feat(third_party/lisp/s-xml): Check in sources & derivation r/438

Checked in the sources for this because it is tracked upstream in CVS
and I can't be bothered to deal with that right now.

6 files changed, 1107 insertions, 0 deletions

diff --git a/third_party/lisp/s-xml/src/dom.lisp b/third_party/lisp/s-xml/src/dom.lisp
new file mode 100644
index 000000000000..74d1c371db22
--- /dev/null
+++ b/third_party/lisp/s-xml/src/dom.lisp
@@ -0,0 +1,75 @@
+;;;; -*- mode: lisp -*-
+;;;;
+;;;; $Id: dom.lisp,v 1.1.1.1 2004/06/07 18:49:56 scaekenberghe Exp $
+;;;;
+;;;; This is the generic simple DOM parser and printer interface.
+;;;;
+;;;; Copyright (C) 2002, 2004 Sven Van Caekenberghe, Beta Nine BVBA.
+;;;;
+;;;; You are granted the rights to distribute and use this software
+;;;; as governed by the terms of the Lisp Lesser General Public License
+;;;; (http://opensource.franz.com/preamble.html), also known as the LLGPL.
+
+(in-package :s-xml)
+
+;;; top level DOM parser interface
+
+(defgeneric parse-xml-dom (stream output-type)
+  (:documentation "Parse a character stream as XML and generate a DOM of output-type"))
+
+(defun parse-xml (stream &key (output-type :lxml))
+  "Parse a character stream as XML and generate a DOM of output-type, defaulting to :lxml"
+  (parse-xml-dom stream output-type))
+  
+(defun parse-xml-string (string &key (output-type :lxml))
+  "Parse a string as XML and generate a DOM of output-type, defaulting to :lxml"
+  (with-input-from-string (stream string)
+    (parse-xml-dom stream output-type)))
+
+(defun parse-xml-file (filename &key (output-type :lxml))
+  "Parse a character file as XML and generate a DOM of output-type, defaulting to :lxml"
+  (with-open-file (in filename :direction :input)
+    (parse-xml-dom in output-type)))
+
+;;; top level DOM printer interface
+
+(defgeneric print-xml-dom (dom input-type stream pretty level)
+  (:documentation "Generate XML output on a character stream from a DOM of input-type, optionally pretty printing using level"))
+
+(defun print-xml (dom &key (stream t) (pretty nil) (input-type :lxml) (header))
+  "Generate XML output on a character stream (t by default) from a DOM of input-type (:lxml by default), optionally pretty printing (off by default), or adding a header (none by default)"
+  (when header (format stream header))
+  (when pretty (terpri stream))
+  (print-xml-dom dom input-type stream pretty 1))
+
+(defun print-xml-string (dom &key (pretty nil) (input-type :lxml))
+  "Generate XML output to a string from a DOM of input-type (:lxml by default), optionally pretty printing (off by default)"
+  (with-output-to-string (stream)
+    (print-xml dom :stream stream :pretty pretty :input-type input-type)))
+
+;;; shared/common support functions
+
+(defun print-spaces (n stream &optional (preceding-newline t))
+  (when preceding-newline 
+    (terpri stream))
+  (loop :repeat n 
+        :do (write-char #\Space stream)))
+
+(defun print-solitary-tag (tag stream)
+  (write-char #\< stream) 
+  (print-identifier tag stream) 
+  (write-string "/>" stream))
+
+(defun print-closing-tag (tag stream)
+  (write-string "</" stream) 
+  (print-identifier tag stream) 
+  (write-char #\> stream))
+  
+(defun print-attribute (name value stream)
+  (write-char #\space stream)
+  (print-identifier name stream t)
+  (write-string "=\"" stream)
+  (print-string-xml value stream)
+  (write-char #\" stream))
+
+;;;; eof
diff --git a/third_party/lisp/s-xml/src/lxml-dom.lisp b/third_party/lisp/s-xml/src/lxml-dom.lisp
new file mode 100644
index 000000000000..d43df6cf8171
--- /dev/null
+++ b/third_party/lisp/s-xml/src/lxml-dom.lisp
@@ -0,0 +1,83 @@
+;;;; -*- mode: lisp -*-
+;;;;
+;;;; $Id: lxml-dom.lisp,v 1.5 2005/09/20 09:57:44 scaekenberghe Exp $
+;;;;
+;;;; LXML implementation of the generic DOM parser and printer.
