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style: Implement the env() function with hardcoded zeros for safe-area-inset.

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Intent to Implement and Ship: https://groups.google.com/d/msg/mozilla.dev.platform/EVKyR1B87T0/_l-_qK8SAAAJ

Differential Revision: https://phabricator.services.mozilla.com/D9609
This commit is contained in:
Emilio Cobos Álvarez 2018-11-05 10:39:46 +00:00
parent 5af6abfb78
commit b7da1bac88
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GPG key ID: 056B727BB9C1027C
11 changed files with 346 additions and 136 deletions
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370
components/style/custom_properties.rs
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@ -21,6 +21,59 @@ use std::fmt::{self, Write};
use std::hash::Hash;
use style_traits::{CssWriter, ParseError, StyleParseErrorKind, ToCss};
/// The environment from which to get `env` function values.
///
/// TODO(emilio): If this becomes a bit more complex we should probably move it
/// to the `media_queries` module, or something.
pub struct CssEnvironment;
struct EnvironmentVariable {
name: Atom,
value: VariableValue,
}
macro_rules! make_variable {
($name:expr, $value:expr) => {{
EnvironmentVariable {
name: $name,
value: {
// TODO(emilio): We could make this be more efficient (though a
// bit less convenient).
let mut input = ParserInput::new($value);
let mut input = Parser::new(&mut input);
let (first_token_type, css, last_token_type) =
parse_self_contained_declaration_value(&mut input, None).unwrap();
VariableValue {
css: css.into_owned(),
first_token_type,
last_token_type,
references: Default::default(),
references_environment: false,
}
},
}
}};
}
lazy_static! {
static ref ENVIRONMENT_VARIABLES: [EnvironmentVariable; 4] = [
make_variable!(atom!("safe-area-inset-top"), "0px"),
make_variable!(atom!("safe-area-inset-bottom"), "0px"),
make_variable!(atom!("safe-area-inset-left"), "0px"),
make_variable!(atom!("safe-area-inset-right"), "0px"),
];
}
impl CssEnvironment {
#[inline]
fn get(&self, name: &Atom) -> Option<&VariableValue> {
let var = ENVIRONMENT_VARIABLES.iter().find(|var| var.name == *name)?;
Some(&var.value)
}
}
/// A custom property name is just an `Atom`.
///
/// Note that this does not include the `--` prefix
@ -48,6 +101,12 @@ pub struct VariableValue {
first_token_type: TokenSerializationType,
last_token_type: TokenSerializationType,
/// Whether a variable value has a reference to an environment variable.
///
/// If this is the case, we need to perform variable substitution on the
/// value.
references_environment: bool,
/// Custom property names in var() functions.
references: PrecomputedHashSet<Name>,
}
@ -216,6 +275,14 @@ where
}
}
/// A struct holding information about the external references to that a custom
/// property value may have.
#[derive(Default)]
struct VarOrEnvReferences {
custom_property_references: PrecomputedHashSet<Name>,
references_environment: bool,
}
impl VariableValue {
fn empty() -> Self {
Self {
@ -223,6 +290,7 @@ impl VariableValue {
last_token_type: TokenSerializationType::nothing(),
first_token_type: TokenSerializationType::nothing(),
references: PrecomputedHashSet::default(),
references_environment: false,
}
}
@ -273,7 +341,7 @@ impl VariableValue {
/// Parse a custom property value.
