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// Copyright Node.js contributors. All rights reserved. MIT License.
import { Encodings } from "../_utils.ts";
import Duplex from "./duplex.ts";
import type { DuplexOptions } from "./duplex.ts";
import type { writeV } from "./writable_internal.ts";
import { ERR_METHOD_NOT_IMPLEMENTED } from "../_errors.ts";
const kCallback = Symbol("kCallback");
type TransformFlush = (
this: Transform,
// deno-lint-ignore no-explicit-any
callback: (error?: Error | null, data?: any) => void,
) => void;
export interface TransformOptions extends DuplexOptions {
read?(this: Transform, size: number): void;
write?(
this: Transform,
// deno-lint-ignore no-explicit-any
chunk: any,
encoding: Encodings,
callback: (error?: Error | null) => void,
): void;
writev?: writeV;
final?(this: Transform, callback: (error?: Error | null) => void): void;
destroy?(
this: Transform,
error: Error | null,
callback: (error: Error | null) => void,
): void;
transform?(
this: Transform,
// deno-lint-ignore no-explicit-any
chunk: any,
encoding: Encodings,
// deno-lint-ignore no-explicit-any
callback: (error?: Error | null, data?: any) => void,
): void;
flush?: TransformFlush;
}
export default class Transform extends Duplex {
[kCallback]: null | ((error?: Error | null) => void);
_flush?: TransformFlush;
constructor(options?: TransformOptions) {
super(options);
this._readableState.sync = false;
this[kCallback] = null;
if (options) {
if (typeof options.transform === "function") {
this._transform = options.transform;
}
if (typeof options.flush === "function") {
this._flush = options.flush;
}
}
this.on("prefinish", function (this: Transform) {
if (typeof this._flush === "function" && !this.destroyed) {
this._flush((er, data) => {
if (er) {
this.destroy(er);
return;
}
if (data != null) {
this.push(data);
}
this.push(null);
});
} else {
this.push(null);
}
});
}
_read = () => {
if (this[kCallback]) {
const callback = this[kCallback] as (error?: Error | null) => void;
this[kCallback] = null;
callback();
}
};
_transform(
// deno-lint-ignore no-explicit-any
_chunk: any,
_encoding: string,
// deno-lint-ignore no-explicit-any
_callback: (error?: Error | null, data?: any) => void,
) {
throw new ERR_METHOD_NOT_IMPLEMENTED("_transform()");
}
_write = (
// deno-lint-ignore no-explicit-any
chunk: any,
encoding: string,
callback: (error?: Error | null) => void,
) => {
const rState = this._readableState;
const wState = this._writableState;
const length = rState.length;
this._transform(chunk, encoding, (err, val) => {
if (err) {
callback(err);
return;
}
if (val != null) {
this.push(val);
}
if (
wState.ended || // Backwards compat.
length === rState.length || // Backwards compat.
rState.length < rState.highWaterMark ||
rState.length === 0
) {
callback();
} else {
this[kCallback] = callback;
}
});
};
}
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