0ee373f9cc
Compared to the recently replaced `URL` polyfill, the new `ReadableStream` polyfill isn't being exported globally for two reasons: - We're currently checking for the existence of a global `ReadableStream` implementation when determining if the Fetch API will be used; please see `isFetchSupported` in the src/display/display_utils.js file. - Given that it's much newer functionality (compared to `URL`) and that not all browsers may implement all parts of the specification yet, not exposing the `ReadableStream` globally seems safer for now.
56 lines
2.0 KiB
JavaScript
56 lines
2.0 KiB
JavaScript
/* Copyright 2017 Mozilla Foundation
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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/* eslint-disable no-restricted-globals */
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if (typeof PDFJSDev !== 'undefined' && PDFJSDev.test('MOZCENTRAL')) {
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if (typeof ReadableStream === 'undefined') {
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throw new Error('Please enable ReadableStream support by resetting the ' +
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'"javascript.options.streams" preference to "true" in about:config.');
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}
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exports.ReadableStream = ReadableStream;
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} else {
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let isReadableStreamSupported = false;
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if (typeof ReadableStream !== 'undefined') {
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// MS Edge may say it has ReadableStream but they are not up to spec yet.
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try {
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// eslint-disable-next-line no-new
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new ReadableStream({
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start(controller) {
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controller.close();
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},
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});
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isReadableStreamSupported = true;
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} catch (e) {
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// The ReadableStream constructor cannot be used.
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}
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}
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if (isReadableStreamSupported) {
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exports.ReadableStream = ReadableStream;
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} else if (typeof PDFJSDev !== 'undefined' &&
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PDFJSDev.test('IMAGE_DECODERS')) {
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class DummyReadableStream {
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constructor() {
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throw new Error('The current image decoders are synchronous, ' +
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'hence `ReadableStream` shouldn\'t need to be ' +
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'polyfilled for the IMAGE_DECODERS build target.');
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}
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}
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exports.ReadableStream = DummyReadableStream;
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} else {
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exports.ReadableStream =
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require('web-streams-polyfill/dist/ponyfill').ReadableStream;
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}
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}
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