CachedSequence<T> Generic Class

⊟ Type Parameters

T

The type of the value to store in the sequence.

⊟ Thread Safety

This type is thread safe.

⊟ Remarks

CachedSequence<T> is useful for caching the current values within a IEnumerable<T> which come from a generator that will generate different values from each invocation. Consider the following generator:

C# Example

internal static IEnumerable<int> RandomValues (Random r, int max) { while (true) yield return r.Next (max); }

The above generator does two things: it generates an infinite sequence, and each time IEnumerable<T>.GetEnumerator is called on the IEnumerable<T> that RandomValues() returns, it may return a different sequence:

Example

var r = new Random(); // prints e.g.: 6, 2, 8 foreach (var v in RandomValues (r, 10).Take(3)) Console.WriteLine (v); // prints e.g.: 1, 4, 3 foreach (var v in RandomValues (r, 10).Take(3)) Console.WriteLine (v);

This is potentially fine if you're aware of the problem, but it can potentially break some algorithms if the generator is referenced multiple times (under the assumption that the sequence won't change):

C# Example

var randSeq = RandomValues (new Random (), 100); // this could pass, but that's highly improbable Assert.IsFalse ( randSeq.Take (10).SelectFromEach (randSeq.Take (10), (l, r) => l + r) .All (x => x % 2 == 0));

The above algorithm attempts to say: give me two sets of 10 random numbers, add them together, and assert that the results are always even (as any number added to itself will be even). This algorithm fails because the generator returns a different sequence on the second randSeq.Take(10) call.

A fix is to "memoize" the sequence. CachedSequence<T> will record the input sequence, so that subsequent iterations will return the same values as the first iteration. This allows the same algorithm to work:

C# Example

var values = new Random (); // Note: wrapping an infinite sequence var randSeq = new CachedSequence<int> (EnumerableTest.RandomValues (values, 10)); Assert.IsTrue ( randSeq.Take (20).SelectFromEach (randSeq.Take (10), (l, r) => l + r) .All (x => x % 2 == 0));

CachedSequence<T> has two modes of operation: as a "fully realized" singly-linked list constructed one node at a time, and (as seen above) as a caching wrapper over an IEnumerable<T> sequence.

Node at a time construction is performed with the CachedSequence<T>(`0) and CachedSequence<T>(`0, CachedSequence<`0>) constructors. For both, the T parameter then becomes accessible via CachedSequence<T>.Head, while CachedSequence<T>.Tail is either null (for the first constructor) or the specified CachedSequence<T> value. The second constructor thus allows creating sequences of arbitrary length.

When wrapping IEnumerable<T> sequences via the CachedSequence<T>(IEnumerable<`0>) constructor, an alternate mode is used. The sequence is not immediately executed; instead, the sequence is evaluated on-demand when the CachedSequence<T>.Head and CachedSequence<T>.Tail properties are accessed. This allows infinite sequences to be wrapped without requiring infinite memory, as seen above with the random sequence generator.

⊟ Requirements

Namespace: Cadenza.Collections
Assembly: Cadenza (in Cadenza.dll)
Assembly Versions: 0.1.0.0

⊟ Members

See Also: Inherited members from object.

⊟ Public Constructors

	CachedSequence (IEnumerable<T>)	Constructs and initializes a new instance of the Cadenza.Collections.CachedSequence<T> class which wraps the specified collection.
	CachedSequence (T)	Constructs and initializes a new instance of the Cadenza.Collections.CachedSequence<T> class using the specified head.
	CachedSequence (T, CachedSequence<T>)	Constructs and initializes a new instance of the Cadenza.Collections.CachedSequence<T> class using the specified head and tail.

⊟ Public Properties

[read-only]	Head	T . Returns the value held by this instance.
[read-only]	Tail	CachedSequence<T> . Obtains the items in the sequence following the current item, CachedSequence<T>.Head.

⊟ Public Methods

	Append (T) : CachedSequence<T> Clones the current sequence with value appended.
	Count () : int Returns the number of elements in the sequence.
	ElementAt (int) : T Returns the value at a specified index in the sequence.
	First () : T Returns CachedSequence<T>.Head.
	FirstOrDefault () : T Returns CachedSequence<T>.Head.
	GetEnumerator () : IEnumerator<T> Returns an enumerator that iterates through the linked list.
	LongCount () : long Returns the number of elements in the sequence.
	Prepend (T) : CachedSequence<T> Returns a new Cadenza.Collections.CachedSequence<T> with value as the CachedSequence<T>.Head and the current sequence as the CachedSequence<T>.Tail.
	Reverse () : CachedSequence<T> Reverse the sequence that the current instance is the start of.

