Way to end `eachMapping` early?

[mheiber]

It doesn't look like there is a way to end eachMapping early.
We have some code that searches through the mappings for a 'bad' mapping. We want to exit the function early at that point, instead of continuing through all the other mappings.

Would you accept a PR to add this functionality? Could be implemented as:

• a done callback
• or return false to stop the iteration
• or return END_ITERATION where END_ITERATION is defined as a special value {}. This has better backwards-compatibility than returning false.

[adjenks]

In the meantime, a hack could be to throw an exception and then catch it. Or just do no operation when the line isn't the one you want. It's similar to a forEach loop in javascript, there's no way to exit except for throwing an error.
If you're looking for a specific line though, I'm not sure why you didn't use "originalPositionFor", it returns the same info for one particular line.

[mheiber]

closing, see @adjenks ' suggestions