The input to the tree construction stage is a sequence of tokens from
the tokenisation stage. The tree construction
stage is associated with a DOM Document object when a parser
is created. The "output" of this stage consists of dynamically modifying
or extending that document's DOM tree.
Tree construction passes through several phases. Initially, UAs must act according to the steps described as being those of the initial phase.
This specification does not define when an interactive user agent has to
render the Document available to the user, or when it has to
begin accepting user input.
When the steps below require the UA to append a
character to a node, the UA must collect it and all subsequent
consecutive characters that would be appended to that node, and insert one
Text node whose data is the concatenation of all those
characters.
DOM mutation events must not fire for changes
caused by the UA parsing the document. (Conceptually, the parser is not
mutating the DOM, it is constructing it.) This includes the parsing of any
content inserted using document.write() and document.writeln() calls.
[DOM3EVENTS]
Not all of the tag names mentioned below are conformant tag names in this specification; many are included to handle legacy content. They still form part of the algorithm that implementations are required to implement to claim conformance.
The algorithm described below places no limit on the depth of the DOM tree generated, or on the length of tag names, attribute names, attribute values, text nodes, etc. While implementators are encouraged to avoid arbitrary limits, it is recognised that practical concerns will likely force user agents to impose nesting depths.
Initially, the tree construction stage must handle each token emitted from the tokenisation stage as follows:
This specification does not define how to handle this case. In particular, user agents may ignore the entirety of this specification altogether for such documents, and instead invoke special parse modes with a greater emphasis on backwards compatibility.
Browsers in particular have generally used DOCTYPE-based sniffing to invoke an "alternative conformance mode" known as quirks mode on certain documents. In this mode, emphasis is put on legacy compatibility rather than on standards compliance. This specification takes no position on this behaviour; documents without DOCTYPEs or with DOCTYPEs that do not conform to the syntax allowed by this specification are considered to be out of scope of this specification.
As far as parsing goes, the quirks I know of are:
<script><!-- document.write('</script>'); --></script>
</br> and </p> do
magical things.
p can contain table
Maybe we should just adopt all those and be done with it. One parsing mode to rule them all. Or legitimise/codify the quirks mode parsing in some way.
Would be interesting to do a search to see how many pages hit each of the above.
Append a DocumentType node to the Document
node, with the name attribute set to the name
given in the DOCTYPE token (which will be "HTML"), and the other
attributes specific to DocumentType objects set to null,
empty lists, or the empty string as appropriate.
Then, switch to the root element phase of the tree construction stage.
Append that character
to the Document node.
After the initial phase, as each token is emitted from the tokenisation stage, it must be processed as described in this section.
Parse error. Ignore the token.
Append a Comment node to the Document object
with the data attribute set to the data given in
the comment token.
Append that character
to the Document node.
Create an HTMLElement node
with the tag name html, in the HTML namespace. Append it to the
Document object. Switch to the main
phase and reprocess the current token.
Should probably make end tags be ignored, so that "</head><!-- --><html>" puts the comment befor the root node (or should we?)
The root element can end up being removed from the Document
object, e.g. by scripts; nothing in particular happens in such cases,
content continues being appended to the nodes as described in the next
section.
After the root element phase, each token emitted from the tokenisation stage must be processed as described in this section. This is by far the most involved part of parsing an HTML document.
The tree construction stage in this phase has several pieces of state: a
stack of open elements, a list of
active formatting elements, a head element pointer, a form element pointer, and an insertion mode.
We could just fold insertion modes and phases into one concept (and duplicate the two rules common to all insertion modes into all of them).
Initially the stack of open elements contains just
the html root element node created in the
last phase before
switching to this phase (or, in the innerHTML case, the html element created to represent the element
whose innerHTML attribute is being set). That's
the topmost node of the stack. It never gets popped off the stack. (This
stack grows downwards.)
The current node is the bottommost node in this stack.
Elements in the stack fall into the following categories:
The following HTML elements have varying levels of special parsing
rules: address, area, base,
basefont, bgsound, blockquote, body, br,
center, col, colgroup, dd,
dir, div, dl, dt, embed, fieldset,
form, frame, frameset, h1, h2, h3, h4, h5, h6, head, hr,
iframe,
image,
img, input,
isindex, li, link, listing, menu, meta,
noembed, noframes, noscript, ol,
optgroup, option, p, param,
plaintext, pre, script, select,
spacer, style, tbody, textarea, tfoot, thead, title, tr,
ul, and wbr.
The following HTML elements introduce new scopes for various parts of the
parsing: button, caption, html, marquee, object, table, td and
th.
The following HTML elements are those that end up in the list of active formatting elements: a, b,
big, em, font, i,
nobr, s, small, strike, strong, tt, and u.
All other elements found while parsing an HTML document.
Still need to add these new elements to the lists:
event-source, section, nav,
article, aside, header,
footer, datagrid, command
The stack of open elements is said to have an element in scope or have an element in table scope when the following algorithm terminates in a match state:
Initialise node to be the current node (the bottommost node of the stack).
If node is the target node, terminate in a match state.
