Splitting CamelCase

Question

This is all asp.net c#.

I have an enum

public enum ControlSelectionType 
{
    NotApplicable = 1,
    SingleSelectRadioButtons = 2,
    SingleSelectD         


        

Answer 1

#JustSayNoToRegex

Takes a C# identifier, with uderscores and numbers, and converts it to space-separated string.

public static class StringExtensions
{
    public static string SplitOnCase(this string identifier)
    {
        if (identifier == null || identifier.Length == 0) return string.Empty;
        var sb = new StringBuilder();

        if (identifier.Length == 1) sb.Append(char.ToUpperInvariant(identifier[0]));

        else if (identifier.Length == 2) sb.Append(char.ToUpperInvariant(identifier[0])).Append(identifier[1]);

        else {
            if (identifier[0] != '_') sb.Append(char.ToUpperInvariant(identifier[0]));
            for (int i = 1; i < identifier.Length; i++) {
                var current = identifier[i];
                var previous = identifier[i - 1];

                if (current == '_' && previous == '_') continue;

                else if (current == '_') {
                    sb.Append(' ');
                }

                else if (char.IsLetter(current) && previous == '_') {
                    sb.Append(char.ToUpperInvariant(current));
                }

                else if (char.IsDigit(current) && char.IsLetter(previous)) {
                    sb.Append(' ').Append(current);
                }

                else if (char.IsLetter(current) && char.IsDigit(previous)) {
                    sb.Append(' ').Append(char.ToUpperInvariant(current));
                }

                else if (char.IsUpper(current) && char.IsLower(previous) 
                    && (i < identifier.Length - 1 && char.IsUpper(identifier[i + 1]) || i == identifier.Length - 1)) {
                        sb.Append(' ').Append(current);
                }

                else if (char.IsUpper(current) && i < identifier.Length - 1 && char.IsLower(identifier[i + 1])) {
                    sb.Append(' ').Append(current);
                }

                else {
                    sb.Append(current);
                }
            }
        }
        return sb.ToString();
    }

}

Tests:

[TestFixture]
static class HelpersTests
{
    [Test]
    public static void Basic()
    {
        Assert.AreEqual("Foo", "foo".SplitOnCase());
        Assert.AreEqual("Foo", "_foo".SplitOnCase());
        Assert.AreEqual("Foo", "__foo".SplitOnCase());
        Assert.AreEqual("Foo", "___foo".SplitOnCase());
        Assert.AreEqual("Foo 2", "foo2".SplitOnCase());
        Assert.AreEqual("Foo 23", "foo23".SplitOnCase());
        Assert.AreEqual("Foo 23 A", "foo23A".SplitOnCase());
        Assert.AreEqual("Foo 23 Ab", "foo23Ab".SplitOnCase());
        Assert.AreEqual("Foo 23 Ab", "foo23_ab".SplitOnCase());
        Assert.AreEqual("Foo 23 Ab", "foo23___ab".SplitOnCase());
        Assert.AreEqual("Foo 23", "foo__23".SplitOnCase());
        Assert.AreEqual("Foo Bar", "Foo_bar".SplitOnCase());
        Assert.AreEqual("Foo Bar", "Foo____bar".SplitOnCase());
        Assert.AreEqual("AAA", "AAA".SplitOnCase());
        Assert.AreEqual("Foo A Aa", "fooAAa".SplitOnCase());
        Assert.AreEqual("Foo AAA", "fooAAA".SplitOnCase());
        Assert.AreEqual("Foo Bar", "FooBar".SplitOnCase());
        Assert.AreEqual("Mn M", "MnM".SplitOnCase());
        Assert.AreEqual("AS", "aS".SplitOnCase());
        Assert.AreEqual("As", "as".SplitOnCase());
        Assert.AreEqual("A", "a".SplitOnCase());
        Assert.AreEqual("_", "_".SplitOnCase());

    }
}