fixed edge case when delimiter length is 0

Author: Guiorgy

src/Enumerators/SplitSequence/SpanSplitSequenceEnumerator.cs

@@ -11,6 +11,7 @@ namespace SpanExtensions.Enumerators
         ReadOnlySpan<T> Span;
         readonly ReadOnlySpan<T> Delimiter;
         readonly int DelimiterLength;
+        readonly bool DelimiterIsEmpty;
         bool EnumerationDone;
 
         /// <summary>
@@ -28,6 +29,7 @@ public SpanSplitSequenceEnumerator(ReadOnlySpan<T> source, ReadOnlySpan<T> delim
             Span = source;
             Delimiter = delimiter;
             DelimiterLength = Delimiter.Length;
+            DelimiterIsEmpty = Delimiter.IsEmpty;
             EnumerationDone = false;
             Current = default;
         }
@@ -53,7 +55,7 @@ public bool MoveNext()
 
             int delimiterIndex = Span.IndexOf(Delimiter);
 
-            if(delimiterIndex == -1)
+            if(delimiterIndex == -1 || DelimiterIsEmpty)
             {
                 EnumerationDone = true;
 

src/Enumerators/SplitSequence/SpanSplitSequenceStringSplitOptionsEnumerator.cs

@@ -10,6 +10,7 @@ public ref struct SpanSplitSequenceStringSplitOptionsEnumerator
         ReadOnlySpan<char> Span;
         readonly ReadOnlySpan<char> Delimiter;
         readonly int DelimiterLength;
+        readonly bool DelimiterIsEmpty;
         readonly bool TrimEntries;
         readonly bool RemoveEmptyEntries;
         bool EnumerationDone;
@@ -29,7 +30,8 @@ public SpanSplitSequenceStringSplitOptionsEnumerator(ReadOnlySpan<char> source,
         {
             Span = source;
             Delimiter = delimiter;
-            DelimiterLength = delimiter.Length;
+            DelimiterLength = Delimiter.Length;
+            DelimiterIsEmpty = Delimiter.IsEmpty;
             TrimEntries = options.IsTrimEntriesSet();
             RemoveEmptyEntries = options.IsRemoveEmptyEntriesSet();
             EnumerationDone = false;
@@ -59,7 +61,7 @@ public bool MoveNext()
             {
                 int delimiterIndex = Span.IndexOf(Delimiter);
 
-                if(delimiterIndex == -1)
+                if(delimiterIndex == -1 || DelimiterIsEmpty)
                 {
                     EnumerationDone = true;
 

src/Enumerators/SplitSequence/SpanSplitSequenceStringSplitOptionsWithCountEnumerator.cs

@@ -10,6 +10,7 @@ public ref struct SpanSplitSequenceStringSplitOptionsWithCountEnumerator
         ReadOnlySpan<char> Span;
         readonly ReadOnlySpan<char> Delimiter;
         readonly int DelimiterLength;
+        readonly bool DelimiterIsEmpty;
         readonly bool TrimEntries;
         readonly bool RemoveEmptyEntries;
         readonly CountExceedingBehaviour CountExceedingBehaviour;
@@ -33,8 +34,9 @@ public SpanSplitSequenceStringSplitOptionsWithCountEnumerator(ReadOnlySpan<char>
         {
             Span = source;
             Delimiter = delimiter;
-            DelimiterLength = delimiter.Length;
-            CurrentCount = count.ThrowIfNegative();
+            DelimiterLength = Delimiter.Length;
+            DelimiterIsEmpty = Delimiter.IsEmpty;
+            CurrentCount = DelimiterIsEmpty ? 0 : count.ThrowIfNegative();
             TrimEntries = options.IsTrimEntriesSet();
             RemoveEmptyEntries = options.IsRemoveEmptyEntriesSet();
             CountExceedingBehaviour = countExceedingBehaviour.ThrowIfInvalid();
@@ -100,7 +102,7 @@ public bool MoveNext()
                     }
                     else
                     {
-                        Current = delimiterIndex == -1 || CountExceedingBehaviour.IsIncludeRemainingElements() ? Span : Span[..delimiterIndex];
+                        Current = delimiterIndex == -1 || CountExceedingBehaviour.IsIncludeRemainingElements() || DelimiterIsEmpty ? Span : Span[..delimiterIndex];
                     }
 
                     if(TrimEntries)

src/Enumerators/SplitSequence/SpanSplitSequenceWithCountEnumerator.cs

@@ -11,6 +11,7 @@ namespace SpanExtensions.Enumerators
         ReadOnlySpan<T> Span;
         readonly ReadOnlySpan<T> Delimiter;
         readonly int DelimiterLength;
+        readonly bool DelimiterIsEmpty;
         readonly CountExceedingBehaviour CountExceedingBehaviour;
         int CurrentCount;
         bool EnumerationDone;
@@ -31,8 +32,9 @@ public SpanSplitSequenceWithCountEnumerator(ReadOnlySpan<T> source, ReadOnlySpan
         {
             Span = source;
             Delimiter = delimiter;
-            DelimiterLength = delimiter.Length;
-            CurrentCount = count.ThrowIfNegative();
+            DelimiterLength = Delimiter.Length;
+            DelimiterIsEmpty = Delimiter.IsEmpty;
+            CurrentCount = DelimiterIsEmpty ? 1 : count.ThrowIfNegative();
             CountExceedingBehaviour = countExceedingBehaviour.ThrowIfInvalid();
             EnumerationDone = count == 0;
             Current = default;
@@ -63,7 +65,7 @@ public bool MoveNext()
             {
                 EnumerationDone = true;
 
-                Current = delimiterIndex == -1 || CountExceedingBehaviour.IsIncludeRemainingElements() ? Span : Span[..delimiterIndex];
+                Current = delimiterIndex == -1 || CountExceedingBehaviour.IsIncludeRemainingElements() || DelimiterIsEmpty ? Span : Span[..delimiterIndex];
 
                 return true;
             }