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//! 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` : B3 Exchange holidays (<https://www.b3.com.br>)
//! * `bdays::calendars::us::USSettlement` : United States federal holidays
//!
//! # Usage
//!
//! Add these dependencies to your `Cargo.toml` file.
//!
//! ```toml
//! [dependencies]
//! bdays = "0.1"
//! chrono = "0.4"
//! ```
//!
//! The following example shows the basic functions from this package.
//!
//! ```rust
//! use chrono::NaiveDate;
//! use bdays::HolidayCalendar;
//!
//! fn main() {
//! // 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
//! 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);
//! }
//! ```
use chrono::Datelike;
use chrono::Weekday;
use std::cmp::PartialOrd;
use std::fmt::Display;
/// Algorithms to calculate easter dates.
pub mod easter;
/// A set of holiday calendars built into bdays crate.
pub mod calendars;
#[cfg(test)]
mod tests;
/// Returns `true` if `date` occurs on a Saturday or a Sunday.
pub fn is_weekend<T: Datelike + Copy>(date: T) -> bool {
matches!(date.weekday(), Weekday::Sat | Weekday::Sun)
}
/// Returns `true` if `date` does not occur on a weekend.
pub fn is_weekday<T: Datelike + Copy>(date: T) -> bool {
!is_weekend(date)
}
fn next_date<T: Datelike + Copy>(date: T, fwd: bool) -> T {
let inc: i32 = {
if fwd {
1
} else {
-1
}
};
match date.with_ordinal((date.ordinal() as i32 + inc) as u32) {
Some(dt) => dt,
None => {
if fwd {
date.with_year(date.year() + 1)
.unwrap()
.with_ordinal(1)
.unwrap()
} else {
date.with_year(date.year() - 1)
.unwrap()
.with_month(12)
.unwrap()
.with_day(31)
.unwrap()
}
}
}
}
/// Abstraction for a Holiday Calendar.
pub trait HolidayCalendar<T: Datelike + Copy + PartialOrd> {
/// Returns `true` if `date` is a holiday.
fn is_holiday(&self, date: T) -> bool;
/// Returns `true` if `date` is a Business Day.
/// A Business Day is defined as a weekday that is not a holiday.
fn is_bday(&self, date: T) -> bool {
!(is_weekend(date) || self.is_holiday(date))
}
/// Adjusts `date` to the last/next business day if it's not a business day.
fn to_bday(&self, mut date: T, adjust_next: bool) -> T {
while !self.is_bday(date) {
date = next_date(date, adjust_next);
}
date
}
/// Advances `bdays_count` number of business days from `date`.
fn advance_bdays(&self, mut date: T, bdays_count: i32) -> T {
date = self.to_bday(date, true);
let inc_fwd = match bdays_count.signum() {
0 => return date, // nothing to do
1 => true, // bdays_count is positive
-1 => false, // bdays_count is negative
_ => panic!("signum function is expected to return 0, 1 or -1."),
};
let mut num_iterations = bdays_count.abs();
while num_iterations > 0 {
date = next_date(date, inc_fwd);
// Looks for previous / next Business Day
while !self.is_bday(date) {
date = next_date(date, inc_fwd);
}
num_iterations += -1;
}
date
}
/// Returns the number of business days between `d0` and `d1`.
fn bdays(&self, mut d0: T, mut d1: T) -> i32 {
d0 = self.to_bday(d0, true);
d1 = self.to_bday(d1, true);
let mut from: T;
let to: T;
let inc: i32;
let mut bdays_count: i32 = 0;
if d0 <= d1 {
inc = 1;
from = d0;
to = d1;
} else {
inc = -1;
from = d1;
to = d0
}
while from < to {
from = self.advance_bdays(from, 1);
bdays_count += inc;
}
bdays_count
}
}
/// Caches business days calculation for a given holiday calendar
/// and a given range of dates. Implements the `HolidayCalendar` trait.
pub struct HolidayCalendarCache<T: Datelike + Copy + PartialOrd> {
is_holiday_vec: Vec<bool>,
is_bday_vec: Vec<bool>,
bdays_counter_vec: Vec<i32>,
dt_min: T,
dt_max: T,
}
impl<T: Datelike + Copy + PartialOrd + Display> HolidayCalendarCache<T> {
/// Creates `HolidayCalendarCache` that caches business days calculation
/// in the range of dates from `dt_min` to `dt_max`.
pub fn new<H: HolidayCalendar<T>>(
calendar: H,
dt_min: T,
dt_max: T,
) -> HolidayCalendarCache<T> {
if dt_min > dt_max {
panic!(
"dt_min {} should not be greater than dt_max {}.",
dt_min, dt_max
);
}
let len = (dt_max.num_days_from_ce() - dt_min.num_days_from_ce() + 1) as usize;
let mut is_holiday_vec: Vec<bool> = Vec::with_capacity(len);
let mut is_bday_vec: Vec<bool> = Vec::with_capacity(len);
let mut bdays_counter_vec: Vec<i32> = Vec::with_capacity(len);
is_holiday_vec.push(calendar.is_holiday(dt_min));
is_bday_vec.push(calendar.is_bday(dt_min));
let mut bdays_counter = 0;
bdays_counter_vec.push(bdays_counter);
let mut dt = next_date(dt_min, true);
for _i in 1..len {
let dt_is_bday = calendar.is_bday(dt);
is_bday_vec.push(dt_is_bday);
is_holiday_vec.push(calendar.is_holiday(dt));
if dt_is_bday {
bdays_counter += 1;
}
bdays_counter_vec.push(bdays_counter);
dt = next_date(dt, true);
}
// lengths must match
debug_assert_eq!(is_bday_vec.len(), bdays_counter_vec.len());
debug_assert_eq!(is_holiday_vec.len(), bdays_counter_vec.len());
HolidayCalendarCache {
is_holiday_vec,
is_bday_vec,
bdays_counter_vec,
dt_min,
dt_max,
}
}
fn row_index(&self, date: T) -> usize {
(date.num_days_from_ce() - self.dt_min.num_days_from_ce()) as usize
}
fn assert_in_bounds(&self, date: T) {
if date < self.dt_min || self.dt_max < date {
panic!(
"Date {} out of bounds of holiday calendar cache. [{}, {}].",
date, self.dt_min, self.dt_max
);
}
}
}
impl<T: Datelike + Copy + PartialOrd + Display> HolidayCalendar<T> for HolidayCalendarCache<T> {
fn is_holiday(&self, date: T) -> bool {
self.assert_in_bounds(date);
self.is_holiday_vec[self.row_index(date)]
}
fn is_bday(&self, date: T) -> bool {
self.assert_in_bounds(date);
self.is_bday_vec[self.row_index(date)]
}
fn bdays(&self, mut d0: T, mut d1: T) -> i32 {
d0 = self.to_bday(d0, true);
d1 = self.to_bday(d1, true);
self.bdays_counter_vec[self.row_index(d1)] - self.bdays_counter_vec[self.row_index(d0)]
}
}