style/properties_and_values/
value.rs

1/* This Source Code Form is subject to the terms of the Mozilla Public
2 * License, v. 2.0. If a copy of the MPL was not distributed with this
3 * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
4
5//! Parsing for registered custom properties.
6
7use std::fmt::{self, Write};
8
9use super::{
10    registry::PropertyRegistrationData,
11    syntax::{
12        data_type::DataType, Component as SyntaxComponent, ComponentName, Descriptor, Multiplier,
13    },
14};
15use crate::custom_properties::ComputedValue as ComputedPropertyValue;
16use crate::parser::{Parse, ParserContext};
17use crate::properties;
18use crate::stylesheets::{CssRuleType, Origin, UrlExtraData};
19use crate::values::{
20    animated::{self, Animate, Procedure},
21    computed::{self, ToComputedValue},
22    specified, CustomIdent,
23};
24use cssparser::{BasicParseErrorKind, ParseErrorKind, Parser as CSSParser, TokenSerializationType};
25use selectors::matching::QuirksMode;
26use servo_arc::Arc;
27use smallvec::SmallVec;
28use style_traits::{
29    owned_str::OwnedStr, CssWriter, ParseError as StyleParseError, ParsingMode,
30    PropertySyntaxParseError, StyleParseErrorKind, ToCss,
31};
32
33/// A single component of the computed value.
34pub type ComputedValueComponent = GenericValueComponent<
35    computed::Length,
36    computed::Number,
37    computed::Percentage,
38    computed::LengthPercentage,
39    computed::Color,
40    computed::Image,
41    computed::url::ComputedUrl,
42    computed::Integer,
43    computed::Angle,
44    computed::Time,
45    computed::Resolution,
46    computed::Transform,
47>;
48
49/// A single component of the specified value.
50pub type SpecifiedValueComponent = GenericValueComponent<
51    specified::Length,
52    specified::Number,
53    specified::Percentage,
54    specified::LengthPercentage,
55    specified::Color,
56    specified::Image,
57    specified::url::SpecifiedUrl,
58    specified::Integer,
59    specified::Angle,
60    specified::Time,
61    specified::Resolution,
62    specified::Transform,
63>;
64
65impl<L, N, P, LP, C, Image, U, Integer, A, T, R, Transform>
66    GenericValueComponent<L, N, P, LP, C, Image, U, Integer, A, T, R, Transform>
67{
68    fn serialization_types(&self) -> (TokenSerializationType, TokenSerializationType) {
69        let first_token_type = match self {
70            Self::Length(_) | Self::Angle(_) | Self::Time(_) | Self::Resolution(_) => {
71                TokenSerializationType::Dimension
72            },
73            Self::Number(_) | Self::Integer(_) => TokenSerializationType::Number,
74            Self::Percentage(_) | Self::LengthPercentage(_) => TokenSerializationType::Percentage,
75            Self::Color(_) |
76            Self::Image(_) |
77            Self::Url(_) |
78            Self::TransformFunction(_) |
79            Self::TransformList(_) => TokenSerializationType::Function,
80            Self::CustomIdent(_) => TokenSerializationType::Ident,
81            Self::String(_) => TokenSerializationType::Other,
82        };
83        let last_token_type = if first_token_type == TokenSerializationType::Function {
84            TokenSerializationType::Other
85        } else {
86            first_token_type
87        };
88        (first_token_type, last_token_type)
89    }
90}
91
92/// A generic enum used for both specified value components and computed value components.
