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extern crate xml;
use std::collections::HashMap;
use std::io::{Read, Write};
use std::borrow::Cow;
use std::fmt;
use xml::reader::{EventReader, XmlEvent};
#[derive(Debug, Clone, PartialEq, Eq)]
pub struct Element {
pub name: String,
pub attributes: HashMap<String, String>,
pub children: Vec<Element>,
pub text: Option<String>
}
#[derive(Debug)]
pub enum ParseError {
MalformedXml(xml::reader::Error),
CannotParse,
}
impl fmt::Display for ParseError {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
match self {
&ParseError::MalformedXml(ref e) => write!(f, "Malformed XML. {}", e),
&ParseError::CannotParse => write!(f, "Cannot parse"),
}
}
}
impl std::error::Error for ParseError {
fn description(&self) -> &str {
match self {
&ParseError::MalformedXml(..) => "Malformed XML",
&ParseError::CannotParse => "Cannot parse",
}
}
fn cause(&self) -> Option<&std::error::Error> {
match self {
&ParseError::MalformedXml(ref e) => Some(e),
&ParseError::CannotParse => None,
}
}
}
fn build<B: Read>(reader: &mut EventReader<B>, mut elem: Element) -> Result<Element, ParseError> {
loop {
match reader.next() {
Ok(XmlEvent::EndElement{ref name}) => {
if name.local_name == elem.name {
return Ok(elem);
}
else {
return Err(ParseError::CannotParse);
}
},
Ok(XmlEvent::StartElement{name, attributes, ..}) => {
let mut attr_map = HashMap::new();
for attr in attributes { attr_map.insert(attr.name.local_name, attr.value); }
let new_elem = Element{name: name.local_name, attributes: attr_map, children: Vec::new(), text: None};
elem.children.push(try!(build(reader, new_elem)));
}
Ok(XmlEvent::Characters(s)) => { elem.text = Some(s); }
Ok(XmlEvent::Whitespace(..)) => (),
Ok(XmlEvent::CData(s)) => { elem.text = Some(s) }
Ok(XmlEvent::Comment(..)) => (),
Ok(XmlEvent::StartDocument { .. }) |
Ok(XmlEvent::EndDocument) |
Ok(XmlEvent::ProcessingInstruction { .. }) => return Err(ParseError::CannotParse),
Err(e) => return Err(ParseError::MalformedXml(e)),
}
}
}
impl Element {
pub fn parse<R: Read>(r: R) -> Result<Element, ParseError> {
let mut reader = EventReader::new(r);
loop {
match reader.next() {
Ok(XmlEvent::StartElement{name, attributes, ..}) => {
let mut attr_map = HashMap::new();
for attr in attributes { attr_map.insert(attr.name.local_name, attr.value); }
let root = Element{name: name.local_name, attributes: attr_map, children: Vec::new(), text: None};
return build(&mut reader, root);
}
Ok(XmlEvent::Comment(..)) |
Ok(XmlEvent::Whitespace(..)) |
Ok(XmlEvent::StartDocument { .. }) => continue,
Ok(XmlEvent::EndDocument) |
Ok(XmlEvent::EndElement { .. }) |
Ok(XmlEvent::Characters(..)) |
Ok(XmlEvent::CData(..)) |
Ok(XmlEvent::ProcessingInstruction { .. }) => return Err(ParseError::CannotParse),
Err(e) => return Err(ParseError::MalformedXml(e)),
}
}
}
fn _write<B: Write>(&self, emitter: &mut xml::writer::EventWriter<B>) {
use xml::writer::events::XmlEvent;
use xml::name::Name;
use xml::namespace::Namespace;
use xml::attribute::Attribute;
let name = Name::local(&self.name);
let mut attributes = Vec::with_capacity(self.attributes.len());
for (k, v) in self.attributes.iter() {
attributes.push(Attribute{name: Name::local(k), value: v});
}
let namespace = Namespace::empty();
emitter.write(XmlEvent::StartElement{name: name, attributes: Cow::Owned(attributes), namespace: Cow::Borrowed(&namespace)}).unwrap();
if let Some(ref t) = self.text {
emitter.write(XmlEvent::Characters(t)).unwrap();
}
for elem in &self.children {
elem._write(emitter);
}
emitter.write(XmlEvent::EndElement{name: Some(name)}).unwrap();
}
pub fn write<W: Write>(&self, w:W) {
use xml::writer::EventWriter;
use xml::writer::events::XmlEvent;
use xml::common::XmlVersion;
let mut emitter = EventWriter::new(w);
emitter.write(XmlEvent::StartDocument{version: XmlVersion::Version10, encoding: None, standalone: None}).unwrap();
self._write(&mut emitter);
}
pub fn get_child<K>(&self, k: K) -> Option<&Element>
where String: PartialEq<K> {
self.children.iter().find(|e| e.name == k)
}
pub fn get_mut_child<'a, K>(&'a mut self, k: K) -> Option<&'a mut Element>
where String: PartialEq<K> {
self.children.iter_mut().find(|e| e.name == k)
}
pub fn take_child<'a, K>(&'a mut self, k: K) -> Option<Element>
where String: PartialEq<K> {
self.children.iter().position(|e| e.name == k).map(|i| self.children.remove(i))
}
}