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[css-navigation-1] Factor out current from/to URL definitions. #13160

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dbaron merged 1 commit into from
Nov 26, 2025
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[css-navigation-1] Factor out current from/to URL definitions. #13160

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240 changes: 123 additions & 117 deletions css-navigation-1/Overview.bs
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Original file line number Diff line number Diff line change
Expand Up @@ -68,12 +68,12 @@ The ''@route'' rule can be defined in one of two ways:
: with the <code>pattern</code> descriptor
:: in this case the URL pattern represented is
the one represented by the <<url-pattern()>> function
given as the descriptor's value.
given as the descriptor's value.
: with the other descriptors named by <<init-descriptor-name>>
:: In this case the URL pattern represented is the result of invoking
[=URL pattern/create|create a URL pattern=] given
[=URL pattern/create|create a URL pattern=] given
<var>input</var> as {{URLPatternInit}}
constructed from the descriptors and their values;
constructed from the descriptors and their values;
if a <code>baseURL</code> descriptor is not given then one is created from
the [=style resource base URL=] of the rule.

Expand Down Expand Up @@ -185,14 +185,14 @@ The syntax of the ''@navigation'' rule is:
with <<navigation-condition>> defined as:

<pre class="prod def" dfn-type="type" nohighlight>
<dfn><<navigation-condition>></dfn> = not <<navigation-in-parens>>
| <<navigation-in-parens>> [ and <<navigation-in-parens>> ]*
| <<navigation-in-parens>> [ or <<navigation-in-parens>> ]*
<dfn><<navigation-in-parens>></dfn> = ( <<navigation-condition>> ) | ( <<navigation-test>> ) | <<general-enclosed>>
<dfn><<navigation-test>></dfn> = <<navigation-location>> | <<navigation-keyword>> : <<navigation-location>>
<dfn><<navigation-keyword>></dfn> = at | from | to
<dfn><<navigation-location>></dfn> = <<route-name>> | <<url-pattern()>>
<dfn><<route-name>></dfn> = <<dashed-ident>>
<dfn><<navigation-condition>></dfn> = not <<navigation-in-parens>>
| <<navigation-in-parens>> [ and <<navigation-in-parens>> ]*
| <<navigation-in-parens>> [ or <<navigation-in-parens>> ]*
<dfn><<navigation-in-parens>></dfn> = ( <<navigation-condition>> ) | ( <<navigation-test>> ) | <<general-enclosed>>
<dfn><<navigation-test>></dfn> = <<navigation-location>> | <<navigation-keyword>> : <<navigation-location>>
<dfn><<navigation-keyword>></dfn> = at | from | to
<dfn><<navigation-location>></dfn> = <<route-name>> | <<url-pattern()>>
<dfn><<route-name>></dfn> = <<dashed-ident>>
</pre>

The above grammar is purposely very loose for forwards-compatibility reasons,
Expand Down Expand Up @@ -231,106 +231,24 @@ as follows:
:: The result is whether the result of
[=URL pattern/match|match a URL pattern=] is non-null
given <var>urlPattern</var> as
the [=navigation location URL pattern=] of <<navigation-location>>,
<var>input</var> as the document's [=Document/URL=].
the [=navigation location URL pattern=] of <<navigation-location>>
and <var>input</var> as the document's [=Document/URL=].

: from: <<navigation-location>>
:: The result is true if
the [=document's navigation API=] of the document
is non-null, and either:

* its [=transition=] is non-null,
its [=from entry=]'s {{NavigationHistoryEntry/url}}
is non-null and
[=URL pattern/match|match a URL pattern=] is non-null when
given <var>urlPattern</var> as
the [=navigation location URL pattern=] of <<navigation-location>>,
<var>input</var> as that
[=from entry=]'s {{NavigationHistoryEntry/url}}.

NOTE: This part handles <code>from:</code> when it matches in the old page.

* its [=activation=] is non-null,
the document's [=has been revealed=] is false or
was false at the start of the current [=task=],
and the activation's {{NavigationActivation/from}}'s
{{NavigationHistoryEntry/url}}
is non-null and
[=URL pattern/match|match a URL pattern=] is non-null when
given <var>urlPattern</var> as
the [=navigation location URL pattern=] of <<navigation-location>>,
<var>input</var> as that
activation's {{NavigationActivation/from}}'s
{{NavigationHistoryEntry/url}}.