Otherwise, if node is a table element, terminate in a failure state.
Otherwise, if the algorithm is the "has an element in scope" variant (rather than the "has an element in table scope" variant), and node is one of the following, terminate in a failure state:
Otherwise, if node is an html element, terminate in a failure state.
(This can only happen if the node is the topmost
node of the stack of open elements, and prevents
the next step from being invoked if there are no more elements in the
stack.)
Otherwise, set node to the previous entry in the stack of open elements and return to step 2. (This will never fail, since the loop will always terminate in the previous step if the top of the stack is reached.)
Nothing happens if at any time any of the elements in the stack of open elements are moved to a new location in,
or removed from, the Document tree. In particular, the stack
is not changed in this situation. This can cause, amongst other strange
effects, content to be appended to nodes that are no longer in the DOM.
In some cases (namely, when closing misnested formatting elements), the stack is manipulated in a random-access fashion.
Initially the list of active formatting elements is empty. It is used to handle mis-nested formatting element tags.
The list contains elements in the formatting
category, and scope markers. The scope markers are inserted when entering
buttons, object elements, marquees,
table cells, and table captions, and are used to prevent formatting from
"leaking" into tables, buttons, object
elements, and marquees.
When the steps below require the UA to reconstruct the active formatting elements, the UA must perform the following steps:
This has the effect of reopening all the formatting elements that were opened in the current body, cell, or caption (whichever is youngest) that haven't been explicitly closed.
The way this specification is written, the list of active formatting elements always consists of elements in chronological order with the least recently added element first and the most recently added element last (except for while steps 8 to 11 of the above algorithm are being executed, of course).
When the steps below require the UA to clear the list of active formatting elements up to the last marker, the UA must perform the following steps:
When the steps below require the UA to create an element for a token, the UA must
create a node implementing the interface appropriate for the element type
corresponding to the tag name of the token (as given in the section of
this specification that defines that element, e.g. for an a element it would be the HTMLAnchorElement interface), with
the tag name being the name of that element, with the node being in the HTML namespace, and with the attributes on the
node being those given in the given token.
When the steps below require the UA to insert an HTML element for a token, the UA must first create an element for the token, and then append this node to the current node, and push it onto the stack of open elements so that it is the new current node.
The steps below may also require that the UA insert an HTML element in a particular place, in which case the UA must create an element for the token and then insert or append the new node in the location specified. (This happens in particular during the parsing of tables with invalid content.)
The interface appropriate for an element that is not defined in this
specification is HTMLElement.
When the steps below require the UA to generate implied
end tags, then, if the current node is a
dd element, a dt element, an li
element, a p element, a td element, a th
element, or a tr element, the UA must act
as if an end tag with the respective tag name had been seen and then generate implied end tags again.
The step that requires the UA to generate implied end tags but lists an element to exclude from the process, then the UA must perform the above steps as if that element was not in the above list.
Initially the head element
pointer and the form
element pointer are both null.
Once a head element has been parsed
(whether implicitly or explicitly) the head element pointer gets set to point to this node.
The form element
pointer points to the last form element that was opened
and whose end tag has not yet been seen. It is used to make form controls
associate with forms in the face of dramatically bad markup, for
historical reasons.
Initially the insertion mode is "before head". It can change to "in head", "after head", "in body", "in table", "in caption", "in column group", "in table body", "in row", "in cell", "in select", "after body", "in frameset", and "after frameset" during the course of the parsing, as described below. It affects how certain tokens are processed.
If the tree construction stage is switched from the main phase to the trailing end phase and back again, the various pieces of state are not reset; the UA must act as if the state was maintained.
When the steps below require the UA to reset the insertion mode appropriately, it means the UA must follow these steps:
innerHTML
attribute is being set is neither a td
element nor a th element, then set node to the element whose innerHTML
attribute is being set. (innerHTML
case)
select element, then
switch the insertion mode to "in select" and
abort these steps. (innerHTML
case)
td or
th element, then switch the insertion mode to "in cell" and abort these steps.
tr
element, then switch the insertion mode to "in row" and abort these
steps.
tbody, thead,
or tfoot element, then switch the insertion mode to "in table body" and abort these
steps.
caption element, then switch the insertion mode to "in caption" and abort these steps.
colgroup element, then switch the insertion mode to "in column group" and abort
these steps. (innerHTML case)
table element, then switch the insertion mode to "in table" and abort these steps.
head
element, then switch the insertion mode to "in body" ("in body"! not
"in head"!)
and abort these steps. (innerHTML
case)
body element, then switch the insertion mode to "in body" and abort these steps.
frameset element, then
switch the insertion mode to "in frameset"
and abort these steps. (innerHTML
case)
html element, then: if the head element pointer is
null, switch the insertion mode to "before head",
otherwise, switch the insertion mode to "after head". In
either case, abort these steps. (innerHTML case)innerHTML case)
Tokens in the main phase must be handled as follows:
Parse error. Ignore the token.
If this start tag token was not the first start tag token, then it is a parse error.
