559 lines
16 KiB
Rust
559 lines
16 KiB
Rust
use crate::CowStr;
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use std::fmt;
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/// Parse attributes, assumed to be valid.
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pub(crate) fn parse(src: &str) -> Attributes {
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let mut a = Attributes::new();
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a.parse(src);
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a
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}
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pub fn valid<I: Iterator<Item = char>>(chars: I) -> (usize, bool) {
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use State::*;
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let mut has_attr = false;
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let mut n = 0;
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let mut state = Start;
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for c in chars {
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n += 1;
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state = state.step(c);
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match state {
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Class | Identifier | Value | ValueQuoted => has_attr = true,
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Done | Invalid => break,
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_ => {}
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}
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}
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if matches!(state, Done) {
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(n, has_attr)
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} else {
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(0, false)
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}
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}
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/// Stores an attribute value that supports backslash escapes of ASCII punctuation upon displaying,
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/// without allocating.
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#[derive(Clone, Debug, Eq, PartialEq)]
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pub struct AttributeValue<'s> {
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raw: CowStr<'s>,
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}
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impl<'s> AttributeValue<'s> {
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/// Processes the attribute value escapes and returns an iterator of the parts of the value
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/// that should be displayed.
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pub fn parts(&'s self) -> AttributeValueParts<'s> {
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AttributeValueParts { ahead: &self.raw }
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}
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// lifetime is 's to avoid allocation if empty value is concatenated with single value
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fn extend(&mut self, s: &'s str) {
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match &mut self.raw {
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CowStr::Borrowed(prev) => {
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if prev.is_empty() {
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*prev = s;
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} else {
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self.raw = format!("{} {}", prev, s).into();
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}
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}
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CowStr::Owned(ref mut prev) => {
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prev.push(' ');
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prev.push_str(s);
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}
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}
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}
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}
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impl<'s> From<&'s str> for AttributeValue<'s> {
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fn from(value: &'s str) -> Self {
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Self { raw: value.into() }
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}
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}
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impl<'s> From<CowStr<'s>> for AttributeValue<'s> {
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fn from(value: CowStr<'s>) -> Self {
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Self { raw: value }
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}
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}
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impl<'s> From<String> for AttributeValue<'s> {
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fn from(value: String) -> Self {
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Self { raw: value.into() }
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}
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}
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impl<'s> fmt::Display for AttributeValue<'s> {
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fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
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self.parts().try_for_each(|part| f.write_str(part))
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}
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}
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/// An iterator over the parts of an [`AttributeValue`] that should be displayed.
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pub struct AttributeValueParts<'s> {
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ahead: &'s str,
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}
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impl<'s> Iterator for AttributeValueParts<'s> {
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type Item = &'s str;
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fn next(&mut self) -> Option<Self::Item> {
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for (i, _) in self.ahead.match_indices('\\') {
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match self.ahead.as_bytes().get(i + 1) {
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Some(b'\\') => {
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let next = &self.ahead[..i + 1];
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self.ahead = &self.ahead[i + 2..];
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return Some(next);
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}
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Some(c) if c.is_ascii_punctuation() => {
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let next = &self.ahead[..i];
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self.ahead = &self.ahead[i + 1..];
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return Some(next);
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}
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_ => {}
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}
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}
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(!self.ahead.is_empty()).then(|| std::mem::take(&mut self.ahead))
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}
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}
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/// A collection of attributes, i.e. a key-value map.
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// Attributes are relatively rare, we choose to pay 8 bytes always and sometimes an extra
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// indirection instead of always 24 bytes.
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#[allow(clippy::box_vec)]
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#[derive(Clone, PartialEq, Eq, Default)]
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pub struct Attributes<'s>(Option<Box<Vec<(&'s str, AttributeValue<'s>)>>>);
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impl<'s> Attributes<'s> {
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/// Create an empty collection.
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#[must_use]
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pub fn new() -> Self {
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Self::default()
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}
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#[must_use]
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pub(crate) fn take(&mut self) -> Self {
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Self(self.0.take())
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}
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/// Parse and append attributes, assumed to be valid.
