StringBuilder - GetIndexAfterNextDoubleQuote

A StringBuilder extension method that gets index after next double quote.

Try it

public static void Main()
{
	var test = new StringBuilder("Fizz\"Buzz\"Fizz",0);

	// C# Extension Method: StringBuilder - GetIndexAfterNextDoubleQuote
    var index = test.GetIndexAfterNextDoubleQuote();
    Console.WriteLine(index);
}

View Source 
using System.Text;

public static partial class Extensions
{
    /// <summary>A StringBuilder extension method that gets index after next double quote.</summary>
    /// <param name="this">The path to act on.</param>
    /// <returns>The index after next double quote.</returns>
    public static int GetIndexAfterNextDoubleQuote(this StringBuilder @this)
    {
        return @this.GetIndexAfterNextDoubleQuote(0, false);
    }

    /// <summary>A StringBuilder extension method that gets index after next double quote.</summary>
    /// <param name="this">The path to act on.</param>
    /// <param name="allowEscape">true to allow, false to deny escape.</param>
    /// <returns>The index after next double quote.</returns>
    public static int GetIndexAfterNextDoubleQuote(this StringBuilder @this, bool allowEscape)
    {
        return @this.GetIndexAfterNextDoubleQuote(0, allowEscape);
    }

    /// <summary>A StringBuilder extension method that gets index after next double quote.</summary>
    /// <param name="this">The path to act on.</param>
    /// <param name="startIndex">The start index.</param>
    /// <returns>The index after next double quote.</returns>
    public static int GetIndexAfterNextDoubleQuote(this StringBuilder @this, int startIndex)
    {
        return @this.GetIndexAfterNextDoubleQuote(startIndex, false);
    }

    /// <summary>A StringBuilder extension method that gets index after next double quote.</summary>
    /// <param name="this">The path to act on.</param>
    /// <param name="startIndex">The start index.</param>
    /// <param name="allowEscape">true to allow, false to deny escape.</param>
    /// <returns>The index after next double quote.</returns>
    public static int GetIndexAfterNextDoubleQuote(this StringBuilder @this, int startIndex, bool allowEscape)
    {
        while (startIndex < @this.Length)
        {
            char ch = @this[startIndex];
            startIndex++;

            char nextChar;
            if (allowEscape && ch == '\\' && startIndex < @this.Length && ((nextChar = @this[startIndex]) == '\\' || nextChar == '"'))
            {
                startIndex++; // Treat as escape character for \\ or \"
            }
            else if (ch == '"')
            {
                return startIndex;
            }
        }

        return startIndex;
    }
}