pub fn parse<'i, 't>(input: &mut Parser<'i, 't>) -> Result<Arc<Self>, ParseError<'i>> {
let mut references = PrecomputedHashSet::default();
let mut references = VarOrEnvReferences::default();
let (first_token_type, css, last_token_type) =
parse_self_contained_declaration_value(input, Some(&mut references))?;
@ -282,7 +350,8 @@ impl VariableValue {
css: css.into_owned(),
first_token_type,
last_token_type,
references,
references: references.custom_property_references,
references_environment: references.references_environment,
}))
}
}
@ -297,7 +366,7 @@ pub fn parse_non_custom_with_var<'i, 't>(
fn parse_self_contained_declaration_value<'i, 't>(
input: &mut Parser<'i, 't>,
references: Option<&mut PrecomputedHashSet<Name>>,
references: Option<&mut VarOrEnvReferences>,
) -> Result<(TokenSerializationType, Cow<'i, str>, TokenSerializationType), ParseError<'i>> {
let start_position = input.position();
let mut missing_closing_characters = String::new();
@ -317,7 +386,7 @@ fn parse_self_contained_declaration_value<'i, 't>(
/// <https://drafts.csswg.org/css-syntax-3/#typedef-declaration-value>
fn parse_declaration_value<'i, 't>(
input: &mut Parser<'i, 't>,
references: Option<&mut PrecomputedHashSet<Name>>,
references: Option<&mut VarOrEnvReferences>,
missing_closing_characters: &mut String,
) -> Result<(TokenSerializationType, TokenSerializationType), ParseError<'i>> {
input.parse_until_before(Delimiter::Bang | Delimiter::Semicolon, |input| {
@ -334,7 +403,7 @@ fn parse_declaration_value<'i, 't>(
/// invalid at the top level
fn parse_declaration_value_block<'i, 't>(
input: &mut Parser<'i, 't>,
mut references: Option<&mut PrecomputedHashSet<Name>>,
mut references: Option<&mut VarOrEnvReferences>,
missing_closing_characters: &mut String,
) -> Result<(TokenSerializationType, TokenSerializationType), ParseError<'i>> {
let mut token_start = input.position();
@ -407,6 +476,12 @@ fn parse_declaration_value_block<'i, 't>(
parse_var_function(input, references.as_mut().map(|r| &mut **r))
})?;
input.reset(&args_start);
} else if name.eq_ignore_ascii_case("env") {
let args_start = input.state();
input.parse_nested_block(|input| {
parse_env_function(input, references.as_mut().map(|r| &mut **r))
})?;
input.reset(&args_start);
}
nested!();
check_closed!(")");
@ -468,29 +543,48 @@ fn parse_declaration_value_block<'i, 't>(
}
}
fn parse_fallback<'i, 't>(input: &mut Parser<'i, 't>) -> Result<(), ParseError<'i>> {
// Exclude `!` and `;` at the top level
// https://drafts.csswg.org/css-syntax/#typedef-declaration-value
input.parse_until_before(Delimiter::Bang | Delimiter::Semicolon, |input| {
// At least one non-comment token.
input.next_including_whitespace()?;
// Skip until the end.
while let Ok(_) = input.next_including_whitespace_and_comments() {}
Ok(())
})
}
// If the var function is valid, return Ok((custom_property_name, fallback))
fn parse_var_function<'i, 't>(
input: &mut Parser<'i, 't>,
references: Option<&mut PrecomputedHashSet<Name>>,
references: Option<&mut VarOrEnvReferences>,
) -> Result<(), ParseError<'i>> {
let name = input.expect_ident_cloned()?;
let name: Result<_, ParseError> = parse_name(&name).map_err(|()| {
let name = parse_name(&name).map_err(|()| {
input.new_custom_error(SelectorParseErrorKind::UnexpectedIdent(name.clone()))
});
let name = name?;
})?;
if input.try(|input| input.expect_comma()).is_ok() {
// Exclude `!` and `;` at the top level
// https://drafts.csswg.org/css-syntax/#typedef-declaration-value
input.parse_until_before(Delimiter::Bang | Delimiter::Semicolon, |input| {
// At least one non-comment token.
input.next_including_whitespace()?;
// Skip until the end.
while let Ok(_) = input.next_including_whitespace_and_comments() {}
Ok(())
})?;
parse_fallback(input)?;
}
if let Some(refs) = references {
refs.insert(Atom::from(name));
refs.custom_property_references.insert(Atom::from(name));
}
Ok(())
}
fn parse_env_function<'i, 't>(
input: &mut Parser<'i, 't>,
references: Option<&mut VarOrEnvReferences>,
) -> Result<(), ParseError<'i>> {
// TODO(emilio): This should be <custom-ident> per spec, but no other
// browser does that, see https://github.com/w3c/csswg-drafts/issues/3262.
input.expect_ident()?;
if input.try(|input| input.expect_comma()).is_ok() {
parse_fallback(input)?;
}
if let Some(references) = references {
references.references_environment = true;
}
Ok(())
}
@ -502,25 +596,26 @@ pub struct CustomPropertiesBuilder<'a> {
may_have_cycles: bool,
custom_properties: Option<CustomPropertiesMap>,
inherited: Option<&'a Arc<CustomPropertiesMap>>,
environment: &'a CssEnvironment,
}
impl<'a> CustomPropertiesBuilder<'a> {
/// Create a new builder, inheriting from a given custom properties map.
