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Update documentation.
git-svn-id: http://htmlpurifier.org/svnroot/htmlpurifier/trunk@147 48356398-32a2-884e-a903-53898d9a118a
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Edward Z. Yang
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docs/spec.txt
113
docs/spec.txt
@ -56,111 +56,6 @@ all this functionality (or not written in HTML at all).
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The rest of this document is pending moving into their associated classes.
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== STAGE 4 - check nesting ==
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Status: B (table custom definition needs to be implemented)
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We know that the document is now well formed. The tokenizer should now take
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things in nodes: when you hit a start tag, keep on going until you get its
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ending tag, and then handle everything inside there. Fortunantely, no
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fancy recursion is necessary as going to the next node is as simple as
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scrolling to the next start tag.
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Suppose we have a node and encounter a problem with one of its children.
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Depending on the complexity of the rule, we will either delete the children,
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or delete the entire node itself.
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The simplest type of rule is zero or more valid elements, denoted like:
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( el1 | el2 | el3 )*
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The next simplest is with one or more valid elements:
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( li )+
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And then you have complex cases:
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table (caption?, (col*|colgroup*), thead?, tfoot?, (tbody+|tr+))
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map ((%block; | form | %misc;)+ | area+)
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html (head, body)
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head (%head.misc;,
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((title, %head.misc;, (base, %head.misc;)?) |
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(base, %head.misc;, (title, %head.misc;))))
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Each of these has to be dealt with. Case 1 is a joy, because you can zap
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as many as you want, but you'll never actually have to kill the node. Two
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and three need the entire node to be killed if you have a problem. This
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can be problematic, as the missing node might cause its parent node to now
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be incorrect. Granted, it's unlikely, and I'm fairly certain that HTML, let
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alone the simplified set I'm allowing will have this problem, but it's worth
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checking for.
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The way, I suppose, one would check for it, is whenever a node is removed,
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scroll to it's parent start, and re-evaluate it. Make sure you're able to do
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that with minimal code repetition.
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The most complex case can probably be done by using some fancy regexp
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expressions and transformations. However, it doesn't seem right that, say,
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a stray <b> in a <table> can cause the entire table to be removed. Depending
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on how much work we want to do, this will at least need a custom child
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definition, and at most require extra element bubbling capabilities to be
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added.
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--
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So, the way we define these cases should work like this:
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class ChildDef with validateChildren($children_tags)
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The function needs to parse into nodes, then into the regex array.
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It can result in one of three actions: the removal of the entire parent node,
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replacement of all of the original child tags with a new set of child
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tags which it returns, or no changes. They shall be denoted as, respectively,
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Remove entire parent node = false
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Replace child tags with this = array of tags
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No changes = true
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If we remove the entire parent node, we must scroll back to the parent of the
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parent.
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--
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Also, what do we do with elements if they're not allowed somewhere? We need
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some sort of default behavior. I reckon that we should be allowed to:
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1. Delete the node
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2. Translate it into text (not okay for areas that don't allow #PCDATA)
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3. Move the node to somewhere where it is okay
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What complicates the matter is that Firefox has the ability to construct
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DOMs and render invalid nestings of elements (like <b><div>asdf</div></b>).
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This means that behavior for stray pcdata in ul/ol is undefined. Behavior
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with data in a table gets bubbled to the start of the table (assuming
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that we actually custom-make the table child validation class).
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So... I say delete the node when PCDATA isn't allowed (or the regex is too
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complicated to determine where PCDATA could be inserted), and translate the node
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to text when PCDATA is allowed.
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--
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ins/del are allowed in block and inline content, but it is
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inappropriate to include block content within an ins element
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occurring in inline content. How would we fix this?
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== STAGE 4 - check attributes ==
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STATUS: F (currently implementing core/i18n)
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@ -261,11 +156,3 @@ These are the elements that only have %attrs and need an alignment transform
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----
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Prepend style transformations, as CSS takes precedence.
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== PART 5 - stringify ==
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Status: A+ (done completely!)
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Should be fairly simple as long as we delegate to appropriate functions.
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It's probably too much trouble to indent the stuff properly, so just output
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stuff raw.
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@ -3,8 +3,33 @@
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require_once 'HTMLPurifier/Strategy.php';
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require_once 'HTMLPurifier/Definition.php';
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// EXTRA: provide a mechanism for elements to be bubbled OUT of a node
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// or "Replace Nodes while including the parent nodes too"
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/**
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* Takes a well formed list of tokens and fixes their nesting.
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*
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* HTML elements dictate which elements are allowed to be their children,
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* for example, you can't have a p tag in a span tag. Other elements have
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* much more rigorous definitions: tables, for instance, require a specific
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* order for their elements. There are also constraints not expressible by
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* document type definitions, such as the chameleon nature of ins/del
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* tags and global child exclusions.
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*
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* The first major objective of this strategy is to iterate through all the
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* nodes (not tokens) of the list of tokens and determine whether or not
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* their children conform to the element's definition. If they do not, the
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* child definition may optionally supply an amended list of elements that
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* is valid or require that the entire node be deleted (and the previous
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* node rescanned).
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*
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* The second objective is to ensure that explicitly excluded elements of
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* an element do not appear in its children. Code that accomplishes this
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* task is pervasive through the strategy, though the two are distinct tasks
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* and could, theoretically, be seperated (although it's not recommended).
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*
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* @note Whether or not unrecognized children are silently dropped or
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* translated into text depends on the child definitions.
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*
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* @todo Enable nodes to be bubbled out of the structure.
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*/
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class HTMLPurifier_Strategy_FixNesting extends HTMLPurifier_Strategy
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{
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