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use derivative::Derivative;
use std::fmt::Debug;
use crate::cascade;
use crate::stream::{TokenStream, TokenTree};
#[derive(Derivative)]
#[derivative(Debug(bound = "D::Error: Debug"))]
pub enum Error<D, S>
where
D: Driver<S> + ?Sized,
S: TokenStream,
{
Cascade(cascade::Error<S>),
Domain(D::Error),
}
pub trait Driver<S>
where
S: TokenStream,
{
type Property;
type Rule;
type Error;
fn parse_property(
&mut self,
name: &[TokenTree<S>],
value: &[TokenTree<S>],
) -> Result<Self::Property, Self::Error>;
fn parse_rule(
&mut self,
selectors: &[TokenTree<S>],
body: &S::Group,
) -> Result<Self::Rule, Vec<Error<Self, S>>>;
}
#[derive(Derivative)]
#[derivative(Debug(bound = "Item<D, S>: Debug"))]
pub struct StyleSheet<D, S>
where
D: Driver<S>,
S: TokenStream,
{
pub items: Vec<Item<D, S>>,
}
impl<D, S> StyleSheet<D, S>
where
D: Driver<S>,
S: TokenStream,
{
pub fn parse(
driver: &mut D,
tokens: &[TokenTree<S>],
) -> Result<StyleSheet<D, S>, Vec<Error<D, S>>> {
let items = cascade::parse(tokens);
match cascade::validate(&items) {
errors if !errors.is_empty() => {
return Err(errors
.into_iter()
.map(|error| Error::Cascade(error))
.collect())
}
_ => {}
};
let mut errors = vec![];
let mut results = vec![];
for item in items {
match item {
cascade::Item::Property(property) => {
match driver.parse_property(property.name, property.value) {
Ok(result) => results.push(Item::Property(result)),
Err(error) => errors.push(Error::Domain(error)),
}
}
cascade::Item::Rule(rule) => {
match driver.parse_rule(rule.selectors, rule.group.unwrap()) {
Ok(result) => results.push(Item::Rule(result)),
Err(error) => errors.extend(error),
}
}
}
}
if errors.is_empty() {
Ok(StyleSheet { items: results })
} else {
Err(errors)
}
}
}
#[derive(Derivative)]
#[derivative(Debug(bound = "D::Property: Debug, D::Rule: Debug"))]
pub enum Item<D, S>
where
D: Driver<S>,
S: TokenStream,
{
Property(D::Property),
Rule(D::Rule),
}