⊟ Explicitly Implemented Interface Members

IEnumerable.GetEnumerator

Returns an enumerator that iterates through the linked list.

⊟ Extension Methods

static	AggregateHistory<TSource> (this IEnumerable<TSource>, Func<TSource, TSource, TSource>) : IEnumerable<TSource> Documentation for this section has not yet been entered.
static	AggregateHistory<TSource,TAccumulate> (this IEnumerable<TSource>, TAccumulate, Func<TAccumulate, TSource, TAccumulate>) : IEnumerable<TAccumulate> Documentation for this section has not yet been entered.
static	AggregateHistory<TSource,TAccumulate,TResult> (this IEnumerable<TSource>, TAccumulate, Func<TAccumulate, TSource, TAccumulate>, Func<TAccumulate, TResult>) : IEnumerable<TResult> Documentation for this section has not yet been entered.
static	AggregateReverse<TSource> (this IEnumerable<TSource>, Func<TSource, TSource, TSource>) : TSource Documentation for this section has not yet been entered.
static	AggregateReverse<TSource,TAccumulate> (this IEnumerable<TSource>, TAccumulate, Func<TAccumulate, TSource, TAccumulate>) : TAccumulate Documentation for this section has not yet been entered.
static	AggregateReverse<TSource,TAccumulate,TResult> (this IEnumerable<TSource>, TAccumulate, Func<TAccumulate, TSource, TAccumulate>, Func<TAccumulate, TResult>) : TResult Documentation for this section has not yet been entered.
static	AggregateReverseHistory<TSource> (this IEnumerable<TSource>, Func<TSource, TSource, TSource>) : IEnumerable<TSource> Documentation for this section has not yet been entered.
static	AggregateReverseHistory<TSource,TAccumulate> (this IEnumerable<TSource>, TAccumulate, Func<TAccumulate, TSource, TAccumulate>) : IEnumerable<TAccumulate> Documentation for this section has not yet been entered.
static	AggregateReverseHistory<TSource,TAccumulate,TResult> (this IEnumerable<TSource>, TAccumulate, Func<TAccumulate, TSource, TAccumulate>, Func<TAccumulate, TResult>) : IEnumerable<TResult> Documentation for this section has not yet been entered.
static	And (this IEnumerable<bool>) : bool Documentation for this section has not yet been entered.
static	Apply<TSource> (this IEnumerable<TSource>) Documentation for this section has not yet been entered.
static	ApplyPairs<TSource> (this IEnumerable<TSource>, params Action<TSource>[]) : IEnumerable<TSource> Documentation for this section has not yet been entered.
static	AsIList<TSource> (this IEnumerable<TSource>) : IList<TSource> Documentation for this section has not yet been entered.
static	Break<TSource> (this IEnumerable<TSource>, Func<TSource, bool>) : Cadenza.Tuple<IEnumerable<TSource>, IEnumerable<TSource>> Documentation for this section has not yet been entered.
static	Cache<T> (this IEnumerable<T>) : CachedSequence<T> Documentation for this section has not yet been entered.
static	CompareWith<T> (this IEnumerable<T>, IEnumerable<T>) : SequenceComparison<T> Compares two enumerations retrieving added, removed and unchanged elements.
static	CompareWith<T> (this IEnumerable<T>, IEnumerable<T>, IEqualityComparer<T>) : SequenceComparison<T> Compares two enumerations retrieving added, removed and unchanged elements.
static	Concat<TSource> (this IEnumerable<TSource>, IEnumerable<IEnumerable<TSource>>) : IEnumerable<TSource> Documentation for this section has not yet been entered.
static	Concat<TSource> (this IEnumerable<TSource>, params IEnumerable<TSource>[]) : IEnumerable<TSource> Documentation for this section has not yet been entered.
static	ContiguousSubsequences<TSource> (this IEnumerable<TSource>, int) : IEnumerable<IEnumerable<TSource>> Documentation for this section has not yet been entered.
static	CopyTo<TSource> (this IEnumerable<TSource>, ICollection<TSource>) Documentation for this section has not yet been entered.
