[css-shadow-parts-1] Rename 'part name map' to 'forwarded part name list' and switch its data model to a list of pairs for easier understanding. Link more terms. Restructure the 'part element list' algo a bit, shouldn't be a normative change.

Author: tabatkins

css-shadow-parts-1/Overview.bs

@@ -118,46 +118,38 @@ using the part and exportparts attributes.
 Each element has a <dfn export for="element">part name list</dfn>
 which is an [=ordered set=] of tokens.
 
-Each element has a <dfn export for="element">part name map</dfn>
-which is an <a>ordered map</a>,
-with keys that are [=strings=]
-(part names to expose to selectors outside this element)
-and values that are [=ordered sets=] of [=strings=]
-(part names that are selectable inside this element).
+Each element has a <dfn export for="element">forwarded part name list</dfn>
+which is a [=list=] of [=pairs=]
+containing a [=string=] for the inner part being forwarded
+and a [=string=] giving the name it will be exposed as.
 
 Each <a>shadow root</a> can be thought of as having a <dfn export for="shadow root">part element map</dfn>
 with keys that are [=strings=]
 and values that are [=ordered sets=] of elements.
 
-The part element map is described
+The [=part element map=] is described
 only as part of the algorithm for calculating style in this spec.
 It is not exposed via the DOM,
 as calculating it may be expensive
 and exposing it could allow access to elements inside closed shadow roots.
 
-Part element maps are affected by the addition and removal of elements
-and changes to the part name lists and part name maps of elements in the DOM.
-
-To calculate the part element map of a shadow root, |outerRoot|:
-
-<ol>
-  <li>For each element, |el| within |outerRoot|
-    <ol>
-      <li>For each |name| in |el|'s part name list,
-        add |el| to |outerRoot|'s part element map
-        under the key |name|.
-      <li>If |el| is a shadow host itself
-      then let |innerRoot| be its shadow root:
-        <ol>
-          <li>Calculate |innerRoot|'s part element map.
-          <li>For each key, |outerName|, in |el|'s part name map
-            and for each token |innerName| under that key
-            look up |innerName| in |innerRoot|'s shadow part element map
-            to get a (possibly empty) set of elements
-            and add these elements to |outerRoot|'s part element map under |outerName|
-        </ol>
-    </ol>
-</ol>
+[=Part element maps=] are affected by the addition and removal of elements
+and changes to the [=part name lists=] and [=forwarded part name lists=] of elements in the DOM.
+
+<div algorithm>
+	To <dfn>calculate the [=part element map=]</dfn> of a shadow root, |outerRoot|:
+
+	1. For each [=descendant=] |el| within |outerRoot|:
+		1. For each |name| in |el|'s [=part name list=],
+			[=list/append=] |el| to |outerRoot|'s [=part element map=][|name|].
+		2. If |el| is a [=shadow host=] itself
+			then let |innerRoot| be its shadow root.
+		3. [=calculate the part element map|Calculate=] |innerRoot|'s [=part element map=].
+		4. For each |innerName|/|outerName| in |el|'s [=forwarded part name list=]:
+			1. Let |innerParts| be |innerRoot|'s [=part element map=][|innerName|]
+			2. [=list/Append=] the elements in |innerParts|
+				to |outerRoot|'s [=part element map=][|outerName|]
+</div>
 
 
 Naming a Shadow Element: the <{html-global/part}> attribute {#part-attr}
@@ -201,10 +193,12 @@ Each part mapping is one of:
 
 <dl class=switch>
     : <code>innerIdent : outerIdent</code>
-    :: this adds «[ outerIdent → innerIdent ]» to el's <a>part name map</a>.
+    :: Adds <code>innerIdent</code>/<code>outerIdent</code> to el's <a>forwarded part name list</a>.
 
     : <code>ident</code>
-    :: Is shorthand for <code>ident : ident</code>.
+    :: Adds <code>ident</code>/<code>ident</code> to el's <a>forwarded part name list</a>.
+
+		Note: This is shorthand for <code>ident : ident</code>.
 
     : anything else
     :: Ignored for error-recovery / future compatibility.