relativedelta 0.2.0

Rust implementation of relativedelta known from Python's dateutil library. An extension to Duration in the chrono library to deal with relative dates.
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relativedelta
=============

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Rust implementation of `relativedelta` known from Python's [dateutil](https://pypi.org/project/python-dateutil/) library.
Extension to the `Duration` from the the [time](https://github.com/rust-lang-deprecated/time) library, which allows for calculating datetimes based on a relative representation of date and time.

## Usage

Put this in your `Cargo.toml`:

```toml
[dependencies]
relativedelta = "0.2"
```

Optional features:
- [`serde1`][]: Enable serialization/deserialization via serde.

[`serde1`]: https://github.com/serde-rs/serde

In the pipeline:
- [X] Hook up to [travis.com](https://travis-ci.com/github/timkaas/relativedelta).
- [ ] Mitigation of month rounding error when init with floats or mul with floats.
- [X] Create a proper crate and publish on [crates.io](https://crates.io/).
- [ ] Documentation and doctest.
- [X] Code coverage setup and badge with [travis.com](https://travis-ci.com/github/timkaas/relativedelta) and [codecov.io](https://codecov.io/gh/timkaas/relativedelta)

Examples:

```rust
// Construction
let years1 = RelativeDelta::with_years(1).new();
let months12 = RelativeDelta::with_months(12).new();
assert_eq!(years1, months12);

let years1 = RelativeDelta::with_years(1).and_days(32).new();
// If same parameter is specified twice, only the latest is applied.
let months6 = RelativeDelta::with_months(12).with_months(6).new();
assert_eq!(months6, RelativeDelta::with_months(6).new());
// Below is identical to: RelativeDelta::yysmmsdds(Some(2020), 1, Some(1), 3, None, 12).new();
let rddt = RelativeDelta::with_year(2020).and_years(1).and_month(1).and_months(3).and_days(12).new();

// Two or more RelativeDeltas can be added and substracted. However, note that constants are lost in the process.
let lhs = RelativeDelta::yysmmsdds(Some(2020), -4, Some(1), 3, None, 0).new();
let rhs = RelativeDelta::yysmmsdds(Some(2020), 1, Some(1), 42, None, 0).new();
assert_eq!(lhs + rhs, RelativeDelta::with_years(-3).and_months(45).new());
assert_eq!(lhs - rhs, RelativeDelta::with_years(-5).and_months(-39).new());
assert_eq!(-lhs + rhs, RelativeDelta::with_years(5).and_months(39).new());

// The RelativeDelta can be multiplied with a f64.
assert_eq!(rhs * 0.5, RelativeDelta::with_years(2).and_year(2020).and_months(3).and_month(1).new());

// This crates party piece is the ability to calculate dates based on already existing chrono::DateTime
// If one would like to get the last day of the month that one is currently in, it could be done with:
println!("{}", Utc::now() + RelativeDelta::with_months(1).and_day(1).and_days(-1).new());
// Above first sets the day of the month to the 1st, then adds a month and subtracts a day.
```