Task: Brace expansion





Java: public class BraceExpansion {

    public static void main(String[] args) {
        for (String s : new String[]{"It{{em,alic}iz,erat}e{d,}, please.",
            "~/{Downloads,Pictures}/*.{jpg,gif,png}",
            "{,{,gotta have{ ,\\, again\\, }}more }cowbell!",
            "{}} some }{,{\\\\{ edge, edge} \\,}{ cases, {here} \\\\\\\\\\}"}) {
            System.out.println();
            expand(s);
        }
    }

    public static void expand(String s) {
        expandR("", s, "");
    }

    private static void expandR(String pre, String s, String suf) {
        int i1 = -1, i2 = 0;
        String noEscape = s.replaceAll("([\\\\]{2}|[\\\\][,}{])", "  ");
        StringBuilder sb = null;

        outer:
        while ((i1 = noEscape.indexOf('{', i1 + 1)) != -1) {
            i2 = i1 + 1;
            sb = new StringBuilder(s);
            for (int depth = 1; i2 < s.length() && depth > 0; i2++) {
                char c = noEscape.charAt(i2);
                depth = (c == '{') ? ++depth : depth;
                depth = (c == '}') ? --depth : depth;
                if (c == ',' && depth == 1) {
                    sb.setCharAt(i2, '\u0000');
                } else if (c == '}' && depth == 0 && sb.indexOf("\u0000") != -1)
                    break outer;
            }
        }
        if (i1 == -1) {
            if (suf.length() > 0)
                expandR(pre + s, suf, "");
            else
                System.out.printf("%s%s%s%n", pre, s, suf);
        } else {
            for (String m : sb.substring(i1 + 1, i2).split("\u0000", -1))
                expandR(pre + s.substring(0, i1), m, s.substring(i2 + 1) + suf);
        }
    }
}




VB: Module Module1

    Function GetGroup(s As String, depth As Integer) As Tuple(Of List(Of String), String)
        Dim out As New List(Of String)
        Dim comma = False
        While Not String.IsNullOrEmpty(s)
            Dim gs = GetItem(s, depth)
            Dim g = gs.Item1
            s = gs.Item2
            If String.IsNullOrEmpty(s) Then
                Exit While
            End If
            out.AddRange(g)

            If s(0) = "}" Then
                If comma Then
                    Return Tuple.Create(out, s.Substring(1))
                End If
                Return Tuple.Create(out.Select(Function(a) "{" + a + "}").ToList(), s.Substring(1))
            End If

            If s(0) = "," Then
                comma = True
                s = s.Substring(1)
            End If
        End While
        Return Nothing
    End Function

    Function GetItem(s As String, Optional depth As Integer = 0) As Tuple(Of List(Of String), String)
        Dim out As New List(Of String) From {""}
        While Not String.IsNullOrEmpty(s)
            Dim c = s(0)
            If depth > 0 AndAlso (c = "," OrElse c = "}") Then
                Return Tuple.Create(out, s)
            End If
            If c = "{" Then
                Dim x = GetGroup(s.Substring(1), depth + 1)
                If Not IsNothing(x) Then
                    Dim tout As New List(Of String)
                    For Each a In out
                        For Each b In x.Item1
                            tout.Add(a + b)
                        Next
                    Next
                    out = tout
                    s = x.Item2
                    Continue While
                End If
            End If
            If c = "\" AndAlso s.Length > 1 Then
                c += s(1)
                s = s.Substring(1)
            End If
            out = out.Select(Function(a) a + c).ToList()
            s = s.Substring(1)
        End While
        Return Tuple.Create(out, s)
    End Function

    Sub Main()
        For Each s In {
            "It{{em,alic}iz,erat}e{d,}, please.",
            "~/{Downloads,Pictures}/*.{jpg,gif,png}",
            "{,{,gotta have{ ,\, again\, }}more }cowbell!",
            "{}} some }{,{\\{ edge, edge} \,}{ cases, {here} \\\\\}"
        }
            Dim fmt = "{0}" + vbNewLine + vbTab + "{1}"
            Dim parts = GetItem(s)
            Dim res = String.Join(vbNewLine + vbTab, parts.Item1)
            Console.WriteLine(fmt, s, res)
        Next
    End Sub

End Module