NOTE: This part handles <code>from:</code> when it matches in the new page.
the [=current from URL=] <var>from</var> of the document is non-null and
[=URL pattern/match|match a URL pattern=] is non-null when
given <var>urlPattern</var> as
the [=navigation location URL pattern=] of <<navigation-location>>
and <var>input</var> as <var>from</var>.

: to: <<navigation-location>>
:: The result is true if
the [=document's navigation API=] of the document
is non-null, and either:

* its [=ongoing navigate event=] is non-null,
[=URL pattern/match|match a URL pattern=] is non-null
given <var>urlPattern</var> as
the [=navigation location URL pattern=] of <<navigation-location>>,
<var>input</var> as the [=current to url=],
where the <dfn>current to url</dfn> is defined as:

* if the {{pageswap}} event has fired since that navigation began,
and its {{PageSwapEvent/activation}} was non-null,
and that {{PageSwapEvent/activation}}'s
{{NavigationActivation/entry}}'s
{{NavigationHistoryEntry/url}} is non-null,
then that
{{NavigationHistoryEntry/url}}.

NOTE: This part <em>does</em> expose the result of redirects.

ISSUE: Is the final "non-null" check needed?

* otherwise, the [=ongoing navigate event=]'s
{{NavigateEvent/destination}}'s
{{NavigationDestination/url}}

NOTE: This part does <em>not</em> expose the result of redirects.

ISSUE: This assumes that the [=ongoing navigate event=]
and the [=transition=] have the same lifetime,
but this isn't really
true if the event is intercepted.
After
<a href="https://github.com/whatwg/html/issues/11690">whatwg/html#11690</a> /
<a href="https://github.com/whatwg/html/pull/11692">whatwg/html#11692</a>.
we could probably define this more like "from" above.
But which lifetime is the one we want?

NOTE: This part handles <code>to:</code> when it matches in the old page.

* its [=activation=] is non-null,
the document's [=has been revealed=] is false or
was false at the start of the current [=task=],
and the activation's {{NavigationActivation/entry}}'s
{{NavigationHistoryEntry/url}}
is non-null and
[=URL pattern/match|match a URL pattern=] is non-null
given <var>urlPattern</var> as
the [=navigation location URL pattern=] of <<navigation-location>>,
<var>input</var> as that
activation's {{NavigationActivation/entry}}'s
{{NavigationHistoryEntry/url}}.

NOTE: This part handles <code>to:</code> when it matches in the new page.

ISSUE: The above definitions of from and to apparently don't work right
if you start a same-document navigation (e.g., with {{History/pushState}})
in the middle of a cross-document navigation.

ISSUE: Generally improve integration with the HTML spec for these definitions,
instead of monkeypatching.
This includes the interaction with [=has been revealed=]
and the interaction with the {{pageswap}} event,
and other things where this section links to non-exported definitions.
the [=current to URL=] <var>to</var> of the document is non-null and
[=URL pattern/match|match a URL pattern=] is non-null when
given <var>urlPattern</var> as
the [=navigation location URL pattern=] of <<navigation-location>>
and <var>input</var> as <var>to</var>.

: <<general-enclosed>>
::
Expand Down Expand Up @@ -539,11 +457,8 @@ if the following steps return true:
1. If <<navigation-param>> is a <<navigation-param-function>>,
and <var>entry</var>'s [=map/key=] is the function's <<ident>>,
then for each <var>navigationUrl</var> of the
current to URL
and current from URL
<span class="issue">extract "current to URL" and
"current from URL" from ''@navigation''
definitions above and link to them</span>:
[=current to URL=]
and [=current from URL=]:
1. Let <var>navigationMatchResult</var> be the result of
[=URL pattern/match|match a URL pattern=]
given <var>urlPattern</var> and <var>navigationUrl</var>.
Expand All @@ -554,20 +469,111 @@ if the following steps return true:
whose [=map/key=] is the same as <var>entry</var>'s key
and whose [=map/value=] is the same as <var>entry</var>'s value.

