53 lines
2.2 KiB
JavaScript
Vendored
53 lines
2.2 KiB
JavaScript
Vendored
"use strict";
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// Copyright 2021-2024 Buf Technologies, Inc.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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Object.defineProperty(exports, "__esModule", { value: true });
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exports.isMessage = void 0;
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const message_js_1 = require("./message.js");
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/**
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* Check whether the given object is any subtype of Message or is a specific
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* Message by passing the type.
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*
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* Just like `instanceof`, `isMessage` narrows the type. The advantage of
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* `isMessage` is that it compares identity by the message type name, not by
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* class identity. This makes it robust against the dual package hazard and
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* similar situations, where the same message is duplicated.
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*
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* This function is _mostly_ equivalent to the `instanceof` operator. For
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* example, `isMessage(foo, MyMessage)` is the same as `foo instanceof MyMessage`,
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* and `isMessage(foo)` is the same as `foo instanceof Message`. In most cases,
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* `isMessage` should be preferred over `instanceof`.
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*
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* However, due to the fact that `isMessage` does not use class identity, there
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* are subtle differences between this function and `instanceof`. Notably,
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* calling `isMessage` on an explicit type of Message will return false.
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*/
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function isMessage(arg, type) {
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if (arg === null || typeof arg != "object") {
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return false;
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}
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if (!Object.getOwnPropertyNames(message_js_1.Message.prototype).every((m) => m in arg && typeof arg[m] == "function")) {
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return false;
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}
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const actualType = arg.getType();
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if (actualType === null ||
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typeof actualType != "function" ||
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!("typeName" in actualType) ||
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typeof actualType.typeName != "string") {
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return false;
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}
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return type === undefined ? true : actualType.typeName == type.typeName;
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}
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exports.isMessage = isMessage;
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