juce_SparseSet.h

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 /*
  ==============================================================================
 
   This file is part of the JUCE library.
   Copyright (c) 2022 - Raw Material Software Limited
 
   JUCE is an open source library subject to commercial or open-source
   licensing.
 
   The code included in this file is provided under the terms of the ISC license
   http://www.isc.org/downloads/software-support-policy/isc-license. Permission
   To use, copy, modify, and/or distribute this software for any purpose with or
   without fee is hereby granted provided that the above copyright notice and
   this permission notice appear in all copies.
 
   JUCE IS PROVIDED "AS IS" WITHOUT ANY WARRANTY, AND ALL WARRANTIES, WHETHER
   EXPRESSED OR IMPLIED, INCLUDING MERCHANTABILITY AND FITNESS FOR PURPOSE, ARE
   DISCLAIMED.
 
  ==============================================================================
*/
 
namespace juce
{
 
//==============================================================================
template <class Type>
class SparseSet
{
public:
    //==============================================================================
    SparseSet() = default;
 
    SparseSet (const SparseSet&) = default;
    SparseSet& operator= (const SparseSet&) = default;
 
    SparseSet (SparseSet&& other) noexcept : ranges (std::move (other.ranges)) {}
    SparseSet& operator= (SparseSet&& other) noexcept { ranges = std::move (other.ranges); return *this; }
 
    //==============================================================================
    void clear()                                { ranges.clear(); }
 
    bool isEmpty() const noexcept               { return ranges.isEmpty(); }
 
    Type size() const noexcept
    {
        Type total = {};
 
        for (auto& r : ranges)
            total += r.getLength();
 
        return total;
    }
 
    Type operator[] (Type index) const noexcept
    {
        Type total = {};
 
        for (auto& r : ranges)
        {
            auto end = total + r.getLength();
 
            if (index < end)
                return r.getStart() + (index - total);
 
            total = end;
        }
 
        return {};
    }
 
    bool contains (Type valueToLookFor) const noexcept
    {
        for (auto& r : ranges)
        {
            if (r.getStart() > valueToLookFor)
                break;
 
            if (r.getEnd() > valueToLookFor)
                return true;
        }
 
        return false;
    }
 
    //==============================================================================
    int getNumRanges() const noexcept                           { return ranges.size(); }
 
    Range<Type> getRange (int rangeIndex) const noexcept        { return ranges[rangeIndex]; }
 
    Range<Type> getTotalRange() const noexcept
    {
        if (ranges.isEmpty())
            return {};
 
        return { ranges.getFirst().getStart(),
                 ranges.getLast().getEnd() };
    }
 
    //==============================================================================
    void addRange (Range<Type> range)
    {
        if (! range.isEmpty())
        {
            removeRange (range);
            ranges.add (range);
            std::sort (ranges.begin(), ranges.end(),
                       [] (Range<Type> a, Range<Type> b) { return a.getStart() < b.getStart(); });
            simplify();
        }
    }
 
    void removeRange (Range<Type> rangeToRemove)
    {
        if (getTotalRange().intersects (rangeToRemove) && ! rangeToRemove.isEmpty())
        {
            for (int i = ranges.size(); --i >= 0;)
            {
                auto& r = ranges.getReference (i);
 
                if (r.getEnd() <= rangeToRemove.getStart())
                    break;
 
                if (r.getStart() >= rangeToRemove.getEnd())
                    continue;
 
                if (rangeToRemove.contains (r))
                {
                    ranges.remove (i);
                }
                else if (r.contains (rangeToRemove))
                {
                    auto r1 = r.withEnd (rangeToRemove.getStart());
                    auto r2 = r.withStart (rangeToRemove.getEnd());
 
                    // this should be covered in if (rangeToRemove.contains (r))
                    jassert (! r1.isEmpty() || ! r2.isEmpty());
 
                    r = r1;
 
                    if (r.isEmpty())
                        r = r2;
 
                    if (! r1.isEmpty() && ! r2.isEmpty())
                        ranges.insert (i + 1, r2);
                }
                else if (rangeToRemove.getEnd() > r.getEnd())
                {
                    r.setEnd (rangeToRemove.getStart());
                }
                else
                {
                    r.setStart (rangeToRemove.getEnd());
                }
            }
        }
    }
 
    void invertRange (Range<Type> range)
    {
        SparseSet newItems;
        newItems.addRange (range);
 
        for (auto& r : ranges)
            newItems.removeRange (r);
 
        removeRange (range);
 
        for (auto& r : newItems.ranges)
            addRange (r);
    }
 
    bool overlapsRange (Range<Type> range) const noexcept
    {
        if (! range.isEmpty())
            for (auto& r : ranges)
                if (r.intersects (range))
                    return true;
 
        return false;
    }
 
    bool containsRange (Range<Type> range) const noexcept
    {
        if (! range.isEmpty())
            for (auto& r : ranges)
                if (r.contains (range))
                    return true;
 
        return false;
    }
 
    const Array<Range<Type>>& getRanges() const noexcept        { return ranges; }
 
    //==============================================================================
    bool operator== (const SparseSet& other) const noexcept     { return ranges == other.ranges; }
    bool operator!= (const SparseSet& other) const noexcept     { return ranges != other.ranges; }
 
private:
    //==============================================================================
    Array<Range<Type>> ranges;
 
    void simplify()
    {
        for (int i = ranges.size(); --i > 0;)
        {
            auto& r1 = ranges.getReference (i - 1);
            auto& r2 = ranges.getReference (i);
 
            if (r1.getEnd() == r2.getStart())
            {
                r1.setEnd (r2.getEnd());
                ranges.remove (i);
            }
        }
    }
};
 
} // namespace juce