NormaliseLongitude.h

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/*
 * (C) Copyright 2013 ECMWF.
 *
 * This software is licensed under the terms of the Apache Licence Version 2.0
 * which can be obtained at http://www.apache.org/licenses/LICENSE-2.0.
 * In applying this licence, ECMWF does not waive the privileges and immunities
 * granted to it by virtue of its status as an intergovernmental organisation
 * nor does it submit to any jurisdiction.
 */

#pragma once


namespace atlas {
namespace util {

class NormaliseLongitude {
public:
    // Normalise longitude between (west - eps, east - eps ) with west = 0., east = 360.
    constexpr NormaliseLongitude() : west_( -eps_ ), east_( 360. - eps_ ) {}

    // Normalise longitude between ( west-eps, east-eps )  with east = west + 360
    constexpr NormaliseLongitude( double west ) : west_( west - eps_ ), east_( west + 360. - eps_ ) {}

    // Normalise longitude between ( west-eps, east+eps )
    constexpr NormaliseLongitude( double west, double east ) : west_( west - eps_ ), east_( east + eps_ ) {}

    constexpr NormaliseLongitude( const NormaliseLongitude& other ) : west_( other.west_ ), east_( other.east_ ) {}

    double operator()( double lon ) const {
        while ( lon < west_ ) {
            lon += 360.;
        }
        while ( lon > east_ ) {
            lon -= 360.;
        }
        return lon;
    }

private:
    double west_;
    double east_;

public:
    static constexpr double eps_ = 1.e-11;
};

}  // namespace util
}  // namespace atlas