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library(xml)This is a package for parsing XML with Prolog, which provides Prolog applications with a simple “Document Value Model” interface to XML documents. A description of the subset of XML that it supports can be found at: http://www.binding-time.co.uk/xmlpl.html
The package, originally written by Binding Time Ltd., is in the public domain and unsupported. To use the package, enter the query:
| ?- use_module(library(xml)).
The package represents XML documents by the abstract data type document, which is defined by the following grammar:
| document | ::= xml(attributes,content) | { well-formed document } |
| malformed(attributes,content) | { malformed document } | |
| attributes | ::= [] | |
| [name=char-data|attributes] | ||
| content | ::= [] | |
| [cterm|content] | ||
| cterm | ::= pcdata(char-data) | { text } |
| comment(char-data) | { an XML comment } | |
| namespace(URI,prefix,element) | { a Namespace } | |
| element(tag,attributes,content) | { <tag>..</tag> encloses content or <tag /> if empty } | |
| instructions(name,char-data) | { A PI <? name char-data ?> } | |
| cdata(char-data) | { <![CDATA[char-data]]> } | |
| doctype(tag,doctype-id) | { DTD <!DOCTYPE .. > } | |
| unparsed(char-data) | { text that hasn’t been parsed } | |
| out_of_context(tag) | { tag is not closed } | |
| tag | ::= atom | { naming an element } |
| name | ::= atom | { not naming an element } |
| URI | ::= atom | { giving the URI of a namespace } |
| char-data | ::= code list | |
| doctype-id | ::= public(char-data,char-data) | |
| public(char-data,dtd-literals) | ||
| system(char-data) | ||
| system(char-data,dtd-literals) | ||
| local | ||
| local,dtd-literals | ||
| dtd-literals | ::= [] | |
| [dtd_literal(char-data)|dtd-literals] |
The following predicates are exported by the package:
xml_parse(?Chars, ?Document)xml_parse(?Chars, ?Document, +Options)Either parses Chars, a code list, to Document, a
document. Chars is not required to represent strictly
well-formed XML.
Or generates Chars, a code list,
from Document, a document.
If Document is not a valid document term representing
well-formed XML, an exception is raised.
In the second usage of the predicate, the only option available is format/1.
Options is a list of zero or more of the following, where
Boolean must be true or false:
format(Boolean)Indent the element content (default true).
extended_characters(Boolean)Use the extended character entities for XHTML (default true).
remove_attribute_prefixes(Boolean)Remove namespace prefixes from attributes when it’s the same as the
prefix of the parent element (default false).
xml_subterm(+Term, ?Subterm)Unifies Subterm with a sub-term of Term, a document. This can be especially useful when trying to test or retrieve a deeply-nested subterm from a document.
xml_pp(+Document)“Pretty prints” Document, a document, on the current output stream.