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readline: replace quadratic regex with linear one

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Simplify regular expression in _wordLeft and _deleteWordLeft readline
methods.

PR-URL: https://github.com/nodejs/node/pull/26778
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>
Reviewed-By: Michaël Zasso <targos@protonmail.com>
This commit is contained in:
Thomas 2019-03-19 14:19:38 +01:00 committed by Michaël Zasso
parent 83c35dc6e8
commit e4e2b0ce13
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GPG Key ID: 770F7A9A5AE15600
2 changed files with 31 additions and 2 deletions
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10
lib/readline.js
View File

@ -577,8 +577,11 @@ function commonPrefix(strings) {
Interface.prototype._wordLeft = function() {
if (this.cursor > 0) {
// Reverse the string and match a word near beginning
// to avoid quadratic time complexity
var leading = this.line.slice(0, this.cursor);
var match = leading.match(/(?:[^\w\s]+|\w+|)\s*$/);
var reversed = leading.split('').reverse().join('');
var match = reversed.match(/^\s*(?:[^\w\s]+|\w+)?/);
this._moveCursor(-match[0].length);
}
};
@ -634,8 +637,11 @@ Interface.prototype._deleteRight = function() {
Interface.prototype._deleteWordLeft = function() {
if (this.cursor > 0) {
// Reverse the string and match a word near beginning
// to avoid quadratic time complexity
var leading = this.line.slice(0, this.cursor);
var match = leading.match(/(?:[^\w\s]+|\w+|)\s*$/);
var reversed = leading.split('').reverse().join('');
var match = reversed.match(/^\s*(?:[^\w\s]+|\w+)?/);
leading = leading.slice(0, leading.length - match[0].length);
this.line = leading + this.line.slice(this.cursor, this.line.length);
this.cursor = leading.length;

23
test/parallel/test-readline-interface.js
View File

@ -1272,3 +1272,26 @@ const crlfDelay = Infinity;
}), delay);
}
});
// Ensure that the _wordLeft method works even for large input
{
const input = new Readable({
read() {
this.push('\x1B[1;5D'); // CTRL + Left
this.push(null);
},
});
const output = new Writable({
write: common.mustCall((data, encoding, cb) => {
assert.strictEqual(rl.cursor, rl.line.length - 1);
cb();
}),
});
const rl = new readline.createInterface({
input: input,
output: output,
terminal: true,
});
rl.line = `a${' '.repeat(1e6)}a`;
rl.cursor = rl.line.length;
}