Support Metapath functions that operate on nodes

[david-waltermire]

User Story

As a Metapath expression author I need support for Metapath functions that operate on nodes.

Goals

Add support for the following functions that operate on nodes:

• fn:name Returns the name of a node, as an xs:string that is either the zero-length string, or has the lexical form of an xs:QName.
• fn:local-name Returns the local part of the name of $arg as an xs:string that is either the zero-length string, or has the lexical form of an xs:NCName.
• fn:namespace-uri Returns the namespace URI part of the name of $arg, as an xs:anyURI value.
• [ ] fn:lang This function tests whether the language of $node, or the context item if the second argument is omitted, as specified by xml:lang attributes is the same as, or is a sublanguage of, the language specified by $testlang. This method is not useful, since Metaschema models do not currently have a concept of language. Instead, this is handled at the application layer.
• fn:root Returns the root of the tree to which $arg belongs. This will usually, but not necessarily, be a document node.
• (already supported) fn:path Returns a path expression that can be used to select the supplied node relative to the root of its containing document.
• fn:has-children Returns true if the supplied node has one or more child nodes (of any kind).
• fn:innermost Returns every node within the input sequence that is not an ancestor of another member of the input sequence; the nodes are returned in document order with duplicates eliminated.
• fn:outermost Returns every node within the input sequence that has no ancestor that is itself a member of the input sequence; the nodes are returned in document order with duplicates eliminated.

Dependencies

none

Acceptance Criteria

• 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