Node and Web streams

Connect match, token or replacement processing to platform streams with backpressure.

Node pipeline

import { createReadStream, createWriteStream } from 'node:fs'
import { pipeline } from 'node:stream/promises'
import AhoCorasick from 'modern-ahocorasick'
import { createReplaceTransform } from 'modern-ahocorasick/stream/node'

await pipeline(
  createReadStream('input.txt'),
  createReplaceTransform(new AhoCorasick(['secret']), '[redacted]'),
  createWriteStream('output.txt'),
)

Web pipeThrough

import AhoCorasick from 'modern-ahocorasick'
import { createReplaceTransform } from 'modern-ahocorasick/stream/web'

const source = new ReadableStream<Uint8Array>({
  start(controller) {
    controller.enqueue(new TextEncoder().encode('a cat!'))
    controller.close()
  },
})
const result = source
  .pipeThrough(new TextDecoderStream())
  .pipeThrough(createReplaceTransform(new AhoCorasick(['cat']), 'DOG'))
const output = await new Response(result.pipeThrough(new TextEncoderStream())).text()
output
// 'a DOG!'

Decoding and cancellation

Node adapters return a Duplex with demand-driven async-generator processing and incremental UTF-8 byte decoding. Prefer consistent byte or string input; switching from bytes to strings flushes any incomplete decoder sequence. Web adapters return a ReadableWritablePair, accepted by pipeThrough(); they are not TransformStream instances. Decode byte sources with TextDecoderStream first. Both platforms support async replacement callbacks, cancellation and backpressure.

Both entries export createMatchTransform(matcher, options?), createTokenTransform(matcher, options?), and createReplaceTransform(matcher, replacement, options?). Node match/token adapters emit objects; replacement emits text. Web adapters emit matches, tokens, or strings respectively.

See Async cancellation contracts.