ApplyRule functions

[aliang8]

TODO:

• Fix case in which replacement occurs multiple times in the result
• return the output instead of result
• Get path of multiple nodes (['args', [0,1,2])

[aliang8]

I'm not exactly sure why getPath has to be incorporated into _matchNode. Couldn't we leave it as a separate function? If not, then yes I am waiting for _matchNodes to be refactored.

[kevinbarabash]

I'm not exactly sure why getPath has to be incorporated into _matchNode.

In the case of

1 + --1 --> 1 + 1

The replacement node is 1. If we search for 1 in the output AST we could get either the first 1 or the second 1. matchNode returns the matchedNode which will be replaced. In this example there is only one --1 node which means finding the path for the matchedNode would work. There could be a more complicated scenario such as

(1 + --1) + (1 + --1)

Since matchNode only returns one of the --1 nodes we can't simply search for it again using traverse. We need to use the same search algorithm which matchNode used to find the node in the first place, namely _matchNode. Since _matchNode is traversing nodes already, we just need to keep track of the path it's traversing. The devil is in the details though and that code is pretty gnarly. I started working on it last night, but it's going to take some time to get it to a place that's good.

[aliang8]

Gnarly it is. I spent some time trying to go through it, but there was too much going on to follow. 😢

[aliang8]

https://github.com/semantic-math/math-rules/commit/c5b2d6ca27d685fac5b3c820754014781cb5b011 has this change.