refactor: yarn runner man

src/yarn-spinner/runtime/evaluator.ts

@@ -499,4 +499,11 @@ export class ExpressionEvaluator {
     getVariable(name: string): unknown {
         return this.variables[name];
     }
+    
+    registerFunctions(functions: Record<string, (...args: unknown[]) => unknown>){
+        this.functions = {
+            ...this.functions,
+            ...functions
+        }
+    }
 }

src/yarn-spinner/runtime/runner.ts

@@ -28,7 +28,6 @@ type CompiledOption = {
 export class YarnRunner {
     private readonly program: IRProgram;
     private readonly variables: Record<string, unknown>;
-    private readonly functions: Record<string, (...args: unknown[]) => unknown>;
     private readonly handleCommand?: (command: string, parsed?: ReturnType<typeof parseCommand>) => void;
     private readonly commandHandler: CommandHandler;
     private readonly evaluator: ExpressionEvaluator;
@@ -59,7 +58,7 @@ export class YarnRunner {
                 this.variables[normalizedKey] = value;
             }
         }
-        this.functions = {
+        let functions = {
             // Default conversion helpers
             string: (v: unknown) => String(v ?? ""),
             number: (v: unknown) => Number(v),
@@ -115,12 +114,25 @@ export class YarnRunner {
         } as Record<string, (...args: unknown[]) => unknown>;
         this.handleCommand = opts.handleCommand;
         this.onStoryEnd = opts.onStoryEnd;
-        this.evaluator = new ExpressionEvaluator(this.variables, this.functions, this.program.enums);
+        this.evaluator = new ExpressionEvaluator(this.variables, functions, this.program.enums);
         this.commandHandler = opts.commandHandler ?? new CommandHandler(this.variables);
         this.nodeTitle = opts.startAt;
 
         this.step();
     }
+    
+    public registerFunctions(functions: Record<string, (...args: unknown[]) => unknown>){
+        this.evaluator.registerFunctions(functions);
+    }
+    
+    public registerCommands(commands: Record<string,  (args: unknown[], evaluator?: ExpressionEvaluator) => void | Promise<void>>) {
+        for(const key in commands){
+            this.commandHandler.register(key, (args, evaluator) => {
+                if(!evaluator) return;
+                commands[key].call(this, args.map(arg => evaluator.evaluateExpression(arg)));
+            });
+        }
+    };
 
     /**
      * Resolve a node title to an actual node (handling node groups).
@@ -599,6 +611,8 @@ export class YarnRunner {
      * Get variable value.
      */
     getVariable(name: string): unknown {
+        if(this.evaluator.isSmartVariable(name))
+            return this.evaluator.evaluateExpression(`$${name}`);
         return this.variables[name];
     }