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Add reusable parser for XML element and use it internally
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| Original file line number | Diff line number | Diff line change |
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| @@ -0,0 +1,113 @@ | ||
| //! Contains a parser for an XML element. | ||
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| /// A parser that search a `>` symbol in the slice outside of quoted regions. | ||
| /// | ||
| /// The parser considers two quoted regions: a double-quoted (`"..."`) and | ||
| /// a single-quoted (`'...'`) region. Matches found inside those regions are not | ||
| /// considered as results. Each region starts and ends by its quote symbol, | ||
| /// which cannot be escaped (but can be encoded as XML character entity or named | ||
| /// entity. Anyway, that encoding does not contain literal quotes). | ||
| /// | ||
| /// To use a parser create an instance of parser and [`feed`] data into it. | ||
| /// After successful search the parser will return [`Some`] with position of | ||
| /// found symbol. If search is unsuccessful, a [`None`] will be returned. You | ||
| /// typically would expect positive result of search, so that you should feed | ||
| /// new data until you get it. | ||
| /// | ||
| /// NOTE: after successful match the parser does not returned to the initial | ||
| /// state and should not be used anymore. Create a new parser if you want to perform | ||
| /// new search. | ||
| /// | ||
| /// # Example | ||
| /// | ||
| /// ``` | ||
| /// # use quick_xml::reader::ElementParser; | ||
| /// # use pretty_assertions::assert_eq; | ||
| /// let mut parser = ElementParser::default(); | ||
| /// | ||
| /// // Parse `<my-element with = 'some > inside'>and the text follow...` | ||
| /// // splitted into three chunks | ||
| /// assert_eq!(parser.feed(b"<my-element"), None); | ||
| /// // ...get new chunk of data | ||
| /// assert_eq!(parser.feed(b" with = 'some >"), None); | ||
| /// // ...get another chunk of data | ||
| /// assert_eq!(parser.feed(b" inside'>and the text follow..."), Some(8)); | ||
| /// // ^ ^ | ||
| /// // 0 8 | ||
| /// ``` | ||
| /// | ||
| /// [`feed`]: Self::feed() | ||
| #[derive(Clone, Copy, Debug, Eq, PartialEq)] | ||
| pub enum ElementParser { | ||
| /// The initial state (inside element, but outside of attribute value). | ||
| Outside, | ||
| /// Inside a single-quoted region (`'...'`). | ||
| SingleQ, | ||
| /// Inside a double-quoted region (`"..."`). | ||
| DoubleQ, | ||
| } | ||
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| impl ElementParser { | ||
| /// Returns number of consumed bytes or `None` if `>` was not found in `bytes`. | ||
| #[inline] | ||
| pub fn feed(&mut self, bytes: &[u8]) -> Option<usize> { | ||
| for i in memchr::memchr3_iter(b'>', b'\'', b'"', bytes) { | ||
| *self = match (*self, bytes[i]) { | ||
| // only allowed to match `>` while we are in state `Outside` | ||
| (Self::Outside, b'>') => return Some(i), | ||
| (Self::Outside, b'\'') => Self::SingleQ, | ||
| (Self::Outside, b'\"') => Self::DoubleQ, | ||
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| // the only end_byte that gets us out if the same character | ||
| (Self::SingleQ, b'\'') | (Self::DoubleQ, b'"') => Self::Outside, | ||
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| // all other bytes: no state change | ||
| _ => continue, | ||
| }; | ||
| } | ||
| None | ||
| } | ||
| } | ||
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| impl Default for ElementParser { | ||
| #[inline] | ||
| fn default() -> Self { | ||
| Self::Outside | ||
| } | ||
| } | ||
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| #[test] | ||
| fn parse() { | ||
| use pretty_assertions::assert_eq; | ||
| use ElementParser::*; | ||
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| /// Returns `Ok(pos)` with the position in the buffer where element is ended. | ||
| /// | ||
| /// Returns `Err(internal_state)` if parsing does not done yet. | ||
| fn parse_element(bytes: &[u8], mut parser: ElementParser) -> Result<usize, ElementParser> { | ||
| match parser.feed(bytes) { | ||
| Some(i) => Ok(i), | ||
| None => Err(parser), | ||
| } | ||
| } | ||
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| assert_eq!(parse_element(b"", Outside), Err(Outside)); | ||
| assert_eq!(parse_element(b"", SingleQ), Err(SingleQ)); | ||
| assert_eq!(parse_element(b"", DoubleQ), Err(DoubleQ)); | ||
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| assert_eq!(parse_element(b"'", Outside), Err(SingleQ)); | ||
| assert_eq!(parse_element(b"'", SingleQ), Err(Outside)); | ||
| assert_eq!(parse_element(b"'", DoubleQ), Err(DoubleQ)); | ||
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| assert_eq!(parse_element(b"\"", Outside), Err(DoubleQ)); | ||
| assert_eq!(parse_element(b"\"", SingleQ), Err(SingleQ)); | ||
| assert_eq!(parse_element(b"\"", DoubleQ), Err(Outside)); | ||
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| assert_eq!(parse_element(b">", Outside), Ok(0)); | ||
| assert_eq!(parse_element(b">", SingleQ), Err(SingleQ)); | ||
| assert_eq!(parse_element(b">", DoubleQ), Err(DoubleQ)); | ||
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| assert_eq!(parse_element(b"''>", Outside), Ok(2)); | ||
| assert_eq!(parse_element(b"''>", SingleQ), Err(SingleQ)); | ||
| assert_eq!(parse_element(b"''>", DoubleQ), Err(DoubleQ)); | ||
| } |
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