109 lines
2.9 KiB
JavaScript
109 lines
2.9 KiB
JavaScript
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'use strict';
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const stream = require('stream');
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const Transform = stream.Transform;
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/**
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* Escapes dots in the beginning of lines. Ends the stream with <CR><LF>.<CR><LF>
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* Also makes sure that only <CR><LF> sequences are used for linebreaks
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*
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* @param {Object} options Stream options
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*/
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class DataStream extends Transform {
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constructor(options) {
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super(options);
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// init Transform
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this.options = options || {};
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this._curLine = '';
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this.inByteCount = 0;
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this.outByteCount = 0;
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this.lastByte = false;
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}
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/**
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* Escapes dots
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*/
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_transform(chunk, encoding, done) {
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let chunks = [];
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let chunklen = 0;
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let i,
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len,
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lastPos = 0;
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let buf;
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if (!chunk || !chunk.length) {
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return done();
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}
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if (typeof chunk === 'string') {
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chunk = Buffer.from(chunk);
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}
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this.inByteCount += chunk.length;
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for (i = 0, len = chunk.length; i < len; i++) {
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if (chunk[i] === 0x2e) {
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// .
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if ((i && chunk[i - 1] === 0x0a) || (!i && (!this.lastByte || this.lastByte === 0x0a))) {
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buf = chunk.slice(lastPos, i + 1);
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chunks.push(buf);
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chunks.push(Buffer.from('.'));
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chunklen += buf.length + 1;
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lastPos = i + 1;
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}
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} else if (chunk[i] === 0x0a) {
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// .
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if ((i && chunk[i - 1] !== 0x0d) || (!i && this.lastByte !== 0x0d)) {
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if (i > lastPos) {
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buf = chunk.slice(lastPos, i);
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chunks.push(buf);
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chunklen += buf.length + 2;
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} else {
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chunklen += 2;
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}
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chunks.push(Buffer.from('\r\n'));
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lastPos = i + 1;
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}
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}
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}
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if (chunklen) {
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// add last piece
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if (lastPos < chunk.length) {
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buf = chunk.slice(lastPos);
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chunks.push(buf);
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chunklen += buf.length;
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}
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this.outByteCount += chunklen;
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this.push(Buffer.concat(chunks, chunklen));
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} else {
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this.outByteCount += chunk.length;
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this.push(chunk);
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}
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this.lastByte = chunk[chunk.length - 1];
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done();
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}
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/**
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* Finalizes the stream with a dot on a single line
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*/
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_flush(done) {
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let buf;
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if (this.lastByte === 0x0a) {
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buf = Buffer.from('.\r\n');
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} else if (this.lastByte === 0x0d) {
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buf = Buffer.from('\n.\r\n');
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} else {
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buf = Buffer.from('\r\n.\r\n');
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}
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this.outByteCount += buf.length;
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this.push(buf);
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done();
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}
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}
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module.exports = DataStream;
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