A recursive grammar replacer based on [tags].

GrammarReplace.cs

// ! Gamejam code, proceed with caution!

// GetFromList is an extension method:
// public static T GetFromList<T>(this Random rnd, List<T> list) {
//    var index = rnd.Next(list.Count);
//    return list[index];
// }

namespace deVoid.Apothecary {
    [CreateAssetMenu(fileName = "GrammarConfig", menuName = "Apothecary/Grammar Config")]
    public class GrammarConfig : ScriptableObject {
        [TextArea]
        public List<string> Elements;
        [TextArea]
        public List<string> Grammars;

        public string Divider = ";";

        private Dictionary<string, List<string>> _grammarElementCacheInternal;

        private Dictionary<string, List<string>> _grammarElementCache {
            get {
                if (_grammarElementCacheInternal == null || _grammarElementCacheInternal.Count <= 1) {
                    RefreshCaches();
                }

                return _grammarElementCacheInternal;
            }
        }

        private void OnValidate() {
            _grammarElementCacheInternal = null;
        }

        public void RefreshCaches() {
            _grammarElementCacheInternal = new Dictionary<string, List<string>>();
            foreach (var contents in Elements) {
                var grammarBits = contents.Split('=');
                _grammarElementCacheInternal.Add(grammarBits[0], new List<string>(grammarBits[1].Split(Divider[0])));
            }
        }

        public string GetRandomFromGrammar(Random rnd) {
            var grammar = rnd.GetFromList(Grammars);
            grammar = ReplaceAllInGrammar(rnd, grammar);
            
            return grammar;
        }

        public string GetRandomFromGrammarIndex(Random rnd, int grammarIndex) {
            var grammar = Grammars[grammarIndex];
            grammar = ReplaceAllInGrammar(rnd, grammar);
            
            return grammar;
        }
        
        public string ReplaceAllInGrammar(Random rnd, string grammar) {
            foreach (var kvPair in _grammarElementCache) {
                grammar = grammar.Replace(kvPair.Key, rnd.GetFromList(kvPair.Value));
            }

            var matches = Regex.Matches(grammar,@"\[([^][]*)]");
            foreach (Match match in matches) {
                if (_grammarElementCache.ContainsKey(match.Value)) {
                    return ReplaceAllInGrammar(rnd, grammar);
                }
            }

            return grammar;
        }
    }
}