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pub(crate) fn parse(&mut self, input: &'s str) {
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let mut parser = Parser::new(self.take());
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parser.parse(input);
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*self = parser.finish();
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}
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/// Combine all attributes from both objects, prioritizing self on conflicts.
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pub(crate) fn union(&mut self, other: Self) {
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if let Some(attrs0) = &mut self.0 {
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if let Some(mut attrs1) = other.0 {
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for (key, val) in attrs1.drain(..) {
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if !attrs0.iter().any(|(k, _)| *k == key) {
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attrs0.push((key, val));
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}
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}
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}
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} else {
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self.0 = other.0;
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}
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}
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/// Insert an attribute. If the attribute already exists, the previous value will be
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/// overwritten, unless it is a "class" attribute. In that case the provided value will be
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/// appended to the existing value.
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pub fn insert(&mut self, key: &'s str, val: AttributeValue<'s>) {
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self.insert_pos(key, val);
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}
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// duplicate of insert but returns position of inserted value
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fn insert_pos(&mut self, key: &'s str, val: AttributeValue<'s>) -> usize {
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if self.0.is_none() {
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self.0 = Some(Vec::new().into());
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};
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let attrs = self.0.as_mut().unwrap();
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if let Some(i) = attrs.iter().position(|(k, _)| *k == key) {
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let prev = &mut attrs[i].1;
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if key == "class" {
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match val.raw {
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CowStr::Borrowed(s) => prev.extend(s),
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CowStr::Owned(s) => {
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*prev = format!("{} {}", prev, s).into();
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}
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}
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} else {
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*prev = val;
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}
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i
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} else {
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let i = attrs.len();
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attrs.push((key, val));
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i
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}
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}
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/// Returns true if the collection contains no attributes.
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#[must_use]
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pub fn is_empty(&self) -> bool {
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self.0.as_ref().map_or(true, |v| v.is_empty())
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}
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/// Returns a reference to the value corresponding to the attribute key.
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#[must_use]
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pub fn get(&self, key: &str) -> Option<&AttributeValue<'s>> {
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self.iter().find(|(k, _)| *k == key).map(|(_, v)| v)
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}
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/// Returns an iterator over the attributes in undefined order.
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pub fn iter(&self) -> impl Iterator<Item = (&'s str, &AttributeValue<'s>)> + '_ {
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self.0.iter().flat_map(|v| v.iter().map(|(a, b)| (*a, b)))
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}
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}
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#[cfg(test)]
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impl<'s> FromIterator<(&'s str, &'s str)> for Attributes<'s> {
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fn from_iter<I: IntoIterator<Item = (&'s str, &'s str)>>(iter: I) -> Self {
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let attrs = iter
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.into_iter()
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.map(|(a, v)| (a, v.into()))
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.collect::<Vec<_>>();
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if attrs.is_empty() {
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Attributes::new()
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} else {
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Attributes(Some(attrs.into()))
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}
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}
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}
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impl<'s> std::fmt::Debug for Attributes<'s> {
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fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
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write!(f, "{{")?;
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let mut first = true;
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for (k, v) in self.iter() {
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if !first {
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write!(f, ", ")?;
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}
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first = false;
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write!(f, "{}=\"{}\"", k, v.raw)?;
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}
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write!(f, "}}")
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}
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}
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#[derive(Clone)]
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pub struct Validator {
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state: State,
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}
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impl Validator {
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pub fn new() -> Self {
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Self {
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state: State::Start,
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}
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}
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pub fn restart(&mut self) {
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self.state = State::Start;
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}
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/// Returns number of valid bytes parsed (0 means invalid) if finished, otherwise more input is
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/// needed.
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pub fn parse(&mut self, input: &str) -> Option<usize> {
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let mut chars = input.chars();
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for c in &mut chars {
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self.state = self.state.step(c);
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match self.state {
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State::Done => return Some(input.len() - chars.as_str().len()),
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State::Invalid => return Some(0),
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_ => {}
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}
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}
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None
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}
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}
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/// Attributes parser, take input of one or more consecutive attributes and create an `Attributes`
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/// object.