pub fn new(inherited: Option<&'a Arc<CustomPropertiesMap>>) -> Self {
pub fn new(
inherited: Option<&'a Arc<CustomPropertiesMap>>,
environment: &'a CssEnvironment,
) -> Self {
Self {
seen: PrecomputedHashSet::default(),
may_have_cycles: false,
custom_properties: None,
inherited,
environment,
}
}
/// Cascade a given custom property declaration.
pub fn cascade(
&mut self,
name: &'a Name,
specified_value: &CustomDeclarationValue,
) {
pub fn cascade(&mut self, name: &'a Name, specified_value: &CustomDeclarationValue) {
let was_already_present = !self.seen.insert(name);
if was_already_present {
return;
@ -540,8 +635,31 @@ impl<'a> CustomPropertiesBuilder<'a> {
let map = self.custom_properties.as_mut().unwrap();
match *specified_value {
CustomDeclarationValue::Value(ref unparsed_value) => {
self.may_have_cycles |= !unparsed_value.references.is_empty();
map.insert(name.clone(), (*unparsed_value).clone());
let has_references = !unparsed_value.references.is_empty();
self.may_have_cycles |= has_references;
// If the variable value has no references and it has an
// environment variable here, perform substitution here instead
// of forcing a full traversal in `substitute_all` afterwards.
let value = if !has_references && unparsed_value.references_environment {
let invalid = Default::default(); // Irrelevant, since there are no references.
let result = substitute_references_in_value(
unparsed_value,
&map,
&invalid,
&self.environment,
);
match result {
Ok(new_value) => Arc::new(new_value),
Err(..) => {
map.remove(name);
return;
},
}
} else {
(*unparsed_value).clone()
};
map.insert(name.clone(), value);
},
CustomDeclarationValue::CSSWideKeyword(keyword) => match keyword {
CSSWideKeyword::Initial => {
@ -553,11 +671,7 @@ impl<'a> CustomPropertiesBuilder<'a> {
}
}
fn value_may_affect_style(
&self,
name: &Name,
value: &CustomDeclarationValue,
) -> bool {
fn value_may_affect_style(&self, name: &Name, value: &CustomDeclarationValue) -> bool {
match *value {
CustomDeclarationValue::CSSWideKeyword(CSSWideKeyword::Unset) |
CustomDeclarationValue::CSSWideKeyword(CSSWideKeyword::Inherit) => {
@ -596,8 +710,8 @@ impl<'a> CustomPropertiesBuilder<'a> {
/// Returns the final map of applicable custom properties.
///
/// If there was any specified property, we've created a new map and now we need
/// to remove any potential cycles, and wrap it in an arc.
/// If there was any specified property, we've created a new map and now we
/// need to remove any potential cycles, and wrap it in an arc.
///
/// Otherwise, just use the inherited custom properties map.
pub fn build(mut self) -> Option<Arc<CustomPropertiesMap>> {
@ -605,9 +719,8 @@ impl<'a> CustomPropertiesBuilder<'a> {
Some(m) => m,
None => return self.inherited.cloned(),
};
if self.may_have_cycles {
substitute_all(&mut map);
substitute_all(&mut map, self.environment);
}
Some(Arc::new(map))
}
@ -616,7 +729,7 @@ impl<'a> CustomPropertiesBuilder<'a> {
/// Resolve all custom properties to either substituted or invalid.
///
/// It does cycle dependencies removal at the same time as substitution.
fn substitute_all(custom_properties_map: &mut CustomPropertiesMap) {
fn substitute_all(custom_properties_map: &mut CustomPropertiesMap, environment: &CssEnvironment) {
// The cycle dependencies removal in this function is a variant
// of Tarjan's algorithm. It is mostly based on the pseudo-code
// listed in
@ -664,6 +777,8 @@ fn substitute_all(custom_properties_map: &mut CustomPropertiesMap) {
map: &'a mut CustomPropertiesMap,
/// The set of invalid custom properties.
invalid: &'a mut PrecomputedHashSet<Name>,
/// The environment to substitute `env()` variables.
environment: &'a CssEnvironment,
}
/// This function combines the traversal for cycle removal and value
@ -686,11 +801,23 @@ fn substitute_all(custom_properties_map: &mut CustomPropertiesMap) {
/// * There is no such variable at all.
fn traverse<'a>(name: Name, context: &mut Context<'a>) -> Option<usize> {
// Some shortcut checks.
