bdays 0.1.1

Business Days calendars for Rustaceans.
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# bdays

[![License][license-image]](LICENSE)
[![bdays on Travis CI][travis-image]][travis]
[![bdays on crates.io][cratesio-image]][cratesio]
[![bdays on docs.rs][docsrs-image]][docsrs]

[license-image]: http://img.shields.io/badge/license-MIT-brightgreen.svg?style=flat
[travis-image]: https://travis-ci.org/felipenoris/bdays.svg?branch=master
[travis]: https://travis-ci.org/felipenoris/bdays
[cratesio-image]: https://img.shields.io/crates/v/bdays.svg
[cratesio]: https://crates.io/crates/bdays
[docsrs-image]: https://docs.rs/bdays/badge.svg
[docsrs]: https://docs.rs/bdays

Provides functions to perform business days calculation between dates,
given a Holiday Calendar.

A Business Day is defined as a weekday that is not a holiday.

To check if a date is a holiday, you must provide an implementation of the `HolidayCalendar` trait.

This crate is a port of [BusinessDays.jl](https://github.com/felipenoris/BusinessDays.jl) to the Rust programming language.

## Provided Holiday Calendars

This crate provides a set of built-in holiday calendars in the `bdays::calendars` submodule.

* `bdays::calendars::WeekendsOnly` : accounts only weekends

* `bdays::calendars::brazil::BRSettlement` : Brazilian banking holidays

* `bdays::calendars::brazil::BrazilExchange` : BMF&BOVESPA Exchange holidays (http://www.bmfbovespa.com.br)

* `bdays::calendars::us::USSettlement` : United States federal holidays

## Usage

```rust
use chrono::NaiveDate;
use bdays::HolidayCalendar;

// creates a holiday calendar instance
let cal = bdays::calendars::WeekendsOnly;

let d0 = NaiveDate::from_ymd(2018, 11, 22);
let d1 = NaiveDate::from_ymd(2018, 11, 24);
let d2 = NaiveDate::from_ymd(2018, 11, 26);

// checks if a date is a holiday
assert_eq!( cal.is_holiday(d0), false );

// checks if a date is a business day
assert_eq!( cal.is_bday(d0), true  );
assert_eq!( cal.is_bday(d1), false );

// adjusts to the last/next business day
assert_eq!( cal.to_bday(d1, false), NaiveDate::from_ymd(2018, 11, 23) );
assert_eq!( cal.to_bday(d1, true) , d2 );

// advances a number of business days
assert_eq!( cal.advance_bdays(d0,  2), d2 );
assert_eq!( cal.advance_bdays(d2, -2), d0 );

// returns the number of business days between dates
assert_eq!( cal.bdays(d0, d2),  2);
assert_eq!( cal.bdays(d2, d0), -2);
```
## HolidayCalendarCache

As a motivation, this example might take some time to finish.
```rust
extern crate bdays;
extern crate chrono;

use chrono::NaiveDate;
use bdays::HolidayCalendar;

let cal = bdays::calendars::brazil::BRSettlement;
let d0 = NaiveDate::from_ymd(2001, 2, 1);
let d1 = NaiveDate::from_ymd(2100, 2, 1);

for _i in 0..30 {
    cal.bdays(d0, d1);
}
```
You can use `HolidayCalendarCache` to perform fast business days calculation
for a given range of dates.

```rust
use chrono::NaiveDate;
use bdays::HolidayCalendar;

let cal = bdays::HolidayCalendarCache::new(
    bdays::calendars::brazil::BRSettlement,
    NaiveDate::from_ymd(1980, 1, 1),
    NaiveDate::from_ymd(2100, 12, 31)
);

let d0 = NaiveDate::from_ymd(2001, 2, 1);
let d1 = NaiveDate::from_ymd(2100, 2, 1);

for _i in 0..30 {
    cal.bdays(d0, d1);
}
```