Question

Spintax allows you to spin various words and sentences such as:

{Hello|Hi} {World|People}! {C{#|++|}|Java} is an {awesome|amazing} language.

The text between the braces would be selected at random to form different sentences.

I am able to possibly come up with a solution myself, but the problem I would have is the nesting. Sometimes the nesting can be very deep. What would be a possible solution to handling the nesting?

I can’t gather the logic needed.

Answer 1

Don’t worry about the nesting, just do it iteratively as follows:

1. Find the first sequence in the string that has {...} with no other braces inside. For your case, that’s {Hello|Hi}. If there are no more of that pattern, go to step 3.

2. Grab all the possibilities out of there and choose a random one, replacing the brace section with its value. Then go back to step 1.

3. There’s your modified string.

Let’s say you have a slightly faulty random number generator that always returns zero. Your string modification history would then be:

a/ {Hello|Hi} {World|People}! {C{#|++|}|Java} is an {awesome|amazing} language.
b/ Hello {World|People}! {C{#|++|}|Java} is an {awesome|amazing} language.
c/ Hello World! {C{#|++|}|Java} is an {awesome|amazing} language.
d/ Hello World! {C#|Java} is an {awesome|amazing} language.
e/ Hello World! C# is an {awesome|amazing} language.
f/ Hello World! C# is an awesome language.

Note particularly the transition from (c) to (d). Because we’re looking for the first brace section that doesn’t have braces inside it, we do the {#|++|} before the {C{#|++|}|Java}.

All you need to add now is the possibility that you may have {, } or | within your actual text – these will need to be escaped somehow to protect them from your modification engine.

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Here’s a little C# program which shows this in action. It’s probably not that impressively written, given my relative inexperience with the language, but it illustrates the process.

using System;
using System.Text.RegularExpressions;

namespace ConsoleApplication1
{
    class Program
    {
        static string spintax(Random rnd, string str) {
            // Loop over string until all patterns exhausted.
            string pattern = "{[^{}]*}";
            Match m = Regex.Match(str, pattern);
            while (m.Success) {
                // Get random choice and replace pattern match.
                string seg = str.Substring(m.Index + 1, m.Length - 2);
                string[] choices = seg.Split('|');
                str = str.Substring(0, m.Index) + choices[rnd.Next(choices.Length)] + str.Substring(m.Index + m.Length);
                m = Regex.Match(str, pattern);
            }

            // Return the modified string.
            return str;
        }

        static void Main(string[] args) {
            Random rnd = new Random();
            string str = "{Hello|Hi} {World|People}! {C{#|++|}|Java} is an {awesome|amazing} language.";
            Console.WriteLine(spintax(rnd, str));
            Console.ReadLine();
        }
    }
}

The output is, in one example run

Hello World! C# is an awesome language.