+;;;;
+;;;; Copyright (C) 2002, 2004 Sven Van Caekenberghe, Beta Nine BVBA.
+;;;;
+;;;; You are granted the rights to distribute and use this software
+;;;; as governed by the terms of the Lisp Lesser General Public License
+;;;; (http://opensource.franz.com/preamble.html), also known as the LLGPL.
+
+(in-package :s-xml)
+
+;;; the lxml hooks to generate lxml
+
+(defun lxml-new-element-hook (name attributes seed)
+  (declare (ignore name attributes seed))
+  '())
+
+(defun lxml-finish-element-hook (name attributes parent-seed seed)
+  (let ((xml-element
+	 (cond ((and (null seed) (null attributes))
+		name)
+	       (attributes
+		`((,name ,@(let (list)
+			     (dolist (attribute attributes list)
+			       (push (cdr attribute) list)
+			       (push (car attribute) list))))
+		  ,@(nreverse seed)))
+	       (t
+		`(,name ,@(nreverse seed))))))
+    (cons xml-element parent-seed)))
+
+(defun lxml-text-hook (string seed)
+  (cons string seed))
+
+;;; standard DOM interfaces
+
+(defmethod parse-xml-dom (stream (output-type (eql :lxml)))
+  (car (start-parse-xml stream
+			(make-instance 'xml-parser-state
+				       :new-element-hook #'lxml-new-element-hook
+				       :finish-element-hook #'lxml-finish-element-hook
+				       :text-hook #'lxml-text-hook))))
+
+(defun plist->alist (plist)
+  (when plist 
+    (cons (cons (first plist) (second plist))
+          (plist->alist (rest (rest plist))))))
+
+(defmethod print-xml-dom (dom (input-type (eql :lxml)) stream pretty level)
+  (declare (special *namespaces*))
+  (cond ((symbolp dom) (print-solitary-tag dom stream))
+	((stringp dom) (print-string-xml dom stream))
+	((consp dom)
+	 (let (tag attributes)
+	   (cond ((symbolp (first dom)) (setf tag (first dom)))
+		 ((consp (first dom)) (setf tag (first (first dom)) 
+                                            attributes (plist->alist (rest (first dom)))))
+		 (t (error "Input not recognized as LXML ~s" dom)))
+           (let ((*namespaces* (extend-namespaces attributes *namespaces*)))
+             (write-char #\< stream) 
+             (print-identifier tag stream)
+             (loop :for (name . value) :in attributes 
+                   :do (print-attribute name value stream))
+             (if (rest dom)
+                 (let ((children (rest dom)))
+                   (write-char #\> stream)
+                   (if (and (= (length children) 1) (stringp (first children)))
+                       (print-string-xml (first children) stream)
+                     (progn
+                       (dolist (child children)
+                         (when pretty (print-spaces (* 2 level) stream))
+                         (if (stringp child)
+                             (print-string-xml child stream)
+                           (print-xml-dom child input-type stream pretty (1+ level))))
+                       (when pretty (print-spaces (* 2 (1- level)) stream))))
+                   (print-closing-tag tag stream))
+               (write-string "/>" stream)))))
+	(t (error "Input not recognized as LXML ~s" dom))))
+  
+;;;; eof
\ No newline at end of file
diff --git a/third_party/lisp/s-xml/src/package.lisp b/third_party/lisp/s-xml/src/package.lisp
new file mode 100644
index 000000000000..f90f0f49a166
--- /dev/null
+++ b/third_party/lisp/s-xml/src/package.lisp
@@ -0,0 +1,46 @@
+;;;; -*- mode: lisp -*-
+;;;;
+;;;; $Id: package.lisp,v 1.7 2006/01/19 20:00:06 scaekenberghe Exp $
+;;;;
+;;;; This is a Common Lisp implementation of a very basic XML parser.
+;;;; The parser is non-validating.
+;;;; The API into the parser is pure functional parser hook model that comes from SSAX,
+;;;; see also http://pobox.com/~oleg/ftp/Scheme/xml.html or http://ssax.sourceforge.net
+;;;; Different DOM models are provided, an XSML, an LXML and a xml-element struct based one.
+;;;;
+;;;; Copyright (C) 2002, 2003, 2004, 2005, 2006 Sven Van Caekenberghe, Beta Nine BVBA.
