Re-implement basic prompts with Tracery

xcode/Subconscious/Shared/Components/AppView.swift

@@ -3189,7 +3189,10 @@ struct AppEnvironment {
     var gatewayProvisioningService: GatewayProvisioningService
 
     var pasteboard = UIPasteboard.general
-
+
+    /// Service for generating creative prompts and oblique strategies
+    var prompt = PromptService.default
+
     /// Create a long polling publisher that never completes
     static func poll(every interval: Double) -> AnyPublisher<Date, Never> {
         Timer.publish(

xcode/Subconscious/Shared/Components/Deck/DeckView.swift

@@ -814,8 +814,8 @@ struct DeckModel: ModelProtocol {
                 context: nil
             )
 
-            let prompt = Prompt.connect.randomElement()!.message
-            
+            let prompt = await environment.prompt.generate(start: "#connect#")
+
             return CardModel(
                 card: .prompt(
                     message: prompt,

xcode/Subconscious/Shared/Library/Mapping.swift

@@ -8,12 +8,6 @@
 
 import Foundation
 
-extension Substring {
-    func toString() -> String {
-        String(self)
-    }
-}
-
 extension Data {
     func toString(encoding: String.Encoding = .utf8) -> String? {
         String(data: self, encoding: encoding)

xcode/Subconscious/Shared/Library/StringUtilities.swift

@@ -8,6 +8,18 @@
 
 import Foundation
 
+extension Substring {
+    func toString() -> String {
+        String(self)
+    }
+}
+
+extension String {
+    func toSubstring() -> Substring {
+        self[...]
+    }
+}
+
 extension String {
     /// Remove leading `prefix` from string if it exists.
     /// - Returns: new  string without prefix

xcode/Subconscious/Shared/Library/Tracery.swift

@@ -0,0 +1,81 @@
+//
+//  MicroTracery.swift
+//  SubconsciousExperiments
+//
+//  Created by Gordon Brander on 1/29/24.
+//
+
+import Foundation
+
+public typealias Grammar = Dictionary<String, Array<String>>
+
+/// Create a Tracery with an optional registry of modifiers
+public struct Tracery {
+    private static let token = /#(\w+)(\.(\w+))?#/
+
+    private var modifiers: Dictionary<String, (String) -> String>
+    private let maxDepth = 500
+
+    /// Create a Tracery parser
+    /// - Parameters
+    ///   - modifiers: a dictionary of named functions that can be used to
+    ///     post-process Tracery tokens.
+    public init(
+        modifiers: Dictionary<String, (String) -> String> = Dictionary()
+    ) {
+        self.modifiers = modifiers
+    }
+
+    /// Recursively flatten a grammar. Internal.
+    /// Call by public method `flatten(grammar:start:)`.
+    /// - Parameters
+    ///   - depth: keeps track of recursion depth so we can exit if exceeding
+    ///   - grammar: the Tracery grammar
+    ///   - start: the start string
+    /// - Returns: the flattened string
+    private func flatten(
+        depth: Int,
+        grammar: Grammar,
+        start: String = "#start#"
+    ) -> String {
+        // Stop flattening at depth > max
+        guard depth <= maxDepth else {
+            return start
+        }
+        return start.replacing(Self.token, with: { match in
+            let key = String(match.1)
+            guard let value = grammar[key]?.randomElement() else {
+                return match.0
+            }
+            guard
+                let modifierKey = match.3?.toString(),
+                let postprocess = modifiers[modifierKey]
+            else {
+                return flatten(
+                    depth: depth + 1,
+                    grammar: grammar,
+                    start: value
+                ).toSubstring()
+            }
+            return postprocess(
+                flatten(
+                    depth: depth + 1,
+                    grammar: grammar,
+                    start: value
+                )
+            ).toSubstring()
+        })
+    }
+
+    /// Flatten the start string using the given Tracery grammar.
+    /// - Parameters
+    ///   - grammar: the Tracery grammar
+    ///   - start: the start string
+    /// - Returns: the flattened string
+    public func flatten(
+        grammar: Grammar,
+        start: String = "#start#"
+    ) -> String {
+        flatten(depth: 0, grammar: grammar, start: start)
+    }
+}