let (name, value) = if let Some(value) = context.map.get(&name) {
// This variable has been resolved. Return the signal value.
if value.references.is_empty() || context.invalid.contains(&name) {
let (name, value) = {
let value = context.map.get(&name)?;
// Nothing to resolve.
if value.references.is_empty() {
debug_assert!(
!value.references_environment,
"Should've been handled earlier"
);
return None;
}
// This variable has already been resolved.
if context.invalid.contains(&name) {
return None;
}
// Whether this variable has been visited in this traversal.
let key;
match context.index_map.entry(name) {
@ -702,12 +829,10 @@ fn substitute_all(custom_properties_map: &mut CustomPropertiesMap) {
entry.insert(context.count);
},
}
// Hold a strong reference to the value so that we don't
// need to keep reference to context.map.
(key, value.clone())
} else {
// The variable doesn't exist at all.
return None;
};
// Add new entry to the information table.
@ -793,29 +918,20 @@ fn substitute_all(custom_properties_map: &mut CustomPropertiesMap) {
// Now we have shown that this variable is not in a loop, and
// all of its dependencies should have been resolved. We can
// start substitution now.
let mut computed_value = ComputedValue::empty();
let mut input = ParserInput::new(&value.css);
let mut input = Parser::new(&mut input);
let mut position = (input.position(), value.first_token_type);
let result = substitute_block(
&mut input,
&mut position,
&mut computed_value,
&mut |name, partial_computed_value| {
if let Some(value) = context.map.get(name) {
if !context.invalid.contains(name) {
partial_computed_value.push_variable(value);
return Ok(value.last_token_type);
}
}
Err(())
},
let result = substitute_references_in_value(
&value,
&context.map,
&context.invalid,
&context.environment,
);
if let Ok(last_token_type) = result {
computed_value.push_from(position, &input, last_token_type);
context.map.insert(name, Arc::new(computed_value));
} else {
context.invalid.insert(name);
match result {
Ok(computed_value) => {
context.map.insert(name, Arc::new(computed_value));
},
Err(..) => {
context.invalid.insert(name);
},
}
// All resolved, so return the signal value.
@ -834,6 +950,7 @@ fn substitute_all(custom_properties_map: &mut CustomPropertiesMap) {
var_info: SmallVec::new(),
map: custom_properties_map,
invalid: &mut invalid,
environment,
};
traverse(name, &mut context);
}
@ -841,25 +958,51 @@ fn substitute_all(custom_properties_map: &mut CustomPropertiesMap) {
custom_properties_map.remove_set(&invalid);
}
/// Replace `var()` and `env()` functions in a pre-existing variable value.
fn substitute_references_in_value<'i>(
value: &'i VariableValue,
custom_properties: &CustomPropertiesMap,
invalid_custom_properties: &PrecomputedHashSet<Name>,
environment: &CssEnvironment,
) -> Result<ComputedValue, ParseError<'i>> {
debug_assert!(!value.references.is_empty() || value.references_environment);
let mut input = ParserInput::new(&value.css);
let mut input = Parser::new(&mut input);
let mut position = (input.position(), value.first_token_type);
let mut computed_value = ComputedValue::empty();
let last_token_type = substitute_block(
&mut input,
&mut position,
&mut computed_value,
custom_properties,
invalid_custom_properties,
environment,
)?;
computed_value.push_from(position, &input, last_token_type);
Ok(computed_value)
}
/// Replace `var()` functions in an arbitrary bit of input.
///
/// The `substitute_one` callback is called for each `var()` function in `input`.
/// If the variable has its initial value,
/// the callback should return `Err(())` and leave `partial_computed_value` unchanged.
/// If the variable has its initial value, the callback should return `Err(())`
/// and leave `partial_computed_value` unchanged.
///
/// Otherwise, it should push the value of the variable (with its own `var()` functions replaced)
/// to `partial_computed_value` and return `Ok(last_token_type of what was pushed)`
///
/// Return `Err(())` if `input` is invalid at computed-value time.
