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DEPARTUREAdvent Calendar 2023

Day 5

色々な言語で簡単なREPLを実装する #typescript

Last updated at Posted at 2023-12-04

続きです。

REPLとは

こちらの記事を参照してください。

Typescriptで実装する

nodejsのreadlineを利用しています。

$ pnpm init
$ pnpm add -D typescript @types/node
$ vim package.json
// scriptsに追加
  "dev": "node main.js",
  "build": "tsc main.ts",

main.ts

import * as readline from 'readline'

const rl = readline.createInterface({
  input: process.stdin,
  output: process.stdout,
})

rl.setPrompt('node> ')
rl.prompt()

rl.on('line', line => {
  try {
    // const prompt = eval(line)
    const prompt = line.trim()
    switch (prompt) {
      case 'exit':
        console.log("Bye!")
        process.exit(0)
      default:
        console.log(prompt)
    }
  } catch (error) {
    console.error("Error: ", error)
  }
  rl.prompt()
}).on('close', () => {
  console.log("\nBye!")
  process.exit(0)
})

実行する

$ pnpm build
$ pnpm dev
node> 1 + 1
1 + 1
node> foobar
foobar
node> baz
baz
node> exit
Bye!

.on('close'...のところでctrl-c、ctrl-dを処理しています。

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