+;;;;
+;;;; You are granted the rights to distribute and use this software
+;;;; as governed by the terms of the Lisp Lesser General Public License
+;;;; (http://opensource.franz.com/preamble.html), also known as the LLGPL.
+
+(defpackage s-xml
+  (:use common-lisp)
+  (:export
+   ;; main parser interface
+   #:start-parse-xml
+   #:print-string-xml
+   #:xml-parser-error #:xml-parser-error-message #:xml-parser-error-args #:xml-parser-error-stream
+   #:xml-parser-state #:get-entities #:get-seed
+   #:get-new-element-hook #:get-finish-element-hook #:get-text-hook
+   ;; callbacks
+   #:*attribute-name-parser*
+   #:*attribute-value-parser*
+   #:parse-attribute-name
+   #:parse-attribute-value
+   ;; dom parser and printer
+   #:parse-xml-dom #:parse-xml #:parse-xml-string #:parse-xml-file
+   #:print-xml-dom #:print-xml #:print-xml-string
+   ;; xml-element structure
+   #:make-xml-element #:xml-element-children #:xml-element-name 
+   #:xml-element-attribute #:xml-element-attributes
+   #:xml-element-p #:new-xml-element #:first-xml-element-child
+   ;; namespaces
+   #:*ignore-namespaces* #:*local-namespace* #:*namespaces*
+   #:*require-existing-symbols* #:*auto-export-symbols* #:*auto-create-namespace-packages*
+   #:find-namespace #:register-namespace #:get-prefix #:get-uri #:get-package
+   #:resolve-identifier #:extend-namespaces #:print-identifier #:split-identifier)
+  (:documentation 
+   "A simple XML parser with an efficient, purely functional, event-based interface as well as a DOM interface"))
+
+;;;; eof
diff --git a/third_party/lisp/s-xml/src/sxml-dom.lisp b/third_party/lisp/s-xml/src/sxml-dom.lisp
new file mode 100644
index 000000000000..c9e0f9e0db4e
--- /dev/null
+++ b/third_party/lisp/s-xml/src/sxml-dom.lisp
@@ -0,0 +1,76 @@
+;;;; -*- mode: lisp -*-
+;;;;
+;;;; $Id: sxml-dom.lisp,v 1.4 2005/09/20 09:57:48 scaekenberghe Exp $
+;;;;
+;;;; LXML implementation of the generic DOM parser and printer.
+;;;;
+;;;; Copyright (C) 2003, 2004 Sven Van Caekenberghe, Beta Nine BVBA.
+;;;;
+;;;; You are granted the rights to distribute and use this software
+;;;; as governed by the terms of the Lisp Lesser General Public License
+;;;; (http://opensource.franz.com/preamble.html), also known as the LLGPL.
+
+(in-package :s-xml)
+
+;;; the sxml hooks to generate sxml
+
+(defun sxml-new-element-hook (name attributes seed)
+  (declare (ignore name attributes seed))
+  '())
+
+(defun sxml-finish-element-hook (name attributes parent-seed seed)
+  (let ((xml-element (append (list name)
+			     (when attributes
+			       (list (let (list)
+				       (dolist (attribute attributes (cons :@ list))
+					 (push (list (car attribute) (cdr attribute)) list)))))
+			     (nreverse seed))))
+    (cons xml-element parent-seed)))
+
+(defun sxml-text-hook (string seed)
+  (cons string seed))
+
+;;; the standard DOM interfaces
+
+(defmethod parse-xml-dom (stream (output-type (eql :sxml)))
+  (car (start-parse-xml stream
+			(make-instance 'xml-parser-state
+				       :new-element-hook #'sxml-new-element-hook
+				       :finish-element-hook #'sxml-finish-element-hook
+				       :text-hook #'sxml-text-hook))))
+
+(defmethod print-xml-dom (dom (input-type (eql :sxml)) stream pretty level)
+  (declare (special *namespaces*))
+  (cond ((stringp dom) (print-string-xml dom stream))
+	((consp dom)
+	 (let ((tag (first dom))
+	       attributes
+	       children)
+	   (if (and (consp (second dom)) (eq (first (second dom)) :@))
+	       (setf attributes (rest (second dom))
+		     children (rest (rest dom)))
+	     (setf children (rest dom)))
+           (let ((*namespaces* (extend-namespaces (loop :for (name value) :in attributes 
+                                                        :collect (cons name value))
+                                                  *namespaces*)))
+             (write-char #\< stream)
+             (print-identifier tag stream)
+             (loop :for (name value) :in attributes