For each attribute on the token, check to see if the attribute is already present on the top element of the stack of open elements. If it is not, add the attribute and its corresponding value to that element.
If there are more than two nodes on the stack of open
elements, or if there are two nodes but the second node is not a
body node, this is a parse error.
Otherwise, if the parser was originally created in order to handle the
setting of an element's innerHTML attribute, and there's more than
one element in the stack of open elements, and the
second node on the stack of open elements is not a
body node, then this is a parse error. (innerHTML case)
This fails because it doesn't imply HEAD and BODY tags. We should probably expand out the insertion modes and merge them with phases and then put the three things here into each insertion mode instead of trying to factor them out so carefully.
Depends on the insertion mode:
Handle the token as follows:
Append the character to the current node.
Append a Comment node to the current node with the data attribute set to the data given in the comment
token.
Create an element for the token.
Set the head element
pointer to this new element node.
Append the new element to the current node and push it onto the stack of open elements.
Change the insertion mode to "in head".
Act as if a start tag token with the tag name "head" and no attributes had been seen, then reprocess the current token.
This will result in a head element being generated, and with the
current token being reprocessed in the "in head" insertion mode.
Act as if a start tag token with the tag name "head" and no attributes had been seen, then reprocess the current token.
Parse error. Ignore the token.
Act as if a start tag token with the tag name "head" and no attributes had been seen, then reprocess the current token.
This will result in an empty head element being generated, with the
current token being reprocessed in the "after head" insertion mode.
Handle the token as follows.
The rules for handling "title", "style", and "script" start tags are similar, but not identical.
It is possible for the tree
construction stage's main phase to be in the "in head" insertion mode without the current node being a head element, e.g. if a head end tag is immediately followed by a
meta start tag.
Append the character to the current node.
Append a Comment node to the current node with the data attribute set to the data given in the comment
token.
Create an element for the token.
Append the new element to the node pointed to by the head element pointer,
or, if that is null (innerHTML
case), to the current node.
Switch the tokeniser's content model flag to the RCDATA state.
Then, collect all the character tokens that the tokeniser returns until it returns a token that is not a character token.
If this process resulted in a collection of character tokens,
append a single Text node to the title element node whose contents is the
concatenation of all those tokens' characters.
The tokeniser's content model flag will have switched back to the PCDATA state.
If the next token is an end tag token with the tag name "title", ignore it. Otherwise, this is a parse error.
Create an element for the token.
Append the new element to the current
node, unless the insertion mode is "in head" and the
head element
pointer is not null, in which case append it to the node pointed
to by the head element
pointer. .
Switch the tokeniser's content model flag to the CDATA state.
Then, collect all the character tokens that the tokeniser returns until it returns a token that is not a character token, or until it stops tokenising.
If this process resulted in a collection of character tokens,
append a single Text node to the style element node whose contents is the
concatenation of all those tokens' characters.
The tokeniser's content model flag will have switched back to the PCDATA state.
If the next token is an end tag token with the tag name "style", ignore it. Otherwise, this is a parse error.
Create an element for the token.
Mark the element as being "parser-inserted". This ensures that, if
the script is external, any document.write() calls in the
script will execute in-line, instead of blowing the document away,
as would happen in most other cases.
Switch the tokeniser's content model flag to the CDATA state.
Then, collect all the character tokens that the tokeniser returns until it returns a token that is not a character token, or until it stops tokenising.
If this process resulted in a collection of character tokens,
append a single Text node to the script element node whose contents is the
concatenation of all those tokens' characters.
The tokeniser's content model flag will have switched back to the PCDATA state.
If the next token is not an end tag token with the tag name
"script", then this is a parse error; mark the
script element as "already executed". Otherwise, the token is the
script element's end tag, so
ignore it.
If the parser was originally created in order to handle the
setting of a node's innerHTML attribute, then mark the
script element as "already executed", and skip the rest of the
processing described for this token (including the part below where
"scripts that will execute as soon as the
parser resumes" are executed). (innerHTML case)
Marking the script
element as "already executed" prevents it from executing when it is
inserted into the document a few paragraphs below. Scripts missing
their end tags and scripts that were inserted using innerHTML
aren't executed.
Let the old insertion point have the same value as the current insertion point. Let the insertion point be just before the next input character.
Append the new element to the current
node, unless the insertion mode is "in head" and the
head element
pointer is not null, in which case append it to the node pointed
to by the head element
pointer.
Special processing
occurs when a script element is inserted into a
document that might cause some script to execute, which might
cause new
characters to be inserted into the tokeniser.
Let the insertion point have the value of the old insertion point. (In other words, restore the insertion point to the value it had before the previous paragraph. This value might be the "undefined" value.)
At this stage, if there is a script that will execute as soon as the parser resumes, then:
document.write():
Abort the processing of any nested invokations of the tokeniser, yielding control back to the caller. (Tokenisation will resume when the caller returns to the "outer" tree construction stage.)
Follow these steps:
Let the script be the script that will execute as soon as the parser resumes. There is no longer a script that will execute as soon as the parser resumes.
Pause until the script has completed loading.
Let the insertion point be just before the next input character.
