//! An extension to Iterator trait.
//!
//! The [`IteratorExt`](IteratorExt) trait extends the capability of those types
//! that implements [`Iterator`](Iterator). It provides `try_filter()`, `try_flatten()`
//! and more fallible adaptors that are analogous to those of [`Iterator`](Iterator).
//!
//! The example demonstrates the usage of the adaptors. It accumulates the values from
//! 0 to 9, and keeps only even outcomes. It raises error when the accumulation exceeds 10.
//!
//! ```rust
//! use iterator_ext::IteratorExt;
//!
//! let results: Vec<_> = (0..10)
//!     .map(Ok)
//!     .try_scan(0, |acc, val| {
//!         *acc += val;
//!         if *acc <= 10 {
//!             Ok(Some(*acc))
//!         } else {
//!             Err("exceed limit")
//!         }
//!     })
//!     .try_filter(|val| Ok(val % 2 == 0))
//!     .collect();
//!
//! assert_eq!(results, vec![Ok(0), Ok(6), Ok(10), Err("exceed limit")]);
//! ```

mod and_then;
mod common;
mod map_err;
mod trait_;
mod try_filter;
mod try_filter_map;
mod try_flat_map;
mod try_flat_map_results;
mod try_flatten;
mod try_flatten_results;
mod try_scan;

pub use and_then::*;
pub use map_err::*;
pub use trait_::*;
pub use try_filter::*;
pub use try_filter_map::*;
pub use try_flat_map::*;
pub use try_flat_map_results::*;
pub use try_flatten::*;
pub use try_flatten_results::*;
pub use try_scan::*;

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn try_scan_test_1() {
        let input = vec![Ok(1usize), Ok(2), Err("err"), Ok(3)];
        let output: Vec<_> = input
            .into_iter()
            .try_scan(0, |acc, val| {
                *acc += val;
                Ok(Some(*acc))
            })
            .collect();
        assert_eq!(output, vec![Ok(1), Ok(3), Err("err")]);
    }

    #[test]
    fn try_scan_test_2() {
        let input = vec![Ok(1usize), Ok(2), Err("err"), Ok(3)];
        let output: Vec<_> = input
            .into_iter()
            .try_scan(0, |acc, val| {
                if val % 2 != 0 {
                    *acc += val;
                    Ok(Some(*acc))
                } else {
                    Ok(None)
                }
            })
            .collect();
        assert_eq!(output, vec![Ok(1)]);
    }

    #[test]
    fn try_scan_test_3() {
        let input = vec![Ok(1usize), Ok(3), Ok(2)];
        let output: Vec<_> = input
            .into_iter()
            .try_scan(0, |acc, val| {
                if val % 2 != 0 {
                    *acc += val;
                    Ok(Some(*acc))
                } else {
                    Err("found even")
                }
            })
            .collect();
        assert_eq!(output, vec![Ok(1), Ok(4), Err("found even")]);
    }

    #[test]
    fn try_flatten_test() {
        let input = vec![Ok(vec![1usize, 2]), Err("err"), Ok(vec![3])];
        let output: Vec<_> = input.into_iter().try_flatten().collect();
        assert_eq!(output, vec![Ok(1), Ok(2), Err("err")]);
    }

    #[test]
    fn try_flat_map_test() {
        let input = vec![Ok(vec![1, 2]), Err("err"), Ok(vec![3])];
        let output: Vec<_> = input.into_iter().try_flat_map(Ok).collect();
        assert_eq!(output, vec![Ok(1usize), Ok(2), Err("err")]);
    }

    #[test]
    fn try_flatten_results_test_1() {
        let input = vec![
            Ok(vec![Ok(1usize), Ok(2)]),
            Ok(vec![Err("err"), Ok(3)]),
            Ok(vec![Ok(4)]),
        ];
        let output: Vec<_> = input.into_iter().try_flatten_results().collect();
        assert_eq!(output, vec![Ok(1usize), Ok(2), Err("err")]);
    }

    #[test]
    fn try_flatten_results_test_2() {
        let input = vec![Ok(vec![Ok(1usize), Ok(2)]), Err("err"), Ok(vec![Ok(3)])];
        let output: Vec<_> = input.into_iter().try_flatten_results().collect();
        assert_eq!(output, vec![Ok(1usize), Ok(2), Err("err")]);
    }

    #[test]
    fn try_flat_map_results_test_1() {
        let input = vec![
            Ok(vec![Ok(1usize), Ok(2)]),
            Ok(vec![Err("err"), Ok(3)]),
            Ok(vec![Ok(4)]),
        ];
        let output: Vec<_> = input.into_iter().try_flat_map_results(Ok).collect();
        assert_eq!(output, vec![Ok(1usize), Ok(2), Err("err")]);
    }

    #[test]
    fn try_flat_map_results_test_2() {
        let input = vec![Ok(vec![Ok(1usize), Ok(2)]), Err("err"), Ok(vec![Ok(3)])];
        let output: Vec<_> = input.into_iter().try_flat_map_results(Ok).collect();
        assert_eq!(output, vec![Ok(1usize), Ok(2), Err("err")]);
    }

    #[test]
    fn try_filter_test() {
        let input = vec![Ok(1usize), Ok(2), Ok(3), Err("err"), Ok(4)];
        let output: Vec<_> = input
            .into_iter()
            .try_filter(|val| Ok(val % 2 == 1))
            .collect();
        assert_eq!(output, vec![Ok(1usize), Ok(3), Err("err")]);
    }

    #[test]
    fn try_filter_map_test() {
        let input = vec![
            Ok(Some(1usize)),
            Ok(None),
            Ok(Some(3usize)),
            Err("err"),
            Ok(Some(4usize)),
        ];
        let output: Vec<_> = input.into_iter().try_filter_map(Ok).collect();
        assert_eq!(output, vec![Ok(1usize), Ok(3), Err("err")]);
    }

    #[test]
    fn and_then_test() {
        let input = vec![Ok(1isize), Ok(2), Err("err"), Ok(3)];
        let output: Vec<_> = input.into_iter().and_then(|val| Ok(-val)).collect();
        assert_eq!(output, vec![Ok(-1), Ok(-2), Err("err")]);
    }
}