urho3d/Source/Urho3D/Base/Algorithm.h

//
// Copyright (c) 2008-2019 the Urho3D project.
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.
//

#pragma once

#include "../Urho3DConfig.h"

namespace Urho3D
{

/// Returns an iterator pointing to the first element in the range [first, last) that is not less than value.
template <class TRandomAccessIterator, class T>
TRandomAccessIterator LowerBound(TRandomAccessIterator first, TRandomAccessIterator last, const T& value)
{
    unsigned count = last - first;

    while (count > 0)
    {
        const unsigned step = count / 2;
        const TRandomAccessIterator it = first + step;
        if (*it < value)
        {
            first = it + 1;
            count -= step + 1;
        }
        else
        {
            count = step;
        }
    }
    return first;
}

/// Returns an iterator pointing to the first element in the range [first, last) that is greater than value.
template <class TRandomAccessIterator, class T>
TRandomAccessIterator UpperBound(TRandomAccessIterator first, TRandomAccessIterator last, const T& value)
{
    unsigned count = last - first;

    while (count > 0)
    {
        const unsigned step = count / 2;
        const TRandomAccessIterator it = first + step;
        if (!(value < *it))
        {
            first = it + 1;
            count -= step + 1;
        }
        else
        {
            count = step;
        };
    }
    return first;
}

}