static	CopyTo<TSource> (this IEnumerable<TSource>, TSource[], int) Documentation for this section has not yet been entered.
static	Cycle<TSource> (this IEnumerable<TSource>) : IEnumerable<TSource> Documentation for this section has not yet been entered.
static	Each<TSource> (this IEnumerable<TSource>, Action<TSource, int>) : IEnumerable<TSource> Documentation for this section has not yet been entered.
static	Each<TSource> (this IEnumerable<TSource>, Action<TSource>) : IEnumerable<TSource> Documentation for this section has not yet been entered.
static	ExceptLast<TSource> (this IEnumerable<TSource>) : IEnumerable<TSource> Documentation for this section has not yet been entered.
static	ExceptLast<TSource> (this IEnumerable<TSource>, int) : IEnumerable<TSource> Documentation for this section has not yet been entered.
static	FindIndex<TSource> (this IEnumerable<TSource>, Func<TSource, bool>) : int Documentation for this section has not yet been entered.
static	FindIndices<TSource> (this IEnumerable<TSource>, Func<TSource, bool>) : IEnumerable<int> Documentation for this section has not yet been entered.
static	ForEach<TSource> (this IEnumerable<TSource>, Action<TSource, int>) Documentation for this section has not yet been entered.
static	ForEach<TSource> (this IEnumerable<TSource>, Action<TSource>) Documentation for this section has not yet been entered.
static	HaskellGroup<TSource> (this IEnumerable<TSource>) : IEnumerable<IEnumerable<TSource>> Documentation for this section has not yet been entered.
static	HaskellGroupBy<TSource> (this IEnumerable<TSource>, Func<TSource, TSource, bool>) : IEnumerable<IEnumerable<TSource>> Split self into a sequence of groups.
static	Implode<TSource> (this IEnumerable<TSource>) : string Documentation for this section has not yet been entered.
static	Implode<TSource> (this IEnumerable<TSource>, string) : string Documentation for this section has not yet been entered.
static	Implode<TSource> (this IEnumerable<TSource>, string, Func<TSource, string>) : string Documentation for this section has not yet been entered.
static	IndexOf<TSource> (this IEnumerable<TSource>, TSource) : int Documentation for this section has not yet been entered.
static	IndexOfAny<TSource> (this IEnumerable<TSource>, IEnumerable<TSource>) : int Documentation for this section has not yet been entered.
static	IndexOfAny<TSource> (this IEnumerable<TSource>, params TSource[]) : int Documentation for this section has not yet been entered.
static	IndicesOf<TSource> (this IEnumerable<TSource>, TSource) : IEnumerable<int> Documentation for this section has not yet been entered.
static	IndicesOfAny<TSource> (this IEnumerable<TSource>, IEnumerable<TSource>) : IEnumerable<int> Documentation for this section has not yet been entered.
static	IndicesOfAny<TSource> (this IEnumerable<TSource>, params TSource[]) : IEnumerable<int> Documentation for this section has not yet been entered.
static	InitialSegments<TSource> (this IEnumerable<TSource>) : IEnumerable<IEnumerable<TSource>> Creates a IEnumerable<IEnumerable<TSource>> containing all leading segments of self, shortest first.
static	Insert<TSource> (this IEnumerable<TSource>, TSource) : IEnumerable<TSource> Documentation for this section has not yet been entered.
static	Insert<TSource> (this IEnumerable<TSource>, TSource, Func<TSource, TSource, int>) : IEnumerable<TSource> Documentation for this section has not yet been entered.
static	Intersperse<TSource> (this IEnumerable<IEnumerable<TSource>>, IEnumerable<TSource>) : IEnumerable<TSource> Documentation for this section has not yet been entered.
static	Intersperse<TSource> (this IEnumerable<TSource>, TSource) : IEnumerable<TSource> Documentation for this section has not yet been entered.