NOTE: This step makes the ''navigation-param()'' function
perform what is essentially a three-way match,
between the target of the link,
the provided URL pattern,
and the from or to URL of the current navigation.
NOTE: This step makes the ''navigation-param()'' function
perform what is essentially a three-way match,
between the target of the link,
the provided URL pattern,
and the from or to URL of the current navigation.

ISSUE: A <<link-condition>> should also be able to be a named route
once those are added back to the spec.

<h2 id="current-nav-urls">Current navigation URLs</h2>

Both the ''@navigation'' rule and the '':link-to()'' pseudo-class
rely on the following definitions of
the [=current from URL=] and [=current to URL=].

The <dfn>current from URL</dfn> of a [=/document=] is a URL or null.
It is defined as follows:

1. If the [=document's navigation API=] of the document is non-null and
its [=transition=] is non-null,
its [=from entry=]'s {{NavigationHistoryEntry/url}}.

NOTE: This part is for when the old document in the navigation
is still the current document.

1. If the [=document's navigation API=] of the document is non-null and
its [=activation=] is non-null,
the document's [=has been revealed=] is false or
was false at the start of the current [=task=],
the activation's {{NavigationActivation/from}}'s
{{NavigationHistoryEntry/url}}.

NOTE: This part is for when the new document in the navigation
has become the current document.

1. Otherwise, null.

NOTE: The previous two branches can also produce null results.

The <dfn>current to URL</dfn> of a [=/document=] is a URL or null.
It is defined as follows:

1. If the [=document's navigation API=] of the document is non-null and
its [=ongoing navigate event=] is non-null:

1. if the {{pageswap}} event has fired since that navigation began,
and its {{PageSwapEvent/activation}} was non-null,
and that {{PageSwapEvent/activation}}'s
{{NavigationActivation/entry}}'s
{{NavigationHistoryEntry/url}} is non-null,
then that
{{NavigationHistoryEntry/url}}.

NOTE: This part <em>does</em> expose the result of redirects.

ISSUE: Is the final "non-null" check needed?

1. otherwise, the [=ongoing navigate event=]'s
{{NavigateEvent/destination}}'s
{{NavigationDestination/url}}

NOTE: This part does <em>not</em> expose the result of redirects.

ISSUE: This assumes that the [=ongoing navigate event=]
and the [=transition=] have the same lifetime,
but this isn't really
true if the event is intercepted.
After
<a href="https://github.com/whatwg/html/issues/11690">whatwg/html#11690</a> /
<a href="https://github.com/whatwg/html/pull/11692">whatwg/html#11692</a>.
we could probably define this more like "from" above.
But which lifetime is the one we want?

NOTE: This part is for when the old document in the navigation
is still the current document.

1. If the [=document's navigation API=] of the document is non-null and
its [=activation=] is non-null,
the document's [=has been revealed=] is false or
was false at the start of the current [=task=],
and the activation's {{NavigationActivation/entry}}'s
{{NavigationHistoryEntry/url}}.

NOTE: This part is for when the new document in the navigation
has become the current document.

1. Otherwise, null.

NOTE: The previous two branches can also produce null results.

ISSUE: The above definitions of from and to apparently don't work right
if you start a same-document navigation (e.g., with {{History/pushState}})
in the middle of a cross-document navigation.

ISSUE: Generally improve integration with the HTML spec for these definitions,
instead of monkeypatching.
This includes the interaction with [=has been revealed=]
and the interaction with the {{pageswap}} event,
and other things where this section links to non-exported definitions.

<h2 id="url-pattern-function">The ''url-pattern()'' function</h2>

<!--

NOTE: We may eventually want to move this to css-values.
NOTE: We may eventually want to move this to css-values.

If we do, the definition of "style resource base URL" probably doesn't need to be
exported any more, since it was exported for this definition.
Expand Down Expand Up @@ -612,7 +618,7 @@ using the steps of the <dfn>create a URL pattern for url-pattern()</dfn> algorit
1. Return the result of [=URL pattern/create|create a URL pattern=] given
<var>arg</var>, <var>baseURL</var>, and an empty [=map=].

NOTE: This function requires that its argument is quoted.
NOTE: This function requires that its argument is quoted.
This differs from the ''url()'' function,
which allows its argument to be quoted or unquoted.

Expand Down