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extend.ts
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/
extend.ts
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import { BufferCodec } from "../types";
/**
* Extend the capabilities of an existing codec by wrapping it with additional
* `parse` and `serialize` methods.
*
* @example
* const numericString = extend(
* string.nullTerminated(),
* s => parseInt(s, 10),
* s => s.toString()
* )
*
* @param codec The codec to extend
* @param parse Transforms the value parsed by `codec`
* @param serialize Transforms the value serialized by `codec`
*/
export const extend = <T, U, C>(
codec: BufferCodec<T, C>,
parse: (from: T, context: C) => U,
serialize: (from: U) => T
): BufferCodec<U, C> => ({
parse: (buffer, context) => {
const { value, byteLength } = codec.parse(buffer, context);
return { value: parse(value, context!), byteLength };
},
serialize: (parsed) => codec.serialize(serialize(parsed)),
});