93#[derive(
94    Animate, Clone, ToCss, ToComputedValue, ToResolvedValue, Debug, MallocSizeOf, PartialEq, ToShmem
95)]
96#[animation(no_bound(Image, Url))]
97pub enum GenericValueComponent<
98    Length,
99    Number,
100    Percentage,
101    LengthPercentage,
102    Color,
103    Image,
104    Url,
105    Integer,
106    Angle,
107    Time,
108    Resolution,
109    TransformFunction,
110> {
111    /// A <length> value
112    Length(Length),
113    /// A <number> value
114    Number(Number),
115    /// A <percentage> value
116    Percentage(Percentage),
117    /// A <length-percentage> value
118    LengthPercentage(LengthPercentage),
119    /// A <color> value
120    Color(Color),
121    /// An <image> value
122    #[animation(error)]
123    Image(Image),
124    /// A <url> value
125    #[animation(error)]
126    Url(Url),
127    /// An <integer> value
128    Integer(Integer),
129    /// An <angle> value
130    Angle(Angle),
131    /// A <time> value
132    Time(Time),
133    /// A <resolution> value
134    Resolution(Resolution),
135    /// A <transform-function> value
136    /// TODO(bug 1884606): <transform-function> `none` should not interpolate.
137    TransformFunction(TransformFunction),
138    /// A <custom-ident> value
139    #[animation(error)]
140    CustomIdent(CustomIdent),
141    /// A <transform-list> value, equivalent to <transform-function>+
142    /// TODO(bug 1884606): <transform-list> `none` should not interpolate.
143    TransformList(ComponentList<Self>),
144    /// A <string> value
145    #[animation(error)]
146    String(OwnedStr),
147}
148
149/// A list of component values, including the list's multiplier.
150#[derive(Clone, ToComputedValue, ToResolvedValue, Debug, MallocSizeOf, PartialEq, ToShmem)]
151pub struct ComponentList<Component> {
152    /// Multiplier
153    pub multiplier: Multiplier,
154    /// The list of components contained.
155    pub components: crate::OwnedSlice<Component>,
156}
157
158impl<Component: Animate> Animate for ComponentList<Component> {
159    fn animate(&self, other: &Self, procedure: Procedure) -> Result<Self, ()> {
160        if self.multiplier != other.multiplier {
161            return Err(());
162        }
163        let components = animated::lists::by_computed_value::animate(
164            &self.components,
165            &other.components,
166            procedure,
167        )?;
168        Ok(Self {
169            multiplier: self.multiplier,
170            components,
171        })
172    }
173}
174
175impl<Component: ToCss> ToCss for ComponentList<Component> {
176    fn to_css<W>(&self, dest: &mut CssWriter<W>) -> fmt::Result
177    where
178        W: Write,
179    {
180        let mut iter = self.components.iter();
181        let Some(first) = iter.next() else {
182            return Ok(());
183        };
184        first.to_css(dest)?;
185
186        // The separator implied by the multiplier for this list.
187        let separator = match self.multiplier {
188            // <https://drafts.csswg.org/cssom-1/#serialize-a-whitespace-separated-list>
189            Multiplier::Space => " ",
190            // <https://drafts.csswg.org/cssom-1/#serialize-a-comma-separated-list>
191            Multiplier::Comma => ", ",
192        };
193        for component in iter {
194            dest.write_str(separator)?;
195            component.to_css(dest)?;
196        }
197        Ok(())
198    }
199}
200
201/// A struct for a single specified registered custom property value that includes its original URL
202// data so the value can be uncomputed later.
203#[derive(Clone, Debug, MallocSizeOf, PartialEq, ToCss, ToComputedValue, ToResolvedValue, ToShmem)]
204pub struct Value<Component> {
205    /// The registered custom property value.
206    pub(crate) v: ValueInner<Component>,
207    /// The URL data of the registered custom property from before it was computed. This is
208    /// necessary to uncompute registered custom properties.
209    #[css(skip)]
210    url_data: UrlExtraData,
211}
212
213impl<Component: Animate> Animate for Value<Component> {
214    fn animate(&self, other: &Self, procedure: Procedure) -> Result<Self, ()> {
215        let v = self.v.animate(&other.v, procedure)?;
216        Ok(Value {
217            v,
218            url_data: self.url_data.clone(),
219        })
220    }
221}
222
223impl<Component> Value<Component> {
224    /// Creates a new registered custom property value.
