ReplicatedView supports slicing (#239)

Author: ryanmrichard

include/tensorwrapper/buffer/buffer_base.hpp

@@ -142,6 +142,8 @@ class BufferBase : public BufferBaseCommon<BufferBase>,
 
     const_layout_reference layout_() const { return *m_layout_; }
 
+    layout_reference layout_() { return *m_layout_; }
+
     dsl_reference addition_assignment_(label_type this_labels,
                                        const_labeled_reference lhs,
                                        const_labeled_reference rhs) override;

include/tensorwrapper/buffer/buffer_base_common.hpp

@@ -35,15 +35,14 @@ class BufferBaseCommon {
     /// Type of *this
     using my_type = BufferBaseCommon<Derived>;
 
-    /// Traits for my_type
-    using traits_type = types::ClassTraits<my_type>;
-
     /// Traits for Derived
-    using derived_traits = types::ClassTraits<Derived>;
+    using traits_type = types::ClassTraits<Derived>;
 
 public:
     ///@{
     using layout_type            = typename traits_type::layout_type;
+    using layout_reference       = typename traits_type::layout_reference;
+    using layout_pointer         = typename traits_type::layout_pointer;
     using const_layout_reference = typename traits_type::const_layout_reference;
     using rank_type              = typename traits_type::rank_type;
     ///@}
@@ -60,6 +59,18 @@ class BufferBaseCommon {
      */
     bool has_layout() const noexcept { return derived_().has_layout_(); }
 
+    /** @brief Retrieves the layout of *this.
+     *
+     *  @return A reference to the layout.
+     *
+     *  @throw std::runtime_error if *this does not have a layout. Strong throw
+     *                            guarantee.
+     */
+    layout_reference layout() {
+        assert_layout_();
+        return derived_().layout_();
+    }
+
     /** @brief Retrieves the layout of *this.
      *
      *  @return A read-only reference to the layout.
@@ -143,7 +154,7 @@ class BufferBaseCommon {
 
     /// Access derived for CRTP
     const Derived& derived_() const noexcept {
-        return *static_cast<const Derived*>(this);
+        return static_cast<const Derived&>(*this);
     }
 };
 

include/tensorwrapper/buffer/buffer_fwd.hpp

@@ -26,10 +26,19 @@ class BufferBase;
 template<typename BufferBaseType>
 class BufferViewBase;
 
-class Contiguous;
-
 class Local;
 
+template<typename LocalType>
+class LocalView;
+
+template<typename Derived>
+class ReplicatedCommon;
+
 class Replicated;
 
+template<typename ReplicatedType>
+class ReplicatedView;
+
+class Contiguous;
+
 } // namespace tensorwrapper::buffer

include/tensorwrapper/buffer/buffer_view_base.hpp

@@ -15,26 +15,28 @@
  */
 
 #pragma once
+#include <memory>
 #include <tensorwrapper/buffer/buffer_base.hpp>
 #include <tensorwrapper/buffer/buffer_base_common.hpp>
+#include <tensorwrapper/buffer/detail_/buffer_view_base_pimpl.hpp>
 #include <type_traits>
 
 namespace tensorwrapper::buffer {
 
 /** @brief View of a BufferBase that aliases existing state instead of owning
- * it.
+ *         it.
  *
  *  BufferViewBase has the same layout/equality API as BufferBase (has_layout(),
- *  layout(), rank(), operator==, operator!=, approximately_equal) but holds a
- *  non-owning pointer to a BufferBase and delegates all operations to it.
+ *  layout(), rank(), operator==, operator!=, approximately_equal) but uses a
+ *  PIMPL. The view delegates layout operations to the PIMPL.
  *
- *  BufferViewBase is templated on the type of the aliased buffer, which must
- *  be either BufferBase or const BufferBase. This controls whether the view is
- *  a mutable or const view of the underlying BufferBase.
+ *  BufferViewBase is templated on the type of the aliased buffer (BufferBase or
+ *  const BufferBase) for API compatibility; construction from a buffer copies
+ *  a non-owning pointer to that buffer's layout into the PIMPL.
  *
- *  The aliased buffer must outlive this view. Default-constructed or
- *  moved-from views have no aliased buffer (has_layout() is false, layout()
- *  throws).
+ *  The referenced layout (and its owner) must outlive this view. Default-
+ *  constructed or moved-from views have no layout (has_layout() is false,
+ *  layout() throws).
  *
  *  @tparam BufferBaseType Either BufferBase or const BufferBase.
  */
@@ -48,61 +50,87 @@ class BufferViewBase : public BufferBaseCommon<BufferViewBase<BufferBaseType>> {
 