Let the insertion point be undefined again.
If there is once again a script that will execute as soon as the parser resumes, then repeat these steps from step 1.
Create an element for the token.
Append the new element to the node pointed to by the head element pointer,
or, if that is null (innerHTML
case), to the current node.
If the current node is a head element, pop the current node off the stack of
open elements. Otherwise, this is a parse
error.
Change the insertion mode to "after head".
Act as described in the "anything else" entry below.
Parse error. Ignore the token.
If the current node is a head element, act as if an end tag token
with the tag name "head" had been seen.
Otherwise, change the insertion mode to "after head".
Then, reprocess the current token.
In certain UAs, some elements don't trigger the "in body" mode straight away, but instead get put into the head. Do we want to copy that?
Handle the token as follows:
Append the character to the current node.
Append a Comment node to the current node with the data attribute set to the data given in the comment
token.
Insert a
body element for the token.
Change the insertion mode to "in body".
Insert a
frameset element for the token.
Change the insertion mode to "in frameset".
Parse error. Switch the insertion mode back to "in head" and reprocess the token.
Act as if a start tag token with the tag name "body" and no attributes had been seen, and then reprocess the current token.
Handle the token as follows:
Append a Comment node to the current node with the data attribute set to the data given in the comment
token.
Process the token as if the insertion mode had been "in head".
Parse error. Process the token as if the insertion mode had been "in head".
If the second element on the stack of open
elements is not a body
element, or, if the stack of open elements has
only one node on it, then ignore the token. (innerHTML case)
Otherwise, for each attribute on the token, check to see if the
attribute is already present on the body element (the second element) on the stack of open elements. If it is not, add the
attribute and its corresponding value to that element.
If the second element in the stack of open
elements is not a body
element, this is a parse error. Ignore the
token. (innerHTML case)
Otherwise:
this needs to handle closing of implied elements, but without closing them
If the current node is not the body element, then this is a parse error.
Change the insertion mode to "after body".
Act as if an end tag with tag name "body" had been seen, then, if that token wasn't ignored, reprocess the current token.
The fake end tag token here can only be ignored in the
innerHTML case.
If the stack of open elements has a p
element in scope, then act as if an end tag with the tag name
p had been seen.
Insert an HTML element for the token.
If the stack of open elements has a p
element in scope, then act as if an end tag with the tag name
p had been seen.
Insert an HTML element for the token.
If the next token is a U+000A LINE FEED (LF) character token, then
ignore that token and move on to the next one. (Newlines at the
start of pre blocks are ignored as
an authoring convenience.)
If the form
element pointer is not null, ignore the token with a parse error.
Otherwise:
If the stack of open elements has a p
element in scope, then act as if an end tag with the tag name
p had been seen.
Insert an HTML
element for the token, and set the form
element pointer to point to the element created.
If the stack of open elements has a p
element in scope, then act as if an end tag with the tag name
p had been seen.
Run the following algorithm:
Initialise node to be the current node (the bottommost node of the stack).
If node is an li element, then pop all the nodes from the
current node up to node, including node, then stop
this algorithm. If more than one node is popped, then this is a parse error.
If node is not in the formatting category, and is not in the phrasing category, and is not an address or div element, then stop this algorithm.
Otherwise, set node to the previous entry in the stack of open elements and return to step 2.
Finally, insert
an li element.
If the stack of open elements has a p
element in scope, then act as if an end tag with the tag name
p had been seen.
Run the following algorithm:
Initialise node to be the current node (the bottommost node of the stack).
If node is a dd or dt
element, then pop all the nodes from the current node up to node,
including node, then stop this algorithm. If
more than one node is popped, then this is a parse error.
If node is not in the formatting category, and is not in the phrasing category, and is not an address or div element, then stop this algorithm.
Otherwise, set node to the previous entry in the stack of open elements and return to step 2.
Finally, insert an HTML element with the same tag name as the token's.
If the stack of open elements has a p
element in scope, then act as if an end tag with the tag name
p had been seen.
Insert an HTML element for the token.
Switch the content model flag to the PLAINTEXT state.
Once a start tag with the tag name "plaintext" has been seen, that will be the last token ever seen other than character tokens (and the end-of-file token), because there is no way to switch the content model flag out of the PLAINTEXT state.
If the stack of open elements has an element in scope with the same tag name as that of the token, then generate implied end tags.
Now, if the current node is not an element with the same tag name as that of the token, then this is a parse error.
If the stack of open elements has an element in scope with the same tag name as that of the token, then pop elements from this stack until an element with that tag name has been popped from the stack.
If the stack of open elements has an element in scope with the same tag name as that of the token, then generate implied end tags.
Now, if the current node is not an element with the same tag name as that of the token, then this is a parse error.
Otherwise, if the current node is an element with the same tag name as that of the token pop that element from the stack.
In any case, set the form element pointer to null.
If the stack of open elements has a p
element in scope, then generate implied end
tags, except for p elements.
If the current node is not a p element, then this is a parse error.
If the stack of open elements has a p
element in scope, then pop elements from this stack until the
stack no longer has a p element in scope.
