pipeline.js•1.11 kB
'use strict'
const MinipassPipeline = require('minipass-pipeline')
class CachingMinipassPipeline extends MinipassPipeline {
#events = []
#data = new Map()
constructor (opts, ...streams) {
// CRITICAL: do NOT pass the streams to the call to super(), this will start
// the flow of data and potentially cause the events we need to catch to emit
// before we've finished our own setup. instead we call super() with no args,
// finish our setup, and then push the streams into ourselves to start the
// data flow
super()
this.#events = opts.events
/* istanbul ignore next - coverage disabled because this is pointless to test here */
if (streams.length) {
this.push(...streams)
}
}
on (event, handler) {
if (this.#events.includes(event) && this.#data.has(event)) {
return handler(...this.#data.get(event))
}
return super.on(event, handler)
}
emit (event, ...data) {
if (this.#events.includes(event)) {
this.#data.set(event, data)
}
return super.emit(event, ...data)
}
}
module.exports = CachingMinipassPipeline