     /// Type *this derives from
     using my_base_type = BufferBaseCommon<BufferViewBase<BufferBaseType>>;
-    using typename my_base_type::const_layout_reference;
 
-    using aliased_type    = BufferBaseType;
-    using aliased_pointer = aliased_type*;
+    /// Type of the PIMPL
+    using pimpl_type            = detail_::BufferViewBasePIMPL<BufferBaseType>;
+    using pimpl_reference       = pimpl_type&;
+    using const_pimpl_reference = const pimpl_type&;
 
 public:
+    using typename my_base_type::const_layout_reference;
+    using typename my_base_type::layout_pointer;
+    using typename my_base_type::layout_reference;
+    using typename my_base_type::layout_type;
     // -------------------------------------------------------------------------
     // -- Ctors and assignment
     // -------------------------------------------------------------------------
 
-    /** @brief Creates a view that aliases no buffer.
+    /** @brief Creates a view with no layout.
      *
      *  @throw None No throw guarantee.
      */
-    BufferViewBase() noexcept : m_aliased_(nullptr) {}
+    BufferViewBase() noexcept : m_pimpl_(nullptr) {}
 
-    /** @brief Creates a view that aliases @p buffer.
+    /** @brief Creates a view that aliases the layout of @p buffer.
      *
-     *  @param[in] buffer The buffer to alias. Must outlive *this.
+     *  @param[in] buffer The buffer whose layout to alias. The layout must
+     *                   outlive *this.
      *
      *  @throw None No throw guarantee.
      */
-    explicit BufferViewBase(aliased_type& buffer) noexcept :
-      m_aliased_(&buffer) {}
+    explicit BufferViewBase(BufferBaseType& buffer) noexcept :
+      m_pimpl_(buffer.has_layout() ?
+                 std::make_unique<pimpl_type>(&buffer.layout()) :
+                 nullptr) {}
+
+    /** Creates a read-only view from a mutable buffer. */
+    template<typename OtherBufferBaseType>
+        requires(!std::is_const_v<OtherBufferBaseType> &&
+                 std::is_const_v<BufferBaseType>)
+    explicit BufferViewBase(OtherBufferBaseType& other) noexcept :
+      m_pimpl_(other.has_layout() ?
+                 std::make_unique<pimpl_type>(&other.layout()) :
+                 nullptr) {}
+
+    explicit BufferViewBase(layout_pointer layout) noexcept :
+      m_pimpl_(std::make_unique<pimpl_type>(layout)) {}
 
-    /** @brief Creates a view that aliases the same buffer as @p other.
+    /** @brief Creates a view that aliases the same layout as @p other.
      *
      *  @param[in] other The view to copy.
      *
      *  @throw None No throw guarantee.
      */
-    BufferViewBase(const BufferViewBase& other) noexcept = default;
+    BufferViewBase(const BufferViewBase& other) noexcept :
+      m_pimpl_(other.m_pimpl_ ? other.m_pimpl_->clone() : nullptr) {}
 
-    /** @brief Creates a view by taking the alias from @p other.
+    /** @brief Creates a view by taking the PIMPL from @p other.
      *
-     *  After construction *this aliases the buffer @p other did, and @p other
-     *  aliases no buffer.
+     *  After construction *this aliases the layout @p other did, and @p other
+     *  has no layout.
      *
      *  @param[in,out] other The view to move from.
      *
      *  @throw None No throw guarantee.
      */
     BufferViewBase(BufferViewBase&& other) noexcept = default;
 
