51 lines
1.8 KiB
C#
51 lines
1.8 KiB
C#
// Copyright (c) Six Labors.
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// Licensed under the Six Labors Split License.
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using System.Runtime.CompilerServices;
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namespace SixLabors.Fonts {
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/// <summary>
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/// Provides a readonly mapped view of an underlying slice, selecting arbitrary indices
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/// from the source array.
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/// </summary>
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/// <typeparam name="T">The type of item contained in the underlying array.</typeparam>
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internal readonly struct ReadonlyMappedArraySlice<T>
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where T : struct
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{
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private readonly ReadOnlyArraySlice<T> data;
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private readonly ReadOnlyArraySlice<int> map;
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/// <summary>
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/// Initializes a new instance of the <see cref="ReadonlyMappedArraySlice{T}"/> struct.
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/// </summary>
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/// <param name="data">The data slice.</param>
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/// <param name="map">The map slice.</param>
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public ReadonlyMappedArraySlice(in ReadOnlyArraySlice<T> data, in ReadOnlyArraySlice<int> map)
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{
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Guard.MustBeGreaterThanOrEqualTo(data.Length, map.Length, nameof(map));
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this.data = data;
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this.map = map;
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}
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/// <summary>
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/// Gets the number of items in the map.
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/// </summary>
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public int Length => this.map.Length;
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/// <summary>
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/// Returns a reference to specified element of the slice.
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/// </summary>
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/// <param name="index">The index of the element to return.</param>
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/// <returns>The <typeparamref name="T"/>.</returns>
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/// <exception cref="IndexOutOfRangeException">
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/// Thrown when index less than 0 or index greater than or equal to <see cref="Length"/>.
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/// </exception>
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public readonly T this[int index]
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{
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[MethodImpl(MethodImplOptions.AggressiveInlining)]
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get => this.data[this.map[index]];
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}
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}
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}
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