98 lines
2.9 KiB
Forth
98 lines
2.9 KiB
Forth
namespace AdventOfCode2023
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open System
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open System.Globalization
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open System.Runtime.CompilerServices
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type EfficientString = System.ReadOnlySpan<char>
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[<RequireQualifiedAccess>]
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module EfficientString =
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let inline isEmpty (s : EfficientString) : bool = s.IsEmpty
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let inline ofString (s : string) : EfficientString = s.AsSpan ()
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let inline toString (s : EfficientString) : string = s.ToString ()
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let inline trimStart (s : EfficientString) : EfficientString = s.TrimStart ()
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let inline slice (start : int) (length : int) (s : EfficientString) : EfficientString = s.Slice (start, length)
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let inline equals (a : string) (other : EfficientString) : bool =
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MemoryExtensions.Equals (other, a.AsSpan (), StringComparison.Ordinal)
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/// Mutates the input to drop up to the first instance of the input char,
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/// and returns what was dropped.
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/// If the char is not present, deletes the input.
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let takeUntil<'a> (c : char) (s : EfficientString byref) : EfficientString =
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let first = s.IndexOf c
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if first < 0 then
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let toRet = s
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s <- EfficientString.Empty
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toRet
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else
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let toRet = slice 0 first s
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s <- slice (first + 1) (s.Length - first - 1) s
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toRet
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[<Struct>]
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[<IsByRefLike>]
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type StringSplitEnumerator =
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internal
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{
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Original : EfficientString
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mutable Remaining : EfficientString
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mutable InternalCurrent : EfficientString
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SplitOn : char
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}
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interface IDisposable with
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member this.Dispose () = ()
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member this.Current : EfficientString = this.InternalCurrent
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member this.MoveNext () =
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if this.Remaining.Length = 0 then
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false
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else
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this.InternalCurrent <- EfficientString.takeUntil this.SplitOn &this.Remaining
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true
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member this.GetEnumerator () = this
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[<RequireQualifiedAccess>]
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module StringSplitEnumerator =
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let make (splitChar : char) (s : string) : StringSplitEnumerator =
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{
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Original = EfficientString.ofString s
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Remaining = EfficientString.ofString s
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InternalCurrent = EfficientString.Empty
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SplitOn = splitChar
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}
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let make' (splitChar : char) (s : ReadOnlySpan<char>) : StringSplitEnumerator =
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{
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Original = s
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Remaining = s
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InternalCurrent = EfficientString.Empty
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SplitOn = splitChar
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}
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let chomp (s : string) (e : byref<StringSplitEnumerator>) : unit =
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#if DEBUG
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if not (e.MoveNext ()) || not (EfficientString.equals s e.Current) then
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failwithf "expected '%s', got '%s'" s (e.Current.ToString ())
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#else
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e.MoveNext () |> ignore
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#endif
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let consumeInt (e : byref<StringSplitEnumerator>) : int =
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if not (e.MoveNext ()) then
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failwith "expected an int, got nothing"
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Int32.Parse e.Current
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