Files
raft-fable/Raft/EfficientString.fs

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#if NETSTANDARD2_0
namespace System.Runtime.CompilerServices
open System
[<Sealed ; AttributeUsage(AttributeTargets.Struct)>]
type IsByRefLikeAttribute () =
inherit Attribute ()
#endif
namespace Raft
open System
open System.Collections
open System.Runtime.CompilerServices
type EfficientString =
#if NETSTANDARD2_0
string
#else
System.ReadOnlySpan<char>
#endif
[<RequireQualifiedAccess>]
module EfficientString =
let inline isEmpty (s : EfficientString) : bool =
#if NETSTANDARD2_0
s = ""
#else
s.IsEmpty
#endif
let inline ofString (s : string) : EfficientString =
#if NETSTANDARD2_0
s
#else
s.AsSpan ()
#endif
let inline toString (s : EfficientString) : string =
#if NETSTANDARD2_0
s
#else
s.ToString ()
#endif
let inline trimStart (s : EfficientString) : EfficientString = s.TrimStart ()
let inline slice (start : int) (length : int) (s : EfficientString) : EfficientString =
#if NETSTANDARD2_0
s.[start .. start + length - 1]
#else
s.Slice (start, length)
#endif
/// Mutates the input to drop up to the first instance of the input char,
/// and returns what was dropped.
/// If the char is not present, deletes the input.
let takeUntil<'a> (c : char) (s : EfficientString byref) : EfficientString =
let first = s.IndexOf c
if first < 0 then
let toRet = s
s <- EfficientString.Empty
toRet
else
let toRet = slice 0 first s
s <- slice (first + 1) (s.Length - first - 1) s
toRet
[<Struct>]
[<IsByRefLike>]
type StringSplitEnumerator =
internal
{
Original : EfficientString
mutable Remaining : EfficientString
mutable InternalCurrent : EfficientString
SplitOn : char
}
interface System.IDisposable with
member this.Dispose () = ()
member this.Current : EfficientString = this.InternalCurrent
member this.MoveNext () =
if this.Remaining.Length = 0 then
false
else
this.InternalCurrent <- EfficientString.takeUntil this.SplitOn &this.Remaining
true
member this.GetEnumerator () = this
[<RequireQualifiedAccess>]
module StringSplitEnumerator =
let make (splitChar : char) (s : string) : StringSplitEnumerator =
{
Original = EfficientString.ofString s
Remaining = EfficientString.ofString s
InternalCurrent = EfficientString.Empty
SplitOn = splitChar
}