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impl for that
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@paleolimbot
paleolimbot committed Jan 5, 2025
1 parent 02f0a3d commit d98dff0
Showing 1 changed file with 78 additions and 8 deletions.
86 changes: 78 additions & 8 deletions src/geoarrow/hpp/array_util.hpp
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Original file line number Diff line number Diff line change
Expand Up @@ -252,6 +252,13 @@ struct CoordSequence {
/// \brief Return the number of coordinates in the sequence
uint32_t size() const { return length; }

CoordSequence<Coord> Slice(uint32_t offset, uint32_t length) const {
CoordSequence<Coord> out = *this;
out.offset += offset;
out.length = length;
return out;
}

using const_iterator = internal::CoordSequenceIterator<CoordSequence>;
const_iterator begin() const { return const_iterator(*this, 0); }
const_iterator end() const { return const_iterator(*this, length); }
Expand Down Expand Up @@ -292,6 +299,16 @@ struct ListSequence {
/// Note that the child may have its own non-zero offset which must also be applied.
T child{};

T ValidChildElements() const {
if (length == 0) {
return child.Slice(0, 0);
} else {
uint32_t first_offset = offsets[offset];
uint32_t last_offset = offsets[offset + length];
return child.Slice(first_offset, last_offset - first_offset);
}
}

/// \brief Initialize a child whose offset and length are unset.
void InitChild(T* child_p) const { *child_p = child; }

Expand All @@ -303,6 +320,13 @@ struct ListSequence {
child_p->length = offsets[offset + i + 1] - child_offset;
}

ListSequence<T> Slice(uint32_t offset, uint32_t length) const {
ListSequence<T> out = *this;
out.offset += offset;
out.length = length;
return out;
}

using const_iterator = internal::ListSequenceIterator<ListSequence>;
const_iterator begin() const { return const_iterator(*this, 0); }
const_iterator end() const { return const_iterator(*this, length); }
Expand Down Expand Up @@ -397,19 +421,23 @@ struct Array {
/// the validity of the ith element in the array is calculated with the expression
/// `validity[i / 8] & (1 << (i % 8))`. This is exactly equal to the definition of
/// the validity bitmap in the Apache Arrow specification.
///
/// Note that the offset of the underlying sequence must be applied.
const uint8_t* validity{};

/// \brief Return the validity of a given element
///
/// Note that this is not an efficient mechanism to check for nullability in a loop.
bool is_valid(uint32_t i) const {
i += value.offset;
return validity == nullptr || validity[i / 8] & (1 << (i % 8));
}

/// \brief Return the nullness of a given element
///
/// Note that this is not an efficient mechanism to check for nullability in a loop.
bool is_null(uint32_t i) const {
i += value.offset;
return validity != nullptr && !(validity[i / 8] & (1 << (i % 8)));
}

Expand All @@ -422,6 +450,14 @@ struct Array {
validity = view->validity_bitmap;
return GEOARROW_OK;
}

protected:
template <typename Impl>
Impl SliceImpl(Impl self, uint32_t offset, uint32_t length) {
self.value.offset += offset;
self.value.length = length;
return self;
}
};

/// \brief An Array of points
Expand All @@ -436,7 +472,11 @@ struct PointArray : public Array<CoordSequence<Coord>> {
/// Note that in the presence of null values, some of the coordinates values
/// are not present in the array (e.g., for the purposes of calculating aggregate
/// statistics).
const CoordSequence<Coord>& Coords() const { return this->value; }
CoordSequence<Coord> Coords() const { return this->value; }

PointArray Slice(uint32_t offset, uint32_t length) {
return this->template SliceImpl<PointArray>(*this, offset, length);
}
};

/// \brief An Array of boxes
Expand Down Expand Up @@ -471,6 +511,10 @@ struct BoxArray : public Array<CoordSequence<typename Coord::box_type>> {

return out;
}

BoxArray Slice(uint32_t offset, uint32_t length) {
return this->template SliceImpl<BoxArray>(*this, offset, length);
}
};

/// \brief An Array of linestrings
Expand All @@ -481,12 +525,16 @@ struct LinestringArray : public Array<ListSequence<CoordSequence<Coord>>> {
static constexpr enum GeoArrowDimensions dimensions =
internal::CoordTraits<Coord>::dimensions;

// \brief Return a view of all coordinates in this array
/// \brief Return a view of all coordinates in this array
///
/// Note that in the presence of null values, some of the coordinates values
/// are not present in the array (e.g., for the purposes of calculating aggregate
/// statistics).
const CoordSequence<Coord>& Coords() const { return this->value.child; }
CoordSequence<Coord> Coords() const { return this->value.ValidChildElements(); }

LinestringArray Slice(uint32_t offset, uint32_t length) {
return this->template SliceImpl<LinestringArray>(*this, offset, length);
}
};

/// \brief An Array of polygons
Expand All @@ -497,12 +545,18 @@ struct PolygonArray : public Array<ListSequence<ListSequence<CoordSequence<Coord
static constexpr enum GeoArrowDimensions dimensions =
internal::CoordTraits<Coord>::dimensions;

// \brief Return a view of all coordinates in this array
/// \brief Return a view of all coordinates in this array
///
/// Note that in the presence of null values, some of the coordinates values
/// are not present in the array (e.g., for the purposes of calculating aggregate
/// statistics).
const CoordSequence<Coord>& Coords() const { return this->value.child.child; }
CoordSequence<Coord> Coords() const {
return this->value.ValidChildElements().ValidChildElements();
}

PolygonArray Slice(uint32_t offset, uint32_t length) {
return this->template SliceImpl<PolygonArray>(*this, offset, length);
}
};

/// \brief An Array of multipoints
Expand All @@ -518,7 +572,11 @@ struct MultipointArray : public Array<CoordSequence<Coord>> {
/// Note that in the presence of null values, some of the coordinates values
/// are not present in the array (e.g., for the purposes of calculating aggregate
/// statistics).
const CoordSequence<Coord>& Coords() const { return this->value.child; }
CoordSequence<Coord> Coords() const { return this->value.ValidChildElements(); }

MultipointArray Slice(uint32_t offset, uint32_t length) {
return this->template SliceImpl<MultipointArray>(*this, offset, length);
}
};

/// \brief An Array of multilinestrings
Expand All @@ -535,7 +593,13 @@ struct MultiLinestringArray
/// Note that in the presence of null values, some of the coordinates values
/// are not present in the array (e.g., for the purposes of calculating aggregate
/// statistics).
const CoordSequence<Coord>& Coords() const { return this->value.child.child; }
CoordSequence<Coord> Coords() const {
return this->value.ValidChildElements().ValidChildElements();
}

MultiLinestringArray Slice(uint32_t offset, uint32_t length) {
return this->template SliceImpl<MultiLinestringArray>(*this, offset, length);
}
};

/// \brief An Array of multipolygons
Expand All @@ -552,7 +616,13 @@ struct MultiPolygonArray
/// Note that in the presence of null values, some of the coordinates values
/// are not present in the array (e.g., for the purposes of calculating aggregate
/// statistics).
const CoordSequence<Coord>& Coords() const { return this->value.child.child.child; }
CoordSequence<Coord> Coords() const {
return this->value.ValidChildElements().ValidChildElements().ValidChildElements();
}

MultiPolygonArray Slice(uint32_t offset, uint32_t length) {
return this->template SliceImpl<MultiPolygonArray>(*this, offset, length);
}
};

} // namespace array_util
Expand Down

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