225    pub fn new(v: ValueInner<Component>, url_data: UrlExtraData) -> Self {
226        Self { v, url_data }
227    }
228
229    /// Creates a new registered custom property value presumed to have universal syntax.
230    pub fn universal(var: Arc<ComputedPropertyValue>) -> Self {
231        let url_data = var.url_data.clone();
232        let v = ValueInner::Universal(var);
233        Self { v, url_data }
234    }
235}
236
237/// A specified registered custom property value.
238#[derive(
239    Animate, ToComputedValue, ToResolvedValue, ToCss, Clone, Debug, MallocSizeOf, PartialEq, ToShmem,
240)]
241pub enum ValueInner<Component> {
242    /// A single specified component value whose syntax descriptor component did not have a
243    /// multiplier.
244    Component(Component),
245    /// A specified value whose syntax descriptor was the universal syntax definition.
246    #[animation(error)]
247    Universal(#[ignore_malloc_size_of = "Arc"] Arc<ComputedPropertyValue>),
248    /// A list of specified component values whose syntax descriptor component had a multiplier.
249    List(#[animation(field_bound)] ComponentList<Component>),
250}
251
252/// Specified custom property value.
253pub type SpecifiedValue = Value<SpecifiedValueComponent>;
254
255/// Computed custom property value.
256pub type ComputedValue = Value<ComputedValueComponent>;
257
258impl SpecifiedValue {
259    /// Convert a registered custom property to a Computed custom property value, given input and a
260    /// property registration.
261    pub fn compute<'i, 't>(
262        input: &mut CSSParser<'i, 't>,
263        registration: &PropertyRegistrationData,
264        url_data: &UrlExtraData,
265        context: &computed::Context,
266        allow_computationally_dependent: AllowComputationallyDependent,
267    ) -> Result<ComputedValue, ()> {
268        debug_assert!(!registration.syntax.is_universal(), "Shouldn't be needed");
269        let Ok(value) = Self::parse(
270            input,
271            &registration.syntax,
272            url_data,
273            allow_computationally_dependent,
274        ) else {
275            return Err(());
276        };
277
278        Ok(value.to_computed_value(context))
279    }
280
281    /// Parse and validate a registered custom property value according to its syntax descriptor,
282    /// and check for computational independence.
283    pub fn parse<'i, 't>(
284        mut input: &mut CSSParser<'i, 't>,
285        syntax: &Descriptor,
286        url_data: &UrlExtraData,
287        allow_computationally_dependent: AllowComputationallyDependent,
288    ) -> Result<Self, StyleParseError<'i>> {
289        if syntax.is_universal() {
290            let parsed = ComputedPropertyValue::parse(&mut input, url_data)?;
291            return Ok(SpecifiedValue {
292                v: ValueInner::Universal(Arc::new(parsed)),
293                url_data: url_data.clone(),
294            });
295        }
296
297        let mut values = SmallComponentVec::new();
298        let mut multiplier = None;
299        {
300            let mut parser = Parser::new(syntax, &mut values, &mut multiplier);
301            parser.parse(&mut input, url_data, allow_computationally_dependent)?;
302        }
303        let v = if let Some(multiplier) = multiplier {
304            ValueInner::List(ComponentList {
305                multiplier,
306                components: values.to_vec().into(),
307            })
308        } else {
309            ValueInner::Component(values[0].clone())
310        };
311        Ok(Self {
312            v,
313            url_data: url_data.clone(),
314        })
315    }
316}
317
318impl ComputedValue {
319    fn serialization_types(&self) -> (TokenSerializationType, TokenSerializationType) {
320        match &self.v {
321            ValueInner::Component(component) => component.serialization_types(),
322            ValueInner::Universal(_) => unreachable!(),
323            ValueInner::List(list) => list
324                .components
325                .first()
326                .map_or(Default::default(), |f| f.serialization_types()),
327        }
328    }
329
330    fn to_declared_value(&self) -> properties::CustomDeclarationValue {
331        if let ValueInner::Universal(ref var) = self.v {
332            return properties::CustomDeclarationValue::Unparsed(Arc::clone(var));
333        }
334        properties::CustomDeclarationValue::Parsed(Arc::new(ToComputedValue::from_computed_value(self)))
335    }
336
337    /// Returns the contained variable value if it exists, otherwise `None`.
