feat: add solution property in result

BREAKING CHANGE
This commit introduces the solution feature that shows the steps taken to achieve the provided result

package.json

@@ -52,6 +52,6 @@
     },
     "packageManager": "pnpm@8.14.0",
     "lint-staged": {
-        ".ts": "pnpm lint"
+        "*.ts": "pnpm test"
     }
 }

src/index.ts

@@ -55,9 +55,9 @@ function generateSolution(raw: string[]) {
     function step(str: string, box: string[]) {
         let tmp = str;
         if (str) {
-            tmp = str.replaceAll(/#\d/g, (m) => map[m]?.result || m);
+            tmp = str.replaceAll(/#\d/g, (m) => map[m]?.result || '');
             box.unshift(tmp);
-            str = str.replaceAll(/#\d/g, (m) => map[m]?.expr || m);
+            str = str.replaceAll(/#\d/g, (m) => map[m]?.expr || '');
             if (!str.includes('#')) {
                 box.unshift(str);
             }

test/interpreter.test.ts

@@ -8,6 +8,6 @@ describe('interpreter', () => {
         const tokens = tokenize(expr);
         const ast = parse(tokens);
         const scope = { variables: { x: 1 } };
-        expect(interpret(ast, scope)).toBe(4);
+        expect(interpret(ast, scope, [], true)).toBe(4);
     });
 });