分析stackoverflow热门问答

use quick_xml::events::attributes::Attribute;

use csv;
use htmlescape::decode_html;
use quick_xml::events::Event;
use quick_xml::Reader;
use std::fs::File;

fn get_attribute<'a, 'b>(attributes: &'b [Attribute<'a>], key: &str, default: &'b str) -> &'b str {
    let v = attributes
        .into_iter()
        .find(|a| a.key == key.as_bytes())
        .map_or(default.as_bytes(), |a| &a.value);
    std::str::from_utf8(v).unwrap()
}

fn main() {
    let mut buf = Vec::new();
    let mut reader = Reader::from_file("Posts.xml").unwrap();

    let mut csvf = File::create("posts.csv").expect("unable to create file");
    let mut wtr = csv::Writer::from_writer(csvf);
    wtr.write_record(&[
        "id",
        "create_date",
        "post_type",
        "score",
        "view_count",
        "tags",
        "answer_count",
        "comment_count",
        "favorite_count",
    ]);
    let mut count = 0;
    loop {
        match reader.read_event(&mut buf) {
            Ok(Event::Start(ref e)) | Ok(Event::Empty(ref e)) => match e.name() {
                b"row" => {
                    count += 1;

                    let attributes = e.attributes().map(|a| a.unwrap()).collect::<Vec<_>>();
                    let id = get_attribute(&attributes, "Id", "0");
                    let create_date =
                        get_attribute(&attributes, "CreationDate", "1990-01-01T01:49:46.220");
                    let post_type = get_attribute(&attributes, "PostTypeId", "0");
                    let score = get_attribute(&attributes, "Score", "0");
                    let view_count = get_attribute(&attributes, "ViewCount", "0");
                    let tags = get_attribute(&attributes, "Tags", "");
                    let answer_count = get_attribute(&attributes, "AnswerCount", "0");
                    let comment_count = get_attribute(&attributes, "CommentCount", "0");
                    let favorite_count = get_attribute(&attributes, "FavoriteCount", "0");

                    let create_date = format!("{} {}", &create_date[0..10], &create_date[11..19]);
                    let create_date = create_date.as_str();

                    let decode_tag = decode_html(tags).unwrap();
                    let tag = decode_tag
                        .trim_matches('>')
                        .trim_matches('<')
                        .split("><")
                        .map(|s| format!("'{}'", s))
                        .collect::<Vec<String>>()
                        .join(",");

                    let tag = format!("[{}]", tag);
                    let tag = tag.as_str();

                    wtr.write_record(&[
                        id,
                        create_date,
                        post_type,
                        score,
                        view_count,
                        tag,
                        answer_count,
                        comment_count,
                        favorite_count,
                    ]);
                }
                _ => println!("{:?}", std::str::from_utf8(e.name()).unwrap()),
            },
            Ok(Event::Eof) => break,
            _ => (),
        }
    }

    wtr.flush();
}