WIP: css variable calc minification

[MoritzLoewenstein]

Trying to implement the following cases:

1. calc with one argument, just keep inner token.

:root {
  --foo: calc(1px);
}

to

:root {
  --foo: 1px;
}

2. calc inside another calc, inner calc can be converted to parenthesis tokens.

:root {
  -foo: calc(1px + calc(1px + 2px));
}

to

:root {
  -foo: calc(1px + (1px + 2px));
}

3. simplify calc with multiple tokens of the same unit(px, deg etc)

:root {
  --foo: calc(1px + 2px);
}

to

:root {
  --foo: 3px;
}

4. simplify parenthesis expression with multiple tokens of the same unit(px, deg etc)

:root {
  --foo: calc(1px + (1px + 2px));
}

to

:root {
  --foo: calc(1px + 3px);
}

5. remove parenthesis around a single token inside a calc expression

:root {
  -foo: calc(1px + (3px));
}

to

:root {
  -foo: calc(1px + 3px);
}

[KTibow]

Is it possible to just take the logic from crate::values::calc and apply it to all properties? That would fix those cases.

[MoritzLoewenstein]

Possibly? If you want, you can try that approach, I was struggling to implement the more useful transforms because I dont have any rust experience anyways.

P.S.: Was also struggling with the general approach, how to make it "understand" the math expression without doing too much work.