hinting similiar commands #151

[minhchu]

Using leven package to calculate the difference between two strings. And displays similiar commands which have leven point smaller than 4.
@dthree please check if I'm doing wrong.

[dthree]

Looks really good!

Could you add in some tests? I would be interested to see the relative results based on different sets of registered commands.

4 seems like a really high edit distance. For example, if you have the commands ls, bb and ck enabled, and entered a, it would probably suggest all of the above.

[minhchu]

I've just run gulp build and added a test suite https://gist.github.com/minhchu/4438f898a8a7bc5fcaa5c72218fca2c6
But there are some problems.
When I run only that test suite mocha --grep "hinting command", it passes. But when I run the whole testmocha`, it throws some unexpected errors:

(node) warning: possible EventEmitter memory leak detected. 11 vorpal_ui_keypres
s listeners added. Use emitter.setMaxListeners() to increase limit.

Do you have any idea ?

---

If you set maximum distance to 4, it still works for your example because leven distance between a and ls is 2 < 4 ...

[AljoschaMeyer]

Node gives that warning when more than 10 (?) listeners are attached to the same emitter. Try require('events').EventEmitter.defaultMaxListeners = Infinity in the test file to fix this. Documentation

The cleaner solution would be to set the maximum for the particular event emitter objects. I was just lazy and copy-pasted that snippet from here.

Vorpal should probably do this itself, the threshold doesn't make sense for vorpal anyways.

[dthree]

Haven't looked far into it, but are you sure we aren't ignoring some problem?

Is this because the test instantiates at least 10 instances of Vorpal?

While developing it I only got this error when I messed something up on the prompt, and had to fix it.

---

I'm willing to believe the problem is in the repeated use of:

mute();
var fixture = '\n  fo is an invalid command. Maybe you mean:\n\n    foo\n    fooz\n    bar\n';
help.execSync('fo');
unmute();

[minhchu]

Let me check again.
I think there is a problem with this approach. For example:
I have a list of commands:

foo:command
foo:anothercommand
foo:awesomecommand

When I type foo, there will be no suggestions.

[dthree]

Yeah, that's all considered one word, and those have a huge edit distance from foo.

[zakhenry]

This can be greatly simplified with es6 syntax.

eg (untested!):

if (invalidString !== ''){

    let catchCmd = this.commands.find(cmd => cmd._catch);

    if (!catchCmd){

        let hints = this.commands.reduce((foundHints, cmd) => {
            if (leven(command, cmd._name) < 4) {
                foundHints.push(cmd._name);
            }
            return foundHints;
        }, []);

        if (hints.length){
            return `\n  ${command} is an invalid command. Maybe you mean:\n\n    ${hints.join('\n    ')}`;
        }
    }
}