refactor: use readonly list input e-k

src/e-k/ElderRay/ElderRay.StaticSeries.cs

@@ -2,14 +2,21 @@ namespace Skender.Stock.Indicators;
 
 // ELDER-RAY (SERIES)
 
-public static partial class Indicator
+public static partial class ElderRay
 {
+    public static IReadOnlyList<ElderRayResult> ToElderRay<TQuote>(
+        this IReadOnlyList<TQuote> quotes,
+        int lookbackPeriods = 13)
+        where TQuote : IQuote => quotes
+            .ToQuoteDList()
+            .CalcElderRay(lookbackPeriods);
+
     private static List<ElderRayResult> CalcElderRay(
         this List<QuoteD> source,
         int lookbackPeriods)
     {
         // check parameter arguments
-        ElderRay.Validate(lookbackPeriods);
+        Validate(lookbackPeriods);
 
         // initialize
         int length = source.Count;

src/e-k/ElderRay/ElderRay.Utilities.cs

@@ -1,9 +1,11 @@
 namespace Skender.Stock.Indicators;
 
-public static partial class Indicator
+// ELDER-RAY (UTILITIES)
+
+public static partial class ElderRay
 {
     // remove recommended periods
-    /// <inheritdoc cref="Utility.RemoveWarmupPeriods{T}(IReadOnlyList{T})"/>
+    /// <inheritdoc cref="Reusable.RemoveWarmupPeriods{T}(IReadOnlyList{T})"/>
     public static IReadOnlyList<ElderRayResult> RemoveWarmupPeriods(
         this IReadOnlyList<ElderRayResult> results)
     {
@@ -13,4 +15,16 @@ public static IReadOnlyList<ElderRayResult> RemoveWarmupPeriods(
 
         return results.Remove(n + 100);
     }
+
+    // parameter validation
+    internal static void Validate(
+        int lookbackPeriods)
+    {
+        // check parameter arguments
+        if (lookbackPeriods <= 0)
+        {
+            throw new ArgumentOutOfRangeException(nameof(lookbackPeriods), lookbackPeriods,
+                "Lookback periods must be greater than 0 for Elder-ray Index.");
+        }
+    }
 }

src/e-k/Ema/Ema.StreamHub.cs

@@ -2,6 +2,25 @@ namespace Skender.Stock.Indicators;
 
 // EXPONENTIAL MOVING AVERAGE (STREAM HUB)
 
+#region hub interface and initializer
+
+public interface IEma
+{
+    int LookbackPeriods { get; }
+    double K { get; }
+}
+
+public static partial class Ema
+{
+    // HUB, from Chain Provider
+    public static EmaHub<T> ToEma<T>(
+        this IChainProvider<T> chainProvider,
+        int lookbackPeriods)
+        where T : IReusable
+        => new(chainProvider, lookbackPeriods);
+}
+#endregion
+
 public class EmaHub<TIn>
     : ChainProvider<TIn, EmaResult>, IEma
     where TIn : IReusable

src/e-k/Epma/Epma.StaticSeries.cs

@@ -2,23 +2,23 @@ namespace Skender.Stock.Indicators;
 
 // ENDPOINT MOVING AVERAGE (SERIES)
 
-public static partial class Indicator
+public static partial class Epma
 {
-    // calculate series
-    private static List<EpmaResult> CalcEpma<T>(
-        this List<T> source,
+    public static IReadOnlyList<EpmaResult> ToEpma<T>(
+        this IReadOnlyList<T> source,
         int lookbackPeriods)
         where T : IReusable
     {
         // check parameter arguments
-        Epma.Validate(lookbackPeriods);
+        ArgumentNullException.ThrowIfNull(source);
+        Validate(lookbackPeriods);
 
         // initialize
         int length = source.Count;
         List<EpmaResult> results = new(length);
 
         IReadOnlyList<SlopeResult> slope
-            = source.CalcSlope(lookbackPeriods);
+            = source.ToSlope(lookbackPeriods);
 
         // roll through source values
         for (int i = 0; i < length; i++)

src/e-k/Epma/Epma.Utilities.cs

@@ -1,9 +1,11 @@
 namespace Skender.Stock.Indicators;
 
