Xmls is a small, simple, non-validating xml parser for Common Lisp. It's designed to be a self-contained, easily embedded parser that recognizes a useful subset of the XML spec. It provides a simple mapping from xml to lisp s-expressions and back.
Parsed xml is represented as a lisp list. A node is represented as follows:
(name (attributes) children*)
A name is either a simple string, if the element does not belong to a namespace, or a list of (name namespace-url) if the element does belong to a namespace.
Attributes are stored as (name value) lists.
Children are stored as a list of either element nodes or text nodes.
For example, the following xml document:
<?xml version="1.0"?> <!-- test document --> <book title='The Cyberiad'> <!-- comment in here --> <author xmlns='http://authors'>Stanislaw Lem</author> <info:subject xmlns:info='http://bookinfo' rank='1'>"Cybernetic Fables"</info:subject> </book>Would parse as:
("book" (("title" "The Cyberiad")) (("author" . "http://authors") NIL "Stanislaw Lem") (("subject" . "http://bookinfo") (("rank" "1")) "\"Cybernetic Fables\""))
Xmls also includes a helper function, make-node for creating xml nodes of this form:
(make-node &key name ns attrs children)
Xmls provides the corresponding accessor functions node-name, node-ns node-attrs, and node-children.
The interface is straightforward. The two main functions are parse and toxml.
(parse source &key (compress-whitespace t))
Parse accepts either a string or an input stream and attempts to parse the xml document contained therein. It will return the s-expr parse tree if it's successful or nil if parsing fails. If compress-whitespace is t, content nodes will be trimmed of whitespace and empty whitespace strings between nodes will be discarded.
(write-xml xml stream &key (indent nil))
write-xml accepts a lisp list in the format described above and writes the equivalent xml string to stream. Currently, if nodes use namespaces xmls will not assign namespaces prefixes but will explicitly assign the namespace to each node. This will be changed in a later release. Xmls will indent the generated xml output if indent is non-nil.
(toxml node &key (indent nil))
Toxml is a convenience wrapper around write-xml that returns the in a newly allocated string.
These are intended to allow programmers to avoid direct manipulation of the s-expression representation. If you use these, your code should be easier to read and you will avoid problems if there is a change in internal representation (such changes would be hard to even find, much less correct, if using the lists directly).
make-xmlrep (tag &key attribs children)
xmlrep-add-child! (xmlrep child)
xmlrep-tagmatch (tag treenode)
xmlrep-find-child-tags (tag treenode)
xmlrep-find-child-tag (tag treenode &optional (if-unfound :error))
xmlrep-attrib-value (attrib treenode &optional (if-undefined :error))
xmlrep-boolean-attrib-value (attrib treenode &optional (if-undefined :error))
xmls can be installed as an asdf system. An asdf system definition is provided with the distribution.
Previous versions of XMLS were single files, and could be installed simply by loading the file xmls.lisp. This option is no longer supported.
Please contact Robert Goldman, rpgoldman AT sift.info with any questions or bug reports.