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.
• fn:current-dateTime Returns the current date and time (with timezone). Implement fn:current-dateTime Metapath function #164
• fn:current-date Returns the current date. Support for fn:current-date #274
• fn:current-time Returns the current time. Support implicitTimezone and currentDate Metapath functions #265
• fn:implicit-timezone Returns the value of the implicit timezone property from the dynamic context. Support implicitTimezone and currentDate Metapath functions #265
• 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?

[david-waltermire]

The remaining functions fn:position and fn:last require significant refactoring and an adjustment to the approach for managing the focus. This work needs to be deferred until work on v3.0.0 starts.

Marking it as blocked for now.