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Cleanup: Slightly improve comments in OffsetIndices header

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Avoid some repetition and clarify/simplify some language.
This commit is contained in:
Hans Goudey
2025-01-21 14:24:48 -05:00
parent 6b0fa709fa
commit 8c381a3b37
1 changed files with 12 additions and 10 deletions
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22
source/blender/blenlib/BLI_offset_indices.hh
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@@ -17,14 +17,15 @@ namespace blender::offset_indices {
struct NoSortCheck {};
/**
* References an array of ascending indices. A pair of consecutive indices encode an index range.
* Another common way to store the same kind of data is to store the start and size of every range
* separately. Using offsets instead halves the memory consumption. The downside is that the
* array has to be one element longer than the total number of ranges. The extra element is
* necessary to be able to get the last index range without requiring an extra branch for the case.
* This class is a thin wrapper around an array of increasing indices that makes it easy to
* retrieve an index range at a specific index. Each index range is typically a representation of
* a contiguous chunk of a larger array.
*
* This class is a thin wrapper around such an array that makes it easy to retrieve the index range
* at a specific index.
* Another common way to store many index ranges is to store the start and size of every range.
* Using #OffsetIndices instead requires that chunks are ordered consecutively but halves the
* memory consumption. Another downside is that the underlying array has to be one element longer
* than the total number of ranges. The extra element necessary to encode the size of the last
* range without requiring a branch for each range access.
*/
template<typename T> class OffsetIndices {
private:
@@ -44,7 +45,7 @@ template<typename T> class OffsetIndices {
* high performance impact making debug builds unusable for files that would be fine otherwise.
* This can be used when it is known that the indices are sorted already.
*/
OffsetIndices(const Span<T> offsets, NoSortCheck) : offsets_(offsets) {}
OffsetIndices(const Span<T> offsets, NoSortCheck /*no_sort_check*/) : offsets_(offsets) {}
/** Return the total number of elements in the referenced arrays. */
T total_size() const
@@ -109,8 +110,8 @@ template<typename T> class OffsetIndices {
* store many grouped arrays, without requiring many small allocations, giving the general benefits
* of using contiguous memory.
*
* \note If the offsets are shared between many #GroupedSpan objects, it will still
* be more efficient to retrieve the #IndexRange only once and slice each span.
* \note If the offsets are shared between many #GroupedSpan objects, it will be more efficient
* to retrieve the #IndexRange only once and slice each span.
*/
template<typename T> struct GroupedSpan {
OffsetIndices<int> offsets;
@@ -177,6 +178,7 @@ inline OffsetIndices<int> gather_selected_offsets(OffsetIndices<int> src_offsets
{
return gather_selected_offsets(src_offsets, selection, 0, dst_offsets);
}
/**
* Create a map from indexed elements to the source indices, in other words from the larger array
* to the smaller array.