90 lines
3.1 KiB
TypeScript
90 lines
3.1 KiB
TypeScript
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// Adapted from https://github.com/canjs/can-ndjson-stream/blob/master/can-ndjson-stream.js
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// Did not use the package because it had a useless dependency on can-namespace which was unlicensed
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// The MIT License (MIT)
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//
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// Copyright 2017 Justin Meyer (justinbmeyer@gmail.com), Fang Lu
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// (cc2lufang@gmail.com), Siyao Wu (wusiyao@umich.edu), Shang Jiang
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// (mrjiangshang@gmail.com)
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//
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// Permission is hereby granted, free of charge, to any person obtaining a copy
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// of this software and associated documentation files (the "Software"), to deal
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// in the Software without restriction, including without limitation the rights
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// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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// copies of the Software, and to permit persons to whom the Software is
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// furnished to do so, subject to the following conditions:
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//
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// The above copyright notice and this permission notice shall be included in
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// all copies or substantial portions of the Software.
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//
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// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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// SOFTWARE.
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export default function ndjsonStream(stream: ReadableStream) {
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// For cancellation
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let is_reader: ReadableStreamDefaultReader | undefined = undefined;
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let cancellationRequest = false;
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return new ReadableStream({
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start: (controller) => {
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const reader = stream.getReader();
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is_reader = reader;
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const decoder = new TextDecoder();
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let data_buf = "";
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reader.read().then(function processResult(result) {
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if (result.done) {
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if (cancellationRequest) {
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// Immediately exit
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return;
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}
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data_buf = data_buf.trim();
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if (data_buf.length !== 0) {
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try {
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const data_l = JSON.parse(data_buf);
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controller.enqueue(data_l);
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} catch (e) {
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controller.error(e);
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return;
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}
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}
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controller.close();
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return;
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}
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const data = decoder.decode(result.value, { stream: true });
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data_buf += data;
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const lines = data_buf.split("\n");
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for (let i = 0; i < lines.length - 1; ++i) {
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const l = lines[i].trim();
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if (l.length > 0) {
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try {
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const data_line = JSON.parse(l);
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controller.enqueue(data_line);
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} catch (e) {
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controller.error(e);
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cancellationRequest = true;
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reader.cancel();
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return;
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}
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}
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}
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data_buf = lines[lines.length - 1];
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return reader.read().then(processResult);
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});
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},
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cancel: (reason) => {
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console.log("Cancel registered due to ", reason);
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cancellationRequest = true;
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is_reader.cancel();
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},
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});
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}
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