2017250 - Add initial infrastructure for list-valued property reification in Typed OM

Status: REOPENED

(Core :: CSS Parsing and Computation, task)

Description

[Jan Varga [:janv]]

Introduce initial infrastructure for reification of list-valued CSS properties in Typed OM.

This includes:

• Changing ToTyped to write into a TypedValueList instead of returning a single value.
• Using existing #[css(iterable)] metadata to trigger subdivision of list-valued properties into iterations.
• Supporting subdivision logic for both StylePropertyMap.get()/getAll() and future CSSStyleValue::parse().

This provides the foundation for proper reification of list-valued properties. As a result, some existing Typed OM WPTs for list-valued properties may start passing. Broader property coverage and more complete reification support will follow in subsequent bugs.

Comment 1

[Jan Varga [:janv]]

In other words, this is mainly about creating the infrastructure so that StylePropertyMap will be able to return multiple values for a list-valued property.

Comment 2

[Jan Varga [:janv]]

Attachment: Bug 2017250 - Change ToTyped to append into a ThinVec; r=emilio

Introduce initial infrastructure for reification of list-valued CSS
properties in Typed OM.

Change the ToTyped trait to append results into a ThinVec<TypedValue> instead
of returning a single TypedValue, allowing values to reify into multiple Typed
OM objects.

Add a convenience helper to_typed_value() which returns the first TypedValue
so existing call sites continue to behave as before, and update the derive and
callers accordingly.

Comment 3

[Jan Varga [:janv]]

Attachment: Bug 2017250 - Return final TypedValue from reify_number/percentage; r=emilio

Refactor reify_number and reify_percentage to return the final TypedValue
type directly.

This prepares for upcoming iterable reification changes where these helpers
will append results into the output vector used by ToTyped::to_typed.

Comment 4

[Jan Varga [:janv]]

Attachment: Bug 2017250 - Extend ToTyped derive to support iterable fields; r=emilio

This patch extends the ToTyped derive to support fields marked with
entries.

When such a field is present, the generated implementation iterates over the
items and delegates to ToTyped for each element, adding the necessary trait
bounds only for the element types involved. This keeps the derive lightweight
and avoids forcing unrelated container types to implement ToTyped.

This builds on the earlier derive_fields support and prepares the groundwork
for proper reification of list-valued CSS properties.

Comment 5

[Jan Varga [:janv]]

Attachment: Bug 2017250 - Fix WPT for container-name; r=emilio

Fix what appears to be a copy/paste error in the WPT for the container-name
property.

The test appears to have been copied from the container-type test. Adjust it
so it correctly reflects the behavior of container-name with multiple values.

Comment 6

[Jan Varga [:janv]]

Attachment: Bug 2017250 - Update documentation for ToTyped derive; r=emilio

Update ToTyped derive documentation to better describe supported attributes
and their behavior.

Comment 7

[Jan Varga [:janv]]

Attachment: Bug 2017250 - Support #[css(comma)] in ToTyped derive for list-valued property reification; r=emilio

Teach the ToTyped derive to recognize #[css(comma)] as a signal that an
iterable field represents a comma-separated CSS list whose items can be
reified as separate TypedValue entries.

If #[css(comma)] is not present and the iterable contains more than one item,
the derive treats the value as unsupported and returns Err(()).

This matches current Typed OM Level 1 behavior reflected by WPT, where only
comma-separated lists are subdivided into iterations. Properties such as
container-name may accept multiple space-separated values but are currently
reified as unsupported when more than one value is present.

Comment 8

[Jan Varga [:janv]]

Attachment: Bug 2017250 - Demonstrate ToTyped derive on iterable field (container-name); r=emilio

Demonstrate iterable-field support in the ToTyped derive using the
container-name property.

The property accepts a list of identifiers, but Typed OM Level 1 currently
treats space-separated multi-value cases as unsupported. Reification therefore
succeeds for a single identifier and returns Err(()) when more than one value
is present.

Comment 9

[Jan Varga [:janv]]

Attachment: Bug 2017250 - Demonstrate ToTyped derive on iterable field (container-name); r=emilio

Demonstrate iterable-field support in the ToTyped derive using the
container-name property.

The property accepts a list of identifiers, but Typed OM Level 1 currently
treats space-separated multi-value cases as unsupported. Reification therefore
succeeds for a single identifier and returns Err(()) when more than one value
is present.

Comment 10

[Jan Varga [:janv]]

Attachment: Bug 2017250 - Demonstrate ToTyped derive on iterable field (container-name); r=emilio

Demonstrate iterable-field support in the ToTyped derive using the
container-name property.