If the stack of open elements has an element in scope whose tag name matches the tag name of the token, then generate implied end tags, except for elements with the same tag name as the token.
If the current node is not an element with the same tag name as the token, then this is a parse error.
If the stack of open elements has an element in scope whose tag name matches the tag name of the token, then pop elements from this stack until an element with that tag name has been popped from the stack.
If the stack of open elements has a p
element in scope, then act as if an end tag with the tag name
p had been seen.
If the stack of open elements has in scope an element whose tag name is one of "h1", "h2", "h3", "h4", "h5", or "h6", then this is a parse error; pop elements from the stack until an element with one of those tag names has been popped from the stack.
Insert an HTML element for the token.
If the stack of open elements has in scope an element whose tag name is one of "h1", "h2", "h3", "h4", "h5", or "h6", then generate implied end tags.
Now, if the current node is not an element with the same tag name as that of the token, then this is a parse error.
If the stack of open elements has in scope an element whose tag name is one of "h1", "h2", "h3", "h4", "h5", or "h6", then pop elements from the stack until an element with one of those tag names has been popped from the stack.
If the list of active formatting elements contains an element whose tag name is "a" between the end of the list and the last marker on the list (or the start of the list if there is no marker on the list), then this is a parse error; act as if an end tag with the tag name "a" had been seen, then remove that element from the list of active formatting elements and the stack of open elements if the end tag didn't already remove it (it might not have if the element is not in table scope).
In the non-conforming stream
<a href="a">a<table><a href="b">b</table>x,
the first a element would be closed
upon seeing the second one, and the "x" character would be inside a
link to "b", not to "a". This is despite the fact that the outer
a element is not in table scope
(meaning that a regular </a> end tag at the start of
the table wouldn't close the outer a
element).
Reconstruct the active formatting elements, if any.
Insert an HTML element for the token. Add that element to the list of active formatting elements.
Reconstruct the active formatting elements, if any.
Insert an HTML element for the token. Add that element to the list of active formatting elements.
Follow these steps:
Let the formatting element be the last element in the list of active formatting elements that:
If there is no such node, or, if that node is also in the stack of open elements but the element is not in scope, then this is a parse error. Abort these steps. The token is ignored.
Otherwise, if there is such a node, but that node is not in the stack of open elements, then this is a parse error; remove the element from the list, and abort these steps.
Otherwise, there is a formatting element and that element is in the stack and is in scope. If the element is not the current node, this is a parse error. In any case, proceed with the algorithm as written in the following steps.
Let the furthest block be the topmost node in the stack of open elements that is lower in the stack than the formatting element, and is not an element in the phrasing or formatting categories. There might not be one.
If there is no furthest block, then the UA must skip the subsequent steps and instead just pop all the nodes from the bottom of the stack of open elements, from the current node up to the formatting element, and remove the formatting element from the list of active formatting elements.
Let the common ancestor be the element immediately above the formatting element in the stack of open elements.
If the furthest block has a parent node, then remove the furthest block from its parent node.
Let a bookmark note the position of the formatting element in the list of active formatting elements relative to the elements on either side of it in the list.
Let node and last node be the furthest block. Follow these steps:
Insert whatever last node ended up being in the previous step into the common ancestor node, first removing it from its previous parent node if any.
Perform a shallow clone of the formatting element.
Take all of the child nodes of the furthest block and append them to the clone created in the last step.
Append that clone to the furthest block.
Remove the formatting element from the list of active formatting elements, and insert the clone into the list of active formatting elements at the position of the aforementioned bookmark.
Remove the formatting element from the stack of open elements, and insert the clone into the stack of open elements immediately after (i.e. in a more deeply nested position than) the position of the furthest block in that stack.
Jump back to step 1 in this series of steps.
The way these steps are defined, only elements in the formatting category ever get cloned by this algorithm.
Because of the way this algorithm causes elements to change parents, it has been dubbed the "adoption agency algorithm" (in contrast with other possibly algorithms for dealing with misnested content, which included the "incest algorithm", the "secret affair algorithm", and the "Heisenberg algorithm").
If the stack of open elements has a
button element in scope, then this is a parse error; act as if an end tag with the tag
name "button" had been seen, then reprocess the token.
Otherwise:
Reconstruct the active formatting elements, if any.
Insert an HTML element for the token.
Insert a marker at the end of the list of active formatting elements.
Reconstruct the active formatting elements, if any.
Insert an HTML element for the token.
Insert a marker at the end of the list of active formatting elements.
If the stack of open elements has in scope an element whose tag name is the same as the tag name of the token, then generate implied end tags.
Now, if the current node is not an element with the same tag name as the token, then this is a parse error.
Now, if the stack of open elements has an element in scope whose tag name matches the tag name of the token, then pop elements from the stack until that element has been popped from the stack, and clear the list of active formatting elements up to the last marker.
Reconstruct the active formatting elements, if any.
Insert an HTML element for the token.
Switch the content model flag to the CDATA state.
If the stack of open elements has a p
element in scope, then act as if an end tag with the tag name
p had been seen.
