(896) forth: implement two new tests

exercises/forth/.meta/tests.toml

@@ -109,10 +109,10 @@
 "588de2f0-c56e-4c68-be0b-0bb1e603c500" = true
 
 # can use different words with the same name
-"ac12aaaf-26c6-4a10-8b3c-1c958fa2914c" = false
+"ac12aaaf-26c6-4a10-8b3c-1c958fa2914c" = true
 
 # can define word that uses word with the same name
-"53f82ef0-2750-4ccb-ac04-5d8c1aefabb1" = false
+"53f82ef0-2750-4ccb-ac04-5d8c1aefabb1" = true
 
 # cannot redefine numbers
 "35958cee-a976-4a0f-9378-f678518fa322" = true

exercises/forth/example.js

@@ -47,9 +47,21 @@ export class Forth {
       throw new Error('Invalid definition');
     }
 
+    let execute;
+
+    // Evaluate subprogram immediately if possible, otherwise evaluate later
+    try {
+      const stackSize = this.stack.length;
+      this.evaluate(subprogram);
+      const result = this.stack.splice(stackSize);
+      execute = () => result;
+    } catch {
+      execute = this.evaluate.bind(this, subprogram);
+    }
+
     this.commands[word] = {
       arity: 0, // handled inside the call
-      execute: this.evaluate.bind(this, subprogram),
+      execute,
     };
   }
 

exercises/forth/forth.spec.js

@@ -234,6 +234,21 @@ describe('Forth', () => {
       expect(forth.stack).toEqual([12]);
     });
 
+    xtest('can use different words with the same name', () => {
+      forth.evaluate(': foo 5 ;');
+      forth.evaluate(': bar foo ;');
+      forth.evaluate(': foo 6 ;');
+      forth.evaluate('bar foo');
+      expect(forth.stack).toEqual([5, 6]);
+    });
+
+    xtest('can define word that uses word with the same name', () => {
+      forth.evaluate(': foo 10 ;');
+      forth.evaluate(': foo foo 1 + ;');
+      forth.evaluate('foo');
+      expect(forth.stack).toEqual([11]);
+    });
+
     xtest('cannot redefine numbers', () => {
       expect(() => {
         forth.evaluate(': 1 2 ;');