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codec.ts
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codec.ts
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/*
* Copyright 2020-2022 The NATS Authors
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
import { TD, TE } from "./encoders.ts";
import { ErrorCode, NatsError } from "./core.ts";
export interface Codec<T> {
/**
* Encode T to an Uint8Array suitable for including in a message payload.
* @param d
*/
encode(d: T): Uint8Array;
/**
* Decode an Uint8Array from a message payload into a T
* @param a
*/
decode(a: Uint8Array): T;
}
/**
* Returns a {@link Codec} for encoding strings to a message payload
* and decoding message payloads into strings.
* @constructor
*/
export function StringCodec(): Codec<string> {
return {
encode(d: string): Uint8Array {
return TE.encode(d);
},
decode(a: Uint8Array): string {
return TD.decode(a);
},
};
}
/**
* Returns a {@link Codec} for encoding JavaScript object to JSON and
* serialize them to an Uint8Array, and conversely, from an
* Uint8Array to JSON to a JavaScript Object.
* @param reviver
* @constructor
*/
export function JSONCodec<T = unknown>(
reviver?: (this: unknown, key: string, value: unknown) => unknown,
): Codec<T> {
return {
encode(d: T): Uint8Array {
try {
if (d === undefined) {
// @ts-ignore: json will not handle undefined
d = null;
}
return TE.encode(JSON.stringify(d));
} catch (err) {
throw NatsError.errorForCode(ErrorCode.BadJson, err);
}
},
decode(a: Uint8Array): T {
try {
return JSON.parse(TD.decode(a), reviver);
} catch (err) {
throw NatsError.errorForCode(ErrorCode.BadJson, err);
}
},
};
}