The property accepts a list of identifiers, but Typed OM Level 1 currently
treats space-separated multi-value cases as unsupported. Reification therefore
succeeds for a single identifier and returns Err(()) when more than one value
is present.

Comment 11

[Jan Varga [:janv]]

Attachment: Bug 2017250 - Demonstrate ToTyped derive on iterable field (container-name); r=emilio

Demonstrate iterable-field support in the ToTyped derive using the
container-name property.

The property accepts a list of identifiers, but Typed OM Level 1 currently
treats space-separated multi-value cases as unsupported. Reification therefore
succeeds for a single identifier and returns Err(()) when more than one value
is present.

Comment 12

[Jan Varga [:janv]]

Attachment: Bug 2017250 - Demonstrate ToTyped derive on iterable field (container-name); r=emilio

Demonstrate iterable-field support in the ToTyped derive using the
container-name property.

The property accepts a list of identifiers, but Typed OM Level 1 currently
treats space-separated multi-value cases as unsupported. Reification therefore
succeeds for a single identifier and returns Err(()) when more than one value
is present.

Comment 13

[Jan Varga [:janv]]

Attachment: Bug 2017250 - Enable reification for OwnedList (computed values) used by predefined types with vector; r=emilio

Enable ToTyped derive for the OwnedList type used for computed values
generated by helpers.mako.rs for predefined types using the vector
field.

This further exercises the iterable-field support recently added to the
ToTyped derive. A few default ToTyped implementations were also added for
element types used by these iterable OwnedList representations.

This makes Typed OM reification pass WPTs for the following properties:

• animation-direction
• animation-fill-mode
• animation-play-state
• backdrop-filter
• background-attachment
• background-blend-mode
• background-clip
• background-image
• background-origin
• background-size
• box-shadow
• filter
• mask-image

Comment 14

[Jan Varga [:janv]]

Attachment: Bug 2017250 - Enable reification for SpecifiedValue used by predefined types with vector; r=emilio

Enable ToTyped derive for SpecifiedValue type generated by helpers.mako.rs for
predefined types using the vector field.

This exercises the recently added iterable-field support in the ToTyped derive
across a broader set of property value types. Some additional ToTyped
implementations were added for element types used by these iterable
SpecifiedValue representations.

No new WPTs pass yet, as relevant tests also require iterable computed values
to be supported.

Comment 15

[Jan Varga [:janv]]

Attachment: Bug 2017250 - Enable reification for ComputedList used by predefined types with vector; r=emilio

Enable ToTyped derive for ComputedList type generated by helpers.mako.rs for
predefined types using the vector field.

This further exercises the iterable-field support recently added to the
ToTyped derive.

This makes Typed OM reification pass WPTs for the text-shadow property.

Comment 16

[Jan Varga [:janv]]

Attachment: Bug 2017250 - Enable reification for AnimationIterationCount; r=emilio

animation-iteration-count values can now be reified into Typed OM values.

Comment 17

[Jan Varga [:janv]]

Attachment: Bug 2017250 - Enable reification for AnimationName; r=emilio

animation-name values can now be reified into Typed OM values.

Comment 18

[Jan Varga [:janv]]

Attachment: Bug 2017250 - Enable reification for BackgroundRepeat; r=emilio

background-repeat values can now be reified into Typed OM values.

Comment 19

[Jan Varga [:janv]]

Attachment: Bug 2017250 - Refactor ToTyped derive to support multiple fields; r=emilio

Refactor the ToTyped derive implementation so that multiple supported fields
can contribute TypedValue items. The derive now accumulates the reified output
of fields into a temporary list and validates the result against the variant's

No observable behavior changes occur yet. Existing derived types either
reify a single field or rely on iterable fields, so existing WPT tests
continue to pass.

A follow-up patch will demonstrate the new behavior by enabling reification
for BackgroundSize type (background-size property).

Comment 20

[Jan Varga [:janv]]

Attachment: Bug 2017250 - Add #[typed_value(skip_if)] support to ToTyped derive; r=emilio

Allow fields participating in ToTyped derive reification to be conditionally
skipped using a new #[typed_value(skip_if = "...")] attribute.

When present, the provided function is called with the field value during
reification. If it returns true, the field is ignored and produces no
TypedValue items.

This is useful for fields that only contribute to reification in specific
situations, without requiring the entire variant or struct to be treated as
unsupported.

Comment 21

[Jan Varga [:janv]]

Attachment: Bug 2017250 - Demonstrate ToTyped derive on multi-field BackgroundSize type; r=emilio

Demonstrate multi-field support in the ToTyped derive using the
background-size property.

The ExplicitSize variant contains separate width and height fields.
Reification now derives TypedValue items for both fields, using

This allows cases such as background-size: 3.14px or 200px 100px to
reify correctly (the former producing a CSSUnitValue while the latter falls
back to CSSUnsupportedValue).