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///
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/// Input is assumed to contain a valid series of attribute sets, the attributes are added as they
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/// are encountered.
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pub struct Parser<'s> {
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attrs: Attributes<'s>,
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i_prev: usize,
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state: State,
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}
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impl<'s> Parser<'s> {
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pub fn new(attrs: Attributes<'s>) -> Self {
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Self {
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attrs,
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i_prev: usize::MAX,
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state: State::Start,
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}
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}
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/// Return value indicates the number of bytes parsed if finished. If None, more input is
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/// required to finish the attributes.
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pub fn parse(&mut self, input: &'s str) {
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use State::*;
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let mut pos = 0;
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let mut pos_prev = 0;
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for c in input.chars() {
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let state_next = self.state.step(c);
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let st = std::mem::replace(&mut self.state, state_next);
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if st != self.state && !matches!((st, self.state), (ValueEscape, _) | (_, ValueEscape))
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{
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let content = &input[pos_prev..pos];
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pos_prev = pos;
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match st {
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Class => self.attrs.insert("class", content.into()),
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Identifier => self.attrs.insert("id", content.into()),
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Key => self.i_prev = self.attrs.insert_pos(content, "".into()),
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Value | ValueQuoted | ValueContinued => {
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self.attrs.0.as_mut().unwrap()[self.i_prev]
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.1
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.extend(&content[usize::from(matches!(st, ValueQuoted))..]);
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}
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_ => {}
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}
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};
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pos += c.len_utf8();
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debug_assert!(!matches!(self.state, Invalid));
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if matches!(self.state, Done) {
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if input[pos..].starts_with('{') {
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self.state = Start;
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} else {
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return;
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}
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}
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}
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}
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pub fn finish(self) -> Attributes<'s> {
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self.attrs
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}
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}
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#[derive(Debug, Clone, Copy, PartialEq, Eq)]
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enum State {
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Start,
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Whitespace,
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Comment,
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ClassFirst,
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Class,
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IdentifierFirst,
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Identifier,
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Key,
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ValueFirst,
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Value,
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ValueQuoted,
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ValueEscape,
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ValueNewline,
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ValueContinued,
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Done,
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Invalid,
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}
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impl State {
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fn step(self, c: char) -> State {
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use State::*;
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match self {
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Start if c == '{' => Whitespace,
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Start => Invalid,
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Whitespace => match c {
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'}' => Done,
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'.' => ClassFirst,
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'#' => IdentifierFirst,
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'%' => Comment,
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c if is_name(c) => Key,
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c if c.is_whitespace() => Whitespace,
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_ => Invalid,
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},
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Comment if c == '%' => Whitespace,
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Comment => Comment,
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ClassFirst if is_name(c) => Class,
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ClassFirst => Invalid,
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IdentifierFirst if is_name(c) => Identifier,
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IdentifierFirst => Invalid,
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s @ (Class | Identifier | Value) if is_name(c) => s,
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Class | Identifier | Value if c.is_whitespace() => Whitespace,
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Class | Identifier | Value if c == '}' => Done,
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Class | Identifier | Value => Invalid,
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Key if is_name(c) => Key,
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Key if c == '=' => ValueFirst,
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Key => Invalid,
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ValueFirst if is_name(c) => Value,
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ValueFirst if c == '"' => ValueQuoted,
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ValueFirst => Invalid,
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ValueQuoted | ValueNewline | ValueContinued if c == '"' => Whitespace,
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ValueQuoted | ValueNewline | ValueContinued | ValueEscape if c == '\n' => ValueNewline,
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ValueQuoted if c == '\\' => ValueEscape,
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ValueQuoted | ValueEscape => ValueQuoted,
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ValueNewline | ValueContinued => ValueContinued,
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Invalid | Done => panic!("{:?}", self),
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}
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}
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}
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pub fn is_name(c: char) -> bool {
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c.is_ascii_alphanumeric() || matches!(c, ':' | '_' | '-')
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}
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#[cfg(test)]
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mod test {
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macro_rules! test_attr {
