Math parser should do more complicated parsing for spec templating

[ishubin]

At the moment galen allows this:

[1 - 9]
menu-item-@
    near: menu-item-@{+1} 0 px right

But what would be nice to have is more complex parsing like this:

[1 - 9]
menu-item-@
    near: menu-item-@{*2 + 1} 0 px right

Or reusing the @ symbol together with brackets

[1 - 9]
menu-item-@
    near: menu-item-@{+(@*2 - @/(@-1))} 0 px right

[alecky]

It would also be good to be able to Iterate based on a condition such as every odd, even element or every 3rd or 4th element

[3n+1]
menu-item-@
    near: menu-item-@{+1} 0 px right

[ishubin]

@alecky Awesome idea! Will work on the concept

[ishubin]

@alecky
I've just realized that this piece of string in Galen Specs "${.....}" - is actually a javascript executor. But the parsing is very stupid so you can't use '{' and '}' symbols inside it. I had to implement a quick solution for ${count("menu-item-*")} so I chose javascript. But here is the crazy thing I tried and it worked:

====================
menu-item-*     css #menu li a
====================

[ ${var a = 2, b = 4; a + " - " + b;} ]
menu-item-@
    width: 100px

In the end that gave me this [ 2 - 4 ]. This means that in theory we can do much more advanced stuff ourselves without waiting for additional function to appear in Galen. But not at the moment as this javascript executor is very limited and doesn't support load("myscript.js") function. So thats what I am going to pick up with this issue. Its hanging for a long time but I just completely forgot about this solution.

So here is how it could look in the end

====================
menu-item-*     css #menu li a
====================

@@ import myscript.js

# or like this

${load("myscript.js")}

[ ${everyEven("menu-item-*")} ]
menu-item-@
    width: 100px

And here is the content of myscript.js:

this.everyEven = function (namePattern) {
    var amountOfAllObjects = count(namePattern);

    var arr = [];

    for (var i=2;i<amountOfAllObjects.length; i+=2) {
        arr.push(i);
    }

    return arr.join(",");
};

[ishubin]

Ready in release-1.4 branch

[ishubin]

Implemented two things Javascript in specs and complex operations in @{ } expression.
Will work like this :

[ 1 - 10]
object-@
   above: object-@{index + 2 * (index - 1)}