Examples

Quick start

use ftracker_identifiers::Isin;

let apple = Isin::parse("US0378331005").unwrap();
assert_eq!(apple.country_code(), "US");
assert_eq!(apple.nsin(), "037833100");
assert_eq!(apple.check_digit(), 5);

let petrobras = Isin::parse("BRPETRACNOR9").unwrap();
assert_eq!(petrobras.nsin(), "PETRACNOR"); // an alphanumeric NSIN

Validating untrusted input

Use Isin::parse right at the boundary where data enters your system (HTTP handler, a CSV import, a CLI argument) so that everything downstream can assume an Isin is already valid:

use ftracker_identifiers::Isin;

fn handle_order(raw_isin: &str) -> Result<(), String> {
    let isin = Isin::parse(raw_isin).map_err(|e| e.to_string())?;
    // From here on, `isin` is guaranteed valid — no need to re-check it.
    place_order(isin);
    Ok(())
}
fn place_order(_: Isin) {}

Sorting and deduplicating a batch

A common data-cleaning task: importing a spreadsheet or CSV export that may contain the same ISIN written multiple ways (mixed case, surrounded by whitespace), and needing a deduplicated, sorted list:

use ftracker_identifiers::Isin;

let mut isins: Vec<Isin> = [
    "US0231351067",
    "US0378331005",
    " us0378331005 ", // same ISIN as above, lower-cased and padded
]
.into_iter()
.map(|s| Isin::parse(s).unwrap())
.collect();

isins.sort();
isins.dedup();
assert_eq!(isins.len(), 2);

Using `Isin` as a map or set key

Because Isin implements Eq and Hash consistently with PartialEq, it works directly as a HashMap/HashSet key (or BTreeMap/BTreeSet, via Ord). Useful for deduplicating records or indexing data by security:

use ftracker_identifiers::Isin;
use std::collections::HashMap;

let mut names: HashMap<Isin, &str> = HashMap::new();
names.insert(Isin::parse("US0378331005").unwrap(), "Apple Inc.");

let lookup = Isin::parse("us0378331005").unwrap();
assert_eq!(names.get(&lookup), Some(&"Apple Inc."));

Grouping securities by issuing country

Since Isin::country_code() identifies the issuing national numbering agency, it’s a natural grouping key when you have a mixed list of securities:

use ftracker_identifiers::Isin;
use std::collections::HashMap;

fn group_by_country(isins: &[Isin]) -> HashMap<&str, Vec<Isin>> {
    let mut groups: HashMap<&str, Vec<Isin>> = HashMap::new();
    for &isin in isins {
        groups.entry(isin.country_code()).or_default().push(isin);
    }
    groups
}

For a config-file or API round-trip example using serde, see Feature Flags.

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