+                   :do (print-attribute name value stream))
+             (if children
+                 (progn
+                   (write-char #\> stream)
+                   (if (and (= (length children) 1) (stringp (first children)))
+                       (print-string-xml (first children) stream)
+                     (progn
+                       (dolist (child children)
+                         (when pretty (print-spaces (* 2 level) stream))
+                         (if (stringp child)
+                             (print-string-xml child stream)
+                           (print-xml-dom child input-type stream pretty (1+ level))))
+                       (when pretty (print-spaces (* 2 (1- level)) stream))))
+                   (print-closing-tag tag stream))
+               (write-string "/>" stream)))))
+	(t (error "Input not recognized as SXML ~s" dom))))
+
+;;;; eof
diff --git a/third_party/lisp/s-xml/src/xml-struct-dom.lisp b/third_party/lisp/s-xml/src/xml-struct-dom.lisp
new file mode 100644
index 000000000000..70373889152f
--- /dev/null
+++ b/third_party/lisp/s-xml/src/xml-struct-dom.lisp
@@ -0,0 +1,125 @@
+;;;; -*- mode: lisp -*-
+;;;;
+;;;; $Id: xml-struct-dom.lisp,v 1.2 2005/08/29 15:01:47 scaekenberghe Exp $
+;;;;
+;;;; XML-STRUCT implementation of the generic DOM parser and printer.
+;;;;
+;;;; Copyright (C) 2002, 2004 Sven Van Caekenberghe, Beta Nine BVBA.
+;;;;
+;;;; You are granted the rights to distribute and use this software
+;;;; as governed by the terms of the Lisp Lesser General Public License
+;;;; (http://opensource.franz.com/preamble.html), also known as the LLGPL.
+
+(in-package :s-xml)
+
+;;; xml-element struct datastructure and API
+
+(defstruct xml-element
+  name        ; :tag-name
+  attributes  ; a assoc list of (:attribute-name . "attribute-value")
+  children    ; a list of children/content either text strings or xml-elements
+  )
+
+(setf (documentation 'xml-element-p 'function)
+      "Return T when the argument is an xml-element struct"
+      (documentation 'xml-element-attributes 'function)
+      "Return the alist of attribute names and values dotted pairs from an xml-element struct"
+      (documentation 'xml-element-children 'function)
+      "Return the list of children from an xml-element struct"
+      (documentation 'xml-element-name 'function)
+      "Return the name from an xml-element struct"
+      (documentation 'make-xml-element 'function)
+      "Make and return a new xml-element struct")
+
+(defun xml-element-attribute (xml-element key)
+  "Return the string value of the attribute with name the keyword :key
+  of xml-element if any, return null if not found"
+  (let ((pair (assoc key (xml-element-attributes xml-element) :test #'eq)))
+    (when pair (cdr pair))))
+
+(defun (setf xml-element-attribute) (value xml-element key)
+  "Set the string value of the attribute with name the keyword :key of
+  xml-element, creating a new attribute if necessary or overwriting an
+  existing one, returning the value"
+  (let ((attributes (xml-element-attributes xml-element)))
+    (if (null attributes)
+	(push (cons key value) (xml-element-attributes xml-element))
+      (let ((pair (assoc key attributes :test #'eq)))
+	(if pair
+	    (setf (cdr pair) value)
+	  (push (cons key value) (xml-element-attributes xml-element)))))
+    value))
+
+(defun new-xml-element (name &rest children)
+  "Make a new xml-element with name and children"
+  (make-xml-element :name name :children children))
+
+(defun first-xml-element-child (xml-element)
+  "Get the first child of an xml-element"
+  (first (xml-element-children xml-element)))
+
+(defun xml-equal (xml-1 xml-2)
+  (and (xml-element-p xml-1)
+       (xml-element-p xml-2)
+       (eq (xml-element-name xml-1)
+	   (xml-element-name xml-2))
+       (equal (xml-element-attributes xml-1)
+	      (xml-element-attributes xml-2))
+       (reduce #'(lambda (&optional (x t) (y t)) (and x y))
+	       (mapcar #'(lambda (x y)