static	Just<T> (this T) : Cadenza.Maybe<T> Create a new Cadenza.Maybe<T> instance initialized to a specified value. The returned value will not be Cadenza.Maybe<T>.Nothing.
static	Match<TSource,TResult> (this TSource, params Func<TSource, Cadenza.Maybe<TResult>>[]) : TResult Converts the TSource instance self into a TResult.
static	NotNull<TSource> (this IEnumerable<Nullable<TSource>>) : IEnumerable<TSource> Documentation for this section has not yet been entered.
static	Or (this IEnumerable<bool>) : bool Documentation for this section has not yet been entered.
static	OrderByNatural<TSource> (this IEnumerable<TSource>, Func<TSource, string>) : IEnumerable<TSource> Documentation for this section has not yet been entered.
static	Partition<TSource> (this IEnumerable<TSource>, Func<TSource, bool>) : Cadenza.Tuple<IEnumerable<TSource>, IEnumerable<TSource>> Partitions self into two sequences, those which contain elements satisfying predicate and those which do not.
static	PathCombine (this IEnumerable<string>) : string Creates a path string by concatenating the elements of self.
static	RemoveFirstOccurrence<TSource> (this IEnumerable<TSource>, TSource) : IEnumerable<TSource> Removes the first occurrence of value from the sequence self.
static	RemoveFirstOccurrence<TSource> (this IEnumerable<TSource>, TSource, IEqualityComparer<TSource>) : IEnumerable<TSource> Removes the first occurrence of value from the sequence self.
static	RemoveFirstOccurrences<TSource> (this IEnumerable<TSource>, TSource, int) : IEnumerable<TSource> Removes the first count occurrences of value from the sequence self.
static	RemoveFirstOccurrences<TSource> (this IEnumerable<TSource>, TSource, int, IEqualityComparer<TSource>) : IEnumerable<TSource> Removes the first count occurrences of value from the sequence self.
static	Repeat<TSource> (this IEnumerable<TSource>, int) : IEnumerable<TSource> Repeats the sequence self for number repetitions.
static	SelectAggregated<TSource,TAccumulate,TResult> (this IEnumerable<TSource>, TAccumulate, Func<TAccumulate, TSource, Cadenza.Tuple<TAccumulate, TResult>>) : Cadenza.Tuple<TAccumulate, List<TResult>> Applies func to each element within self, returning the final value of the accumulator and the list of intermediate values.
static	SelectBreadthFirst<TSource,TResult> (this IEnumerable<TSource>, Func<TSource, TResult>, Func<TSource, IEnumerable<TSource>>) : IEnumerable<TResult> Traverse a sequence of nodes in a breadth-first fashion, converting each encountered node.
static	SelectDepthFirst<TSource,TResult> (this IEnumerable<TSource>, Func<TSource, TResult>, Func<TSource, IEnumerable<TSource>>) : IEnumerable<TResult> Traverse a sequence of nodes in a depth-first fashion, converting each encountered node.
static	SelectFromEach<T1,T2,TResult> (this IEnumerable<T1>, IEnumerable<T2>, Func<T1, T2, TResult>) : IEnumerable<TResult> Projects each corresponding element from multiple sequences into a new form.
static	SelectFromEach<T1,T2,T3,TResult> (this IEnumerable<T1>, IEnumerable<T2>, IEnumerable<T3>, Func<T1, T2, T3, TResult>) : IEnumerable<TResult> Projects each corresponding element from multiple sequences into a new form.
static	SelectFromEach<T1,T2,T3,T4,TResult> (this IEnumerable<T1>, IEnumerable<T2>, IEnumerable<T3>, IEnumerable<T4>, Func<T1, T2, T3, T4, TResult>) : IEnumerable<TResult> Projects each corresponding element from multiple sequences into a new form.
static	SelectReverseAggregated<TSource,TAccumulate,TResult> (this IEnumerable<TSource>, TAccumulate, Func<TAccumulate, TSource, Cadenza.Tuple<TAccumulate, TResult>>) : Cadenza.Tuple<TAccumulate, List<TResult>> Applies func to each element within self in reverse order, returning the final value of the accumulator and the list of intermediate values.
