The size, in bytes, of <c>TElem</c>.</summary>
protected static readonly int ElemSize = InteropExtensions.SizeOf(typeof(TElem));
@ -56,6 +56,17 @@ namespace Vanara.InteropServices
{
}
/// <summary>Gets or sets the <typeparamref name="TElem"/> value at the specified index.</summary>
/// <value>The <typeparamref name="TElem"/> value.</value>
/// <param name="index">The index.</param>
/// <returns></returns>
/// <exception cref="ArgumentOutOfRangeException">index or index</exception>
public virtual TElem this[TPrefix index]
{
get => handle.ToStructure<TElem>(Size, ElemOffset(index));
set => handle.Write(value, ElemOffset(index), Size);
}
/// <summary>Gets the number of elements contained in the <see cref="SafeElementArray{TElem, TPrefix, TMem}"/>.</summary>
protected TPrefix Count
{
@ -87,6 +98,10 @@ namespace Vanara.InteropServices
set => Count = (TPrefix)Convert.ChangeType(value, typeof(TPrefix));
}
int IReadOnlyCollection<TElem>.Count => Count.ToInt32(null);
TElem IReadOnlyList<TElem>.this[int index] => this[(TPrefix)Convert.ChangeType(index, typeof(TPrefix))];
/// <summary>Returns an enumerator that iterates through the collection.</summary>
/// <returns>A <see cref="IEnumerator{TElem}"/> that can be used to iterate through the collection.</returns>
public IEnumerator<TElem> GetEnumerator() => ((IEnumerable<TElem>)Elements).GetEnumerator();
@ -95,6 +110,8 @@ namespace Vanara.InteropServices
/// <returns>An <see cref="IEnumerator"/> object that can be used to iterate through the collection.</returns>
IEnumerator IEnumerable.GetEnumerator() => GetEnumerator();
private int ElemOffset(TPrefix index) => index.ToUInt64(null) >= 0 && index.ToUInt64(null) < Count.ToUInt64(null) ? index.ToInt32(null) * ElemSize + PrefixSize : throw new ArgumentOutOfRangeException(nameof(index));
/// <summary>Converts a byte count to a element count.</summary>
/// <param name="byteSize">The byte count.</param>
/// <returns>The converted element count.</returns>