+			   (or (and (stringp x) (stringp y) (string= x y))
+			       (xml-equal x y)))
+		       (xml-element-children xml-1)
+		       (xml-element-children xml-2)))))
+
+;;; printing xml structures
+
+(defmethod print-xml-dom (xml-element (input-type (eql :xml-struct)) stream pretty level)
+  (declare (special *namespaces*))
+  (let ((*namespaces* (extend-namespaces (xml-element-attributes xml-element)
+                                         *namespaces*)))
+    (write-char #\< stream)
+    (print-identifier (xml-element-name xml-element) stream)
+    (loop :for (name . value) :in (xml-element-attributes xml-element)
+          :do (print-attribute name value stream))
+    (let ((children (xml-element-children xml-element))) 
+      (if children
+          (progn
+            (write-char #\> stream)
+            (if (and (= (length children) 1) (stringp (first children)))
+                (print-string-xml (first children) stream)
+              (progn
+                (dolist (child children)
+                  (when pretty (print-spaces (* 2 level) stream))
+                  (if (stringp child)
+                      (print-string-xml child stream)
+                    (print-xml-dom child input-type stream pretty (1+ level))))
+                (when pretty (print-spaces (* 2 (1- level)) stream))))
+            (print-closing-tag (xml-element-name xml-element) stream))
+        (write-string "/>" stream)))))
+
+;;; the standard hooks to generate xml-element structs
+
+(defun standard-new-element-hook (name attributes seed)
+  (declare (ignore name attributes seed))
+  '())
+
+(defun standard-finish-element-hook (name attributes parent-seed seed)
+  (let ((xml-element (make-xml-element :name name
+				       :attributes attributes
+				       :children (nreverse seed))))
+    (cons xml-element parent-seed)))
+
+(defun standard-text-hook (string seed)
+  (cons string seed))
+
+;;; top level standard parser interfaces
+
+(defmethod parse-xml-dom (stream (output-type (eql :xml-struct)))
+  (car (start-parse-xml stream
+			(make-instance 'xml-parser-state
+				       :new-element-hook #'standard-new-element-hook
+				       :finish-element-hook #'standard-finish-element-hook
+				       :text-hook #'standard-text-hook))))
+
+;;;; eof
diff --git a/third_party/lisp/s-xml/src/xml.lisp b/third_party/lisp/s-xml/src/xml.lisp
new file mode 100644
index 000000000000..8a2076985a49
--- /dev/null
+++ b/third_party/lisp/s-xml/src/xml.lisp
@@ -0,0 +1,702 @@
+;;;; -*- mode: lisp -*-
+;;;;
+;;;; $Id: xml.lisp,v 1.15 2006/01/19 20:00:06 scaekenberghe Exp $
+;;;;
+;;;; This is a Common Lisp implementation of a basic but usable XML parser.
+;;;; The parser is non-validating and not complete (no PI).
+;;;; Namespace and entities are handled.
+;;;; The API into the parser is a pure functional parser hook model that comes from SSAX,
+;;;; see also http://pobox.com/~oleg/ftp/Scheme/xml.html or http://ssax.sourceforge.net
+;;;; Different DOM models are provided, an XSML, an LXML and a xml-element struct based one.
+;;;;
+;;;; Copyright (C) 2002, 2003, 2004, 2005, 2006 Sven Van Caekenberghe, Beta Nine BVBA.
+;;;;
+;;;; You are granted the rights to distribute and use this software
+;;;; as governed by the terms of the Lisp Lesser General Public License
+;;;; (http://opensource.franz.com/preamble.html), also known as the LLGPL.
+
+(in-package :s-xml)
+
+;;; (tazjin): moved up here because something was wonky with the
+;;; definition order
+(defvar *ignore-namespaces* nil
+  "When t, namespaces are ignored like in the old version of S-XML")
+
+;;; error reporting
+
+(define-condition xml-parser-error (error)
+  ((message :initarg :message :reader xml-parser-error-message)
+   (args :initarg :args :reader xml-parser-error-args)
+   (stream :initarg :stream :reader xml-parser-error-stream :initform nil))
+  (:report (lambda (condition stream)
+	     (format stream
+		     "XML parser ~?~@[ near stream position ~d~]."
