attr: step one char at a time
make sure attr can keep track of all state so one char can be provided at a time this allows not restarting from beginning if we find out we need more chars to finish parsing attributes
This commit is contained in:
Noah Hellman
parent
e1b12ba642
commit
172f555272
1 changed files with 90 additions and 160 deletions
250
src/attr.rs
250
src/attr.rs
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@ -12,16 +12,21 @@ pub(crate) fn parse(src: &str) -> Attributes {
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pub fn valid<I: Iterator<Item = char>>(chars: I) -> (usize, bool) {
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let mut has_attr = false;
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let mut p = Parser::new(chars);
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for e in &mut p {
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match e {
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Element::Class(..) | Element::Identifier(..) | Element::Attribute(..) => {
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has_attr = true;
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}
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Element::Invalid => return (0, false),
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let mut p = Parser::new();
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for c in chars {
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if p.step(c).is_some() {
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has_attr = true;
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}
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if matches!(p.state, Done | Invalid) {
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break;
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}
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}
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(p.pos, has_attr)
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if matches!(p.state, Done) {
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(p.pos, 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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@ -112,15 +117,20 @@ impl<'s> Attributes<'s> {
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}
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pub(crate) fn parse(&mut self, input: &'s str) -> bool {
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for elem in Parser::new(input.chars()) {
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match elem {
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Element::Class(c) => self.insert("class", c.of(input).into()),
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Element::Identifier(i) => self.insert("id", i.of(input).into()),
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Element::Attribute(a, v) => self.insert(a.of(input), v.of(input).into()),
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Element::Invalid => return false,
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let mut p = Parser::new();
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for c in input.chars() {
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if let Some(elem) = p.step(c) {
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match elem {
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Element::Class(c) => self.insert("class", c.of(input).into()),
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Element::Identifier(i) => self.insert("id", i.of(input).into()),
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Element::Attribute(a, v) => self.insert(a.of(input), v.of(input).into()),
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}
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}
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if matches!(p.state, Done | Invalid) {
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break;
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}
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}
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true
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matches!(p.state, Done)
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}
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/// Combine all attributes from both objects, prioritizing self on conflicts.
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@ -220,132 +230,93 @@ enum State {
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ValueFirst,
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Value,
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ValueQuoted,
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ValueEscape,
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Done,
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Invalid,
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}
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struct Parser<I> {
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chars: I,
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impl State {
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fn step(self, c: char) -> 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 if c == '"' => Whitespace,
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ValueQuoted if c == '\\' => ValueEscape,
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ValueQuoted | ValueEscape => ValueQuoted,
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Invalid | Done => panic!("{:?}", self),
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}
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}
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}
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struct Parser {
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pos: usize,
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pos_prev: usize,
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span1: Span,
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state: State,
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}
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impl<I: Iterator<Item = char>> Parser<I> {
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fn new(chars: I) -> Self {
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impl Parser {
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fn new() -> Self {
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Parser {
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chars,
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pos: 0,
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pos_prev: 0,
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span1: Span::new(0, 0),
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state: Start,
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}
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}
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fn step_char(&mut self) -> Option<State> {
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self.chars.next().map(|c| {
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fn step(&mut self, c: char) -> Option<Element> {
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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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let elem = if st != self.state
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&& !matches!((st, self.state), (ValueEscape, _) | (_, ValueEscape))
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{
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let span0 = Span::new(self.pos_prev, self.pos);
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self.pos_prev = self.pos;
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self.pos += c.len_utf8();
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match self.state {
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Start => match c {
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'{' => Whitespace,
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_ => Invalid,
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},
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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 c.is_ascii_alphanumeric() || matches!(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 => {
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if c == '%' {
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Whitespace
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} else {
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Comment
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}
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}
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s @ (ClassFirst | IdentifierFirst) => {
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if is_name(c) {
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match s {
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ClassFirst => Class,
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IdentifierFirst => Identifier,
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_ => panic!(),
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}
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} else {
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Invalid
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}
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}
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s @ (Class | Identifier | Value) => {
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if is_name(c) {
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s
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} else if c.is_whitespace() {
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Whitespace
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} else if c == '}' {
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Done
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} else {
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Invalid
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}
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}
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match st {
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Key => {
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if is_name(c) {
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Key
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} else if c == '=' {
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ValueFirst
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} else {
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Invalid
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}
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self.span1 = span0;
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None
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}
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ValueFirst => {
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if is_name(c) {
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Value
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} else if c == '"' {
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ValueQuoted
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} else {
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Invalid
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}
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}
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ValueQuoted => match c {
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'\\' => {
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if let Some(c) = self.chars.next() {
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self.pos_prev = self.pos;
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self.pos += c.len_utf8();
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}
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ValueQuoted
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}
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'"' => Whitespace,
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_ => ValueQuoted,
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},
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Invalid | Done => panic!("{:?}", self.state),
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Class => Some(Element::Class(span0)),
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Identifier => Some(Element::Identifier(span0)),
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Value => Some(Element::Attribute(self.span1, span0)),
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ValueQuoted => Some(Element::Attribute(self.span1, span0.skip(1))),
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_ => None,
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}
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})
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}
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} else {
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None
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};
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fn step(&mut self) -> (State, Span) {
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let start = self.pos_prev;
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self.pos += c.len_utf8();
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if self.state == Done {
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return (Done, Span::empty_at(start));
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}
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if self.state == Invalid {
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return (Invalid, Span::empty_at(start));
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}
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while let Some(state_next) = self.step_char() {
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if self.state != state_next {
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return (
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std::mem::replace(&mut self.state, state_next),
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Span::new(start, self.pos_prev),
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);
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}
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}
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(
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if self.state == Done { Done } else { Invalid },
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Span::new(start, self.pos_prev),
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)
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elem
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}
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}
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@ -357,47 +328,6 @@ enum Element {
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Class(Span),
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Identifier(Span),
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Attribute(Span, Span),
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Invalid,
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}
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impl<I: Iterator<Item = char>> Iterator for Parser<I> {
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type Item = Element;
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fn next(&mut self) -> Option<Self::Item> {
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loop {
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let (st, span0) = self.step();
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return match st {
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ClassFirst | IdentifierFirst => {
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let (st, span1) = self.step();
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Some(match st {
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Class => Element::Class(span1),
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Identifier => Element::Identifier(span1),
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_ => return Some(Element::Invalid),
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})
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}
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Key => {
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let (st, _span1) = self.step();
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match st {
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ValueFirst => {
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let (st, span2) = self.step();
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match st {
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Value => Some(Element::Attribute(span0, span2)),
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ValueQuoted => Some(Element::Attribute(span0, span2.skip(1))),
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Invalid => Some(Element::Invalid),
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_ => panic!("{:?}", st),
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}
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}
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Invalid => Some(Element::Invalid),
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_ => panic!("{:?}", st),
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}
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}
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Comment | Start | Whitespace => continue,
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Done => None,
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Invalid => Some(Element::Invalid),
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_ => panic!("{:?}", st),
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};
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}
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}
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}
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#[cfg(test)]
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