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+[[!meta title="LibDOM/MinimalSubset"]]
+[[!meta author="Tlsa"]]
+[[!meta date="2012-03-31T09:51:42Z"]]
+
+
+[[!toc]]
+
+Overview
+--------
+
+This page enumerates the minimal subset required before it's worth
+integrating LibDOM with NetSurf's current engine:
+
+-   Core (Document, Element, Attribute, etc)
+-   EventTarget
+-   HTMLDocument, HTMLElement
+
+With the above interfaces, we can create an HTMLDocument instance per
+page and create a tree of HTMLElement instances for the content.
+Specialised HTMLElement subclasses can be added as required.
+
+Current Status
+--------------
+
+We now have all the above interfaces implemented (to some level of
+completeness). The example dom-structure-dump code is now capable of
+building an HTMLDocument using HTMLElement nodes and not leaking dynamic
+resources.
+
+Before integration can proceed, the following (at least) needs doing:
+
+-   <s>We need to invent an API to permit comparison of classes to
+    satisfy LibCSS' has\_class selection callback's needs.</s>
+    -   <s>Implement this API</s>.
+
+Once the above things are complete, integration may proceed as follows:
+
+-   <s>Remove the parser binding infrastructure from NetSurf's HTML
+    content handler and replace it with instantiation of LibDOM.</s>
+-   <s>Port the box tree constructor to the LibDOM API</s>
+-   <s>Fix up anything else that expects a libxml tree (save complete is
+    a likely candidate)</s>
+-   Construct form gadgets during box tree construction & register them
+    with the relevant DOM node
+
+In order to not have memory consumption issues and performance
+regressions, we also need to to:
+
+-   <s>Replace the hash table of EventListeners on an EventTarget with a
+    linked list, or similar -- the current implementation is both a
+    memory hog and broken.</s>
+-   <s>Replace the hash tables for Attributes attached to Element nodes
+    with linked lists, or similar. Again, this is currently wasting
+    memory for no benefit.</s>
+-   The Hubbub parser binding needs bringing into sync with the feature
+    set of the parser binding used in NetSurf. Feature parity must be
+    ensured to avoid regressions. Specifically:
+    -   <s>There needs to be a way to set the quirks mode of a document,
+        and retrieve it (i.e. specialised API on HTMLDocument)</s>
+    -   Form association needs implementing (i.e. specialised API on
+        HTMLFormElement)
+        -   Fix the mess that is/implement HTMLCollection,
+            HTMLOptionsCollection, HTMLFormElement, HTMLInputElement,
+            HTMLSelectElement, HTMLOptionElement, HTMLTextareaElement
+            (May get away with just HTMLCollection and HTMLFormElement
+            initially)
+            -   HTMLCollection can \*not\* assume that the collection
+                contents all live beneath a fixed root node
+                (particularly for form inputs)
+        -   Register form control elements with their form
+        -   Work out when to deregister them again
+    -   <s>Class/id attribute optimisations need retaining (see
+        below)</s>
+-   <s>HTMLElement needs to gain optimisations for class attributes
+    (i.e. pre-parse the value string into individual class identifiers).
+    See NetSurf's existing Hubbub binding for an approximation of what's
+    needed -- HTMLElement.setAttr(NS) is probably where this needs to
+    live (or possibly implement it in Element.setAttr(NS) or
+    Attr.setValue if we want the same behaviour for XML documents). </s>
+
+The above work can be done in parallel with the integration work but
+must be completed before a release can occur.
+
+To tidy things up before a libdom release, we need to do the following:
+
+-   Get speed back to pre-libdom.
+-   Sort out DOM events.
+-   Cleanup idea:
+    -   Every point in netsurf which uses libdom should ensure any time
+        it passes a pointer to a dom\_node pointer, it makes it NULL
+        first.
+    -   Then every API in libdom which takes a pointer to a dom\_node
+        pointer in order to return a dom\_node pointer, it asserts that
+        the pointer points to a NULL.
+    -   Then once we're sure that no user is asserting we alter that
+        assert to an "if not NULL, unref and set to NULL"
+    -   Then we can simplify callers, often into for() loops rather than
+        complex while loops with unreffings.
+