-    /** @brief Makes *this alias the same buffer as @p rhs.
+    /** @brief Makes *this alias the same layout as @p rhs.
      *
      *  @param[in] rhs The view to copy.
      *
      *  @return *this.
      *
      *  @throw None No throw guarantee.
      */
-    BufferViewBase& operator=(const BufferViewBase& rhs) noexcept = default;
+    BufferViewBase& operator=(const BufferViewBase& rhs) noexcept {
+        if(this != &rhs) {
+            m_pimpl_ = rhs.m_pimpl_ ? rhs.m_pimpl_->clone() : nullptr;
+        }
+        return *this;
+    }
 
-    /** @brief Replaces the alias in *this with that of @p rhs.
+    /** @brief Replaces the PIMPL in *this with that of @p rhs.
      *
      *  @param[in,out] rhs The view to move from.
      *
@@ -133,41 +161,53 @@ class BufferViewBase : public BufferBaseCommon<BufferViewBase<BufferBaseType>> {
     // -------------------------------------------------------------------------
 
     bool has_layout_() const noexcept {
-        return m_aliased_ != nullptr && m_aliased_->has_layout();
+        return m_pimpl_ != nullptr && m_pimpl_->has_layout();
+    }
+
+    layout_reference layout_() { return pimpl_().layout(); }
+
+    const_layout_reference layout_() const { return pimpl_().layout(); }
+
+    // Will be polymorphic eventually
+    template<typename OtherBufferBaseType>
+    bool approximately_equal_(const BufferViewBase<OtherBufferBaseType>& rhs,
+                              double) const {
+        return *this == rhs;
+    }
+
+    // Will be polymorphic eventually
+    bool approximately_equal_(const BufferBase& rhs, double) const {
+        return *this == rhs;
     }
 
-    const_layout_reference layout_() const {
-        if(m_aliased_ == nullptr) {
+private:
+    void assert_pimpl_() const {
+        if(!m_pimpl_) {
             throw std::runtime_error(
-              "Buffer has no layout. Was it default initialized?");
+              "BufferViewBase has no PIMPL. Was it default initialized?");
         }
-        return m_aliased_->layout();
     }
-
-    template<typename OtherBufferBase>
-    bool approximately_equal_(const BufferViewBase<OtherBufferBase>& rhs,
-                              double tol) const {
-        if(m_aliased_ == nullptr) return !rhs.has_layout();
-        return m_aliased_->approximately_equal(*rhs.m_aliased_, tol);
+    pimpl_reference pimpl_() {
+        assert_pimpl_();
+        return *m_pimpl_;
     }
 
-    bool approximately_equal_(const BufferBase& rhs, double tol) const {
-        if(m_aliased_ == nullptr) return !rhs.has_layout();
-        return m_aliased_->approximately_equal(rhs, tol);
+    const_pimpl_reference pimpl_() const {
+        assert_pimpl_();
+        return *m_pimpl_;
     }
 
-private:
-    /// The buffer *this aliases (non-owning)
-    aliased_pointer m_aliased_;
+    /// PIMPL holding non-owning pointer to the aliased layout
+    std::unique_ptr<pimpl_type> m_pimpl_;
 };
 
-// Out-of-line definition so both BufferBase and BufferViewBase are complete
+// Out-of-line definition so both BufferBase and BufferViewBase are complete.
+
 template<typename BufferBaseType>
 bool BufferBase::approximately_equal_(const BufferViewBase<BufferBaseType>& rhs,
                                       double tol) const {
     if(!rhs.has_layout()) return !has_layout();
-    return approximately_equal_(
-      *static_cast<const BufferBaseType*>(rhs.m_aliased_), tol);
+    return !this->layout().are_different(rhs.layout());
 }
 
 } // namespace tensorwrapper::buffer