Shape

Developer notes for include/stratax/core/Shape.hpp.

Purpose

Stores tensor dimensions and exposes rank and total element count metadata.

Main API

Constructors

• Default constructor
• Shape({ ... })

Metadata

• elements()
• rank()
• empty()

Element Access

• operator()(dimension_index)

Iteration and Utilities

• begin() / end()
• operator==
• operator!=
• swap()
• operator<<

Invariants

• rank() always equals the number of stored dimensions.
• Dimensions are stored in declaration order.
• elements() is the product of all dimensions, except empty shape returns 0.
• Any zero dimension makes elements() return 0.
• Shape equality requires the same rank and the same dimension values in order.

Validation Notes

• operator() checks dimension index bounds through core::validation::require_index().
• elements() returns total element count using core::validation::checked_multiply().
• Empty shape has element count 0.
• Element count multiplication checks overflow and throws Exceptions::DimensionError.

Implementation Notes

• Public shape indexing should use operator().
• Shape stores dimensions in Buffer<std::size_t>.
• Use rank() when comparing number of dimensions.
• Keep overflow and bounds checks routed through Validation.hpp.
• operator<< is inline because this file is header-only.

Time Complexity

• Default construction, rank(), empty(), operator()(index), iterator access, and swap() are O(1).
• Initializer-list and buffer construction are O(r), where r is rank.
• elements(), equality, inequality, and stream output are O(r).

Future Work

• Decide scalar-shape semantics for empty shapes.
• Add shape construction from iterator ranges.
• Add more shape arithmetic helpers.