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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
//! The context within which CSS code is parsed.
use crate::context::QuirksMode;
use crate::error_reporting::{ContextualParseError, ParseErrorReporter};
use crate::stylesheets::{CssRuleType, CssRuleTypes, Namespaces, Origin, UrlExtraData};
use crate::use_counters::UseCounters;
use cssparser::{Parser, SourceLocation, UnicodeRange};
use selectors::parser::ParseRelative;
use std::borrow::Cow;
use style_traits::{OneOrMoreSeparated, ParseError, ParsingMode, Separator};
/// Nesting context for parsing rules.
#[derive(Clone, Copy)]
pub struct NestingContext {
/// All rule types we've nested into, if any.
pub rule_types: CssRuleTypes,
/// Whether or not parsing relative selector syntax should be allowed.
pub parse_relative: ParseRelative,
}
impl NestingContext {
fn parse_relative_for(rule_type: CssRuleType) -> ParseRelative {
match rule_type {
CssRuleType::Scope => ParseRelative::ForScope,
CssRuleType::Style => ParseRelative::ForNesting,
_ => ParseRelative::No,
}
}
/// Create a new nesting context.
pub fn new(rule_types: CssRuleTypes, parse_nested_rule_type: Option<CssRuleType>) -> Self {
Self {
rule_types,
parse_relative: parse_nested_rule_type
.map_or(ParseRelative::No, Self::parse_relative_for)
}
}
/// Create a new nesting context based on the given rule.
pub fn new_from_rule(rule_type: Option<CssRuleType>) -> Self {
Self {
rule_types: rule_type.map(CssRuleTypes::from).unwrap_or_default(),
parse_relative: rule_type
.map(Self::parse_relative_for)
.unwrap_or(ParseRelative::No),
}
}
/// Save the current nesting context.
pub fn save(&mut self, rule_type: CssRuleType) -> Self {
let old = *self;
self.rule_types.insert(rule_type);
let new_parse_relative = Self::parse_relative_for(rule_type);
if new_parse_relative != ParseRelative::No {
self.parse_relative = new_parse_relative;
}
old
}
/// Load the saved nesting context.
pub fn restore(&mut self, saved: Self) {
*self = saved;
}
}
/// The data that the parser needs from outside in order to parse a stylesheet.
pub struct ParserContext<'a> {
/// The `Origin` of the stylesheet, whether it's a user, author or
/// user-agent stylesheet.
pub stylesheet_origin: Origin,
/// The extra data we need for resolving url values.
pub url_data: &'a UrlExtraData,
/// The mode to use when parsing.
pub parsing_mode: ParsingMode,
/// The quirks mode of this stylesheet.
pub quirks_mode: QuirksMode,
/// The active error reporter, or none if error reporting is disabled.
error_reporter: Option<&'a dyn ParseErrorReporter>,
/// The currently active namespaces.
pub namespaces: Cow<'a, Namespaces>,
/// The use counters we want to record while parsing style rules, if any.
pub use_counters: Option<&'a UseCounters>,
/// Current nesting context.
pub nesting_context: NestingContext,
}
impl<'a> ParserContext<'a> {
/// Create a parser context.
#[inline]
pub fn new(
stylesheet_origin: Origin,
url_data: &'a UrlExtraData,
rule_type: Option<CssRuleType>,
parsing_mode: ParsingMode,
quirks_mode: QuirksMode,
namespaces: Cow<'a, Namespaces>,
error_reporter: Option<&'a dyn ParseErrorReporter>,
use_counters: Option<&'a UseCounters>,
) -> Self {
Self {
stylesheet_origin,
url_data,
parsing_mode,
quirks_mode,
error_reporter,
namespaces,
use_counters,
nesting_context: NestingContext::new_from_rule(rule_type),
}
}
/// Temporarily sets the rule_type and executes the callback function, returning its result.
pub fn nest_for_rule<R>(
&mut self,
rule_type: CssRuleType,
cb: impl FnOnce(&mut Self) -> R,
) -> R {
let old = self.nesting_context.save(rule_type);
let r = cb(self);
self.nesting_context.restore(old);
r
}
/// Whether we're in a @page rule.
#[inline]
pub fn in_page_rule(&self) -> bool {
self.nesting_context.rule_types.contains(CssRuleType::Page)
}
/// Get the rule type, which assumes that one is available.
pub fn rule_types(&self) -> CssRuleTypes {
self.nesting_context.rule_types
}
/// Returns whether CSS error reporting is enabled.
#[inline]
pub fn error_reporting_enabled(&self) -> bool {
self.error_reporter.is_some()
}
/// Record a CSS parse error with this context’s error reporting.
pub fn log_css_error(&self, location: SourceLocation, error: ContextualParseError) {
let error_reporter = match self.error_reporter {
Some(r) => r,
None => return,
};
error_reporter.report_error(self.url_data, location, error)
}
/// Whether we're in a user-agent stylesheet.
#[inline]
pub fn in_ua_sheet(&self) -> bool {
self.stylesheet_origin == Origin::UserAgent
}
/// Returns whether chrome-only rules should be parsed.
#[inline]
pub fn chrome_rules_enabled(&self) -> bool {
self.url_data.chrome_rules_enabled() || self.stylesheet_origin != Origin::Author
}
}
/// A trait to abstract parsing of a specified value given a `ParserContext` and
/// CSS input.
///
/// This can be derived on keywords with `#[derive(Parse)]`.
///
/// The derive code understands the following attributes on each of the variants:
///
/// * `#[parse(aliases = "foo,bar")]` can be used to alias a value with another
/// at parse-time.
///
/// * `#[parse(condition = "function")]` can be used to make the parsing of the
/// value conditional on `function`, which needs to fulfill
/// `fn(&ParserContext) -> bool`.
pub trait Parse: Sized {
/// Parse a value of this type.
///
/// Returns an error on failure.
fn parse<'i, 't>(
context: &ParserContext,
input: &mut Parser<'i, 't>,
) -> Result<Self, ParseError<'i>>;
}
impl<T> Parse for Vec<T>
where
T: Parse + OneOrMoreSeparated,
<T as OneOrMoreSeparated>::S: Separator,
{
fn parse<'i, 't>(
context: &ParserContext,
input: &mut Parser<'i, 't>,
) -> Result<Self, ParseError<'i>> {
<T as OneOrMoreSeparated>::S::parse(input, |i| T::parse(context, i))
}
}
impl<T> Parse for Box<T>
where
T: Parse,
{
fn parse<'i, 't>(
context: &ParserContext,
input: &mut Parser<'i, 't>,
) -> Result<Self, ParseError<'i>> {
T::parse(context, input).map(Box::new)
}
}
impl Parse for crate::OwnedStr {
fn parse<'i, 't>(
_: &ParserContext,
input: &mut Parser<'i, 't>,
) -> Result<Self, ParseError<'i>> {
Ok(input.expect_string()?.as_ref().to_owned().into())
}
}
impl Parse for UnicodeRange {
fn parse<'i, 't>(
_: &ParserContext,
input: &mut Parser<'i, 't>,
) -> Result<Self, ParseError<'i>> {
Ok(UnicodeRange::parse(input)?)
}
}