-public static partial class Indicator
+// ENDPOINT MOVING AVERAGE (UTILITIES)
+
+public static partial class Epma
 {
     // remove recommended periods
-    /// <inheritdoc cref="Utility.RemoveWarmupPeriods{T}(IReadOnlyList{T})"/>
+    /// <inheritdoc cref="Reusable.RemoveWarmupPeriods{T}(IReadOnlyList{T})"/>
     public static IReadOnlyList<EpmaResult> RemoveWarmupPeriods(
         this IReadOnlyList<EpmaResult> results)
     {
@@ -13,4 +15,16 @@ public static IReadOnlyList<EpmaResult> RemoveWarmupPeriods(
 
         return results.Remove(removePeriods);
     }
+
+    // parameter validation
+    internal static void Validate(
+        int lookbackPeriods)
+    {
+        // check parameter arguments
+        if (lookbackPeriods <= 0)
+        {
+            throw new ArgumentOutOfRangeException(nameof(lookbackPeriods), lookbackPeriods,
+                "Lookback periods must be greater than 0 for Epma.");
+        }
+    }
 }

src/e-k/Fcb/Fcb.StaticSeries.cs

@@ -2,22 +2,23 @@ namespace Skender.Stock.Indicators;
 
 // FRACTAL CHAOS BANDS (SERIES)
 
-public static partial class Indicator
+public static partial class Fcb
 {
-    private static List<FcbResult> CalcFcb<TQuote>(
-        this List<TQuote> quotesList,
-        int windowSpan)
+    public static IReadOnlyList<FcbResult> ToFcb<TQuote>(
+        this IReadOnlyList<TQuote> quotes,
+        int windowSpan = 2)
         where TQuote : IQuote
     {
         // check parameter arguments
-        Fcb.Validate(windowSpan);
+        ArgumentNullException.ThrowIfNull(quotes);
+        Validate(windowSpan);
 
         // initialize
-        int length = quotesList.Count;
+        int length = quotes.Count;
         List<FcbResult> results = new(length);
 
-        List<FractalResult> fractals = quotesList
-            .CalcFractal(windowSpan, windowSpan, EndType.HighLow);
+        IReadOnlyList<FractalResult> fractals = quotes
+            .ToFractal(windowSpan, windowSpan, EndType.HighLow);
 
         decimal? upperLine = null;
         decimal? lowerLine = null;

src/e-k/Fcb/Fcb.Utilities.cs

@@ -1,9 +1,10 @@
 namespace Skender.Stock.Indicators;
 
-public static partial class Indicator
+// FRACTAL CHAOS BANDS (UTILITIES)
+
+public static partial class Fcb
 {
-    // CONDENSE (REMOVE null results)
-    /// <inheritdoc cref="Utility.Condense{T}(IReadOnlyList{T})"/>
+    /// <inheritdoc cref="Reusable.Condense{T}(IReadOnlyList{T})"/>
     public static IReadOnlyList<FcbResult> Condense(
         this IReadOnlyList<FcbResult> results)
     {
@@ -17,8 +18,7 @@ public static IReadOnlyList<FcbResult> Condense(
         return resultsList.ToSortedList();
     }
 
-    // remove recommended periods
-    /// <inheritdoc cref="Utility.RemoveWarmupPeriods{T}(IReadOnlyList{T})"/>
+    /// <inheritdoc cref="Reusable.RemoveWarmupPeriods{T}(IReadOnlyList{T})"/>
     public static IReadOnlyList<FcbResult> RemoveWarmupPeriods(
         this IReadOnlyList<FcbResult> results)
     {
@@ -28,4 +28,16 @@ public static IReadOnlyList<FcbResult> RemoveWarmupPeriods(
 
         return results.Remove(removePeriods);
     }
+
+    // parameter validation
+    internal static void Validate(
+        int windowSpan)
+    {
+        // check parameter arguments
+        if (windowSpan < 2)
+        {
+            throw new ArgumentOutOfRangeException(nameof(windowSpan), windowSpan,
+                "Window span must be at least 2 for FCB.");
+        }
+    }
 }

src/e-k/FisherTransform/FisherTransform.StaticSeries.cs

@@ -2,8 +2,16 @@ namespace Skender.Stock.Indicators;
 
 // FISHER TRANSFORM (SERIES)
 
-public static partial class Indicator
+public static partial class FisherTransform
 {
+    public static IReadOnlyList<FisherTransformResult> ToFisherTransform<T>(
+        this IReadOnlyList<T> results,
+        int lookbackPeriods = 10)
+        where T : IReusable
+        => results
+            .ToSortedList(CandlePart.HL2)
+            .CalcFisherTransform(lookbackPeriods);
+
     private static List<FisherTransformResult> CalcFisherTransform<T>(
         this List<T> source,
         int lookbackPeriods)

src/e-k/FisherTransform/FisherTransform.Common.cs → src/e-k/FisherTransform/FisherTransform.Utilities.cs

@@ -1,8 +1,8 @@
 namespace Skender.Stock.Indicators;
 
-// FISHER TRANSFORM (COMMON)
+// FISHER TRANSFORM (UTILITIES)
 
-public static class FisherTransform
+public static partial class FisherTransform
 {
     // parameter validation
     internal static void Validate(
@@ -15,5 +15,4 @@ internal static void Validate(
                 "Lookback periods must be greater than 0 for Fisher Transform.");
         }
     }
-
 }