Comment 22

[Jan Varga [:janv]]

Attachment: Bug 2017250 - Add custom computed value testing for background-size: <percentage>; r=emilio

Negative values are invalid per the property definition, but in computed-value
tests they effectively appear as 0. Without custom handling in the test,
negative percentage inputs were compared directly, causing failures across
browsers (e.g. when setting values such as -3.14%).

Add a custom computed-value assertion that clamps percentage values below 0
to 0 before comparison.

Comment 23

[Jan Varga [:janv]]

Attachment: Bug 2017250 - Fix WPT for fill-rule; r=emilio

Fix what appears to be a copy/paste error in the WPT for the fill-rule
property.

The test currently uses the helper intended for list-valued properties even
though fill-rule is not list-valued. This does not affect the actual coverage,
since the helper ultimately delegates to the same underlying test logic, but
it is misleading.

Switch the test to the appropriate helper so it correctly reflects the
behavior of fill-rule.

Comment 24

[Jan Varga [:janv]]

Attachment: Bug 2017250 - Enable reification for TimingFunction; r=emilio

transition-timing-function values can now be reified into Typed OM values.

Comment 25

[Pulsebot]

Pushed by [e-mail]:
https://github.com/mozilla-firefox/firefox/commit/cfe4b640ee6d
https://hg.mozilla.org/integration/autoland/rev/703247f3dc89
Return final TypedValue from reify_number/percentage; r=firefox-style-system-reviewers,dshin

Comment 26

[amarc]

https://hg.mozilla.org/mozilla-central/rev/703247f3dc89

Comment 27

[Pulsebot]

Pushed by [e-mail]:
https://github.com/mozilla-firefox/firefox/commit/3f9dbb9c2200
https://hg.mozilla.org/integration/autoland/rev/1b93cd4c1ad0
Change ToTyped to append into a ThinVec; r=firefox-style-system-reviewers,dshin

Comment 28

[Cristian Tuns]

https://hg.mozilla.org/mozilla-central/rev/1b93cd4c1ad0

Comment 29

[Pulsebot]

Pushed by [e-mail]:
https://github.com/mozilla-firefox/firefox/commit/58495e10c188
https://hg.mozilla.org/integration/autoland/rev/e5f3f483bd3e
Update documentation for ToTyped derive; r=firefox-style-system-reviewers,dshin
https://github.com/mozilla-firefox/firefox/commit/e96510b03d61
https://hg.mozilla.org/integration/autoland/rev/d966f63c2771
Extend ToTyped derive to support iterable fields; r=firefox-style-system-reviewers,dshin

Comment 30

[Serban Stanca [:SerbanS]]

https://hg.mozilla.org/mozilla-central/rev/e5f3f483bd3e
https://hg.mozilla.org/mozilla-central/rev/d966f63c2771

Comment 31

[Pulsebot]

Pushed by [e-mail]:
https://github.com/mozilla-firefox/firefox/commit/2a395257ca40
https://hg.mozilla.org/integration/autoland/rev/083dcd6e7206
Support #[css(comma)] in ToTyped derive for list-valued property reification; r=firefox-style-system-reviewers,dshin

Comment 32

[amarc]

https://hg.mozilla.org/mozilla-central/rev/083dcd6e7206

Comment 33

[Pulsebot]

Pushed by [e-mail]:
https://github.com/mozilla-firefox/firefox/commit/af02207f9eb4
https://hg.mozilla.org/integration/autoland/rev/0de69603f757
Fix WPT for container-name; r=dshin

Comment 34

[Web Platform Test Sync Bot [:wpt-sync] (Matrix: #interop:mozilla.org)]

Created web-platform-tests PR https://github.com/web-platform-tests/wpt/pull/58505 for changes under testing/web-platform/tests

Comment 35

[Silaghi Andreea]

https://hg.mozilla.org/mozilla-central/rev/0de69603f757

Comment 36

[Web Platform Test Sync Bot [:wpt-sync] (Matrix: #interop:mozilla.org)]

Upstream PR merged by moz-wptsync-bot

Comment 37

[Pulsebot]

Pushed by [e-mail]:
https://github.com/mozilla-firefox/firefox/commit/8da047f2352d
https://hg.mozilla.org/integration/autoland/rev/080771f8e35b
Demonstrate ToTyped derive on iterable field (container-name); r=emilio,firefox-style-system-reviewers

Comment 38

[rperta]

https://hg.mozilla.org/mozilla-central/rev/080771f8e35b

Comment 39

[Pulsebot]

