[css-cascade-4] wip first version of fetching steps for @import w3c#4838

Author: tabatkins

css-cascade-4/Overview.bs

@@ -27,19 +27,42 @@ Informative Classes: ex
 
 <pre class=link-defaults>
 spec:css-values-3; type: value; text:ex
+spec:css-color-4; type:property; text:color
 spec:css-conditional-3; type:at-rule; text:@media
-spec:mediaqueries-4; type:type; for:@media; text:all
-spec:mediaqueries-4; type:type; text:<media-query>
+spec:css-fonts-4; type:property;
+	text:font-family
+	text:font-style
+spec:mediaqueries-4;
+	type:type; text:<media-query>
+	type:value; text:all; for:@media
 spec:css2; type:property; text:display
 spec:css2; type:value; text:red
+spec:html; type:element; text:style
 </pre>
 
 <pre class=ignored-specs>
 spec:mediaqueries-5
 spec:css-values-4
-spec:css-fonts-4
 </pre>
 
+<style>
+/* Put nice boxes around each algorithm. */
+[data-algorithm]:not(.heading) {
+  padding: .5em;
+  border: thin solid #ddd; border-radius: .5em;
+  margin: .5em calc(-0.5em - 1px);
+}
+[data-algorithm]:not(.heading) > :first-child {
+  margin-top: 0;
+}
+[data-algorithm]:not(.heading) > :last-child {
+  margin-bottom: 0;
+}
+[data-algorithm] [data-algorithm] {
+    margin: 1em 0;
+}
+</style>
+
 <h2 id="intro">
 Introduction</h2>
 
@@ -239,6 +262,87 @@ Processing Stylesheet Imports</h3>
 
 	The <a>environment encoding</a> of an imported style sheet is the encoding of the style sheet that imported it. [[css-syntax-3]]
 
+	<div algorithm>
+		To <dfn export>fetch an @import</dfn>, given an ''@import'' rule |rule|:
+
+		1. If |rule| has a <<supports-condition>>,
+			and that condition is not true,
+			return nothing.
+
+		1. [=Parse a URL=] given |rule|'s URL,
+			relative to |rule|'s [=CSSRule/parent CSS style sheet's=] [=CSSStyleSheet/location=].
+
+			Issue: Make sure this is defined correctly,
+			drawing from the document when it's a <{style}> element, etc.
+
+			If that fails, then return nothing. Otherwise, let |url| be the [=resulting URL record=].
+
+		2. Let |request| be a new [=/request=]
+			whose [=request/URL=] is |url|,
+			[=request/destination=] is <code>"style"</code>,
+			[=request/mode=] is <code>"no-cors"</code>,
+			[=request/credentials mode=] is <code>"include"</code>,
+			and whose [=request/use-URL-credentials flag=] is set.
+
+		3. Set |request|'s client to ????
+
+			Issue: The Fetch spec doesn't provide any information about what a client is
+			or what it does,
+			so I have no idea of what to provide here.
+
+		4. Run the following steps [=in parallel=]:
+
+			1. Let |response| be the result of [=/fetching=] |request|.
+
+			2. Let |success| initially be true.
+
+			3. If |response| is a [=network error=]
+				or its [=response/status=] is not an [=ok status=],
+				set |success| to false.
+
+			4. If |rule|'s [=CSSRule/parent style sheet=] is in [=quirks mode=]
+				and |response| is [=CORS-same-origin=],
+				let |content type| be <code>"text/css"</code>.
+				Otherwise, let |content type| be the Content Type metadata of |response|.
+
+			5. If |content type| is not <code>"text/css"</code>,
+				return.
+
+			6. Issue: Do we wait for sub-imports to run now?
+				Need to explore this.
+
+			7. Let |global| be the result of [=finding the relevant global object for a stylesheet=]
+				given |rule|'s [=CSSRule/parent CSS style sheet=].
+
+			8. [=Queue a global task=],
+				given the [=networking task source=]
+				and |global|,
+				to [=process an imported stylesheet=]
+				given |rule|,
+				|success|,
+				and |response|.
+	</div>
+
+	<div algorithm>
+		To <dfn export>find the relevant global object for a stylesheet</dfn> given a CSS style sheet |stylesheet|:
+
+		1. If |stylesheet| has a [=CSSStyleSheet/parent CSS style sheet=],
+			return the result of [=finding the relevant global object for a stylesheet=]
+			given the [=CSSStyleSheet/parent CSS style sheet=].
+
+		2. If |stylesheet| has an [=CSSStyleSheet/owner node=],
+			return the [=CSSStyleSheet/owner node's=] [=relevant global object=].
+	</div>
+
+	<div algorithm>
+		To <dfn export>process an imported stylesheet</dfn>
+		given a parent rule |rule|,
+		a success flag |success|,
+		and a response |response|:
+
+		Issue: Create a stylesheet, assign it to the parent rule.
+	</div>
+
 <h3 id='content-type'>
 Content-Type of CSS Style Sheets</h3>