support return statement and closure (#40)

src/evaluator/evaluated/index.test.ts

@@ -4,7 +4,9 @@ import {
   makeEvaluatedBoolean,
   makeEvaluatedFunction,
   makeEvaluatedEmpty,
+  wrapReturnValue,
 } from "./";
+import type { Evaluated } from "./";
 import type {
   FunctionExpression
 } from "../../parser/syntax-tree";
@@ -80,3 +82,13 @@ describe("makeEvaluatedEmpty()", () => {
     expect(evaluated.representation).toBe("(비어있음)");
   });
 });
+
+describe("wrapReturnValue()", () => {
+  it("wrap return value", () => {
+    const valueMock = {} as Evaluated;
+
+    const wrapped = wrapReturnValue(valueMock);
+
+    expect(wrapped.type).toBe("return value");
+  });
+});

src/evaluator/evaluated/index.ts

@@ -35,6 +35,11 @@ export interface EvaluatedEmpty extends EvaluatedBase {
   readonly type: "empty";
 }
 
+export interface ReturnValue {
+  readonly type: "return value";
+  readonly value: Evaluated;
+}
+
 export type Evaluated =
   EvaluatedPrimitive |
   EvaluatedFunction |
@@ -93,3 +98,9 @@ export const makeEvaluatedEmpty: MakeEvaluatedEmpty = () => ({
     return "(비어있음)";
   },
 });
+
+export type WrapReturnValue = (value: Evaluated) => ReturnValue;
+export const wrapReturnValue: WrapReturnValue = value => ({
+  type: "return value",
+  value,
+});

src/evaluator/index.test.ts

@@ -329,9 +329,31 @@ describe("evaluate()", () => {
     const cases = [
       {
         name: "function call with function literal",
-        input: "함수(바나나) { 바나나 + 1 }(42)",
+        input: "함수(바나나) { 결과 바나나 + 1 }(42)",
         expected: 43,
       },
+      {
+        name: "function call with identifier",
+        input: "더하기 = 함수(숫자1, 숫자2) { 결과 숫자1 + 숫자2 }  더하기(3, 4)",
+        expected: 7,
+      },
+    ];
+
+    it.each(cases)("evaluate $name", testEvaluatingPrimitive);
+  });
+
+  describe("complex statements with function and calls", () => {
+    const cases = [
+      {
+        name: "make and call function containing branch statement",
+        input: "과일 = 함수(색깔) { 만약 (색깔 == '빨강') { 결과 '사과' } 아니면 { '포도' } }  과일('빨강')",
+        expected: "사과",
+      },
+      {
+        name: "make and call closure",
+        input: "더하기 = 함수(숫자1) { 결과 함수(숫자2) { 결과 숫자1+숫자2 } }  하나더하기 = 더하기(1)  하나더하기(4)",
+        expected: 5,
+      },
     ];
 
     it.each(cases)("evaluate $name", testEvaluatingPrimitive);