/// or `Ok(last_token_type that was pushed to partial_computed_value)` otherwise.
fn substitute_block<'i, 't, F>(
fn substitute_block<'i, 't>(
input: &mut Parser<'i, 't>,
position: &mut (SourcePosition, TokenSerializationType),
partial_computed_value: &mut ComputedValue,
substitute_one: &mut F,
) -> Result<TokenSerializationType, ParseError<'i>>
where
F: FnMut(&Name, &mut ComputedValue) -> Result<TokenSerializationType, ()>,
{
custom_properties: &CustomPropertiesMap,
invalid_custom_properties: &PrecomputedHashSet<Name>,
env: &CssEnvironment,
) -> Result<TokenSerializationType, ParseError<'i>> {
let mut last_token_type = TokenSerializationType::nothing();
let mut set_position_at_next_iteration = false;
loop {
@ -883,27 +1026,49 @@ where
Err(..) => break,
};
match token {
Token::Function(ref name) if name.eq_ignore_ascii_case("var") => {
Token::Function(ref name)
if name.eq_ignore_ascii_case("var") || name.eq_ignore_ascii_case("env") =>
{
let is_env = name.eq_ignore_ascii_case("env");
partial_computed_value.push(
input.slice(position.0..before_this_token),
position.1,
last_token_type,
);
input.parse_nested_block(|input| {
// parse_var_function() ensures neither .unwrap() will fail.
let name = input.expect_ident_cloned().unwrap();
let name = Atom::from(parse_name(&name).unwrap());
// parse_var_function() / parse_env_function() ensure neither .unwrap() will fail.
let name = {
let name = input.expect_ident().unwrap();
if is_env {
Atom::from(&**name)
} else {
Atom::from(parse_name(&name).unwrap())
}
};
if let Ok(last) = substitute_one(&name, partial_computed_value) {
last_token_type = last;
let value = if is_env {
env.get(&name)
} else {
if invalid_custom_properties.contains(&name) {
None
} else {
custom_properties.get(&name).map(|v| &**v)
}
};
if let Some(v) = value {
last_token_type = v.last_token_type;
partial_computed_value.push_variable(v);
// Skip over the fallback, as `parse_nested_block` would return `Err`
// if we don’t consume all of `input`.
// if we don't consume all of `input`.
// FIXME: Add a specialized method to cssparser to do this with less work.
while let Ok(_) = input.next() {}
while input.next().is_ok() {}
} else {
input.expect_comma()?;
let after_comma = input.state();
let first_token_type = input.next_including_whitespace_and_comments()
let first_token_type = input
.next_including_whitespace_and_comments()
// parse_var_function() ensures that .unwrap() will not fail.
.unwrap()
.serialization_type();
@ -913,23 +1078,31 @@ where
input,
&mut position,
partial_computed_value,
substitute_one,
custom_properties,
invalid_custom_properties,
env,
)?;
partial_computed_value.push_from(position, input, last_token_type);
}
Ok(())
})?;
set_position_at_next_iteration = true
},
}
Token::Function(_) |
Token::ParenthesisBlock |
Token::CurlyBracketBlock |
Token::SquareBracketBlock => {
input.parse_nested_block(|input| {
substitute_block(input, position, partial_computed_value, substitute_one)
substitute_block(
input,
position,
partial_computed_value,
custom_properties,
invalid_custom_properties,
env,
)
})?;
// It’s the same type for CloseCurlyBracket and CloseSquareBracket.
// It's the same type for CloseCurlyBracket and CloseSquareBracket.
last_token_type = Token::CloseParenthesis.serialization_type();
},
@ -945,29 +1118,32 @@ where
Ok(last_token_type)
}
/// Replace `var()` functions for a non-custom property.
/// Replace `var()` and `env()` functions for a non-custom property.
///
/// Return `Err(())` for invalid at computed time.
pub fn substitute<'i>(
input: &'i str,
first_token_type: TokenSerializationType,
computed_values_map: Option<&Arc<CustomPropertiesMap>>,
env: &CssEnvironment,
) -> Result<String, ParseError<'i>> {
let mut substituted = ComputedValue::empty();
let mut input = ParserInput::new(input);
let mut input = Parser::new(&mut input);
let mut position = (input.position(), first_token_type);
let invalid = PrecomputedHashSet::default();
let empty_map = CustomPropertiesMap::new();
let custom_properties = match computed_values_map {
Some(m) => &**m,
None => &empty_map,
};
let last_token_type = substitute_block(
&mut input,
&mut position,
&mut substituted,
&mut |name, substituted| {
if let Some(value) = computed_values_map.and_then(|map| map.get(name)) {
substituted.push_variable(value);
Ok(value.last_token_type)
} else {
Err(())
}
},
&custom_properties,
&invalid,
env,
)?;
substituted.push_from(position, &input, last_token_type);
Ok(substituted.css)