Consider updating prefixes and base definitions and representations in SXP

[gkellogg]

Is your feature request related to a problem? Please describe.
Coming from SPARQL, if a sub-expression containing a URI with a lexical representation using a prefix or base definition is extracted, the to_sxp method will use that representation even if the prefix or base definition is no longer included.

Describe the solution you'd like
A method for managing prefix and base definition within an S-Expression (SPARQL-specific) which would recursively update the lexical representations of embedded URIs (including literal datatypes) would be nice.

# Possible refinements

# Adds a prefix declaration to an Array representation of an S-Exp and recursively update the lexical representations of contained URIs
def add_prefix(pfx, uri); end

# Adds a prefix declaration to an Array representation of an S-Exp and recursively update the lexical representations of contained URIs
def add_base(uri); end

# Returns a deep copy of an Array representation of an S-Exp without  the specified prefix and removes any lexical representations from included URIs recursively
def remove_prefix(pfx); end

# Returns a deep copy of an Array representation of an S-Exp without  the specified base and removes any lexical representations from included URIs recursively
def remove_base(); end

# Returns a deep copy of an Array representation of an S-Exp without any prefix or base declarations.
def clear_prefixes; end

# Return the prefix definitions from an an Array representation of an S-Exp
def prefixes; end

Additional context
See the email thread at https://lists.w3.org/Archives/Public/public-rdf-ruby/2021Dec/0014.html

[gkellogg]

This issue was settled without the described API changes. Instead, the signature of .to_sxp was changed to include keyword parameters prefixes and base_uri, which is propagated down. When RDF is included, the Array#to_sxp method looks to see if the array is of the form [:base _iri_ _expr_] or [prefix [['pfx:', _iri_], ...], _expr_] and extracts and passes the prefixes and base_uri parameters to recursive calls of _expr_.to_sxp.