Insert an HTML element for the token.
Change the insertion mode to "in table".
Reconstruct the active formatting elements, if any.
Insert an HTML element for the token. Immediately pop the current node off the stack of open elements.
If the stack of open elements has a p
element in scope, then act as if an end tag with the tag name
p had been seen.
Insert an HTML element for the token. Immediately pop the current node off the stack of open elements.
Parse error. Change the token's tag name to "img" and reprocess it. (Don't ask.)
Reconstruct the active formatting elements, if any.
Insert an
input element for the token.
If the form element
pointer is not null, then associate
the input element with the form element
pointed to by the form
element pointer.
Pop that input element off the stack
of open elements.
If the form element
pointer is not null, then ignore the token.
Otherwise:
Act as if a start tag token with the tag name "form" had been seen.
Act as if a start tag token with the tag name "hr" had been seen.
Act as if a start tag token with the tag name "p" had been seen.
Act as if a start tag token with the tag name "label" had been seen.
Act as if a stream of character tokens had been seen (see below for what they should say).
Act as if a start tag token with the tag name "input" had been seen, with all the attributes from the "isindex" token, except with the "name" attribute set to the value "isindex" (ignoring any explicit "name" attribute).
Act as if a stream of character tokens had been seen (see below for what they should say).
Act as if an end tag token with the tag name "label" had been seen.
Act as if an end tag token with the tag name "p" had been seen.
Act as if a start tag token with the tag name "hr" had been seen.
Act as if an end tag token with the tag name "form" had been seen.
The two streams of character tokens together should, together with
the input element, express the equivalent of "This is a
searchable index. Insert your search keywords here: (input field)"
in the user's preferred language.
Then need to specify that if the form submission causes just a single form control, whose name is "isindex", to be submitted, then we submit just the value part, not the "isindex=" part.
Create an element for the token.
If the form element
pointer is not null, then associate
the textarea element with the form element
pointed to by the form
element pointer.
Append the new element to the current node.
Switch the tokeniser's content model flag to the RCDATA state.
If the next token is a U+000A LINE FEED (LF) character token, then
ignore that token and move on to the next one. (Newlines at the
start of textarea elements are ignored as an authoring
convenience.)
Then, collect all the character tokens that the tokeniser returns until it returns a token that is not a character token, or until it stops tokenising.
If this process resulted in a collection of character tokens,
append a single Text node, whose contents is the
concatenation of all those tokens' characters, to the new element
node.
The tokeniser's content model flag will have switched back to the PCDATA state.
If the next token is an end tag token with the tag name "textarea", ignore it. Otherwise, this is a parse error.
Create an element for the token.
For "iframe" tags, the node must be an HTMLIFrameElement object, for
the other tags it must be an HTMLElement object.
Append the new element to the current node.
Switch the tokeniser's content model flag to the CDATA state.
Then, collect all the character tokens that the tokeniser returns until it returns a token that is not a character token, or until it stops tokenising.
If this process resulted in a collection of character tokens,
append a single Text node, whose contents is the
concatenation of all those tokens' characters, to the new element
node.
The tokeniser's content model flag will have switched back to the PCDATA state.
If the next token is an end tag token with the same tag name as the start tag token, ignore it. Otherwise, this is a parse error.
Reconstruct the active formatting elements, if any.
Insert an HTML element for the token.
Change the insertion mode to "in select".
Parse error. Ignore the token.
Work in progress!
Reconstruct the active formatting elements, if any.
Insert an HTML element for the token.
This element will be a phrasing element.
Run the following algorithm:
Initialise node to be the current node (the bottommost node of the stack).
If node has the same tag name as the end tag token, then:
If the tag name of the end tag token does not match the tag name of the current node, this is a parse error.
Pop all the nodes from the current node up to node, including node, then stop this algorithm.
Otherwise, if node is in neither the formatting category nor the phrasing category, then this is a parse error. Stop this algorithm. The end tag token is ignored.
Set node to the previous entry in the stack of open elements.
Return to step 2.
Append the character to the current node.
Append a Comment node to the current node with the data attribute set to the data given in the comment
token.
Clear the stack back to a table context. (See below.)
Insert a marker at the end of the list of active formatting elements.
Insert an HTML element for the token, then switch the insertion mode to "in caption".
Clear the stack back to a table context. (See below.)
Insert an HTML element for the token, then switch the insertion mode to "in column group".
Act as if a start tag token with the tag name "colgroup" had been seen, then reprocess the current token.
Clear the stack back to a table context. (See below.)
Insert an HTML element for the token, then switch the insertion mode to "in table body".
Act as if a start tag token with the tag name "tbody" had been seen, then reprocess the current token.
Parse error. Act as if an end tag token with the tag name "table" had been seen, then, if that token wasn't ignored, reprocess the current token.
The fake end tag token here can only be ignored in the
innerHTML case.
If the stack of open elements does not have an
element in table scope with the same tag name as the token, this
is a parse error. Ignore the token. (innerHTML case)
Otherwise:
Now, if the current node is not a table element, then this is a parse error.