338    pub fn as_universal(&self) -> Option<&Arc<ComputedPropertyValue>> {
339        if let ValueInner::Universal(ref var) = self.v {
340            Some(var)
341        } else {
342            None
343        }
344    }
345
346    /// Convert to an untyped variable value.
347    pub fn to_variable_value(&self) -> ComputedPropertyValue {
348        if let ValueInner::Universal(ref value) = self.v {
349            return (**value).clone();
350        }
351        let serialization_types = self.serialization_types();
352        ComputedPropertyValue::new(
353            self.to_css_string(),
354            &self.url_data,
355            serialization_types.0,
356            serialization_types.1,
357        )
358    }
359}
360
361/// Whether the computed value parsing should allow computationaly dependent values like 3em or
362/// var(-foo).
363///
364/// https://drafts.css-houdini.org/css-properties-values-api-1/#computationally-independent
365pub enum AllowComputationallyDependent {
366    /// Only computationally independent values are allowed.
367    No,
368    /// Computationally independent and dependent values are allowed.
369    Yes,
370}
371
372type SmallComponentVec = SmallVec<[SpecifiedValueComponent; 1]>;
373
374struct Parser<'a> {
375    syntax: &'a Descriptor,
376    output: &'a mut SmallComponentVec,
377    output_multiplier: &'a mut Option<Multiplier>,
378}
379
380impl<'a> Parser<'a> {
381    fn new(
382        syntax: &'a Descriptor,
383        output: &'a mut SmallComponentVec,
384        output_multiplier: &'a mut Option<Multiplier>,
385    ) -> Self {
386        Self {
387            syntax,
388            output,
389            output_multiplier,
390        }
391    }
392
393    fn parse<'i, 't>(
394        &mut self,
395        input: &mut CSSParser<'i, 't>,
396        url_data: &UrlExtraData,
397        allow_computationally_dependent: AllowComputationallyDependent,
398    ) -> Result<(), StyleParseError<'i>> {
399        use self::AllowComputationallyDependent::*;
400        let parsing_mode = match allow_computationally_dependent {
401            No => ParsingMode::DISALLOW_COMPUTATIONALLY_DEPENDENT,
402            Yes => ParsingMode::DEFAULT,
403        };
404        let ref context = ParserContext::new(
405            Origin::Author,
406            url_data,
407            Some(CssRuleType::Style),
408            parsing_mode,
409            QuirksMode::NoQuirks,
410            /* namespaces = */ Default::default(),
411            None,
412            None,
413        );
414        for component in self.syntax.components.iter() {
415            let result = input.try_parse(|input| {
416                input.parse_entirely(|input| {
417                    Self::parse_value(context, input, &component.unpremultiplied())
418                })
419            });
420            let Ok(values) = result else { continue };
421            self.output.extend(values);
422            *self.output_multiplier = component.multiplier();
423            break;
424        }
425        if self.output.is_empty() {
426            return Err(input.new_error(BasicParseErrorKind::EndOfInput));
427        }
428        Ok(())
429    }
430
431    fn parse_value<'i, 't>(
432        context: &ParserContext,
433        input: &mut CSSParser<'i, 't>,
434        component: &SyntaxComponent,
435    ) -> Result<SmallComponentVec, StyleParseError<'i>> {
436        let mut values = SmallComponentVec::new();
437        values.push(Self::parse_component_without_multiplier(
438            context, input, component,
439        )?);
440
441        if let Some(multiplier) = component.multiplier() {
442            loop {
443                let result = Self::expect_multiplier(input, &multiplier);
444                if Self::expect_multiplier_yielded_eof_error(&result) {
445                    break;
446                }
447                result?;
448                values.push(Self::parse_component_without_multiplier(
449                    context, input, component,
450                )?);
451            }
452        }
453        Ok(values)
454    }
455
456    fn parse_component_without_multiplier<'i, 't>(
457        context: &ParserContext,
458        input: &mut CSSParser<'i, 't>,
459        component: &SyntaxComponent,
460    ) -> Result<SpecifiedValueComponent, StyleParseError<'i>> {
461        let data_type = match component.name() {
462            ComponentName::DataType(ty) => ty,
463            ComponentName::Ident(ref name) => {
464                let ident = CustomIdent::parse(input, &[])?;
465                if ident != *name {
466                    return Err(input.new_custom_error(StyleParseErrorKind::UnspecifiedError));
467                }
468                return Ok(SpecifiedValueComponent::CustomIdent(ident));
469            },
470        };
