目录
inquirer命令行交互原理?(一)readline的实现方法和原理
inquirer命令行交互原理?(二)手写readline实现
背景
上篇已经详细的描述了readline源码的实现,现在就是来检验下学习的情况,手动来实现一个readline
代码
(1)先监听输入流
function stepRead(callback) {
function onkeypress(s) {
output.write(s);
}
const input = process.stdin;
const output = process.stdout;
let line = '';
emikeypressEvents(input);
input.on('keypress', onkeypress);
};
function emikeypressEvents(stream) {
function onData(chunk){
g.next(chunk.toString())
}
const g = emitkeys(stream);
g.next()
stream.on('data',onData)
};
function *emitkeys(stream) {
while(true){
let ch = yield;
stream.emit('keyPress',ch);
}
}
stepRead();
(2)逐个字母监听输入流,并返回结果
知识点:
input.setRawMode(true);
input.resume();
// 重新开始,重启
function stepRead(callback) {
function onkeypress(s) {
output.write(s);
line += s;
switch (s) {
case '\r':
input.pause();
callback(line)
break;
}
}
const input = process.stdin;
const output = process.stdout;
let line = '';
emitKeypressEvents(input);
input.on('keypress', onkeypress);
input.setRawMode(true);
input.resume();
};
function emitKeypressEvents(stream) {
function onData(chunk){
g.next(chunk.toString())
}
const g = emitkeys(stream);
g.next()
stream.on('data',onData)
};
function* emitkeys(stream) {
while(true){
let ch = yield;
stream.emit('keypress',ch);
}
}
stepRead(function(s){
console.log(s);
console.log('answer=', s);
});
讲解
(1)先将输入流和输出流进行缓存,将输入流要填写的信息放在line变量中;
const input = process.stdin;
const output = process.stdout;
let line = '';
(2)调用emitKeypressEvents(input),执行emitkyes的Generator函数。.next()
;stream.on('data',onData)
绑定输入流
function emitKeypressEvents(stream) {
function onData(chunk){
g.next(chunk.toString())
}
const g = emitkeys(stream);
g.next()
stream.on('data',onData)
};
function* emitkeys(stream) {
while(true){
let ch = yield;
stream.emit('keypress',ch);
}
}
(3)input.on('keypress', onkeypress);
绑定了onkeypress事件;输出流写入信息;如果是回车('\r')的话,shitch 来进行判断。
function onkeypress(s) {
output.write(s); // 输入的信息进行打印
line += s;
switch (s) {
case '\r':
input.pause();
callback(line)
break;
}
}
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