Getting (+-) instead of diff (tilde) when comparing arrays

[stripedpumpkin]

Hello. I find the following behavior (using Hashdiff 1.0.1) somewhat unexpected:

Hashdiff.diff(%w[a b c], %w[a b d])
=> [["-", "[2]", "c"], ["+", "[2]", "d"]]

Would not it be better to get

Hashdiff.diff(%w[a b c], %w[a b d])
=> [["~", "[2]", "c", "d"]]

?

Is there an option to get this behavior ?

Thanks for reading!

[liufengyun]

I think it's possible to achieve that. It will be much appreciated if someone can give a hand on this.

[krzysiek1507]

This does it:

Hashdiff.diff(%w[a b c], %w[a b d], use_lcs: false)

[liufengyun]

This does it:

Hashdiff.diff(%w[a b c], %w[a b d], use_lcs: false)

This is a workaround. I'm wondering if it is possible to make the algorithm smarter. Conceptually, it seems possible.

[krzysiek1507]

Does LCS algorithm have a strict specification?

[liufengyun]

Does LCS algorithm have a strict specification?

I don't think it has. The tests + implementation are the de facto spec. In this case, the algorithm performs better, it might be acceptable to users even if it differs from previous results.