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($src:expr $(,$($av:expr),* $(,)?)?) => {
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#[allow(unused)]
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let mut attr = super::Attributes::new();
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attr.parse($src);
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let actual = attr.iter().collect::<Vec<_>>();
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let expected = &[$($($av),*,)?];
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for i in 0..actual.len() {
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let actual_val = format!("{}", actual[i].1);
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assert_eq!((actual[i].0, actual_val.as_str()), expected[i], "\n\n{}\n\n", $src);
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}
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};
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}
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#[test]
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fn empty() {
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test_attr!("{}");
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}
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#[test]
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fn class_id() {
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test_attr!(
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"{.some_class #some_id}",
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("class", "some_class"),
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("id", "some_id"),
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);
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test_attr!("{.a .b}", ("class", "a b"));
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test_attr!("{#a #b}", ("id", "b"));
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}
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#[test]
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fn unicode_whitespace() {
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test_attr!("{.a .b}", ("class", "a b"));
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}
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#[test]
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fn value_unquoted() {
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test_attr!(
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"{attr0=val0 attr1=val1}",
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("attr0", "val0"),
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("attr1", "val1"),
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);
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}
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#[test]
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fn value_quoted() {
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test_attr!(
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r#"{attr0="val0" attr1="val1"}"#,
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("attr0", "val0"),
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("attr1", "val1"),
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);
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test_attr!(
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r#"{#id .class style="color:red"}"#,
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("id", "id"),
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("class", "class"),
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("style", "color:red")
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);
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}
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#[test]
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fn value_newline() {
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test_attr!("{attr0=\"abc\ndef\"}", ("attr0", "abc def"));
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}
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#[test]
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fn comment() {
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test_attr!("{%%}");
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test_attr!("{ % abc % }");
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test_attr!(
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"{ .some_class % abc % #some_id}",
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("class", "some_class"),
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("id", "some_id"),
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);
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}
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#[test]
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fn escape() {
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test_attr!(
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r#"{attr="with escaped \~ char"}"#,
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("attr", "with escaped ~ char")
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);
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test_attr!(
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r#"{key="quotes \" should be escaped"}"#,
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("key", r#"quotes " should be escaped"#)
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);
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}
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#[test]
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fn escape_backslash() {
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test_attr!(r#"{attr="with\\backslash"}"#, ("attr", r"with\backslash"));
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test_attr!(
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r#"{attr="with many backslashes\\\\"}"#,
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("attr", r"with many backslashes\\")
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);
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test_attr!(
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r#"{attr="\\escaped backslash at start"}"#,
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("attr", r"\escaped backslash at start")
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);
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}
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#[test]
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fn only_escape_punctuation() {
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test_attr!(r#"{attr="do not \escape"}"#, ("attr", r"do not \escape"));
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test_attr!(
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r#"{attr="\backslash at the beginning"}"#,
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("attr", r"\backslash at the beginning")
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);
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}
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#[test]
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fn valid_full() {
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let src = "{.class %comment%}";
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assert_eq!(super::valid(src.chars()), (src.len(), true));
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}
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#[test]
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fn valid_empty() {
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let src = "{}";
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assert_eq!(super::valid(src.chars()), (src.len(), false));
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}
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#[test]
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fn valid_whitespace() {
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let src = "{ \n }";
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assert_eq!(super::valid(src.chars()), (src.len(), false));
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}
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#[test]
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fn valid_comment() {
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let src = "{%comment%}";
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assert_eq!(super::valid(src.chars()), (src.len(), false));
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}
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#[test]
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fn valid_trailing() {
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let src = "{.class}";
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assert_eq!(
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super::valid(src.chars().chain("{.ignore}".chars())),
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||
(src.len(), true),
|
||
);
|
||
}
|
||
|
||
#[test]
|
||
fn valid_invalid() {
|
||
assert_eq!(super::valid(" {.valid}".chars()), (0, false));
|
||
assert_eq!(super::valid("{.class invalid}".chars()), (0, false));
|
||
assert_eq!(super::valid("abc".chars()), (0, false));
|
||
assert_eq!(super::valid("{.abc.}".chars()), (0, false));
|
||
}
|
||
}
|