Stratax 0.2.0
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Strides

Strides

Version: v0.2.0

Status: Complete

Header: include/stratax/core/containers/Strides.hpp

Overview

Strides stores row-major stride metadata for a Shape.

It maps logical multi-dimensional indices to flat storage offsets and is used as lightweight layout metadata by Stratax containers.

Responsibilities

The Strides class is responsible for:

  • Computing row-major strides from a Shape
  • Storing stride values contiguously
  • Providing checked and unchecked stride access
  • Providing iteration over stride values
  • Supporting comparison and swap

The Strides class is not responsible for:

  • Owning array element data
  • Performing numerical algorithms
  • Shape validation beyond stride-index access
  • Multidimensional indexing logic itself

Relationships

Strides
│
└── buffer_ : Buffer<std::size_t>
Stored stride values

Depends on:

Used by:

  • Vector
  • Matrix
  • Tensor

Related classes:

  • Shape
  • Buffer

Internal Data

Member Description
Buffer<std::size_t> buffer_ Contiguous storage of stride values

Invariants

The following conditions are always true:

  • rank() equals size().
  • Empty shape produces empty strides.
  • For non-empty row-major shapes, the last stride is 1.
  • at(index) validates bounds and throws on invalid access.
  • operator== compares both rank and all stride values.

Public Interface

Iterator Aliases

using iterator = Buffer<std::size_t>::const_iterator;
using const_iterator = Buffer<std::size_t>::const_iterator;
using reverse_iterator = Buffer<std::size_t>::const_reverse_iterator;
using const_reverse_iterator = Buffer<std::size_t>::const_reverse_iterator;

Strides intentionally exposes const-backed iterator aliases because stride values are derived metadata.

Constructors

Default Constructor

Strides() noexcept;

Constructs an empty stride vector.

Complexity

  • O(1)

Throws

  • None

Shape Constructor

explicit Strides(const Shape& shape);

Constructs row-major strides for a shape.

Complexity

  • O(n)

Throws

Copy Constructor

Strides(const Strides&) = default;

Complexity

  • O(n)

Move Constructor

Strides(Strides&&) noexcept = default;

Complexity

  • O(1)

Destructor

~Strides() = default;

Complexity

  • O(n)

Assignment Operators

Copy Assignment

Strides& operator=(const Strides&) = default;

Complexity

  • O(n)

Move Assignment

Strides& operator=(Strides&&) noexcept = default;

Complexity

  • O(1)

Methods

size()

[[nodiscard]] std::size_t size() const noexcept;

Returns the number of stored stride values.

Complexity

  • O(1)

rank()

[[nodiscard]] std::size_t rank() const noexcept;

Returns the represented dimensional rank.

Complexity

  • O(1)

empty()

[[nodiscard]] bool empty() const noexcept;

Returns true if no strides are stored.

Complexity

  • O(1)

at()

const std::size_t& at(std::size_t index) const;

Returns a stride value with bounds checking.

Complexity

  • O(1)

Throws

front()

const std::size_t& front() const;

Returns first stride.

Preconditions

  • Strides must not be empty.

Complexity

  • O(1)

back()

const std::size_t& back() const;

Returns last stride.

Preconditions

  • Strides must not be empty.

Complexity

  • O(1)

data()

[[nodiscard]] const std::size_t* data() const noexcept;

Returns pointer to first stride value.

Complexity

  • O(1)

begin()/end()/cbegin()/cend()

[[nodiscard]] iterator begin() noexcept;
[[nodiscard]] const_iterator begin() const noexcept;
[[nodiscard]] const_iterator cbegin() const noexcept;
[[nodiscard]] iterator end() noexcept;
[[nodiscard]] const_iterator end() const noexcept;
[[nodiscard]] const_iterator cend() const noexcept;

Provides iteration over stride values.

Complexity

  • O(1)

rbegin()/rend()/crbegin()/crend()

[[nodiscard]] reverse_iterator rbegin() noexcept;
[[nodiscard]] const_reverse_iterator rbegin() const noexcept;
[[nodiscard]] const_reverse_iterator crbegin() const noexcept;
[[nodiscard]] reverse_iterator rend() noexcept;
[[nodiscard]] const_reverse_iterator rend() const noexcept;
[[nodiscard]] const_reverse_iterator crend() const noexcept;

Provides reverse iteration over stride values.

Complexity

  • O(1)

swap()

void swap(Strides& other) noexcept;

Exchanges stride storage with another instance.

Complexity

  • O(1)

Operators

operator()

const std::size_t& operator()(std::size_t index) const;

Returns stride value without bounds checking.

Complexity

  • O(1)

See Also

const std::size_t& at(std::size_t index) const;

operator== / operator!=

[[nodiscard]] bool operator==(const Strides& other) const noexcept;
[[nodiscard]] bool operator!=(const Strides& other) const noexcept;

Compares stride vectors by rank and values.

Complexity

  • O(n)

stream operator

std::ostream& operator<<(std::ostream& os, const Strides& stride);

Writes tuple-like stride representation, for example (12, 4, 1) and (1,) for rank-1.

Complexity

  • O(n)

Complexity Summary

Operation Complexity
Default construction O(1)
Shape construction O(n)
Copy construction O(n)
Move construction O(1)
Copy assignment O(n)
Move assignment O(1)
Destruction O(n)
size() / rank() / empty() O(1)
operator() / at() O(1)
front() / back() O(1)
operator== / operator!= O(n)
Iteration O(n)
swap() O(1)

Examples

Building Strides From a Shape

Shape shape(2, 3, 4);
Strides strides(shape);
std::cout << strides << '\n'; // (12, 4, 1)

Accessing Strides

Strides strides(Shape(2, 3, 4));
auto first = strides(0); // unchecked
auto safe = strides.at(1); // checked

Design Notes

Strides stores only layout metadata and intentionally avoids array value ownership.

By separating shape and stride metadata from value storage, Stratax keeps indexing and layout logic explicit and reusable across Vector, Matrix, and Tensor.

Future Improvements

  • Optional column-major stride construction helper
  • Utility helpers for broadcast-aware stride derivation
  • Additional constexpr-friendly constructors

See Also