xso: make Context use a builder-like pattern
That way, we can (hopefully) add more fields in the future without breaking stuff. I don't yet know what such fields could be, though.
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57972e9db0
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2 changed files with 46 additions and 18 deletions
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@ -648,7 +648,8 @@ impl<T: FromXml> ReadXsoState<T> {
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}
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Ok(Some(rxml::Event::StartElement(_, name, attrs))) => {
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let source_tmp = source.as_mut();
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let ctx = xso::Context::new(source_tmp.lang_stack.current());
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let ctx = xso::Context::empty()
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.with_language(source_tmp.lang_stack.current());
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*self = ReadXsoState::Parsing(
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<Result<T, xso::error::Error> as FromXml>::from_events(
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name, attrs, &ctx,
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@ -708,7 +709,7 @@ impl<T: FromXml> ReadXsoState<T> {
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};
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let source_tmp = source.as_mut();
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let ctx = xso::Context::new(source_tmp.lang_stack.current());
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let ctx = xso::Context::empty().with_language(source_tmp.lang_stack.current());
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match builder.feed(ev, &ctx) {
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Err(err) => {
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*self = ReadXsoState::Done;
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@ -150,24 +150,33 @@ pub trait AsXml {
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fn as_xml_iter(&self) -> Result<Self::ItemIter<'_>, self::error::Error>;
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}
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/// Additional parsing context supplied to [`FromEventsBuilder`]
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/// implementations.
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/// # Parsing context for [`FromEventsBuilder`]
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///
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/// For the most part, [`FromEventsBuilder`] implementations can work with
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/// only the information inside the [`rxml::Event`] which is delivered to
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/// them (and any information they may have stored from previous events).
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///
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/// However, there is (currently) one special case: the `xml:lang` attribute.
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/// That attribute is inherited across the entire document tree hierarchy. If
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/// the parsed element is not the top-level element, there may be an implicit
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/// value for `xml:lang`.
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#[derive(Debug)]
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pub struct Context<'x> {
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language: Option<&'x str>,
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}
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impl<'x> Context<'x> {
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/// A context suitable for the beginning of the document.
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///
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/// `xml:lang` is assumed to be unset.
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pub fn empty() -> Self {
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Self { language: None }
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}
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/// Create a new context.
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///
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/// - `language` must be the effective value of the `xml:lang` value at
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/// the end of the current event.
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pub fn new(language: Option<&'x str>) -> Self {
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Self { language }
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/// Set the effective `xml:lang` value on the context and return it.
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pub fn with_language(mut self, language: Option<&'x str>) -> Self {
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self.language = language;
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self
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}
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/// Return the `xml:lang` value in effect at the end of the event which
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@ -474,7 +483,11 @@ pub fn transform<T: FromXml, F: AsXml>(from: &F) -> Result<T, self::error::Error
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_ => panic!("into_event_iter did not start with StartElement event!"),
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};
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languages.push_from_attrs(&attrs);
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let mut sink = match T::from_events(qname, attrs, &Context::new(languages.current())) {
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let mut sink = match T::from_events(
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qname,
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attrs,
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&Context::empty().with_language(languages.current()),
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) {
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Ok(v) => v,
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Err(self::error::FromEventsError::Mismatch { .. }) => {
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return Err(self::error::Error::TypeMismatch)
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@ -484,7 +497,7 @@ pub fn transform<T: FromXml, F: AsXml>(from: &F) -> Result<T, self::error::Error
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for event in iter {
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let event = event?;
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languages.handle_event(&event);
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if let Some(v) = sink.feed(event, &Context::new(languages.current()))? {
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if let Some(v) = sink.feed(event, &Context::empty().with_language(languages.current()))? {
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return Ok(v);
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}
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}
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@ -510,7 +523,11 @@ pub fn try_from_element<T: FromXml>(
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let (qname, attrs) = minidom_compat::make_start_ev_parts(&from)?;
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languages.push_from_attrs(&attrs);
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let mut sink = match T::from_events(qname, attrs, &Context::new(languages.current())) {
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let mut sink = match T::from_events(
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qname,
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attrs,
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&Context::empty().with_language(languages.current()),
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) {
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Ok(v) => v,
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Err(self::error::FromEventsError::Mismatch { .. }) => {
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return Err(self::error::FromElementError::Mismatch(from))
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@ -541,7 +558,7 @@ pub fn try_from_element<T: FromXml>(
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for event in iter {
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let event = event?;
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languages.handle_event(&event);
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if let Some(v) = sink.feed(event, &Context::new(languages.current()))? {
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if let Some(v) = sink.feed(event, &Context::empty().with_language(languages.current()))? {
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return Ok(v);
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}
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}
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@ -576,7 +593,11 @@ pub fn from_bytes<T: FromXml>(mut buf: &[u8]) -> Result<T, self::error::Error> {
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}
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};
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languages.push_from_attrs(&attrs);
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let mut builder = match T::from_events(name, attrs, &Context::new(languages.current())) {
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let mut builder = match T::from_events(
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name,
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attrs,
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&Context::empty().with_language(languages.current()),
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) {
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Ok(v) => v,
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Err(self::error::FromEventsError::Mismatch { .. }) => {
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return Err(self::error::Error::TypeMismatch);
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@ -590,7 +611,9 @@ pub fn from_bytes<T: FromXml>(mut buf: &[u8]) -> Result<T, self::error::Error> {
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match parser.parse(&mut buf, true) {
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Ok(Some(ev)) => {
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languages.handle_event(&ev);
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if let Some(v) = builder.feed(ev, &Context::new(languages.current()))? {
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if let Some(v) =
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builder.feed(ev, &Context::empty().with_language(languages.current()))?
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{
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return Ok(v);
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}
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}
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@ -631,7 +654,11 @@ fn read_start_event_io(
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pub fn from_reader<T: FromXml, R: io::BufRead>(r: R) -> io::Result<T> {
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let mut reader = rxml::XmlLangTracker::wrap(rxml::Reader::new(r));
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let (name, attrs) = read_start_event_io(&mut reader)?;
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let mut builder = match T::from_events(name, attrs, &Context::new(reader.language())) {
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let mut builder = match T::from_events(
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name,
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attrs,
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&Context::empty().with_language(reader.language()),
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) {
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Ok(v) => v,
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Err(self::error::FromEventsError::Mismatch { .. }) => {
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return Err(self::error::Error::TypeMismatch)
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@ -643,7 +670,7 @@ pub fn from_reader<T: FromXml, R: io::BufRead>(r: R) -> io::Result<T> {
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};
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while let Some(ev) = reader.next() {
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if let Some(v) = builder
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.feed(ev?, &Context::new(reader.language()))
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.feed(ev?, &Context::empty().with_language(reader.language()))
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.map_err(|e| io::Error::new(io::ErrorKind::InvalidData, e))?
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{
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return Ok(v);
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