use quick_xml::events::Event;
use quick_xml::reader::Reader;

let xml = r#"<tag1 att1 = "test">
                <tag2><!--Test comment-->Test</tag2>
                <tag2>Test 2</tag2>
             </tag1>"#;
let mut reader = Reader::from_str(xml);
reader.trim_text(true);

let mut count = 0;
let mut txt = Vec::new();
let mut buf = Vec::new();

// The `Reader` does not implement `Iterator` because it outputs borrowed data (`Cow`s)
loop {
    // NOTE: this is the generic case when we don't know about the input BufRead.
    // when the input is a &str or a &[u8], we don't actually need to use another
    // buffer, we could directly call `reader.read_event()`
    match reader.read_event_into(&mut buf) {
        Err(e) => panic!("Error at position {}: {:?}", reader.buffer_position(), e),
        // exits the loop when reaching end of file
        Ok(Event::Eof) => break,

        Ok(Event::Start(e)) => {
            match e.name().as_ref() {
                b"tag1" => println!("attributes values: {:?}",
                                    e.attributes().map(|a| a.unwrap().value)
                                    .collect::<Vec<_>>()),
                b"tag2" => count += 1,
                _ => (),
            }
        }
        Ok(Event::Text(e)) => txt.push(e.unescape().unwrap().into_owned()),

        // There are several other `Event`s we do not consider here
        _ => (),
    }
    // if we don't keep a borrow elsewhere, we can clear the buffer to keep memory usage low
    buf.clear();
}

use quick_xml::events::{Event, BytesEnd, BytesStart};
use quick_xml::reader::Reader;
use quick_xml::writer::Writer;
use std::io::Cursor;

let xml = r#"<this_tag k1="v1" k2="v2"><child>text</child></this_tag>"#;
let mut reader = Reader::from_str(xml);
reader.trim_text(true);
let mut writer = Writer::new(Cursor::new(Vec::new()));
loop {
    match reader.read_event() {
        Ok(Event::Start(e)) if e.name().as_ref() == b"this_tag" => {

            // crates a new element ... alternatively we could reuse `e` by calling
            // `e.into_owned()`
            let mut elem = BytesStart::new("my_elem");

            // collect existing attributes
            elem.extend_attributes(e.attributes().map(|attr| attr.unwrap()));

            // copy existing attributes, adds a new my-key="some value" attribute
            elem.push_attribute(("my-key", "some value"));

            // writes the event to the writer
            assert!(writer.write_event(Event::Start(elem)).is_ok());
        },
        Ok(Event::End(e)) if e.name().as_ref() == b"this_tag" => {
            assert!(writer.write_event(Event::End(BytesEnd::new("my_elem"))).is_ok());
        },
        Ok(Event::Eof) => break,
        // we can either move or borrow the event to write, depending on your use-case
        Ok(e) => assert!(writer.write_event(e).is_ok()),
        Err(e) => panic!("Error at position {}: {:?}", reader.buffer_position(), e),
    }
}

let result = writer.into_inner().into_inner();
let expected = r#"<my_elem k1="v1" k2="v2" my-key="some value"><child>text</child></my_elem>"#;
assert_eq!(result, expected.as_bytes());

struct Foo {
    #[serde(rename = "@abc")]
    pub abc: String,
    #[serde(rename = "$text")]
    pub body: String,
}