Pop elements from this stack until a table element has been popped from the
stack.
Parse error. Ignore the token.
Parse error. Process the token as if the insertion mode was "in body", with the following exception:
If the current node is a table, tbody, tfoot, thead, or tr element, then, whenever a node would be
inserted into the current node, it must
instead be inserted into the foster parent
element.
The foster parent element is the parent
element of the last table element
in the stack of open elements, if there is a
table element and it has such a
parent element. If there is no table element in the stack
of open elements (innerHTML
case), then the foster parent
element is the first element in the stack
of open elements (the html
element). Otherwise, if there is a table element in the stack
of open elements, but the last table element in the stack
of open elements has no parent, or its parent node is not an
element, then the foster parent
element is the element before the last table element in the stack
of open elements.
If the foster parent element is the
parent element of the last table
element in the stack of open elements, then the
new node must be inserted immediately before the last
table element in the stack of open elements in the foster parent element; otherwise, the new node
must be appended to the foster parent
element.
When the steps above require the UA to clear the
stack back to a table context, it means that the UA must, while
the current node is not a table element or an html element, pop elements from the stack of open elements. If this causes any elements
to be popped from the stack, then this is a parse
error.
The current node being an
html element after this process is an
innerHTML case.
If the stack of open elements does not have an
element in table scope with the same tag name as the token, this
is a parse error. Ignore the token. (innerHTML case)
Otherwise:
Now, if the current node is not a caption element, then this is a parse error.
Pop elements from this stack until a caption element has been popped from the
stack.
Clear the list of active formatting elements up to the last marker.
Switch the insertion mode to "in table".
Parse error. Act as if an end tag with the tag name "caption" had been seen, then, if that token wasn't ignored, reprocess the current token.
The fake end tag token here can only be ignored in the
innerHTML case.
Parse error. Ignore the token.
Process the token as if the insertion mode was "in body".
Append the character to the current node.
Append a Comment node to the current node with the data attribute set to the data given in the comment
token.
Insert a
col element for the token. Immediately pop the current node off the stack of
open elements.
If the current node is the root html element, then this is a parse error, ignore the token. (innerHTML case)
Otherwise, pop the current node (which
will be a colgroup element)
from the stack of open elements. Switch the insertion mode to "in table".
Parse error. Ignore the token.
Act as if an end tag with the tag name "colgroup" had been seen, and then, if that token wasn't ignored, reprocess the current token.
The fake end tag token here can only be ignored in the
innerHTML case.
Clear the stack back to a table body context. (See below.)
Insert a
tr element for the token, then switch the insertion mode to "in row".
Parse error. Act as if a start tag with the tag name "tr" had been seen, then reprocess the current token.
If the stack of open elements does not have an element in table scope with the same tag name as the token, this is a parse error. Ignore the token.
Otherwise:
Clear the stack back to a table body context. (See below.)
Pop the current node from the stack of open elements. Switch the insertion mode to "in table".
If the stack of open elements does not have a
tbody, thead, or tfoot
element in table scope, this is a parse
error. Ignore the token. (innerHTML case)
Otherwise:
Clear the stack back to a table body context. (See below.)
Act as if an end tag with the same tag name as the current node ("tbody", "tfoot", or "thead") had been seen, then reprocess the current token.
Parse error. Ignore the token.
Process the token as if the insertion mode was "in table".
When the steps above require the UA to clear the
stack back to a table body context, it means that the UA must,
while the current node is not a tbody, tfoot, thead, or html element, pop elements from the stack of open elements. If this causes any elements
to be popped from the stack, then this is a parse
error.
The current node being an
html element after this process is an
innerHTML case.
Clear the stack back to a table row context. (See below.)
Insert an HTML element for the token, then switch the insertion mode to "in cell".
Insert a marker at the end of the list of active formatting elements.
If the stack of open elements does not have an
element in table scope with the same tag name as the token, this
is a parse error. Ignore the token. (innerHTML case)
Otherwise:
Clear the stack back to a table row context. (See below.)
Pop the current node (which will be a
tr element) from the stack of open elements. Switch the insertion mode to "in table body".
Act as if an end tag with the tag name "tr" had been seen, then, if that token wasn't ignored, reprocess the current token.
The fake end tag token here can only be ignored in the
innerHTML case.
If the stack of open elements does not have an element in table scope with the same tag name as the token, this is a parse error. Ignore the token.
Otherwise, act as if an end tag with the tag name "tr" had been seen, then reprocess the current token.
Parse error. Ignore the token.
Process the token as if the insertion mode was "in table".
When the steps above require the UA to clear the
stack back to a table row context, it means that the UA must,
while the current node is not a tr element or an html element, pop elements from the stack of open elements. If this causes any elements
to be popped from the stack, then this is a parse
error.
The current node being an
html element after this process is an
innerHTML case.
If the stack of open elements does not have an element in table scope with the same tag name as that of the token, then this is a parse error and the token must be ignored.
Otherwise:
Generate implied end tags, except for elements with the same tag name as the token.
