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- function ItoI(a) {
- return a;
- }
- function innerCreateMedium(defaults, middleware = ItoI) {
- let buffer = [];
- let assigned = false;
- const medium = {
- read() {
- if (assigned) {
- throw new Error('Sidecar: could not `read` from an `assigned` medium. `read` could be used only with `useMedium`.');
- }
- if (buffer.length) {
- return buffer[buffer.length - 1];
- }
- return defaults;
- },
- useMedium(data) {
- const item = middleware(data, assigned);
- buffer.push(item);
- return () => {
- buffer = buffer.filter((x) => x !== item);
- };
- },
- assignSyncMedium(cb) {
- assigned = true;
- while (buffer.length) {
- const cbs = buffer;
- buffer = [];
- cbs.forEach(cb);
- }
- buffer = {
- push: (x) => cb(x),
- filter: () => buffer,
- };
- },
- assignMedium(cb) {
- assigned = true;
- let pendingQueue = [];
- if (buffer.length) {
- const cbs = buffer;
- buffer = [];
- cbs.forEach(cb);
- pendingQueue = buffer;
- }
- const executeQueue = () => {
- const cbs = pendingQueue;
- pendingQueue = [];
- cbs.forEach(cb);
- };
- const cycle = () => Promise.resolve().then(executeQueue);
- cycle();
- buffer = {
- push: (x) => {
- pendingQueue.push(x);
- cycle();
- },
- filter: (filter) => {
- pendingQueue = pendingQueue.filter(filter);
- return buffer;
- },
- };
- },
- };
- return medium;
- }
- export function createMedium(defaults, middleware = ItoI) {
- return innerCreateMedium(defaults, middleware);
- }
- // eslint-disable-next-line @typescript-eslint/ban-types
- export function createSidecarMedium(options = {}) {
- const medium = innerCreateMedium(null);
- medium.options = {
- async: true,
- ssr: false,
- ...options,
- };
- return medium;
- }
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