Support the Metapath context funtions

[david-waltermire]

User Story

As a Metapath expression author, such as when writing Metaschema constraints, there is need query information provided by the Metapath dynamic context. such as the current date/time and information about the current document being operated on. The metapath context functions provide this information.

Goals

Implement the following Metapath functions:

• [ ] fn:position Returns the context position from the dynamic context.
• [ ] fn:last Returns the context size from the dynamic context.
• [x] fn:current-dateTime Returns the current date and time (with timezone). #164
• [ ] fn:current-date Returns the current date.
• [ ] fn:current-time Returns the current time.
• [ ] fn:implicit-timezone Returns the value of the implicit timezone property from the dynamic context.
• [ ] fn:default-language Returns the value of the default language property from the dynamic context.
• (already implemented) fn:static-base-uri This function returns the value of the static base URI property from the static context.

Dependencies

None.

Acceptance Criteria

• [ ] Positive test cases with full coverage are created for each function.
• [ ] Negative test cases that cover error conditions are created for each function.
• [ ] All website and readme documentation affected by the changes in this issue have been updated.
• [ ] A Pull Request (PR) is submitted that fully addresses the goals of this User Story. This issue is referenced in the PR.
• [ ] The CI-CD build process runs without any reported errors on the PR. This can be confirmed by reviewing that all checks have passed in the PR.

Revisions

No response

[aj-stein-gsa]

Thank you for explaining what makes these functions different re context and proposing the work. I agree these are super important and deserving to implement. Is a now or P2/P3 priority in registry parlance terms?