TextVariationHandler selects sub sections of text within [|] following some simple rules and keeps a hashed history

- a la Ink
Writer and Menu make use of TextVariation

Assets/Fungus/Scripts/Components/MenuDialog.cs

@@ -318,6 +318,8 @@ namespace Fungus
             Text textComponent = button.GetComponentInChildren<Text>();
             if (textComponent != null)
             {
+                text = TextVariationHandler.SelectVariations(text);
+
                 textComponent.text = text;
             }
             button.onClick.AddListener(action);

Assets/Fungus/Scripts/Components/Writer.cs

@@ -928,7 +928,8 @@ namespace Fungus
             // If this clip is null then WriterAudio will play the default sound effect (if any)
             NotifyStart(audioClip);
 
-            string tokenText = content;
+            string tokenText = TextVariationHandler.SelectVariations(content);
+            
             if (waitForInput)
             {
                 tokenText += "{wi}";

Assets/Fungus/Scripts/Utils/TextVariationHandler.cs

@@ -0,0 +1,118 @@
+using System.Collections.Generic;
+using System.Text;
+using System.Text.RegularExpressions;
+
+namespace Fungus
+{
+    /// <summary>
+    /// Handles replacing vary text segments. Keeps history of previous replacements to allow for ordered 
+    /// sequence of variation. Inspired by https://github.com/inkle/ink/blob/master/Documentation/WritingWithInk.md#6-variable-text
+    /// 
+    /// [] mark the bounds of the vary section
+    /// | divide elements within the variation
+    /// 
+    /// Default behaviour is to show one element after another and hold the final element. Such that [a|b|c] will show
+    /// a the first time it is parsed, b the second and every subsequent time it will show c.
+    /// 
+    /// This behaviour can be modified with certain characters at the start of the [], eg. [&a|b|c];
+    /// - & does not hold the final element it wraps back around to the begining in a looping fashion
+    /// - ! does not hold the final element, it instead returns empty for the varying section
+    /// - ~ chooses a random element every time it is encountered 
+    /// </summary>
+    public static class TextVariationHandler
+    {
+        static Dictionary<int, int> hashedSections = new Dictionary<int, int>();
+        static StringBuilder sb = new StringBuilder();
+        const string pattern = @"\[([^]]+?)\]";
+        static Regex r = new Regex(pattern);
+
+        private enum VaryType
+        {
+            Sequence,
+            Cycle,
+            Once,
+            Random
+        }
+
+        static public string SelectVariations(string input)
+        {
+            sb.Length = 0;
+            sb.Append(input);
+
+            // Match the regular expression pattern against a text string.
+            var results = r.Matches(input);
+            for (int i = 0; i < results.Count; i++)
+            {
+                Match match = results[i];
+
+                //determine type
+                VaryType t = VaryType.Sequence;
+
+                var typedIndicatingChar = match.Value[1];
+                switch (typedIndicatingChar)
+                {
+                    case '~':
+                        t = VaryType.Random;
+                        break;
+                    case '&':
+                        t = VaryType.Cycle;
+                        break;
+                    case '!':
+                        t = VaryType.Once;
+                        break;
+                    default:
+                        break;
+                }
+
+                //explode and remove the control char
+                int startSubStrIndex = t != VaryType.Sequence ? 2 : 1;
+                int subStrLen = match.Value.Length - 1 - startSubStrIndex;
+                var exploded = match.Value.Substring(startSubStrIndex, subStrLen).Split('|');
+                string selected = string.Empty;
+
+                //fetched hashed value
+                int index = -1;
+                int key = input.GetHashCode() ^ match.Value.GetHashCode();
+
+                int foundVal = 0;
+                if(hashedSections.TryGetValue(key, out foundVal))
+                {
+                    index = foundVal;
+                }
+                
+                index++;
+
+                switch (t)
+                {
+                    case VaryType.Sequence:
+                        index = UnityEngine.Mathf.Min(index, exploded.Length - 1);
+                        break;
+                    case VaryType.Cycle:
+                        index = index % exploded.Length;
+                        break;
+                    case VaryType.Once:
+                        //clamp to 1 more than options
+                        index = UnityEngine.Mathf.Min(index, exploded.Length);
+                        break;
+                    case VaryType.Random:
+                        index = UnityEngine.Random.Range(0, exploded.Length - 1);
+                        break;
+                    default:
+                        break;
+                }
+
+                //update hashed value
+                hashedSections[key] = index;
+
+                //selected updated if valid
+                if(index >=0 && index < exploded.Length)
+                    selected = exploded[index];
+
+
+                sb.Replace(match.Value, selected);
+            }
+
+            return sb.ToString();
+        }
+    }
+}

Assets/Fungus/Scripts/Utils/TextVariationHandler.cs.meta

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Assets/FungusExamples/VariationText.meta

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