FilterMap.cs (2834B)
1 using Std.Convert; 2 using Std.Maybe; 3 using Std.Ops; 4 using Std.Result; 5 using System; 6 using System.Runtime.InteropServices; 7 #region Namespaces 8 namespace Std.Iter { 9 #region Types 10 [StructLayout(LayoutKind.Sequential, CharSet = CharSet.Unicode, Pack = 0)] 11 public struct FilterMap<T, TIter, T2>: IInto<FilterMap<T, TIter, T2>>, IIterator<T2> where T: notnull where TIter: notnull, IIterator<T> where T2: notnull { 12 13 #region Type-level Constructors 14 #endregion 15 16 #region Instance Constructors 17 public FilterMap() => throw new InvalidOperationException("Parameterless constructor is not allowed to be called!"); 18 internal FilterMap(TIter iter, Fn<T, Maybe<T2>> f) => (_iter, _f) = (iter, f); 19 #endregion 20 21 #region Type-level Fields 22 #endregion 23 24 #region Instance Fields 25 readonly Fn<T, Maybe<T2>> _f; 26 TIter _iter; 27 #endregion 28 29 #region Type-level Properties 30 #endregion 31 32 #region Instance Properties 33 #endregion 34 35 #region Type-level Functions 36 #endregion 37 38 #region Instance Functions 39 public Result<Unit, ulong> AdvanceBy(ulong n) => IIterator<T2>.AdvanceByDefault(ref this, n); 40 public ulong Count() => IIterator<T2>.CountDefault(ref this); 41 public override readonly bool Equals(object? _) => false; 42 public TInit Fold<TInit>(TInit init, Fn<TInit, T2, TInit> f) where TInit: notnull { 43 44 static Fn<TInit, T, TInit> fn(Fn<T, Maybe<T2>> g, Fn<TInit, T2, TInit> h) => (acc, item) => { var val = g(item); return val.IsSome ? h(acc, val._some) : acc; }; 45 return _iter.Fold(init, fn(_f, f)); 46 } 47 public override readonly int GetHashCode() => 0; 48 public readonly FilterMap<T, TIter, T2> Into() => this; 49 public Maybe<T2> Last() => IIterator<T2>.LastDefault(ref this); 50 public Maybe<T2> Next() => IIterator<T>.FindMap(ref _iter, _f); 51 public Prod<ulong, Maybe<ulong>> SizeHint() => new(ulong.MinValue, _iter.SizeHint().Item1); 52 public override readonly string ToString() => string.Empty; 53 public Result<TInit, TErr> TryFold<TInit, TErr>(TInit init, Fn<TInit, T2, Result<TInit, TErr>> f) where TInit: notnull where TErr: notnull { 54 static Fn<TInit, T, Result<TInit, TErr>> fn(Fn<T, Maybe<T2>> g, Fn<TInit, T2, Result<TInit, TErr>> h) => (acc, item) => { var val = g(item); return val.IsSome ? h(acc, val._some) : new(acc); }; 55 return _iter.TryFold(init, fn(_f, f)); 56 } 57 readonly Result<FilterMap<T, TIter, T2>, Bottom> ITryInto<FilterMap<T, TIter, T2>, Bottom>.TryInto() => new(this); 58 #endregion 59 60 #region Operators 61 #endregion 62 63 #region Types 64 #endregion 65 } 66 #endregion 67 68 #region Namespaces 69 #endregion 70 } 71 #endregion