Node.js：是否可以为 python 交互式 shell (REPL) 制作适配器？

Question

可以在Node.js中使用readline读取一行python代码，然后作为子进程发送到python交互shellspawned，然后接收输出？

我知道这是可能的：

import { spawn } from "child_process";

const py = spawn("python", ["-i"]);

py.stdout.on("data", (data) => {
  console.log(`stdout: ${data}`);
});

py.stdin.write('print("hello from python!")\n');

// will get 'stdout: hello from python!'

但是，这不起作用：

import { spawn } from "child_process";
import * as readline from "readline";

const py = spawn("python", ["-i"]);

py.stdout.on("data", (data) => {
  console.log(`stdout: ${data}`);
});

py.stdin.write('print("hello from python!")\n');

const rl = readline.createInterface({
  input: process.stdin,
  output: process.stdout,
});
rl.prompt();
rl.on("line", (line) => {
  py.stdin.write(line);
  rl.prompt();
}).on("close", () => {
  process.exit()
});

我想这样做是因为我想在 Node.js 中为 python 开发一个接口。通过spawn 执行独立的python 命令/文件很简单，但我想构建一个功能齐全的界面，它具有与R 中的Reticulate 类似的功能。

Answer 1

我有一个类似的应用程序，我设法让它运行得足以满足我的需要：a processToPromise function。 缺点是它总是必须在每个call 上注册新的事件监听器。基本上，它会在您的命令完成后等待交互式 Python shell 打印它的 >>>，并为您提供同时出现的输出。

此外，您不能多次异步调用此函数而不会得到混乱的结果。 先尝试一些简单的 print 语句，看看是否得到了预期的结果。

---

一些代码供参考：

const child_process = require('child_process');

class InteractiveProcessHandle {
    private process: any;

    public outputLog: string;
    public latestOutput: string;

    private processToPromise(process: any) {
        return new Promise<string>((resolve, reject) => {
            console.log("+++ creating promise");
            process.stdout.removeAllListeners();
            process.stderr.removeAllListeners();
            process.stdin.removeAllListeners();

            let lastString: string = '';

            process.stdout.on("data", (data: any) => {
                data = data.toString().trim();
                this.update(data);
                if (data.endsWith('>>>')) {
                    resolve(lastString);
                }
                lastString = data;
            });
            process.stderr.on("data", (data: any) => {
                data = data.toString().trim();
                this.update(data);
                if (data.endsWith('>>>')) {
                    resolve(lastString);
                }
                lastString = data;
            });
            process.stdin.on("error", () => {
                console.log("Failure in stdin! ... error");
                reject();
            });
            process.stdin.on("close", () => {
                console.log("Failure in stdin! ... close");
                reject();
            });
            process.stdin.on("end", () => {
                console.log("Failure in stdin! ... end");
                reject();
            });
            process.stdin.on("disconnect", () => {
                console.log("Failure in stdin! ... disconnect");
                reject();
            });
            process.stdout.on("error", () => {
                console.log("Failure in stdout! ... error");
                reject();
            });
            process.stdout.on("close", () => {
                console.log("Failure in stdout! ... close");
                reject();
            });
            process.stdout.on("end", () => {
                console.log("Failure in stdout! ... end");
                reject();
            });
            process.stderr.on("error", () => {
                console.log("Failure in stderr! ... error");
                reject();
            });
            process.stderr.on("close", () => {
                console.log("Failure in stderr! ... close");
                reject();
            });
            process.stderr.on("end", () => {
                console.log("Failure in stderr! ... end");
                reject();
            });
            console.log("+++ done creating promise");
        });
    }

    private update(data: any) {
        this.latestOutput = data;
        this.outputLog += data + "\n";
        console.log(`logging from update: "${data}"`);
    }

    public call(command: string): Promise<string> {
        console.log(`called: "${command.trim()}"`);
        let promise = this.processToPromise(this.process);
        this.process.stdin.write(command);
        return promise;
    }

    constructor(call: any, options: any) {
        this.latestOutput = "";
        this.outputLog = "";

        this.process = child_process.spawn(call, options, { shell: true });
        this.process.stdout.setEncoding('utf8');
        this.process.stderr.setEncoding('utf8');
    }
};

var interactive_python = new InteractiveProcessHandle('python', ['-i']);

async () => {
    await interactive_python .call('');
    await interactive_python .call('x = 20');
    let x = await clang_build.call('print(x)\n');
    console.log('x = ', x);
}