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'use strict';
var _Object$setPrototypeO;
function _defineProperty(obj, key, value) { if (key in obj) { Object.defineProperty(obj, key, { value: value, enumerable: true, configurable: true, writable: true }); } else { obj[key] = value; } return obj; }
var finished = require('./end-of-stream');
var kLastResolve = Symbol('lastResolve');
var kLastReject = Symbol('lastReject');
var kError = Symbol('error');
var kEnded = Symbol('ended');
var kLastPromise = Symbol('lastPromise');
var kHandlePromise = Symbol('handlePromise');
var kStream = Symbol('stream');
function createIterResult(value, done) {
return {
value: value,
done: done
};
}
function readAndResolve(iter) {
var resolve = iter[kLastResolve];
if (resolve !== null) {
var data = iter[kStream].read(); // we defer if data is null
// we can be expecting either 'end' or
// 'error'
if (data !== null) {
iter[kLastPromise] = null;
iter[kLastResolve] = null;
iter[kLastReject] = null;
resolve(createIterResult(data, false));
}
}
}
function onReadable(iter) {
// we wait for the next tick, because it might
// emit an error with process.nextTick
process.nextTick(readAndResolve, iter);
}
function wrapForNext(lastPromise, iter) {
return function (resolve, reject) {
lastPromise.then(function () {
iter[kHandlePromise](resolve, reject);
}, reject);
};
}
var AsyncIteratorPrototype = Object.getPrototypeOf(function () {});
var ReadableStreamAsyncIteratorPrototype = Object.setPrototypeOf((_Object$setPrototypeO = {
get stream() {
return this[kStream];
},
next: function next() {
var _this = this;
// if we have detected an error in the meanwhile
// reject straight away
var error = this[kError];
if (error !== null) {
return Promise.reject(error);
}
if (this[kEnded]) {
return Promise.resolve(createIterResult(null, true));
}
if (this[kStream].destroyed) {
// We need to defer via nextTick because if .destroy(err) is
// called, the error will be emitted via nextTick, and
// we cannot guarantee that there is no error lingering around
// waiting to be emitted.
return new Promise(function (resolve, reject) {
process.nextTick(function () {
if (_this[kError]) {
reject(_this[kError]);
} else {
resolve(createIterResult(null, true));
}
});
});
} // if we have multiple next() calls
// we will wait for the previous Promise to finish
// this logic is optimized to support for await loops,
// where next() is only called once at a time
var lastPromise = this[kLastPromise];
var promise;
if (lastPromise) {
promise = new Promise(wrapForNext(lastPromise, this));
} else {
// fast path needed to support multiple this.push()
// without triggering the next() queue
var data = this[kStream].read();
if (data !== null) {
return Promise.resolve(createIterResult(data, false));
}
promise = new Promise(this[kHandlePromise]);
}
this[kLastPromise] = promise;
return promise;
}
}, _defineProperty(_Object$setPrototypeO, Symbol.asyncIterator, function () {
return this;
}), _defineProperty(_Object$setPrototypeO, "return", function _return() {
var _this2 = this;
// destroy(err, cb) is a private API
// we can guarantee we have that here, because we control the
// Readable class this is attached to
return new Promise(function (resolve, reject) {
_this2[kStream].destroy(null, function (err) {
if (err) {
reject(err);
return;
}
resolve(createIterResult(null, true));
});
});
}), _Object$setPrototypeO), AsyncIteratorPrototype);
var createReadableStreamAsyncIterator = function createReadableStreamAsyncIterator(stream) {
var _Object$create;
var iterator = Object.create(ReadableStreamAsyncIteratorPrototype, (_Object$create = {}, _defineProperty(_Object$create, kStream, {
value: stream,
writable: true
}), _defineProperty(_Object$create, kLastResolve, {
value: null,
writable: true
}), _defineProperty(_Object$create, kLastReject, {
value: null,
writable: true
}), _defineProperty(_Object$create, kError, {
value: null,
writable: true
}), _defineProperty(_Object$create, kEnded, {
value: stream._readableState.endEmitted,
writable: true
}), _defineProperty(_Object$create, kLastPromise, {
value: null,
writable: true
}), _defineProperty(_Object$create, kHandlePromise, {
value: function value(resolve, reject) {
var data = iterator[kStream].read();
if (data) {
iterator[kLastPromise] = null;
iterator[kLastResolve] = null;
iterator[kLastReject] = null;
resolve(createIterResult(data, false));
} else {
iterator[kLastResolve] = resolve;
iterator[kLastReject] = reject;
}
},
writable: true
}), _Object$create));
finished(stream, function (err) {
if (err && err.code !== 'ERR_STREAM_PREMATURE_CLOSE') {
var reject = iterator[kLastReject]; // reject if we are waiting for data in the Promise
// returned by next() and store the error
if (reject !== null) {
iterator[kLastPromise] = null;
iterator[kLastResolve] = null;
iterator[kLastReject] = null;
reject(err);
}
iterator[kError] = err;
return;
}
var resolve = iterator[kLastResolve];
if (resolve !== null) {
iterator[kLastPromise] = null;
iterator[kLastResolve] = null;
iterator[kLastReject] = null;
resolve(createIterResult(null, true));
}
iterator[kEnded] = true;
});
stream.on('readable', onReadable.bind(null, iterator));
return iterator;
};
module.exports = createReadableStreamAsyncIterator;
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