配列代入時に存在チェックをする (#491)

* existence check before array assignment

* add and fix test

* Update CHANGELOG.md

CHANGELOG.md

@@ -7,6 +7,7 @@
 - Fix: チェイン系（インデックスアクセス`[]`、プロパティアクセス`.`、関数呼び出し`()`）と括弧を組み合わせた時に不正な挙動をするバグを修正
 - 関数`Str#charcode_at` `Str#to_arr` `Str#to_char_arr` `Str#to_charcode_arr` `Str#to_utf8_byte_arr` `Str#to_unicode_codepoint_arr` `Str:from_unicode_codepoints` `Str:from_utf8_bytes`を追加
 - Fix: `Str#codepoint_at`がサロゲートペアに対応していないのを修正
+- 配列の範囲外および非整数のインデックスへの代入でエラーを出すように
 ## Note
 バージョン0.16.0に記録漏れがありました。
 >- 関数`Str:from_codepoint` `Str#codepoint_at`を追加

src/interpreter/index.ts

@@ -612,7 +612,10 @@ export class Interpreter {
 			const i = await this._eval(dest.index, scope);
 			if (isArray(assignee)) {
 				assertNumber(i);
-				assignee.value[i.value] = value; // TODO: 存在チェック
+				if (assignee.value[i.value] === undefined) {
+					throw new AiScriptIndexOutOfRangeError(`Index out of range. index: ${i.value} max: ${assignee.value.length - 1}`);
+				}
+				assignee.value[i.value] = value;
 			} else if (isObject(assignee)) {
 				assertString(i);
 				assignee.value.set(i.value, value);

test/index.ts

@@ -940,6 +940,32 @@ describe('Array', () => {
 		}
 		assert.fail();
 	});
+
+	test.concurrent('index out of range on assignment', async () => {
+		try {
+			await exe(`
+			var a = []
+	 		a[2] = 'hoge'
+			`);
+		} catch (e) {
+			assert.equal(e instanceof AiScriptIndexOutOfRangeError, true);
+			return;
+		}
+		assert.fail();
+	});
+
+	test.concurrent('non-integer-indexed assignment', async () => {
+		try {
+			await exe(`
+			var a = []
+	 		a[6.21] = 'hoge'
+			`);
+		} catch (e) {
+			assert.equal(e instanceof AiScriptIndexOutOfRangeError, true);
+			return;
+		}
+		assert.fail();
+	});
 });
 
 describe('chain', () => {
@@ -2041,10 +2067,10 @@ describe('type declaration', () => {
 	test.concurrent('fn def', async () => {
 		const res = await exe(`
 		@f(x: arr<num>, y: str, z: @(num) => bool): arr<num> {
-			x[3] = 0
+			x.push(0)
 			y = "abc"
 			var r: bool = z(x[0])
-			x[4] = if r 5 else 10
+			x.push(if r 5 else 10)
 			x
 		}