471
472        let value = match data_type {
473            DataType::Length => {
474                SpecifiedValueComponent::Length(specified::Length::parse(context, input)?)
475            },
476            DataType::Number => {
477                SpecifiedValueComponent::Number(specified::Number::parse(context, input)?)
478            },
479            DataType::Percentage => {
480                SpecifiedValueComponent::Percentage(specified::Percentage::parse(context, input)?)
481            },
482            DataType::LengthPercentage => SpecifiedValueComponent::LengthPercentage(
483                specified::LengthPercentage::parse(context, input)?,
484            ),
485            DataType::Color => {
486                SpecifiedValueComponent::Color(specified::Color::parse(context, input)?)
487            },
488            DataType::Image => {
489                SpecifiedValueComponent::Image(specified::Image::parse(context, input)?)
490            },
491            DataType::Url => {
492                SpecifiedValueComponent::Url(specified::url::SpecifiedUrl::parse(context, input)?)
493            },
494            DataType::Integer => {
495                SpecifiedValueComponent::Integer(specified::Integer::parse(context, input)?)
496            },
497            DataType::Angle => {
498                SpecifiedValueComponent::Angle(specified::Angle::parse(context, input)?)
499            },
500            DataType::Time => {
501                SpecifiedValueComponent::Time(specified::Time::parse(context, input)?)
502            },
503            DataType::Resolution => {
504                SpecifiedValueComponent::Resolution(specified::Resolution::parse(context, input)?)
505            },
506            DataType::TransformFunction => SpecifiedValueComponent::TransformFunction(
507                specified::Transform::parse(context, input)?,
508            ),
509            DataType::CustomIdent => {
510                let name = CustomIdent::parse(input, &[])?;
511                SpecifiedValueComponent::CustomIdent(name)
512            },
513            DataType::TransformList => {
514                let mut values = vec![];
515                let Some(multiplier) = component.unpremultiplied().multiplier() else {
516                    debug_assert!(false, "Unpremultiplied <transform-list> had no multiplier?");
517                    return Err(
518                        input.new_custom_error(StyleParseErrorKind::PropertySyntaxField(
519                            PropertySyntaxParseError::UnexpectedEOF,
520                        )),
521                    );
522                };
523                debug_assert_matches!(multiplier, Multiplier::Space);
524                loop {
525                    values.push(SpecifiedValueComponent::TransformFunction(
526                        specified::Transform::parse(context, input)?,
527                    ));
528                    let result = Self::expect_multiplier(input, &multiplier);
529                    if Self::expect_multiplier_yielded_eof_error(&result) {
530                        break;
531                    }
532                    result?;
533                }
534                let list = ComponentList {
535                    multiplier,
536                    components: values.into(),
537                };
538                SpecifiedValueComponent::TransformList(list)
539            },
540            DataType::String => {
541                let string = input.expect_string()?;
542                SpecifiedValueComponent::String(string.as_ref().to_owned().into())
543            },
544        };
545        Ok(value)
546    }
547
548    fn expect_multiplier_yielded_eof_error<'i>(result: &Result<(), StyleParseError<'i>>) -> bool {
549        matches!(
550            result,
551            Err(StyleParseError {
552                kind: ParseErrorKind::Basic(BasicParseErrorKind::EndOfInput),
553                ..
