83 lines
2.9 KiB
C#
83 lines
2.9 KiB
C#
namespace System
|
|
{
|
|
public readonly struct Index
|
|
{
|
|
private readonly int _value;
|
|
|
|
public int Value => _value < 0 ? ~_value : _value;
|
|
public bool FromEnd => _value < 0;
|
|
|
|
public Index(int value, bool fromEnd)
|
|
{
|
|
if (value < 0) throw new ArgumentException("Index must not be negative.", nameof(value));
|
|
|
|
_value = fromEnd ? ~value : value;
|
|
}
|
|
|
|
public static implicit operator Index(int value)
|
|
=> new Index(value, fromEnd: false);
|
|
}
|
|
|
|
public readonly struct Range
|
|
{
|
|
public Index Start { get; }
|
|
public Index End { get; }
|
|
|
|
private Range(Index start, Index end)
|
|
{
|
|
this.Start = start;
|
|
this.End = end;
|
|
}
|
|
|
|
public static Range Create(Index start, Index end) => new Range(start, end);
|
|
public static Range FromStart(Index start) => new Range(start, new Index(0, fromEnd: true));
|
|
public static Range ToEnd(Index end) => new Range(new Index(0, fromEnd: false), end);
|
|
public static Range All() => new Range(new Index(0, fromEnd: false), new Index(0, fromEnd: true));
|
|
}
|
|
|
|
static class Extensions
|
|
{
|
|
public static int get_IndexerExtension(this int[] array, Index index) =>
|
|
index.FromEnd ? array[array.Length - index.Value] : array[index.Value];
|
|
|
|
public static int get_IndexerExtension(this Span<int> span, Index index) =>
|
|
index.FromEnd ? span[span.Length - index.Value] : span[index.Value];
|
|
|
|
public static char get_IndexerExtension(this string s, Index index) =>
|
|
index.FromEnd ? s[s.Length - index.Value] : s[index.Value];
|
|
|
|
public static Span<int> get_IndexerExtension(this int[] array, Range range) =>
|
|
array.Slice(range);
|
|
|
|
public static Span<int> get_IndexerExtension(this Span<int> span, Range range) =>
|
|
span.Slice(range);
|
|
|
|
public static string get_IndexerExtension(this string s, Range range) =>
|
|
s.Substring(range);
|
|
|
|
public static Span<T> Slice<T>(this T[] array, Range range)
|
|
=> array.AsSpan().Slice(range);
|
|
|
|
public static Span<T> Slice<T>(this Span<T> span, Range range)
|
|
{
|
|
var (start, length) = GetStartAndLength(range, span.Length);
|
|
return span.Slice(start, length);
|
|
}
|
|
|
|
public static string Substring(this string s, Range range)
|
|
{
|
|
var (start, length) = GetStartAndLength(range, s.Length);
|
|
return s.Substring(start, length);
|
|
}
|
|
|
|
private static (int start, int length) GetStartAndLength(Range range, int entityLength)
|
|
{
|
|
var start = range.Start.FromEnd ? entityLength - range.Start.Value : range.Start.Value;
|
|
var end = range.End.FromEnd ? entityLength - range.End.Value : range.End.Value;
|
|
var length = end - start;
|
|
|
|
return (start, length);
|
|
}
|
|
}
|
|
}
|