stillwater-sc / universal / 25641836814

84%

master: 84%

Build Type

push

github

Committed by web-flow

Commit Message

feat(edecimal): partial constexpr support (API surface) (#824)

Promote the edecimal type's user-facing surface to constexpr where
C++20's transient-allocation rule permits.  edecimal inherits from
std::vector<uint8_t>, so any non-empty digit storage disqualifies the
object from being a constexpr variable.  Mirrors the partial-constexpr
playbook from PR #820 (unum) and PR #821 (valid).

Promoted (this PR)

  * default constructor: constexpr / noexcept; uses
    std::is_constant_evaluated() to keep parallel invariants -- empty
    vector at constant evaluation (canonical constexpr zero, recognized
    by iszero() via the size() == 0 branch); push_back(0) at runtime to
    preserve the historical "size() == 1, [0] == 0" representation that
    comparison and arithmetic operators rely on
  * defaulted copy / move ctor + assignment operators marked constexpr
    (std::vector copy/move is constexpr in C++20 on empty source)
  * iszero() constexpr (range-for over the digit vector; trivially true
    on the empty constant-evaluated state)
  * sign-only selectors: sign(), isneg(), ispos() constexpr (read only
    the bool member)
  * sign-only modifiers: setsign(), setneg(), setpos() constexpr (write
    only the bool member)

Constexpr-callable surface today (gcc + clang, C++20)

  * Default ctor and selectors at constant evaluation
  * Sign modifier round-trips at constant evaluation
  * Copy and copy-assignment at constant evaluation (when source is the
    empty default-constructed state)

Limited at constant evaluation today (heap-escape boundary)

  * setzero / setdigit / setbits          (call push_back)
  * native-type ctors and operator=       (convert_integer / convert_ieee754)
  * compound arithmetic (+= -= *= /= %=)  (mutate the digit vector)
  * unary -, ++, --                       (allocate temporary edecimals)
  * conversion-out (operator double etc.) (iterate the digit vector)
  * comparison operators (==, <, ...)     (read the digit vector)
... (continued)

Coverage Stats

18 of 18 new or added lines in 1 file covered. (100.0%)

10 existing lines in 2 files now uncovered.

45870 of 54651 relevant lines covered (83.93%)

6482138.24 hits per line