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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 http://mozilla.org/MPL/2.0/. */
//! https://drafts.csswg.org/css-syntax/#urange
use crate::tokenizer::Token;
use crate::{BasicParseError, Parser, ToCss};
use std::char;
use std::fmt;
/// One contiguous range of code points.
///
/// Can not be empty. Can represent a single code point when start == end.
#[derive(PartialEq, Eq, Clone, Hash)]
#[repr(C)]
pub struct UnicodeRange {
/// Inclusive start of the range. In [0, end].
pub start: u32,
/// Inclusive end of the range. In [0, 0x10FFFF].
pub end: u32,
}
impl UnicodeRange {
/// https://drafts.csswg.org/css-syntax/#urange-syntax
pub fn parse<'i, 't>(input: &mut Parser<'i, 't>) -> Result<Self, BasicParseError<'i>> {
// <urange> =
// u '+' <ident-token> '?'* |
// u <dimension-token> '?'* |
// u <number-token> '?'* |
// u <number-token> <dimension-token> |
// u <number-token> <number-token> |
// u '+' '?'+
input.expect_ident_matching("u")?;
let after_u = input.position();
parse_tokens(input)?;
// This deviates from the spec in case there are CSS comments
// between tokens in the middle of one <unicode-range>,
// but oh well…
let concatenated_tokens = input.slice_from(after_u);
let range = match parse_concatenated(concatenated_tokens.as_bytes()) {
Ok(range) => range,
Err(()) => {
return Err(input
.new_basic_unexpected_token_error(Token::Ident(concatenated_tokens.into())))
}
};
if range.end > char::MAX as u32 || range.start > range.end {
Err(input.new_basic_unexpected_token_error(Token::Ident(concatenated_tokens.into())))
} else {
Ok(range)
}
}
}
fn parse_tokens<'i, 't>(input: &mut Parser<'i, 't>) -> Result<(), BasicParseError<'i>> {
match input.next_including_whitespace()?.clone() {
Token::Delim('+') => {
match *input.next_including_whitespace()? {
Token::Ident(_) => {}
Token::Delim('?') => {}
ref t => {
let t = t.clone();
return Err(input.new_basic_unexpected_token_error(t));
}
}
parse_question_marks(input)
}
Token::Dimension { .. } => parse_question_marks(input),
Token::Number { .. } => {
let after_number = input.state();
match input.next_including_whitespace() {
Ok(&Token::Delim('?')) => parse_question_marks(input),
Ok(&Token::Dimension { .. }) => {}
Ok(&Token::Number { .. }) => {}
_ => input.reset(&after_number),
}
}
t => return Err(input.new_basic_unexpected_token_error(t)),
}
Ok(())
}
/// Consume as many '?' as possible
fn parse_question_marks(input: &mut Parser) {
loop {
let start = input.state();
match input.next_including_whitespace() {
Ok(&Token::Delim('?')) => {}
_ => {
input.reset(&start);
return;
}
}
}
}
fn parse_concatenated(text: &[u8]) -> Result<UnicodeRange, ()> {
let mut text = match text.split_first() {
Some((&b'+', text)) => text,
_ => return Err(()),
};
let (first_hex_value, hex_digit_count) = consume_hex(&mut text);
let question_marks = consume_question_marks(&mut text);
let consumed = hex_digit_count + question_marks;
if consumed == 0 || consumed > 6 {
return Err(());
}
if question_marks > 0 {
if text.is_empty() {
return Ok(UnicodeRange {
start: first_hex_value << (question_marks * 4),
end: ((first_hex_value + 1) << (question_marks * 4)) - 1,
});
}
} else if text.is_empty() {
return Ok(UnicodeRange {
start: first_hex_value,
end: first_hex_value,
});
} else {
if let Some((&b'-', mut text)) = text.split_first() {
let (second_hex_value, hex_digit_count) = consume_hex(&mut text);
if hex_digit_count > 0 && hex_digit_count <= 6 && text.is_empty() {
return Ok(UnicodeRange {
start: first_hex_value,
end: second_hex_value,
});
}
}
}
Err(())
}
fn consume_hex(text: &mut &[u8]) -> (u32, usize) {
let mut value = 0;
let mut digits = 0;
while let Some((&byte, rest)) = text.split_first() {
if let Some(digit_value) = (byte as char).to_digit(16) {
value = value * 0x10 + digit_value;
digits += 1;
*text = rest
} else {
break;
}
}
(value, digits)
}
fn consume_question_marks(text: &mut &[u8]) -> usize {
let mut question_marks = 0;
while let Some((&b'?', rest)) = text.split_first() {
question_marks += 1;
*text = rest
}
question_marks
}
impl fmt::Debug for UnicodeRange {
fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
self.to_css(formatter)
}
}
impl ToCss for UnicodeRange {
fn to_css<W>(&self, dest: &mut W) -> fmt::Result
where
W: fmt::Write,
{
write!(dest, "U+{:X}", self.start)?;
if self.end != self.start {
write!(dest, "-{:X}", self.end)?;
}
Ok(())
}
}
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