Added field of boolean type to config for enabling/disabling of implicit multiplication.

[nicholasnbg]

Issue: #1334

It's my first contribution to the project, please let me know if this is wrong, or if I've missed something.

[ericman314]

Could just leave the implicitMultiplication option undocumented until the logic is implemented in the parser.

[ericman314]

If you do want to implement the full logic of enabling/disabling implicit multiplication, this can help you get started.

The file you should be editing is https://github.com/josdejong/mathjs/blob/develop/src/expression/parse.js. The parser is structured as a chain of functions that get called recursively in order of increasing operator precedence. Each function matches its own part of the expression, then calls the next function.

Here is a small part of the chain:

• parseAddSubtract(), which calls:
• parseMultiplyDivide(), which calls:
• parseImplicitMultiplication(), which calls:
• parseRule2(), which calls:
• parseUnary(), etc.

In order to disable implicit multiplication, the functions parseImplicitMultiplication() and parseRule2() would need to be skipped:

• parseAddSubtract(), which calls:
• parseMultiplyDivide(), which calls:
• parseUnary(), etc.

Hope that helps :-)

[harrysarson]

Out of curiosity: what does parseRule2() do?

[ericman314]

@harrysarson it is in reference to this: #792 (comment)

[nicholasnbg]

@ericman314 I'm happy to implement it as well, would you like that to be in this PR or a separate one?

[ericman314]

Thanks! I think you're good to do it in this PR.

[josdejong]

Thanks Nick! I agree with Eric, the actual enabling/disabling of implicit multiplication in parse.js can be part of this PR, these two parts are strongly dependent on each other.

Maybe change the description of the option to something like "Enable implicit multiplication in the expression parser. Default value is true".

Please don't forget to add some unit tests :)

[josdejong]

@nicholasnbg I see this PR is still open. Do you still plan on implementing this new option? It would be a nice addition.