【Rust日报】2019-12-25 grex：根据测试用例生成正则表达式

let regexp = grex::RegExpBuilder::from(&["a", "aa", "aaa"]).build();
assert_eq!(regexp, "^a(aa?)?$");

fn main() {
    let data = vec![
        Data { label: "dd1".into(), value: 4.0, color: Some(Color::Red), fill: '•' },
        Data { label: "dd2".into(), value: 2.0, color: Some(Color::Green), fill: '•' },
        Data { label: "dd3".into(), value: 2.6, color: Some(Color::Blue), fill: '•' },
    ];

    Chart::new()
        .radius(9)
        .aspect_ratio(2)
        .legend(true)
        .draw(&data);
}