overwrite previous lines on copy paste in REPL with ANSI escapes codes - node.js

Question

I have Node.js REPL with syntax highlighting for Scheme language using ANSI escape codes. The problem is that when I copy-paste the code I need to overwrite previous text with new text that is highlighted. I'm using F ANSI escape to move the cursor up clear each line (K code) and write color text on top.
Here is my code:
function run_repl(err, rl) {
const dynamic = options.d || options.dynamic;
var code = '';
var multiline = false;
var resolve;
// we use promise loop to fix issue when copy paste list of S-Expression
var prev_eval = Promise.resolve();
if (process.stdin.isTTY) {
rl.prompt();
}
var prev_line;
boostrap(interp).then(function() {
rl.on('line', function(line) {
code += line + '\n';
const lines = code.split('\n');
const cols = process.stdout.columns;
// fix formatting for previous lines that was echo
// ReadLine will not handle those
if (terminal && lines.length > 0) {
var f = new Formatter(code);
code = f.format();
const stdout = scheme(code).split('\n').map((line, i) => {
var prefix;
if (i === 0) {
prefix = unify_prompt(prompt, continuePrompt);
} else {
prefix = unify_prompt(continuePrompt, prompt);
}
return '\x1b[K' + prefix + line;
}).join('\n');
let num = lines.length - 1;
const format = `\x1b[${num}F${stdout}`;
process.stdout.write(format);
}
try {
if (balanced_parenthesis(code)) {
// we need to clear the prompt because resume
// is adding the prompt that was present when pause was called
// https://github.com/nodejs/node/issues/11699
rl.setPrompt('');
rl.pause();
prev_eval = prev_eval.then(function() {
var result = run(code, interp, dynamic);
code = '';
return result;
}).then(function(result) {
if (process.stdin.isTTY) {
print(result);
if (newline) {
// readline doesn't work with not ended lines
// it ignore those, so we end them ourselves
process.stdout.write("\n");
newline = false;
}
if (multiline) {
multiline = false;
}
}
rl.setPrompt(prompt);
rl.prompt();
rl.resume();
}).catch(function() {
if (process.stdin.isTTY) {
if (multiline) {
multiline = false;
}
}
rl.setPrompt(prompt);
rl.prompt();
rl.resume();
});
} else {
multiline = true;
// write spaces for next line according to indent rules
var ind = indent(code, 2, prompt.length - continuePrompt.length);
rl.setPrompt(continuePrompt);
rl.prompt();
spaces = new Array(ind + 1).join(' ');
if (terminal) {
rl.write(spaces);
}
}
} catch (e) {
console.error(e.message);
console.error(e.stack);
code = '';
rl.setPrompt(prompt);
rl.prompt();
}
});
}).catch(function(e) {
log_error('Internal Error: boostrap filed');
log_error(e.message || e);
console.error('Internal Error: boostrap filed');
});
}
this is my main function, I also have hacked on top of readline that highlight text while the user is typing but it's cleared after you press enter that's why I need to update previous lines on each enter (copy/paste also works the same as enter key because it generates line event).
The only relevant code is this part:
rl.on('line', function(line) {
code += line + '\n';
const lines = code.split('\n');
const cols = process.stdout.columns;
// fix formatting for previous lines that was echo
// ReadLine will not handle those
if (terminal && lines.length > 2) {
const stdout = scheme(code).split('\n').map((line, i) => {
var prefix;
if (i === 0) {
prefix = unify_prompt(prompt, continuePrompt);
} else {
prefix = unify_prompt(continuePrompt, prompt);
}
return '\x1b[K' + prefix + line;
}).join('\n');
let num = lines.length - 1;
const format = `\x1b[${num}F${stdout}`;
process.stdout.write(format);
}
try {
if (balanced_parenthesis(code)) {
// ...
// when Scheme code is not finished else is executed.
} else {
multiline = true;
// write spaces for next line according to indent rules
var ind = indent(code, 2, prompt.length - continuePrompt.length);
rl.setPrompt(continuePrompt);
rl.prompt();
spaces = new Array(ind + 1).join(' ');
if (terminal) {
rl.write(spaces);
}
}
} catch (e) {
}
});
The code works fine unless original lines wrap into multiple lines, and it happens very often because you can't detect copy paste and the code is inserting spaces (auto-indent feature when user type code and press enter) so if the original pasted command already have indentation they are doubled.
I'm testing with this expression:
(define foo (lambda ()
(let ()
(define foo (lambda ()
(let ()
(define foo (lambda ()
(let ()
(define foo (lambda ()
(let ()
(define foo (lambda ()
(let ()
(display "x"))))))))))))))))
The problematic code is on GitHub https://github.com/jcubic/lips/blob/devel/bin/lips.js
The problem is how to clear what was already written in the terminal with ANSI escape codes.
EDIT:
This is my latest code that shows the same error when copy-pasting:
function run_repl(err, rl) {
const dynamic = options.d || options.dynamic;
var code = '';
var multiline = false;
var resolve;
// we use promise loop to fix issue when copy paste list of S-Expression
let prev_eval = Promise.resolve();
if (process.stdin.isTTY) {
rl.prompt();
}
let prev_line;
bootstrap(interp).then(function() {
rl.on('line', function(line) {
code += line;
const lines = code.split('\n');
const cols = process.stdout.columns;
// fix formatting for previous lines that was echo
// ReadLine will not handle those
if (terminal && lines.length > 2) {
var count = 0;
// correction when line wrapps in original line
// that will be overwritten
lines.map(line => {
if (line.length > cols) {
count += Math.ceil(line.length / cols) - 1;
}
});
var f = new Formatter(code);
code = f.format();
const stdout = scheme(code).split('\n').map((line, i) => {
var prefix;
if (i === 0) {
prefix = unify_prompt(prompt, continuePrompt);
} else {
prefix = unify_prompt(continuePrompt, prompt);
}
return '\x1b[K' + prefix + line;
}).join('\n');
let num = lines.length + count;
const format = `\x1b[${num}F${stdout}\n`;
process.stdout.write(format);
}
code += '\n';
try {
if (balanced_parenthesis(code)) {
// we need to clear the prompt because resume
// is adding the prompt that was present when pause was called
// https://github.com/nodejs/node/issues/11699
rl.setPrompt('');
rl.pause();
prev_eval = prev_eval.then(function() {
const result = run(code, interp, dynamic, null, options.t || options.trace);
code = '';
return result;
}).then(function(result) {
if (process.stdin.isTTY) {
print(result);
if (newline) {
// readline doesn't work with not ended lines
// it ignore those, so we end them ourselves
process.stdout.write("\n");
newline = false;
}
if (multiline) {
multiline = false;
}
}
rl.setPrompt(prompt);
rl.prompt();
rl.resume();
}).catch(function() {
if (process.stdin.isTTY) {
if (multiline) {
multiline = false;
}
}
rl.setPrompt(prompt);
rl.prompt();
rl.resume();
});
} else {
multiline = true;
const ind = indent(code, 2, prompt.length - continuePrompt.length);
rl.setPrompt(continuePrompt);
rl.prompt();
const spaces = new Array(ind + 1).join(' ');
if (terminal) {
rl.write(spaces);
}
}
} catch (e) {
console.error(e.message);
console.error(e.stack);
code = '';
rl.setPrompt(prompt);
rl.prompt();
}
});
}).catch(function(e) {
log_error('Internal Error: bootstrap filed');
log_error(e.message || e);
console.error('Internal Error: bootstrap filed');
});
}
if you want to see the working code look at the LIPS git repo.