static	SequenceCompare<TSource> (this IEnumerable<TSource>, IEnumerable<TSource>) : int Compares the elements of two sequences by using the default comparer for their type.
static	SequenceCompare<TSource> (this IEnumerable<TSource>, IEnumerable<TSource>, IComparer<TSource>) : int Compares the elements of two sequences by using a specified IComparer<TSource>.
static	Shuffle<TSource> (this IEnumerable<TSource>) : IEnumerable<TSource> Randomizes the ordering of items within self.
static	Shuffle<TSource> (this IEnumerable<TSource>, Random) : IEnumerable<TSource> Randomizes the ordering of items within self.
static	SkipPrefix<TSource> (this IEnumerable<TSource>, IEnumerable<TSource>) : IEnumerable<TSource> Skips over prefix, returning the elements following prefix.
static	SkipPrefix<TSource> (this IEnumerable<TSource>, IEnumerable<TSource>, IEqualityComparer<TSource>) : IEnumerable<TSource> Skips over prefix, returning the elements following prefix.
static	Sort<TSource> (this IEnumerable<TSource>) : IEnumerable<TSource> Sorts the elements in the sequence self using the default comparer.
static	Sort<TSource> (this IEnumerable<TSource>, IComparer<TSource>) : IEnumerable<TSource> Sorts the elements in the sequence self using the specified comparer.
static	Sort<TSource> (this IEnumerable<TSource>, Comparison<TSource>) : IEnumerable<TSource> Sorts the elements in the sequence self using the specified comparer.
static	SortNatural (this IEnumerable<string>) : IEnumerable<string> Returns a new IEnumerable<TSource> which contains the elements within self sorted using the Cadenza.NaturalStringComparer.Default comparer.
static	Span<TSource> (this IEnumerable<TSource>, Func<TSource, bool>) : Cadenza.Tuple<IEnumerable<TSource>, IEnumerable<TSource>> Creates a Cadenza.Tuple<IEnumerable<TSource>, IEnumerable<TSource>> of the contiguous elements at the start of self which satisfy predicate.
static	SplitAt<TSource> (this IEnumerable<TSource>, int) : Cadenza.Tuple<IEnumerable<TSource>, IEnumerable<TSource>> Splits self at firstLength, creating a Cadenza.Tuple<IEnumerable<TSource>, IEnumerable<TSource>>.
static	Subsets<TSource> (this IEnumerable<TSource>) : IEnumerable<IEnumerable<TSource>> Creates all subsets of a given input sequence.
static	Subsets<TSource> (this IEnumerable<TSource>, Func<IEnumerable<TSource>,System.Boolean>) : IEnumerable<IEnumerable<TSource>> Creates all subsets that match predicate.
static	Tokens<TSource,TAccumulate,TResult> (this IEnumerable<TSource>, TAccumulate, Func<TAccumulate, TSource, TAccumulate>, Func<TAccumulate, Cadenza.Tuple<TResult, TAccumulate>>, params Func<TAccumulate, TSource, bool>[]) : IEnumerable<TResult> A simple lexer to convert an IEnumerable<TSource> into a IEnumerable<TResult>, where the resulting sequence may have a different number of elements than the source sequence.
static	ToList<TSource> (this IEnumerable<IEnumerable<TSource>>) : List<List<TSource>> Creates a List<List<TSource>> with the same ordering and values as self.
static	ToMaybe<T> (this T) : Cadenza.Maybe<T> Create a new Cadenza.Maybe<T> instance initialized to a specified value. The returned value may be Cadenza.Maybe<T>.Nothing.
static	ToReadOnlyDictionary<TSource,TKey> (this IEnumerable<TSource>, Func<TSource, TKey>) : ReadOnlyDictionary<TKey, TSource> Creates a Cadenza.Collections.ReadOnlyDictionary<TKey, TSource> from an IEnumerable<TSource> according to a specified key selector and value selector delegate.
static	ToReadOnlyDictionary<TSource,TKey,TValue> (this IEnumerable<TSource>, Func<TSource, TKey>, Func<TSource, TValue>) : ReadOnlyDictionary<TKey, TValue> Creates a Cadenza.Collections.ReadOnlyDictionary<TKey, TValue> from an IEnumerable<TSource> according to a specified key selector and value selector delegate.