554            })
555        )
556    }
557
558    fn expect_multiplier<'i, 't>(
559        input: &mut CSSParser<'i, 't>,
560        multiplier: &Multiplier,
561    ) -> Result<(), StyleParseError<'i>> {
562        match multiplier {
563            Multiplier::Space => {
564                input.expect_whitespace()?;
565                if input.is_exhausted() {
566                    // If there was trailing whitespace, do not interpret it as a multiplier
567                    return Err(input.new_error(BasicParseErrorKind::EndOfInput));
568                }
569                Ok(())
570            },
571            Multiplier::Comma => Ok(input.expect_comma()?),
572        }
573    }
574}
575
576/// An animated value for custom property.
577#[derive(Clone, Debug, MallocSizeOf, PartialEq)]
578pub struct CustomAnimatedValue {
579    /// The name of the custom property.
580    pub(crate) name: crate::custom_properties::Name,
581    /// The computed value of the custom property.
582    value: ComputedValue,
583}
584
585impl Animate for CustomAnimatedValue {
586    fn animate(&self, other: &Self, procedure: Procedure) -> Result<Self, ()> {
587        if self.name != other.name {
588            return Err(());
589        }
590        let value = self.value.animate(&other.value, procedure)?;
591        Ok(Self {
592            name: self.name.clone(),
593            value,
594        })
595    }
596}
597
598impl CustomAnimatedValue {
599    pub(crate) fn from_computed(
600        name: &crate::custom_properties::Name,
601        value: &ComputedValue,
602    ) -> Self {
603        Self {
604            name: name.clone(),
605            value: value.clone(),
606        }
607    }
608
609    pub(crate) fn from_declaration(
610        declaration: &properties::CustomDeclaration,
611        context: &mut computed::Context,
612        _initial: &properties::ComputedValues,
613    ) -> Option<Self> {
614        let computed_value = match declaration.value {
615            properties::CustomDeclarationValue::Unparsed(ref value) => {
616                debug_assert!(
617                    context.builder.stylist.is_some(),
618                    "Need a Stylist to get property registration!"
619                );
620                let registration = context
621                    .builder
622                    .stylist
623                    .unwrap()
624                    .get_custom_property_registration(&declaration.name);
625                if registration.syntax.is_universal() {
626                    // FIXME: Do we need to perform substitution here somehow?
627                    ComputedValue {
628                        v: ValueInner::Universal(Arc::clone(value)),
629                        url_data: value.url_data.clone(),
630                    }
631                } else {
632                    let mut input = cssparser::ParserInput::new(&value.css);
633                    let mut input = CSSParser::new(&mut input);
634                    SpecifiedValue::compute(
635                        &mut input,
636                        registration,
637                        &value.url_data,
638                        context,
639                        AllowComputationallyDependent::Yes,
640                    ).unwrap_or_else(|_| {
641                        ComputedValue {
642                            v: ValueInner::Universal(Arc::clone(value)),
643                            url_data: value.url_data.clone(),
644                        }
645                    })
646                }
647            }
648            properties::CustomDeclarationValue::Parsed(ref v) => v.to_computed_value(context),
649            // FIXME: This should be made to work to the extent possible like for non-custom
650            // properties (using `initial` at least to handle unset / inherit).
651            properties::CustomDeclarationValue::CSSWideKeyword(..) => return None,
652        };
653        Some(Self {
654            name: declaration.name.clone(),
655            value: computed_value,
656        })
657    }
658
659    pub(crate) fn to_declaration(&self) -> properties::PropertyDeclaration {
660        properties::PropertyDeclaration::Custom(properties::CustomDeclaration {
661            name: self.name.clone(),
662            value: self.value.to_declared_value(),
663        })
664    }
665}
style/properties_and_values/value.rs

style/properties_and_values/
value.rs
