[Bf-blender-cvs] [bf620020f13] master: BLI: improve implicit conversions of spans
Jacques Lucke
noreply at git.blender.org
Wed Mar 17 15:27:39 CET 2021
Commit: bf620020f135eab149b6327b79de8b378d99be7e
Author: Jacques Lucke
Date: Wed Mar 17 15:26:17 2021 +0100
Branches: master
https://developer.blender.org/rBbf620020f135eab149b6327b79de8b378d99be7e
BLI: improve implicit conversions of spans
Some conversions that should work did not work before.
For example, `MutableSpan<int *> -> MutableSpan<const int *>`.
===================================================================
M source/blender/blenlib/BLI_span.hh
M source/blender/blenlib/tests/BLI_span_test.cc
===================================================================
diff --git a/source/blender/blenlib/BLI_span.hh b/source/blender/blenlib/BLI_span.hh
index 5f55efe3f63..f4960df8ab9 100644
--- a/source/blender/blenlib/BLI_span.hh
+++ b/source/blender/blenlib/BLI_span.hh
@@ -132,12 +132,11 @@ template<typename T> class Span {
}
/**
- * Support implicit conversions like the ones below:
+ * Support implicit conversions like the one below:
* Span<T *> -> Span<const T *>
*/
-
template<typename U, typename std::enable_if_t<is_span_convertible_pointer_v<U, T>> * = nullptr>
- constexpr Span(Span<U> array) : data_(static_cast<const T *>(array.data())), size_(array.size())
+ constexpr Span(Span<U> span) : data_(static_cast<const T *>(span.data())), size_(span.size())
{
}
@@ -467,11 +466,27 @@ template<typename T> class MutableSpan {
{
}
+ /**
+ * Support implicit conversions like the one below:
+ * MutableSpan<T *> -> MutableSpan<const T *>
+ */
+ template<typename U, typename std::enable_if_t<is_span_convertible_pointer_v<U, T>> * = nullptr>
+ constexpr MutableSpan(MutableSpan<U> span)
+ : data_(static_cast<T *>(span.data())), size_(span.size())
+ {
+ }
+
constexpr operator Span<T>() const
{
return Span<T>(data_, size_);
}
+ template<typename U, typename std::enable_if_t<is_span_convertible_pointer_v<T, U>> * = nullptr>
+ constexpr operator Span<U>() const
+ {
+ return Span<U>(static_cast<const U *>(data_), size_);
+ }
+
/**
* Returns the number of elements in the array.
*/
@@ -653,12 +668,13 @@ template<typename T> class MutableSpan {
/**
* Returns a new span to the same underlying memory buffer. No conversions are done.
+ * The caller is responsible for making sure that the type cast is valid.
*/
template<typename NewT> constexpr MutableSpan<NewT> cast() const
{
BLI_assert((size_ * sizeof(T)) % sizeof(NewT) == 0);
int64_t new_size = size_ * sizeof(T) / sizeof(NewT);
- return MutableSpan<NewT>(reinterpret_cast<NewT *>(data_), new_size);
+ return MutableSpan<NewT>((NewT *)data_, new_size);
}
};
diff --git a/source/blender/blenlib/tests/BLI_span_test.cc b/source/blender/blenlib/tests/BLI_span_test.cc
index 002c97b0c7d..f611529b47e 100644
--- a/source/blender/blenlib/tests/BLI_span_test.cc
+++ b/source/blender/blenlib/tests/BLI_span_test.cc
@@ -392,4 +392,16 @@ TEST(span, Constexpr)
EXPECT_EQ(span.slice(1, 2).size(), 2);
}
+TEST(span, ImplicitConversions)
+{
+ BLI_STATIC_ASSERT((std::is_convertible_v<MutableSpan<int>, Span<int>>), "");
+ BLI_STATIC_ASSERT((std::is_convertible_v<Span<int *>, Span<const int *>>), "");
+ BLI_STATIC_ASSERT((std::is_convertible_v<MutableSpan<int *>, Span<int *>>), "");
+ BLI_STATIC_ASSERT((std::is_convertible_v<MutableSpan<int *>, Span<const int *>>), "");
+ BLI_STATIC_ASSERT((std::is_convertible_v<MutableSpan<int *>, MutableSpan<const int *>>), "");
+ BLI_STATIC_ASSERT((!std::is_convertible_v<MutableSpan<const int *>, MutableSpan<int *>>), "");
+ BLI_STATIC_ASSERT((!std::is_convertible_v<Span<const int *>, Span<int *>>), "");
+ BLI_STATIC_ASSERT((!std::is_convertible_v<Span<int *>, MutableSpan<const int *>>), "");
+}
+
} // namespace blender::tests
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