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use super::Constraint;

///
/// A rectangle
///
/// A set of the form `{x : xmin <= x <= xmax}`, where `<=` is meant in the
/// element-wise sense and either of `xmin` and `xmax` can be equal to infinity.
pub struct Rectangle<'a> {
    xmin: Option<&'a [f64]>,
    xmax: Option<&'a [f64]>,
}

impl<'a> Rectangle<'a> {
    /// Construct a new rectangle with given `xmin` and `xmax`
    pub fn new(xmin: Option<&'a [f64]>, xmax: Option<&'a [f64]>) -> Rectangle<'a> {
        assert!(xmin != None || xmax != None); // xmin or xmax must be Some
        assert!(
            xmin.is_none() || xmax.is_none() || xmin.unwrap().len() == xmax.unwrap().len(),
            "incompatible dimensions of xmin and xmax"
        );
        Rectangle { xmin, xmax }
    }
}

impl<'a> Constraint for Rectangle<'a> {
    fn project(&self, x: &mut [f64]) {
        if let Some(xmin) = &self.xmin {
            x.iter_mut().zip(xmin.iter()).for_each(|(x_, xmin_)| {
                if *x_ < *xmin_ {
                    *x_ = *xmin_
                };
            });
        }

        if let Some(xmax) = &self.xmax {
            x.iter_mut().zip(xmax.iter()).for_each(|(x_, xmax_)| {
                if *x_ > *xmax_ {
                    *x_ = *xmax_
                };
            });
        }
    }
}