An alternative to the StringBuilder class, with minimal memory allocation.
The default StringBuilder implementation in Mono/.NET 4.0+/.NET Core is optimized for the common case of multiple calls to Append by storing strings in a linked-list of chunks.[1] This can lead to non-obvious performance issues, for example allocations when using Clear() on a builder with multiple chunks.
This implementation is more similar to the one in .NET 2.0, in the way that it is optimized for better performance in the case of frequent Insert/Remove operations.
You can get zero allocations (other than the ToString() call) by re-using the same StringBuilder instance.
[1] https://codingsight.com/stringbuilder-the-past-and-the-future/
IList<char>ICollection<char>IReadOnlyList<char>IReadOnlyCollection<char>IEnumerable<char>IEnumerable
/// <summary> Return the string result </summary>
public override string ToString();
/// <summary> Clears the StringBuilder instance (preserving allocated capacity) </summary>
public StringBuilder Clear();
/// <summary> Insert string at given index </summary>
public StringBuilder Insert(int index, string text);
/// <summary> Insert character at given index </summary>
public StringBuilder Insert(int index, char character);
/// <summary> Remove characters starting from specified index </summary>
public StringBuilder Remove(int index, int count);
/// <summary> Append the content of another StringBuilder instance </summary>
public StringBuilder Append(StringBuilder other);
/// <summary> Append a string </summary>
public StringBuilder Append(string value);
/// <summary> Append a substring of a string </summary>
public StringBuilder Append(string value, int valueStartIndex = 0, int? valueLength = default);
/// <summary> Append a character </summary>
public StringBuilder Append(char c);
/// <summary> Append a character </summary>
public StringBuilder Append(char c, int repeat);
/// <summary> Append an object (calls .ToString()) </summary>
public StringBuilder Append(object value);
/// <summary> Append an int without memory allocation </summary>
public StringBuilder Append(int value);
/// <summary> Append a float without memory allocation. </summary>
public StringBuilder Append(float valueF);
/// <summary> Replace all occurences of a character </summary>
public StringBuilder Replace(char a, char b);
/// <summary> Replace all occurences of a string by another one </summary>
public StringBuilder Replace(string oldStr, string newStr);
public bool StartsWith(string value);
public bool StartsWith(string value, bool ignoreCase);
public bool StartsWith(string value, int startIndex = 0, bool ignoreCase = false);
public int IndexOf(char value);
public int IndexOf(char value, int startIndex);
public int IndexOf(string value);
public int IndexOf(string value, int startIndex);
public int IndexOf(string value, bool ignoreCase);
public int IndexOf(string value, int startIndex, bool ignoreCase);
int ICollection<char>.Count;
int IReadOnlyCollection<char>.Count;
bool ICollection<char>.IsReadOnly;
void IList<char>.RemoveAt(int index);
void IList<char>.Insert(int index, char item);
void ICollection<char>.Clear();
void ICollection<char>.Add(char character);
bool ICollection<char>.Contains(char item);
public void CopyTo(char[] array, int arrayIndex);
bool ICollection<char>.Remove(char item);
public List<char>.Enumerator GetEnumerator();
IEnumerator IEnumerable.GetEnumerator();
IEnumerator<char> IEnumerable<char>.GetEnumerator();
public static implicit operator string(StringBuilder builder);