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/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at https://mozilla.org/MPL/2.0/. */
//! Parse/serialize and resolve a single color component.
use super::{
parsing::{rcs_enabled, ChannelKeyword},
AbsoluteColor,
};
use crate::{
parser::ParserContext,
values::{
generics::calc::CalcUnits,
specified::calc::{CalcNode as SpecifiedCalcNode, Leaf as SpecifiedLeaf},
},
};
use cssparser::{Parser, Token};
use style_traits::{ParseError, StyleParseErrorKind};
/// A single color component.
#[derive(Clone, Debug, MallocSizeOf, PartialEq, ToShmem)]
pub enum ColorComponent<ValueType> {
/// The "none" keyword.
None,
/// A absolute value.
Value(ValueType),
}
impl<ValueType> ColorComponent<ValueType> {
/// Return true if the component is "none".
#[inline]
pub fn is_none(&self) -> bool {
matches!(self, Self::None)
}
/// If the component contains a value, map it to another value.
pub fn map_value<OutType>(
self,
f: impl FnOnce(ValueType) -> OutType,
) -> ColorComponent<OutType> {
match self {
Self::None => ColorComponent::None,
Self::Value(value) => ColorComponent::Value(f(value)),
}
}
/// Return the component as its value.
pub fn into_value(self) -> ValueType {
match self {
Self::None => panic!("value not available when component is None"),
Self::Value(value) => value,
}
}
/// Return the component as its value or a default value.
pub fn into_value_or(self, default: ValueType) -> ValueType {
match self {
Self::None => default,
Self::Value(value) => value,
}
}
}
/// An utility trait that allows the construction of [ColorComponent]
/// `ValueType`'s after parsing a color component.
pub trait ColorComponentType: Sized {
// TODO(tlouw): This function should be named according to the rules in the spec
// stating that all the values coming from color components are
// numbers and that each has their own rules dependeing on types.
/// Construct a new component from a single value.
fn from_value(value: f32) -> Self;
/// Return the [CalcUnits] flags that the impl can handle.
fn units() -> CalcUnits;
/// Try to create a new component from the given token.
fn try_from_token(token: &Token) -> Result<Self, ()>;
/// Try to create a new component from the given [CalcNodeLeaf] that was
/// resolved from a [CalcNode].
fn try_from_leaf(leaf: &SpecifiedLeaf) -> Result<Self, ()>;
}
impl<ValueType: ColorComponentType> ColorComponent<ValueType> {
/// Parse a single [ColorComponent].
pub fn parse<'i, 't>(
context: &ParserContext,
input: &mut Parser<'i, 't>,
allow_none: bool,
origin_color: Option<&AbsoluteColor>,
) -> Result<Self, ParseError<'i>> {
let location = input.current_source_location();
match *input.next()? {
Token::Ident(ref value) if allow_none && value.eq_ignore_ascii_case("none") => {
Ok(ColorComponent::None)
},
ref t @ Token::Ident(ref ident) if origin_color.is_some() => {
if let Ok(channel_keyword) = ChannelKeyword::from_ident(ident) {
if let Ok(value) = origin_color
.unwrap()
.get_component_by_channel_keyword(channel_keyword)
{
Ok(Self::Value(ValueType::from_value(value.unwrap_or(0.0))))
} else {
Err(location.new_unexpected_token_error(t.clone()))
}
} else {
Err(location.new_unexpected_token_error(t.clone()))
}
},
Token::Function(ref name) => {
let function = SpecifiedCalcNode::math_function(context, name, location)?;
let units = if rcs_enabled() {
ValueType::units() | CalcUnits::COLOR_COMPONENT
} else {
ValueType::units()
};
let node = SpecifiedCalcNode::parse(context, input, function, units)?;
let Ok(resolved_leaf) = node.resolve_map(|leaf| {
//
Ok(match leaf {
SpecifiedLeaf::ColorComponent(channel_keyword) => {
if let Some(origin_color) = origin_color {
if let Ok(value) =
origin_color.get_component_by_channel_keyword(*channel_keyword)
{
SpecifiedLeaf::Number(value.unwrap_or(0.0))
} else {
return Err(());
}
} else {
return Err(());
}
},
l => l.clone(),
})
}) else {
return Err(location.new_custom_error(StyleParseErrorKind::UnspecifiedError));
};
ValueType::try_from_leaf(&resolved_leaf)
.map(Self::Value)
.map_err(|_| location.new_custom_error(StyleParseErrorKind::UnspecifiedError))
},
ref t => ValueType::try_from_token(t)
.map(Self::Value)
.map_err(|_| location.new_unexpected_token_error(t.clone())),
}
}
}
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