Pushed by [e-mail]:
https://github.com/mozilla-firefox/firefox/commit/cb6a88b9bb17
https://hg.mozilla.org/integration/autoland/rev/b21e681bfaa2
Enable reification for SpecifiedValue used by predefined types with vector; r=firefox-style-system-reviewers,boris

Comment 40

[Silaghi Andreea]

https://hg.mozilla.org/mozilla-central/rev/b21e681bfaa2

Comment 41

[Pulsebot]

Pushed by [e-mail]:
https://github.com/mozilla-firefox/firefox/commit/0ce894ada67d
https://hg.mozilla.org/integration/autoland/rev/4e3d5741d554
Enable reification for OwnedList (computed values) used by predefined types with vector; r=firefox-style-system-reviewers,boris

Comment 42

[Sandor Molnar[:smolnar]]

https://hg.mozilla.org/mozilla-central/rev/4e3d5741d554

Comment 43

[Pulsebot]

Pushed by [e-mail]:
https://github.com/mozilla-firefox/firefox/commit/9e20cf6a61f7
https://hg.mozilla.org/integration/autoland/rev/75ced7b38d80
Enable reification for ComputedList used by predefined types with vector; r=firefox-style-system-reviewers,boris

Comment 44

[amarc]

https://hg.mozilla.org/mozilla-central/rev/75ced7b38d80

Comment 45

[Pulsebot]

Pushed by [e-mail]:
https://github.com/mozilla-firefox/firefox/commit/684219f31d6b
https://hg.mozilla.org/integration/autoland/rev/c93c5649168b
Enable reification for AnimationIterationCount; r=firefox-style-system-reviewers,boris
https://github.com/mozilla-firefox/firefox/commit/81324e5fb4e0
https://hg.mozilla.org/integration/autoland/rev/5d0d81c73930
Enable reification for AnimationName; r=firefox-style-system-reviewers,boris
https://github.com/mozilla-firefox/firefox/commit/d88050142b25
https://hg.mozilla.org/integration/autoland/rev/79aa8c3d89b1
Enable reification for BackgroundRepeat; r=firefox-style-system-reviewers,boris

Comment 46

[Serban Stanca [:SerbanS]]

https://hg.mozilla.org/mozilla-central/rev/c93c5649168b
https://hg.mozilla.org/mozilla-central/rev/5d0d81c73930
https://hg.mozilla.org/mozilla-central/rev/79aa8c3d89b1

Comment 47

[Pulsebot]

Pushed by [e-mail]:
https://github.com/mozilla-firefox/firefox/commit/547b95d07407
https://hg.mozilla.org/integration/autoland/rev/e6e038b4bcdf
Refactor ToTyped derive to support multiple fields; r=emilio,firefox-style-system-reviewers
https://github.com/mozilla-firefox/firefox/commit/522123402214
https://hg.mozilla.org/integration/autoland/rev/3c83e7cabfb2
Add #[typed_value(skip_if)] support to ToTyped derive; r=emilio,firefox-style-system-reviewers

Comment 48

[Norisz Fay [:noriszfay]]

https://hg.mozilla.org/mozilla-central/rev/e6e038b4bcdf
https://hg.mozilla.org/mozilla-central/rev/3c83e7cabfb2

Comment 49

[Pulsebot]

Pushed by [e-mail]:
https://github.com/mozilla-firefox/firefox/commit/694922b9874b
https://hg.mozilla.org/integration/autoland/rev/4366bbb28043
Add custom computed value testing for background-size: <percentage>; r=emilio

Comment 50

[Atila Butkovits]

https://hg.mozilla.org/mozilla-central/rev/4366bbb28043

Comment 51

[Pulsebot]

Pushed by [e-mail]:
https://github.com/mozilla-firefox/firefox/commit/922c8db835a4
https://hg.mozilla.org/integration/autoland/rev/222a9e780b85
Demonstrate ToTyped derive on multi-field BackgroundSize type; r=emilio,firefox-style-system-reviewers

Comment 52

[amarc]

https://hg.mozilla.org/mozilla-central/rev/222a9e780b85

Comment 53

[Pulsebot]

Pushed by [e-mail]:
https://github.com/mozilla-firefox/firefox/commit/b0d6b7b382c6
https://hg.mozilla.org/integration/autoland/rev/7e6ab139d052
Fix WPT for fill-rule; r=emilio

Comment 54

[Web Platform Test Sync Bot [:wpt-sync] (Matrix: #interop:mozilla.org)]

Created web-platform-tests PR https://github.com/web-platform-tests/wpt/pull/58664 for changes under testing/web-platform/tests

Comment 55

[Web Platform Test Sync Bot [:wpt-sync] (Matrix: #interop:mozilla.org)]

Upstream PR merged by moz-wptsync-bot