static	ToValueReader (this IEnumerable<string>) : Cadenza.IO.TextValueReader Creates a Cadenza.IO.TextValueReader which will extract values from an IEnumerable<string>.
static	ToValueReader<TSource> (this IEnumerable<TSource>) : Cadenza.IO.EnumerableValueReader<TSource> Creates a Cadenza.IO.EnumerableValueReader which will extract values from an IEnumerable<TSource>.
static	TrailingSegments<TSource> (this IEnumerable<TSource>) : IEnumerable<IEnumerable<TSource>> Creates a IEnumerable<IEnumerable<TSource>> containing all final segments of self, longest first.
static	Transpose<TSource> (this IEnumerable<IEnumerable<TSource>>) : IEnumerable<IEnumerable<TSource>> Transposes self, so that rows become columns and columns become rows in the returned IEnumerable<IEnumerable<TSource>>.
static	TraverseBreadthFirst<TSource,TResult> (this TSource, Func<TSource, TResult>, Func<TSource, IEnumerable<TSource>>) : IEnumerable<TResult> Traverse a tree in a breadth-first fashion, converting each encountered node.
static	TraverseBreadthFirstWithParent<TSource,TResult> (this TSource, Func<TSource, TResult>, Func<TSource, IEnumerable<TSource>>) : IEnumerable<KeyValuePair<TSource, TResult>> Traverse a tree in a breadth-first fashion, converting each encountered node.
static	TraverseDepthFirst<TSource,TResult> (this TSource, Func<TSource, TResult>, Func<TSource, IEnumerable<TSource>>) : IEnumerable<TResult> Traverse a tree in a depth-first fashion, converting each encountered node.
static	TraverseDepthFirstWithParent<TSource,TResult> (this TSource, Func<TSource, TResult>, Func<TSource, IEnumerable<TSource>>) : IEnumerable<KeyValuePair<TSource, TResult>> Traverse a tree in a depth-first fashion, converting each encountered node.
static	TryGetFirst<TSource> (this IEnumerable<TSource>, out TSource) : bool Attempts to obtain the first element in the sequence.
static	TryGetFirst<TSource> (this IEnumerable<TSource>, Func<TSource, bool>, out TSource) : bool Attempts to obtain the first element in the sequence that satisfies the specified condition.
static	Unzip<T1,T2> (this IEnumerable<Cadenza.Tuple<T1, T2>>) : Cadenza.Tuple<IEnumerable<T1>, IEnumerable<T2>> Converts an IEnumerable<Cadenza.Tuple<T1, T2>> into a tuple of lists, one for each Cadenza.Tuple<T1, T2> element.
static	Unzip<T1,T2,T3> (this IEnumerable<Cadenza.Tuple<T1, T2, T3>>) : Cadenza.Tuple<IEnumerable<T1>, IEnumerable<T2>, IEnumerable<T3>> Converts an IEnumerable<Cadenza.Tuple<T1, T2, T3>> into a tuple of lists, one for each Cadenza.Tuple<T1, T2, T3> element.
static	Unzip<T1,T2,T3,T4> (this IEnumerable<Cadenza.Tuple<T1, T2, T3, T4>>) : Cadenza.Tuple<IEnumerable<T1>, IEnumerable<T2>, IEnumerable<T3>, IEnumerable<T4>> Converts an IEnumerable<Cadenza.Tuple<T1, T2, T3, T4>> into a tuple of lists, one for each Cadenza.Tuple<T1, T2, T3, T4> element.
static	With<TSource,TResult> (this TSource, Func<TSource, TResult>) : TResult Supports chaining otherwise temporary values.
static	Zip<T1,T2> (this IEnumerable<T1>, IEnumerable<T2>) : IEnumerable<Cadenza.Tuple<T1, T2>> Creates and returns an IEnumerable<Cadenza.Tuple<T1, T2>> containing the corresponding items from self and source2.
static	Zip<T1,T2,T3> (this IEnumerable<T1>, IEnumerable<T2>, IEnumerable<T3>) : IEnumerable<Cadenza.Tuple<T1, T2, T3>> Creates and returns an IEnumerable<Cadenza.Tuple<T1, T2, T3>> containing the corresponding items from self, source2, and source3.
static	Zip<T1,T2,T3,T4> (this IEnumerable<T1>, IEnumerable<T2>, IEnumerable<T3>, IEnumerable<T4>) : IEnumerable<Cadenza.Tuple<T1, T2, T3, T4>> Creates and returns an IEnumerable<Cadenza.Tuple<T1, T2, T3, T4>> containing the corresponding items from self, source2, source3, and source4.