Move IntervalList to FEXCore

FEXCore/include/FEXCore/Utils/IntervalList.h

@@ -0,0 +1,162 @@
+// SPDX-License-Identifier: MIT
+#pragma once
+
+#include <utility>
+#include <algorithm>
+
+#include <FEXCore/fextl/vector.h>
+
+namespace FEXCore {
+template<typename SizeType>
+class IntervalList {
+public:
+  using DifferenceType = decltype(std::declval<SizeType>() - std::declval<SizeType>());
+
+  struct Interval {
+    SizeType Offset;
+    SizeType End;
+
+    Interval() = default;
+
+    Interval(SizeType Offset, SizeType End)
+      : Offset {Offset}
+      , End {End} {}
+  };
+
+private:
+  fextl::vector<Interval> Intervals; ///< list of intervals sorted by their end offset
+
+public:
+  struct QueryResult {
+    bool Enclosed;       ///< If the given offset was enclosed by an interval
+    DifferenceType Size; ///< Size of the interval starting from the query offset, or distance to the next interval if
+                         /// `Enclosed` is false (if there is no next interval, size is 0)
+  };
+
+  void Clear() {
+    Intervals.clear();
+  }
+
+  void Insert(Interval Entry) {
+    if (Entry.Offset == Entry.End) {
+      return;
+    }
+
+    auto [FirstIt, EndIt] =
+      std::equal_range(Intervals.begin(), Intervals.end(), Entry, [](const auto& LHS, const auto& RHS) { return LHS.End <= RHS.Offset; });
+
+    if (FirstIt == EndIt) {
+      // No overlaps
+      Intervals.insert(FirstIt, Entry);
+      return;
+    }
+
+    auto LastIt = std::prev(EndIt);
+    // FirstIt/LastIt are the lowest/highest offset intervals respectively that overlap with the new interval
+
+    const SizeType Offset = std::min(Entry.Offset, FirstIt->Offset);
+    const SizeType End = std::max(LastIt->End, Entry.End);
+
+    // Erase all overlapping entries but the first
+    const auto EraseStartIt = std::next(FirstIt);
+    const auto EraseEndIt = std::next(LastIt);
+    LastIt = Intervals.erase(EraseStartIt, EraseEndIt);
+    FirstIt = std::prev(LastIt);
+
+    FirstIt->Offset = Offset;
+    FirstIt->End = End;
+  }
+
+  void Insert(const IntervalList<SizeType>& Other) {
+    for (const auto& Interval : Other.Intervals) {
+      Insert(Interval);
+    }
+  }
+
+  void Remove(Interval Entry) {
+    if (Entry.Offset == Entry.End) {
+      return;
+    }
+
+    auto [FirstIt, EndIt] =
+      std::equal_range(Intervals.begin(), Intervals.end(), Entry, [](const auto& LHS, const auto& RHS) { return LHS.End <= RHS.Offset; });
+
+    if (FirstIt == EndIt) {
+      // No intersecting intervals present, nothing more to do
+      return;
+    }
+
+    if (FirstIt->Offset < Entry.Offset && FirstIt->End > Entry.End) {
+      // The interval to be removed is fully enclosed by an existing interval
+
+      // Break the single interval into two smaller intervals on either side on the interval being removed
+      const auto FirstPredecessorIt = Intervals.insert(FirstIt, *FirstIt);
+      FirstIt = std::next(FirstPredecessorIt);
+      FirstPredecessorIt->End = Entry.Offset;
+      FirstIt->Offset = Entry.End;
+      return;
+    }
+
+    auto LastIt = std::prev(EndIt);
+    // FirstIt/LastIt are the lowest/highest offset intervals respectively that overlap with the new interval
+
+    if (FirstIt->Offset < Entry.Offset) {
+      // The first overlap straddles the start of the interval to be removed
+      FirstIt->End = Entry.Offset;
+      if (FirstIt == LastIt) {
+        // No more overlaps left, nothing more to do
+        return;
+      } else {
+        FirstIt++;
+      }
+    }
+
+    if (LastIt->End > Entry.End) {
+      // The last overlap straddles the end of the interval to be removed
+      LastIt->Offset = Entry.End;
+      if (LastIt == FirstIt) {
+        // No more overlaps left, nothing more to do
+        return;
+      } else {
+        LastIt--;
+      }
+    }
+
+    // Now none of the overlaps straddle the edges of the interval to be removed they can all be erased
+    const auto EraseStartIt = FirstIt;
+    const auto EraseEndIt = std::next(LastIt);
+    Intervals.erase(EraseStartIt, EraseEndIt);
+  }
+
+  QueryResult Query(SizeType Offset) const {
+    const auto It = std::upper_bound(Intervals.begin(), Intervals.end(), Offset, [](const auto& LHS, const auto& RHS) {
+      return LHS < RHS.End;
+    }); // Lowest offset interval that (maybe) overlaps with the query offset
+
+    if (It == Intervals.end()) { // No overlaps past offset
+      return {false, {}};
+    } else if (It->Offset > Offset) { // No overlap, return the distance to the next possible overlap
+      return {false, It->Offset - Offset};
+    } else { // Overlap, return the distance to the end of the overlap
+      return {true, It->End - Offset};
+    }
+  }
+
+  bool Intersect(Interval Entry) const {
+    const auto It = std::upper_bound(Intervals.begin(), Intervals.end(), Entry, [](const auto& LHS, const auto& RHS) {
+      return LHS.Offset < RHS.End;
+    }); // Lowest offset interval that (maybe) overlaps with the query offset
+
+    return It != Intervals.end() && It->Offset < Entry.End;
+  }
+
+  bool Contains(Interval Entry) const {
+    const auto It = std::upper_bound(Intervals.begin(), Intervals.end(), Entry, [](const auto& LHS, const auto& RHS) {
+      return LHS.Offset < RHS.End;
+    }); // Lowest offset interval that (maybe) overlaps with the query offset
+
+    return It != Intervals.end() && It->Offset <= Entry.Offset && It->End >= Entry.End;
+  }
+};
+
+} // namespace FEXCore