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const EventEmitter = require('events')
const waitForData = require('./waitForData')
const ansi = require('./ansi')
module.exports = class CommandLineInterfacer extends EventEmitter {
constructor(inStream = process.stdin, outStream = process.stdout) {
super()
this.inStream = inStream
this.outStream = outStream
inStream.on('data', buffer => {
this.emit('inputData', buffer)
})
inStream.setRawMode(true)
}
async getScreenSize() {
const waitUntil = cond => waitForData(this.inStream, cond)
// Get old cursor position..
this.outStream.write(ansi.requestCursorPosition())
const { options: oldCoords } = this.parseANSICommand(
await waitUntil(buf => ansi.isANSICommand(buf, 82))
)
// Move far to the bottom right of the screen, then get cursor position..
// (We could use moveCursor here, but the 0-index offset isn't really
// relevant.)
this.outStream.write(ansi.moveCursorRaw(9999, 9999))
this.outStream.write(ansi.requestCursorPosition())
const { options: sizeCoords } = this.parseANSICommand(
await waitUntil(buf => ansi.isANSICommand(buf, 82))
)
// Restore to old cursor position.. (Using moveCursorRaw is actaully
// necessary here, since we'll be passing the coordinates returned from
// another ANSI command.)
this.outStream.write(ansi.moveCursorRaw(oldCoords[0], oldCoords[1]))
// And return dimensions.
const [ sizeLine, sizeCol ] = sizeCoords
return {
lines: sizeLine, cols: sizeCol,
width: sizeCol, height: sizeLine
}
}
parseANSICommand(buffer) {
// Typically ANSI commands are written ESC[1;2;3;4C
// ..where ESC is the ANSI escape code, equal to hexadecimal 1B and
// decimal 33
// ..where [ and ; are the literal strings "[" and ";"
// ..where 1, 2, 3, and 4 are decimal integer arguments written in ASCII
// that may last more than one byte (e.g. "15")
// ..where C is some number representing the code of the command
if (buffer[0] !== 0x1b || buffer[1] !== 0x5b) {
throw new Error('Not an ANSI command')
}
const options = []
let curOption = ''
let commandCode = null
for (let val of buffer.slice(2)) {
if (48 <= val && val <= 57) { // 0124356789
curOption = curOption.concat(val - 48)
} else {
options.push(parseInt(curOption))
curOption = ''
if (val !== 59) { // ;
commandCode = val
break
}
}
}
return {code: commandCode, options: options}
}
write(data) {
this.outStream.write(data)
}
}
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