enhance: null値のアサーション関数を追加

Author: kakkokari-gtyih

src/interpreter/util.ts

@@ -1,18 +1,46 @@
 import { AiScriptRuntimeError } from '../error.js';
 import { STR, NUM, ARR, OBJ, NULL, BOOL } from './value.js';
-import type { Value, VStr, VNum, VBool, VFn, VObj, VArr } from './value.js';
+import type { Value, VStr, VNum, VBool, VFn, VObj, VArr, VNull } from './value.js';
 
 export function expectAny(val: Value | null | undefined): asserts val is Value {
 	if (val == null) {
 		throw new AiScriptRuntimeError('Expect anything, but got nothing.');
 	}
 }
 
+export function isBoolean(val: Value): val is VBool {
+	return val.type === 'bool';
+}
+
+export function isFunction(val: Value): val is VFn {
+	return val.type === 'fn';
+}
+
+export function isString(val: Value): val is VStr {
+	return val.type === 'str';
+}
+
+export function isNumber(val: Value): val is VNum {
+	return val.type === 'num';
+}
+
+export function isObject(val: Value): val is VObj {
+	return val.type === 'obj';
+}
+
+export function isArray(val: Value): val is VArr {
+	return val.type === 'arr';
+}
+
+export function isNull(val: Value): val is VNull {
+	return val.type === 'null';
+}
+
 export function assertBoolean(val: Value | null | undefined): asserts val is VBool {
 	if (val == null) {
 		throw new AiScriptRuntimeError('Expect boolean, but got nothing.');
 	}
-	if (val.type !== 'bool') {
+	if (!isBoolean(val)) {
 		throw new AiScriptRuntimeError(`Expect boolean, but got ${val.type}.`);
 	}
 }
@@ -21,7 +49,7 @@ export function assertFunction(val: Value | null | undefined): asserts val is VF
 	if (val == null) {
 		throw new AiScriptRuntimeError('Expect function, but got nothing.');
 	}
-	if (val.type !== 'fn') {
+	if (!isFunction(val)) {
 		throw new AiScriptRuntimeError(`Expect function, but got ${val.type}.`);
 	}
 }
@@ -30,7 +58,7 @@ export function assertString(val: Value | null | undefined): asserts val is VStr
 	if (val == null) {
 		throw new AiScriptRuntimeError('Expect string, but got nothing.');
 	}
-	if (val.type !== 'str') {
+	if (!isString(val)) {
 		throw new AiScriptRuntimeError(`Expect string, but got ${val.type}.`);
 	}
 }
@@ -39,7 +67,7 @@ export function assertNumber(val: Value | null | undefined): asserts val is VNum
 	if (val == null) {
 		throw new AiScriptRuntimeError('Expect number, but got nothing.');
 	}
-	if (val.type !== 'num') {
+	if (!isNumber(val)) {
 		throw new AiScriptRuntimeError(`Expect number, but got ${val.type}.`);
 	}
 }
@@ -48,7 +76,7 @@ export function assertObject(val: Value | null | undefined): asserts val is VObj
 	if (val == null) {
 		throw new AiScriptRuntimeError('Expect object, but got nothing.');
 	}
-	if (val.type !== 'obj') {
+	if (!isObject(val)) {
 		throw new AiScriptRuntimeError(`Expect object, but got ${val.type}.`);
 	}
 }
@@ -57,33 +85,18 @@ export function assertArray(val: Value | null | undefined): asserts val is VArr
 	if (val == null) {
 		throw new AiScriptRuntimeError('Expect array, but got nothing.');
 	}
-	if (val.type !== 'arr') {
+	if (!isArray(val)) {
 		throw new AiScriptRuntimeError(`Expect array, but got ${val.type}.`);
 	}
 }
 
-export function isBoolean(val: Value): val is VBool {
-	return val.type === 'bool';
-}
-
-export function isFunction(val: Value): val is VFn {
-	return val.type === 'fn';
-}
-
-export function isString(val: Value): val is VStr {
-	return val.type === 'str';
-}
-
-export function isNumber(val: Value): val is VNum {
-	return val.type === 'num';
-}
-
-export function isObject(val: Value): val is VObj {
-	return val.type === 'obj';
-}
-
-export function isArray(val: Value): val is VArr {
-	return val.type === 'arr';
+export function assertNull(val: Value | null | undefined): asserts val is VNull {
+	if (val == null) {
+		throw new AiScriptRuntimeError('Expect null, but got nothing.');
+	}
+	if (!isNull(val)) {
+		throw new AiScriptRuntimeError(`Expect null, but got ${val.type}.`);
+	}
 }
 
 export function eq(a: Value, b: Value): boolean {