Now, if the current node is not an element with the same tag name as the token, then this is a parse error.
Pop elements from this stack until an element with the same tag name as the token has been popped from the stack.
Clear the list of active formatting elements up to the last marker.
Switch the insertion mode to "in row". (The current node will be a tr element at this point.)
If the stack of open elements does
not have a td or th element in table
scope, then this is a parse error; ignore
the token. (innerHTML case)
Otherwise, close the cell (see below) and reprocess the current token.
Parse error. Ignore the token.
If the stack of open elements does not have an
element in table scope with the same tag name as that of the
token (which can only happen for "tbody", "tfoot" and "thead", or,
in the innerHTML case), then
this is a parse error and the token must be
ignored.
Otherwise, close the cell (see below) and reprocess the current token.
Process the token as if the insertion mode was "in body".
Where the steps above say to close the cell, they mean to follow the following algorithm:
If the stack of open elements has a
td element in table scope, then act as if an end
tag token with the tag name "td" had been seen.
Otherwise, the stack of open elements will have a
th element in table scope; act as if an end tag
token with the tag name "th" had been seen.
The stack of open elements cannot
have both a td and a th element in table scope at the same time, nor can
it have neither when the insertion mode is
"in cell".
Handle the token as follows:
Append a Comment node to the current node with the data attribute set to the data given in the comment
token.
If the current node is an
option element, act as if an end tag with the tag name
"option" had been seen.
Insert an HTML element for the token.
If the current node is an
option element, act as if an end tag with the tag name
"option" had been seen.
If the current node is an
optgroup element, act as if an end tag with the tag
name "optgroup" had been seen.
Insert an HTML element for the token.
First, if the current node is an
option element, and the node immediately before it in
the stack of open elements is an
optgroup element, then act as if an end tag with the
tag name "option" had been seen.
If the current node is an
optgroup element, then pop that node from the stack of open elements. Otherwise, this is a parse error, ignore the token.
If the current node is an
option element, then pop that node from the stack of open elements. Otherwise, this is a parse error, ignore the token.
If the stack of open elements does not have an
element in table scope with the same tag name as the token, this
is a parse error. Ignore the token. (innerHTML case)
Otherwise:
Pop elements from the stack of open elements
until a select element has been popped from the stack.
Parse error. Act as if the token had been an end tag with the tag name "select" instead.
If the stack of open elements has an element in table scope with the same tag name as that of the token, then act as if an end tag with the tag name "select" had been seen, and reprocess the token. Otherwise, ignore the token.
Parse error. Ignore the token.
Handle the token as follows:
Process the token as it would be processed if the insertion mode was "in body".
Append a Comment node to the first element in the stack of open elements (the html element), with the data attribute set to the data given in the comment
token.
If the parser was originally created in order to handle the
setting of an element's innerHTML attribute, this is a parse error; ignore the token. (The element will
be an html element in this case.)
(innerHTML case)
Otherwise, switch to the trailing end phase.
Parse error. Set the insertion mode to "in body" and reprocess the token.
Handle the token as follows:
Append the character to the current node.
Append a Comment node to the current node with the data attribute set to the data given in the comment
token.
Insert a
frameset element for the token.
If the current node is the root html element, then this is a parse error; ignore the token. (innerHTML case)
Otherwise, pop the current node from the stack of open elements.
If the parser was not originally created in order to
handle the setting of an element's innerHTML attribute (innerHTML case), and the current node is no longer a
frameset element, then change the insertion mode to "after frameset".
Insert an HTML element for the token. Immediately pop the current node off the stack of open elements.
Process the token as if the insertion mode had been "in body".
Parse error. Ignore the token.
Handle the token as follows:
Append the character to the current node.
Append a Comment node to the current node with the data attribute set to the data given in the comment
token.
Switch to the trailing end phase.
Process the token as if the insertion mode had been "in body".
Parse error. Ignore the token.
This doesn't handle UAs that don't support frames, or that do support frames but want to show the NOFRAMES content. Supporting the former is easy; supporting the latter is harder.
After the main phase, as each token is emitted from the tokenisation stage, it must be processed as described in this section.
Parse error. Ignore the token.
Append a Comment node to the Document object
with the data attribute set to the data given in
the comment token.
Process the token as it would be processed in the main phase.
Parse error. Switch back to the main phase and reprocess the token.
Once the user agent stops parsing the document, the user agent must follow the steps in this section.
First, the rules for when a script completes loading start applying (script execution is no longer managed by the parser).
If any of the scripts in the list of scripts that
will execute as soon as possible have completed
loading, or if the list of
scripts that will execute asynchronously is not empty and the first
script in that list has completed loading,
then the user agent must act as if those scripts just completed loading,
following the rules given for that in the script element definition.
Then, if the list of scripts that will execute when the document has finished parsing is not empty, and the first item in this list has already completed loading, then the user agent must act as if that script just finished loading.
By this point, there will be no scripts that have loaded but have not yet been executed.
The user agent must then fire a simple event
called DOMContentLoaded at the
Document.
Once everything that delays
the load event has completed, the user agent must fire a load
event at the body element.