[css-layout-api] Add in passing of data between layouts.

Author: bfgeek

css-layout-api/Overview.bs

@@ -36,12 +36,13 @@ spec:css-break-3; type:dfn; text:fragment
 spec:css-display-3; type:dfn; text:box
 spec:css-display-3; type:value; for:display; text:none
 spec:css-display-3; type:value; for:<display-inside>; text:grid
-spec:dom; type:dfn; for:/; text:element
-spec:infra; type:dfn; text:list
 spec:css-pseudo-4; type:selector; text:::after
 spec:css-pseudo-4; type:selector; text:::before
 spec:css-pseudo-4; type:selector; text:::first-letter
 spec:css-pseudo-4; type:selector; text:::first-line
+spec:dom; type:dfn; for:/; text:element
+spec:infra; type:dfn; text:list
+spec:html; type:dfn; for:global object; text:realm
 </pre>
 
 <pre class="anchors">
@@ -75,6 +76,9 @@ urlPrefix: https://drafts.csswg.org/css-break/#; type: dfn
     text: fragmentation break
 urlPrefix: https://www.w3.org/TR/CSS21/box.html#; type: dfn
     url: box-dimensions; text: box model edges
+urlPrefix: https://html.spec.whatwg.org/#; type: dfn
+    text: structuredserializeforstorage
+    text: structureddeserialize
 </pre>
 
 Introduction {#intro}
@@ -299,12 +303,11 @@ registerLayout('block-like', class {
             blockSize: availableBlockSize,
         });
 
-        let blockOffset = edges.all.blockStart;
-
         const childFragments = yeild children.map((child) => {
             return child.layoutNextFragment(childConstraintSpace);
         });
 
+        let blockOffset = edges.all.blockStart;
         for (let fragment of childFragments) {
             // Position the fragment in a block like manner, centering it in the
             // inline direction.
@@ -330,6 +333,10 @@ registerLayout('block-like', class {
 </pre>
 </div>
 
+A <a>layout API container</a> can communicate with other <a>layout API containers</a> by using the
+{{Fragment/data}} attribute. This is set by the {{FragmentResultOptions/data}} member in the
+{{FragmentResultOptions}} dictionary.
+
 The {{Fragment}}'s {{Fragment/breakToken}} specifies where the {{LayoutChild}} last fragmented. If
 the {{Fragment/breakToken}} is null the {{LayoutChild}} wont produce any more {{Fragment}}s for that
 token chain. The {{Fragment/breakToken}} can be passed to the {{LayoutChild/layoutNextFragment()}}
@@ -508,15 +515,13 @@ dictionary BreakTokenOptions {
     any data = null;
 };
 
-enum BreakType { "none", "inline", "inline-hyphen", "column", "page", "region" };
+enum BreakType { "none", "line", "column", "page", "region" };
 </pre>
 
-Issue: Fill out other inline type break types.
-
 A {{LayoutChild}} can produce multiple {{Fragment}}s. A {{LayoutChild}} may fragment in the block
 direction if a {{ConstraintSpace/blockFragmentationType}} is not none.  Additionally {{LayoutChild}}
-which represents <a>inline-level</a> content, may fragment line by line if the displayType is
-<code>"normal"</code>.
+which represents <a>inline-level</a> content, may fragment line by line if the <a for="layout
+definition">child display</a> (set by <code>childDisplay</code>) is <code>"normal"</code>.
 
 A subsequent {{Fragment}} is produced by using the previous {{Fragment}}'s {{Fragment/breakToken}}.
 This tells the <a>child layout</a> to produce a {{Fragment}} starting at the point encoded in the
@@ -537,7 +542,7 @@ resume the layout.
 
 <pre class="lang-javascript">
 registerLayout('basic-inline', class {
-    static displayType = 'normal';
+    static childDisplay = 'normal';
 
     *layout(space, children, styleMap, edges, breakToken) {
         // Resolve our inline size.
@@ -1137,6 +1142,7 @@ dictionary FragmentResultOptions {
     double inlineSize = 0;
     double blockSize = 0;
     sequence&lt;Fragment> childFragments = [];
+    any data = null;
     BreakTokenOptions breakToken = null;
 };
 
@@ -1402,7 +1408,10 @@ following steps:
         - The <a>fragmentation break</a> information set to |fragment|'s
             {{FragmentResultOptions/breakToken}}.
 
-            TODO: storage of the break token.
+        - Let |clonedData| be the result of invoking <a>StructuredSerializeForStorage</a> on
+            |fragment|'s {{FragmentResultOptions/data}}.
+
+            The user agent must store |clonedData| with the <a>fragment</a>.
 </div>
 
 ### Utility Algorithms ### {#utility-algorithms}
@@ -1520,7 +1529,9 @@ When the user agent wants to <dfn>run a generator</dfn> given |generator|, and |
                     <a>fragment</a> based on |layoutChild|, |childConstraintSpace|, and
                     |childBreakToken|.
 
-                5. Let |result| be a new {{Fragment}} with:
+                5. Let |targetRealm| be |generator|'s <a>Realm</a>.
+
+                6. Let |result| be a new {{Fragment}} with:
 
                     - {{Fragment/inlineSize}} being |internalFragment|'s <a>inline size</a>.
 
@@ -1533,6 +1544,10 @@ When the user agent wants to <dfn>run a generator</dfn> given |generator|, and |
                     - {{Fragment/breakToken}} being a new {{ChildBreakToken}} representing
                         |layoutChild|'s internal break token.
 
+                    - If |internalFragment| has a |clonedData| object stored with it, let
+                        {{Fragment/data}} being the result of
+                        <a>StructuredDeserialize</a>(|clonedData|, |targetRealm|), otherwise null.
+
             4. If |result| is null (that is neither of the above branches was taken), return
                 failure, and abort all these steps.