Fixed multiple interpolations in a property

[taneba]

related to #20 #21

This change enable to use multiple interpolations in a property at once.

  width: 20px;
  border: ${borderWidth} ${borderStyle} ${color};

is now translated to:

 width: 20px;
 border: $borderWidth -styled-mixin: borderStyle; -styled-mixin: color;

This changes above to:

 width: 20px;
 border: $borderWidth $borderStyle $color;

Cc: @mxstbr

[coveralls]

Coverage remained the same at 99.333% when pulling 65eae14 on taneba:master into 3c43e97 on styled-components:master.

[mxstbr]

I don't quite get why this is false now? That line is only whitespace? (same for all other lines) Why does that fix multiple interpolations?

[taneba]

I think isLastLineWhitespaceOnly() basically resolves the interpolation which includes property and value.

`${props => props.primary && css`background: #ffffff;`}`

in this case, isLastLineWhitespaceOnly returns true and then interleave() provides -styled-mixin: undefined;.

And when interpolation is value of any property:

`background: ${color}`

in this case, isLastLineWhitespaceOnly returns false and then interleave() provides background: $color;.

But what if the multiple interpolations in value?

`background: ${box} ${color}`

In this case, isLastLineWhitespaceOnly now returns true and then interleave() provides background: $box -styled-mixin: color; that causes syntax error.
It is because quasis[1] is ' '(between two interpolations).

So I change isLastLineWhitespaceOnly returns false when receive ' ' or '' , then above case returns true and interleave() provides background: $box $color.

Is this correct?

[ismay]

I don't really get how this fixes the interpolations either. If it does that's great but as I see it isLastLineWhitespaceOnly now returns the exact opposite of what I'd expect it to return.

I'd suggest refactoring some more so that the cause of the interpolations breaking is fixed without breaking isLastLineWhitespaceOnly's current behaviour, or at least keeping the behaviour in line with the function name.

[coveralls]

Coverage increased (+0.04%) to 99.375% when pulling 73ee889 on taneba:master into 3c43e97 on styled-components:master.

[taneba]

I've refactored by following suggestion by @ismay
How about this?

[ismay]

Thanks for the update @taneba. To me this looks good. If there aren't any objections I think this is ready for merging.

[coveralls]

Coverage increased (+0.04%) to 99.375% when pulling 217b008 on taneba:master into 55b94d9 on styled-components:master.

[ismay]

Thanks for the PR @taneba !