sass, custom selectors based on parent - css

Question

I have the following mixins to make easy work with BEM syntax, sass 3.3.2 code:
=b($name)
.#{$name}
#content
=e($name)
&__#{$name}
#content
=m($name)
&--#{$name}
#content
+b(menu)
+e(item)
color: grey
+e(item)
+m(alert)
color: red
This gives me the desired result:
.menu__item {color: grey;}
.menu__item--alert {color: red;}
So this works pretty nice for element level modifiers, however when i want to have block level modifiers the problem begins:
+b(menu)
+m(theme-1)
+e(item)
color: blue
css output:
.menu--theme-1__item {color: blue;}
when the thing i really want is this:
.menu--theme-1 .menu__item {color: blue;}
So i need a way to check what the context of an element is, when the context is a block there is no problem but when is a modifier the syntax fails. I tried inside e mixin to take the parent selector as string, so when e parent is b it will not have the -- syntax, in the other way when his parent is m it will have the -- syntax, with that i could decide what syntax use for both context.
I didn't find a way to take the parent selector as a string and i think is not possible, is there a way to make this works?
Update
I found a not very straightforward solution with it works fine, it uses a context argument in the element mixin:
=e($name, $context:null)
#if $context
&
+b($context)
&__#{$name}
#content
#else
&__#{$name}
#content
Now i can call the mixin as follows:
+b(menu)
+m(theme-1)
+e(item, nav)
color: blue
getting:
.menu--theme-1 .menu__item {color: blue;}

Answer 1

Answering a 2 year old question - long shot :) But hopefully could help someone else as well.
So a more robust way would be to improve your Element mixin to check if the parent selector has a modifier.
So you would need 2 functions:
one to check if a selector contains a modifier
one to get the block name from that selector
#function _bem-selector-has-modifier($selector) {
$selector: _bem-selector-to-string($selector);
#if str-index($selector, $bem-modifier-separator) or str-index($selector, ':') {
#return true;
} #else {
#return false;
}
}
#function _bem-get-block-name($selector) {
$selector: _bem-selector-to-string($selector);
$modifier-separator: '--';
$modifier-start: str-index($selector, $modifier-separator) - 1;
#return str-slice($selector, 0, $modifier-start);
}
And then you just need to apply the check in your element mixin
$bem-element-separator: '__';
#mixin element($element) {
$selector: &;
#if _bem-selector-has-modifier($selector) {
$block: _bem-get-block-name($selector);
#at-root {
#{$selector} {
.#{$block + '__' + $element} {
#content;
}
}
}
} #else {
#at-root {
#{$selector +'__' + $element} {
#content;
}
}
}
}
So calling element('item') inside a modifier('with-modifier') should render a .block--with-modifier .block__item selector in your compiled CSS and you won't have to manually pass the context.
The code posted is SCSS, but the idea should be the same with SASS.