Parse numbers from spans without allocations

using System;
using System.Collections.Generic;
using System.Globalization;

/// <summary>Parses delimited numbers straight from a span, no substrings.</summary>
public static class SpanNumbers
{
    public static List<double> ParseCsv(ReadOnlySpan<char> line, char separator = ',')
    {
        var values = new List<double>();
        var start = 0;
        for (var i = 0; i <= line.Length; i++)
        {
            if (i < line.Length && line[i] != separator)
            {
                continue;
            }
            var part = line[start..i].Trim();
            if (!part.IsEmpty)
            {
                values.Add(double.Parse(part, NumberStyles.Float, CultureInfo.InvariantCulture));
            }
            start = i + 1;
        }
        return values;
    }

    public static void Main()
    {
        ReadOnlySpan<char> line = " 1.5, 2.25 ,, 3,4.75 ";
        Console.WriteLine(string.Join(" | ", ParseCsv(line))); // 1.5 | 2.25 | 3 | 4.75
    }
}