Improve parsing logic for set_variable action types

[t-hale]

Fixes coinbase/mesh-cli#248

Motivation

To improve the parsing logic for set_variable action types

Solution

Before splitting the string to determine if the remaining line contains an arithmetic operator, we first check to see if the remaining line (sans ; suffix) is valid JSON

Open questions

Is there any possibility of arithmetic and JSON in the same line?

[shrimalmadhur]

Is there any possibility of arithmetic and JSON in the same line?

@t-hale Can you give me an example of what it will look like. I did not get this case?

[t-hale]

Is there any possibility of arithmetic and JSON in the same line?

@t-hale Can you give me an example of what it will look like. I did not get this case?

I take it by your confusion that it's not possible. I'm pretty new to the Rosetta DSL, so I wasn't sure if there was a possibility of these two cases math and set_variable occurring on the same line (this case would make the new logic I added in this PR invalid)

[t-hale]

@shrimalmadhur bumping this one back up

[shrimalmadhur]

@t-hale sorry about this delay. I think there's not possibility of JSON and math op in same line. so this should be good. I see some build failures - Possibly due to stale code. Could you please rebase? Thank you and again apologies for the delays.

[t-hale]

@t-hale sorry about this delay. I think there's not possibility of JSON and math op in same line. so this should be good. I see some build failures - Possibly due to stale code. Could you please rebase? Thank you and again apologies for the delays.

No worries - I've gone ahead and rebased