57 lines
1.3 KiB
JavaScript
57 lines
1.3 KiB
JavaScript
'use strict'
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const { Transform, Writable } = require('stream')
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function validateTopic (topic, message) {
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if (!topic || topic.length === 0) { // [MQTT-3.8.3-3]
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return new Error('impossible to ' + message + ' to an empty topic')
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}
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const end = topic.length - 1
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const endMinus = end - 1
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const slashInPreEnd = endMinus > 0 && topic.charCodeAt(endMinus) !== 47
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for (let i = 0; i < topic.length; i++) {
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switch (topic.charCodeAt(i)) {
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case 35: { // #
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const notAtTheEnd = i !== end
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if (notAtTheEnd || slashInPreEnd) {
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return new Error('# is only allowed in ' + message + ' in the last position')
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}
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break
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}
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case 43: { // +
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const pastChar = i < end - 1 && topic.charCodeAt(i + 1) !== 47
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const preChar = i > 1 && topic.charCodeAt(i - 1) !== 47
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if (pastChar || preChar) {
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return new Error('+ is only allowed in ' + message + ' between /')
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}
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break
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}
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}
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}
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}
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function through (transform) {
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return new Transform({
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objectMode: true,
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transform
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})
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}
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function bulk (fn) {
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return new Writable({
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objectMode: true,
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writev: function (chunks, cb) {
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fn(chunks.map(chunk => chunk.chunk), cb)
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}
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})
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}
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module.exports = {
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validateTopic,
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through,
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bulk,
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$SYS_PREFIX: '$SYS/'
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}
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