Defining 'assert' and 'formatter' functions externally about binary-parser HOT 4 CLOSED

Here's what I did in my use-case:

let outside = /* JS array of strings here */;
let formatter = (function formatter(i) { return outside[i] || i; });
let formatterstr = formatter.toString().replace("outside", JSON.stringify(outside));

parser = parser.uint8(name, {
    formatter: new Function("x", "return (" + formatterstr + ")(x)"),
});

it would be equivalent of doing:

parser = parser.uint8(name, {
    formatter: item => outside[item] || item
});

(if you come here from search, you may also be interested in my comment in #75)

from binary-parser.

Very interested in something for this. I'm in the process of replacing the old binary module with this one (which rocks BTW!), but the lack of the ability to use my own functions easily makes some work very cumbersome.

from binary-parser.

Could own functions be injected perhaps? Something along new Parser( [range] )?

from binary-parser.

I was going to raise a related issue but I won't because I think its root cause is the same as this one: binary-parser generates JS code that gets evaled, so that has profound implications on what you can do in an assert or formatter.

In my case I wasn't using external values at all. My formatter was simply (value) => value.readUIntLE(0, 3). But because I'm using TypeScript, the generated code referenced some external values so I got some pretty unhelpful errors like cov_1ux0jwh81w is not defined.

I think there should be a big warning about this.

@p0358's workaround worked for me, although I really wish I didn't have to do that:

{
  formatter: new Function('buf', 'return buf.readUIntLE(0, 3)'),
}

from binary-parser.