diff options
Diffstat (limited to 'corp/russian/data-import/src/oc_parser.rs')
| -rw-r--r-- | corp/russian/data-import/src/oc_parser.rs | 262 |
1 files changed, 262 insertions, 0 deletions
diff --git a/corp/russian/data-import/src/oc_parser.rs b/corp/russian/data-import/src/oc_parser.rs new file mode 100644 index 0000000000..c7a9b8247f --- /dev/null +++ b/corp/russian/data-import/src/oc_parser.rs @@ -0,0 +1,262 @@ +use super::{bail, Ensure}; +use log::info; +use xml::attribute::OwnedAttribute; +use xml::name::OwnedName; +use xml::reader::XmlEvent; +use xml::EventReader; + +#[derive(Default, Debug)] +pub struct Grammeme { + parent: Option<String>, + name: String, + alias: String, + description: String, +} + +#[derive(Debug)] +pub struct Lemma {} + +#[derive(Debug)] +pub enum OcElement { + Grammeme(Grammeme), + Lemma(Lemma), +} + +#[derive(Debug, PartialEq)] +enum ParserState { + /// Parser is not parsing any particular section and waiting for a + /// start tag instead. + Init, + + /// Parser is parsing grammemes. + Grammemes, + + /// Parser is parsing lemmata. + Lemmata, + + /// Parser has seen the end of the line and nothing more is + /// available. + Ended, +} + +pub struct OpenCorporaParser<R: std::io::Read> { + reader: EventReader<R>, + state: ParserState, +} + +#[derive(PartialEq)] +enum SectionState { + /// Actively interested in parsing this section. + Active, + + /// Section is known, but currently ignored. + Inactive, + + /// Section is unknown (probably a bug). + Unknown, +} + +fn section_state(section: &str) -> SectionState { + match section { + "grammemes" | "lemmata" => SectionState::Active, + "restrictions" | "link_types" | "links" => SectionState::Inactive, + _ => SectionState::Unknown, + } +} + +impl<R: std::io::Read> OpenCorporaParser<R> { + pub fn new(reader: R) -> Self { + let config = xml::ParserConfig::new().trim_whitespace(true); + let reader = EventReader::new_with_config(reader, config); + + Self { + reader, + state: ParserState::Init, + } + } + + /// Pull an `OcElement` out of the parser. Returns `None` if the + /// parser stream has ended. + pub fn next_element(&mut self) -> Option<OcElement> { + if self.state == ParserState::Ended { + return None; + } + + // Pull the next element to determine what context to enter + // next. + loop { + match &self.next() { + // no-op events that do not affect parser state + XmlEvent::Comment(_) + | XmlEvent::Whitespace(_) + | XmlEvent::ProcessingInstruction { .. } + | XmlEvent::StartDocument { .. } => continue, + XmlEvent::StartElement { name, .. } | XmlEvent::EndElement { name } + if name.local_name == "dictionary" => + { + continue + } + + // end of the file, nothing more to return + XmlEvent::EndDocument => { + self.state = ParserState::Ended; + return None; + } + + // some sections are skipped + XmlEvent::StartElement { name, .. } | XmlEvent::EndElement { name } + if section_state(&name.local_name) == SectionState::Inactive => + { + info!("skipping {} section", name.local_name); + self.skip_section(&name.local_name); + } + + // active section events start specific parser states ... + XmlEvent::StartElement { name, .. } + if section_state(&name.local_name) == SectionState::Active => + { + self.state = match name.local_name.as_str() { + "grammemes" => ParserState::Grammemes, + "lemmata" => ParserState::Lemmata, + _ => unreachable!(), + }; + } + + // ... or end them + XmlEvent::EndElement { name, .. } + if section_state(&name.local_name) == SectionState::Active => + { + // TODO: assert that the right section ended + self.state = ParserState::Init; + } + + // actual beginning of an actual element, dispatch accordingly + event @ XmlEvent::StartElement { + name, attributes, .. + } => match self.state { + ParserState::Grammemes => { + return Some(OcElement::Grammeme(self.parse_grammeme(name, attributes))) + } + ParserState::Lemmata => { + return Some(OcElement::Lemma(self.parse_lemma(name, attributes))) + } + + ParserState::Init | ParserState::Ended => bail(format!( + "parser received an unexpected start element while in state {:?}: {:?}", + self.state, event + )), + }, + + // finally, events that indicate a bug if they're + // encountered here + event @ XmlEvent::EndElement { .. } + | event @ XmlEvent::CData(_) + | event @ XmlEvent::Characters(_) => { + bail(format!("unexpected XML event: {:?}", event)) + } + } + } + } + + /// Skip a section by advancing the parser state until we see an + /// end element for the skipped section. + fn skip_section(&mut self, section: &str) { + loop { + match self.next() { + XmlEvent::EndElement { name } if name.local_name == section => return, + _ => continue, + } + } + } + + fn next(&mut self) -> XmlEvent { + self.reader.next().ensure("XML parsing failed") + } + + /// Parse a tag that should have plain string content. + fn parse_string(&mut self, tag_name: &str) -> String { + let mut out = String::new(); + + loop { + match self.next() { + // ignore irrelevant things + XmlEvent::Comment(_) | XmlEvent::Whitespace(_) => continue, + + // set the content + XmlEvent::Characters(content) => { + out = content; + } + + // expect the end of the element + XmlEvent::EndElement { name } if name.local_name == tag_name => return out, + + // fail on everything unexpected + event => bail(format!( + "unexpected element while parsing <{}>: {:?}", + tag_name, event + )), + } + } + } + + fn parse_grammeme(&mut self, name: &OwnedName, attributes: &[OwnedAttribute]) -> Grammeme { + if name.local_name != "grammeme" { + bail(format!( + "expected to parse a grammeme, but found <{}>", + name.local_name + )); + } + + let mut grammeme = Grammeme::default(); + + for attr in attributes { + if attr.name.local_name == "parent" && !attr.value.is_empty() { + grammeme.parent = Some(attr.value.clone()); + } + } + + loop { + match self.next() { + // ignore irrelevant things + XmlEvent::Comment(_) | XmlEvent::Whitespace(_) => continue, + + // expect known tags + XmlEvent::StartElement { name, .. } if name.local_name == "name" => { + grammeme.name = self.parse_string("name"); + } + + XmlEvent::StartElement { name, .. } if name.local_name == "alias" => { + grammeme.alias = self.parse_string("alias"); + } + + XmlEvent::StartElement { name, .. } if name.local_name == "description" => { + grammeme.description = self.parse_string("description"); + } + + // handle end of the grammeme + XmlEvent::EndElement { name } if name.local_name == "grammeme" => break, + + // fail on everything unexpected + event => bail(format!( + "unexpected element while parsing <grammeme>: {:?}", + event + )), + } + } + + grammeme + } + + fn parse_lemma(&mut self, name: &OwnedName, _attributes: &[OwnedAttribute]) -> Lemma { + if name.local_name != "lemma" { + bail(format!( + "expected to parse a lemma, but found <{}>", + name.local_name + )); + } + + self.skip_section("lemma"); + + Lemma {} + } +} |