time: Add is_datetime() for RFC 3339 Internet Date/Time Format

[vtushar06]

Body

Adds sourcemeta::core::is_datetime() to src/core/time following the same pattern as is_ipv4() and is_ipv6() in src/core/ip.

This is a building block for format-assertion support in Blaze for Draft 4 and Draft 6.

Function signature:

auto is_datetime(std::string_view value) -> bool;

Pure string_view state machine. No heap allocations. No external dependencies.

RFC 3339 §5.6 compliance:

• full-date "T" full-time production rule
• Leap year per Appendix C formula
• Accepts second=60 (leap seconds) per §5.7
• Case-insensitive T and Z per §5.6 NOTE
• Rejects colonless offsets (+0530)
• Rejects space separator
• Rejects missing timezone
• Year range 0000-9999 per §1

Tests: 40 cases (17 valid, 23 invalid)

Files changed:

File	Action
src/core/time/include/sourcemeta/core/time.h	Add is_datetime() declaration
src/core/time/datetime.cc	New — implementation
src/core/time/CMakeLists.txt	Add datetime.cc to SOURCES
test/time/datetime_test.cc	New — 40 unit tests
test/time/CMakeLists.txt	Add datetime_test.cc to SOURCES

Out of scope for this PR:

Blaze integration - is_datetime() is the building block. Hooking it into format-assertion in the Blaze compiler is a separate PR once this is reviewed.

[Copilot]

Pull request overview

Adds sourcemeta::core::is_datetime(std::string_view) -> bool to validate RFC 3339 date-time strings (Section 5.6) using a pure string_view state machine, and introduces a dedicated unit test suite.

Changes:

• Add is_datetime() public API to sourcemeta::core::time.
• Implement RFC 3339 date-time validation (including leap-year rules, leap seconds, and required timezone).
• Add comprehensive unit tests and wire new sources into the build.

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
src/core/time/include/sourcemeta/core/time.h	Declares is_datetime() and documents RFC 3339 expectations/usage.
src/core/time/datetime.cc	Implements the RFC 3339 date-time validator as a zero-allocation parser.
src/core/time/CMakeLists.txt	Adds datetime.cc to the time library build.
test/time/datetime_test.cc	Adds 40 unit tests covering valid/invalid RFC 3339 date-time cases.
test/time/CMakeLists.txt	Adds datetime_test.cc to the time unit test target.

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[cubic-dev-ai]

1 issue found across 5 files

Prompt for AI agents (unresolved issues)

Check if these issues are valid — if so, understand the root cause of each and fix them. If appropriate, use sub-agents to investigate and fix each issue separately.


<file name="src/core/time/datetime.cc">

<violation number="1" location="src/core/time/datetime.cc:128">
P2: `is_datetime` accepts `:60` unconditionally, making RFC 3339 validation too permissive for leap-second semantics.</violation>
</file>

_{Reply with feedback, questions, or to request a fix. Tag @cubic-dev-ai to re-run a review.}

[Copilot]

Pull request overview

Copilot reviewed 5 out of 5 changed files in this pull request and generated 1 comment.

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[vtushar06]

hey @jviotti, PR is ready for review, let me know if any further tweaks are needed :)