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246 lines
9.3 KiB
Plaintext
246 lines
9.3 KiB
Plaintext
---
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title: Selector Functions
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---
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## Selector Values
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These functions inspect and manipulate selectors. Whenever they return a
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selector, it's always a comma-separated [list][] (the selector list) that
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contains space-separated lists (the complex selectors) that contain [unquoted
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strings][] (the compound selectors). For example, the selector `.main
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aside:hover, .sidebar p` would be returned as:
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[list]: ../values/lists
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[unquoted strings]: ../values/strings#unquoted
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```scss
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@debug ((unquote(".main") unquote("aside:hover")),
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(unquote(".sidebar") unquote("p")));
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// .main aside:hover, .sidebar p
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```
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Selector arguments to these functions may be in the same format, but they can
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also just be normal strings (quoted or unquoted), or a combination. For example,
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`".main aside:hover, .sidebar p"` is a valid selector argument.
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<% function 'is-superselector($super, $sub)', returns: 'boolean' do %>
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Returns whether the selector `$super` matches all the elements that the
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selector `$sub` matches.
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Still returns true even if `$super` matches *more* elements than `$sub`.
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The `$super` and `$sub` selectors may contain [placeholder selectors][], but
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not [parent selectors][].
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[placeholder selectors]: ../style-rules/placeholder-selectors
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[parent selectors]: ../style-rules/parent-selector
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<% example(autogen_css: false) do %>
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@debug is-superselector("a", "a.disabled"); // true
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@debug is-superselector("a.disabled", "a"); // false
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@debug is-superselector("a", "sidebar a"); // true
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@debug is-superselector("sidebar a", "a"); // false
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@debug is-superselector("a", "a"); // true
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===
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@debug is-superselector("a", "a.disabled") // true
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@debug is-superselector("a.disabled", "a") // false
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@debug is-superselector("a", "sidebar a") // true
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@debug is-superselector("sidebar a", "a") // false
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@debug is-superselector("a", "a") // true
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<% end %>
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<% end %>
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<% function 'selector-append($selectors...)', returns: 'selector' do %>
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Combines `$selectors` without [descendant combinators][]—that is, without
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whitespace between them.
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[descendant combinators]: https://developer.mozilla.org/en-US/docs/Web/CSS/Descendant_selectors
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If any selector in `$selectors` is a selector list, each complex selector is
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combined separately.
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The `$selectors` may contain [placeholder selectors][], but not [parent
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selectors][].
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[placeholder selectors]: ../style-rules/placeholder-selectors
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[parent selectors]: ../style-rules/parent-selector
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See also [`selector-nest()`](#selector-nest).
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<% example(autogen_css: false) do %>
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@debug selector-append("a", ".disabled"); // a.disabled
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@debug selector-append(".accordion", "__copy"); // .accordion__copy
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@debug selector-append(".accordion", "__copy, __image");
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// .accordion__copy, .accordion__image
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===
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@debug selector-append("a", ".disabled") // a.disabled
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@debug selector-append(".accordion", "__copy") // .accordion__copy
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@debug selector-append(".accordion", "__copy, __image")
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// .accordion__copy, .accordion__image
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<% end %>
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<% end %>
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<% function 'selector-extend($selector, $extendee, $extender)', returns: 'selector' do %>
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Extends `$selector` as with the [`@extend` rule][].
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[`@extend` rule]: ../at-rules/extend
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Returns a copy of `$selector` modified with the following `@extend` rule:
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```scss
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#{$extender} {
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@extend #{$extendee};
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}
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```
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In other words, replaces all instances of `$extendee` in `$selector` with
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`$extendee, $extender`. If `$selector` doesn't contain `$extendee`, returns it
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as-is.
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The `$selector`, `$extendee`, and `$extender` selectors may contain
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[placeholder selectors][], but not [parent selectors][].
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[placeholder selectors]: ../style-rules/placeholder-selectors
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[parent selectors]: ../style-rules/parent-selector
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See also [`selector-replace()`](#selector-replace).
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<% example(autogen_css: false) do %>
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@debug selector-extend("a.disabled", "a", ".link"); // a.disabled, .link.disabled
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@debug selector-extend("a.disabled", "h1", "h2"); // a.disabled
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@debug selector-extend(".guide .info", ".info", ".content nav.sidebar");
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// .guide .info, .guide .content nav.sidebar, .content .guide nav.sidebar
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===
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@debug selector-extend("a.disabled", "a", ".link") // a.disabled, .link.disabled
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@debug selector-extend("a.disabled", "h1", "h2") // a.disabled
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@debug selector-extend(".guide .info", ".info", ".content nav.sidebar")
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// .guide .info, .guide .content nav.sidebar, .content .guide nav.sidebar
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<% end %>
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<% end %>
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<% function 'selector-nest($selectors...)', returns: 'selector' do %>
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Combines `$selectors` as though they were nested within one another in the
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stylesheet.
