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denoland-deno/std/node/fs.ts

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2019-11-12 15:51:14 -05:00
import { notImplemented, intoCallbackAPIWithIntercept } from "./_utils.ts";
const { readFile: denoReadFile, readFileSync: denoReadFileSync } = Deno;
type ReadFileCallback = (err: Error | null, data: string | Uint8Array) => void;
interface ReadFileOptions {
encoding?: string | null;
flag?: string;
}
function getEncoding(
optOrCallback?: ReadFileOptions | ReadFileCallback
): string | null {
if (!optOrCallback || typeof optOrCallback === "function") {
return null;
} else {
if (optOrCallback.encoding) {
if (
optOrCallback.encoding === "utf8" ||
optOrCallback.encoding === "utf-8"
) {
return "utf8";
} else {
notImplemented();
}
}
return null;
}
}
function maybeDecode(
data: Uint8Array,
encoding: string | null
): string | Uint8Array {
if (encoding === "utf8") {
return new TextDecoder().decode(data);
}
return data;
}
export function readFile(
path: string,
optOrCallback: ReadFileCallback | ReadFileOptions,
callback?: ReadFileCallback
): void {
let cb: ReadFileCallback | undefined;
if (typeof optOrCallback === "function") {
cb = optOrCallback;
} else {
cb = callback;
}
const encoding = getEncoding(optOrCallback);
intoCallbackAPIWithIntercept<Uint8Array, string | Uint8Array>(
denoReadFile,
(data: Uint8Array): string | Uint8Array => maybeDecode(data, encoding),
cb,
path
);
}
export function readFileSync(
path: string,
opt?: ReadFileOptions
): string | Uint8Array {
return maybeDecode(denoReadFileSync(path), getEncoding(opt));
}