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The `$selectors` may contain [placeholder selectors][]. Unlike other selector
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functions, all of them except the first may also contain [parent selectors][].
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[placeholder selectors]: ../style-rules/placeholder-selectors
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[parent selectors]: ../style-rules/parent-selector
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See also [`selector-append()`][].
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<% example(autogen_css: false) do %>
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@debug selector-nest("ul", "li"); // ul li
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@debug selector-nest(".alert, .warning", "p"); // .alert p, .warning p
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@debug selector-nest(".alert", "&:hover"); // .alert:hover
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@debug selector-nest(".accordion", "&__copy"); // .accordion__copy
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===
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@debug selector-nest("ul", "li") // ul li
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@debug selector-nest(".alert, .warning", "p") // .alert p, .warning p
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@debug selector-nest(".alert", "&:hover") // .alert:hover
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@debug selector-nest(".accordion", "&__copy") // .accordion__copy
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<% end %>
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<% end %>
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<% function 'selector-parse($selector)', returns: 'selector' do %>
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Returns `$selector` in the [selector value](#selector-values) format.
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<% example(autogen_css: false) do %>
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@debug selector-parse(".main aside:hover, .sidebar p");
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// ((unquote(".main") unquote("aside:hover")),
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// (unquote(".sidebar") unquote("p")))
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===
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@debug selector-parse(".main aside:hover, .sidebar p")
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// ((unquote(".main") unquote("aside:hover")),
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// (unquote(".sidebar") unquote("p")))
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<% end %>
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<% end %>
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<% function 'selector-replace($selector, $original, $replacement)', returns: 'selector' do %>
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Returns a copy of `$selector` with all instances of `$original` replaced by
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`$replacement`.
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This uses the [`@extend` rule][]'s [intelligent unification][] to make sure
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`$replacement` is seamlessly integrated into `$selector`. If `$selector`
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doesn't contain `$original`, returns it as-is.
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[`@extend` rule]: ../at-rules/extend
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[intelligent unification]: ../at-rules/extend#how-it-works
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The `$selector`, `$original`, and `$replacement` selectors may contain
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[placeholder selectors][], but not [parent selectors][].
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[placeholder selectors]: ../style-rules/placeholder-selectors
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[parent selectors]: ../style-rules/parent-selector
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See also [`selector-extend()`](#selector-extend).
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<% example(autogen_css: false) do %>
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@debug selector-replace("a.disabled", "a", ".link"); // .link.disabled
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@debug selector-replace("a.disabled", "h1", "h2"); // a.disabled
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@debug selector-replace(".guide .info", ".info", ".content nav.sidebar");
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// .guide .content nav.sidebar, .content .guide nav.sidebar
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===
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@debug selector-replace("a.disabled", "a", ".link") // .link.disabled
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@debug selector-replace("a.disabled", "h1", "h2") // a.disabled
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@debug selector-replace(".guide .info", ".info", ".content nav.sidebar")
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// .guide .content nav.sidebar, .content .guide nav.sidebar
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<% end %>
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<% end %>
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<% function 'selector-unify($selector1, $selector2)', returns: 'selector | null' do %>
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Returns a selector that matches only elements matched by *both* `$selector1`
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and `$selector2`.
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Returns `null` if `$selector1` and `$selector2` don't match any of the same
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elements, or if there's no selector that can express their overlap.
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Like selectors generated by the [`@extend` rule][], the returned selector
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isn't guaranteed to match *all* the elements matched by both `$selector1` and
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`$selector2` if they're both complex selectors.
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[`@extend` rule]: ../at-rules/extend#html-heuristics
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<% example(autogen_css: false) do %>
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@debug selector-unify("a", ".disabled"); // a.disabled
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@debug selector-unify("a.disabled", "a.outgoing"); // a.disabled.outgoing
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@debug selector-unify("a", "h1"); // null
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@debug selector-unify(".warning a", "main a"); // .warning main a, main .warning a
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===
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@debug selector-unify("a", ".disabled") // a.disabled
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@debug selector-unify("a.disabled", "a.outgoing") // a.disabled.outgoing
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@debug selector-unify("a", "h1") // null
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@debug selector-unify(".warning a", "main a") // .warning main a, main .warning a
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<% end %>
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<% end %>
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<% function 'simple-selectors($selector)', returns: 'list' do %>
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Returns a list of simple selectors in `$selector`.
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The `$selector` must be a single string that contains a compound selector.
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This means it may not contains combinators (including spaces) or commas.
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The returned list is comma-separated, and the simple selectors are unquoted
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strings.
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<% example(autogen_css: false) do %>
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@debug compound-selectors("a.disabled"); // a, .disabled
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@debug compound-selectors("main.blog:after"); // main, .blog, :after
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===
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@debug compound-selectors("a.disabled") // a, .disabled
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@debug compound-selectors("main.blog:after") // main, .blog, :after
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<% end %>
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<% end %>
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