+		     (xml-parser-error-message condition)
+		     (xml-parser-error-args condition)
+		     (and (xml-parser-error-stream condition)
+			  (file-position (xml-parser-error-stream condition))))))
+  (:documentation "Thrown by the XML parser to indicate errorneous input"))
+
+(setf (documentation 'xml-parser-error-message 'function)
+      "Get the message from an XML parser error"
+      (documentation 'xml-parser-error-args 'function)
+      "Get the error arguments from an XML parser error"
+      (documentation 'xml-parser-error-stream 'function)
+      "Get the stream from an XML parser error")
+
+(defun parser-error (message &optional args stream)
+  (make-condition 'xml-parser-error
+		  :message message
+		  :args args
+		  :stream stream))
+
+;; attribute parsing hooks
+;; this is a bit complicated, refer to the mailing lists for a more detailed explanation
+
+(defun parse-attribute-name (string)
+  "Default parser for the attribute name"
+  (declare (special *namespaces*))
+  (resolve-identifier string *namespaces* t))
+
+(defun parse-attribute-value (name string)
+  "Default parser for the attribute value"
+  (declare (ignore name)
+           (special *ignore-namespace*))
+  (if *ignore-namespaces*
+      (copy-seq string)
+      string))
+
+(defparameter *attribute-name-parser* #'parse-attribute-name
+  "Called to compute interned attribute name from a buffer that will be reused")
+
+(defparameter *attribute-value-parser* #'parse-attribute-value
+  "Called to compute an element of an attribute list from a buffer that will be reused")
+
+;;; utilities
+
+(defun whitespace-char-p (char)
+  "Is char an XML whitespace character ?"
+  (declare (type character char))
+  (or (char= char #\space)
+      (char= char #\tab)
+      (char= char #\return)
+      (char= char #\linefeed)))
+
+(defun identifier-char-p (char)
+  "Is char an XML identifier character ?"
+  (declare (type character char))
+  (or (and (char<= #\A char) (char<= char #\Z))
+      (and (char<= #\a char) (char<= char #\z))
+      (and (char<= #\0 char) (char<= char #\9))
+      (char= char #\-)
+      (char= char #\_)
+      (char= char #\.)
+      (char= char #\:)))
+
+(defun skip-whitespace (stream)
+  "Skip over XML whitespace in stream, return first non-whitespace
+  character which was peeked but not read, return nil on eof"
+  (loop
+   (let ((char (peek-char nil stream nil #\Null)))
+     (declare (type character char))
+     (if (whitespace-char-p char)
+	 (read-char stream)
+       (return char)))))
+
+(defun make-extendable-string (&optional (size 10))
+  "Make an extendable string which is a one-dimensional character
+  array which is adjustable and has a fill pointer"
+  (make-array size
+	      :element-type 'character
+	      :adjustable t
+	      :fill-pointer 0))
+
+(defun print-string-xml (string stream &key (start 0) end)
+  "Write the characters of string to stream using basic XML conventions"
+  (loop for offset upfrom start below (or end (length string))
+        for char = (char string offset)
+	do (case char
+	     (#\& (write-string "&amp;" stream))
+	     (#\< (write-string "&lt;" stream))
+	     (#\> (write-string "&gt;" stream))
+	     (#\" (write-string "&quot;" stream))
+             ((#\newline #\return #\tab) (write-char char stream))
+	     (t (if (and (<= 32 (char-code char))
+			 (<= (char-code char) 126))
+		    (write-char char stream)
+		  (progn
+		    (write-string "&#x" stream)
+		    (write (char-code char) :stream stream :base 16)
+		    (write-char #\; stream)))))))
+
+(defun make-standard-entities ()
+  "A hashtable mapping XML entity names to their replacement strings,
+  filled with the standard set"
+  (let ((entities (make-hash-table :test #'equal)))
+    (setf (gethash "amp" entities) (string #\&)
+	  (gethash "quot" entities) (string #\")
+	  (gethash "apos" entities) (string #\')
+	  (gethash "lt" entities) (string #\<)
+	  (gethash "gt" entities) (string #\>)
+	  (gethash "nbsp" entities) (string #\space))
+    entities))
+
+(defun resolve-entity (stream extendable-string entities entity)
+  "Read and resolve an XML entity from stream, positioned after the '&' entity marker,
+  accepting &name; &#DEC; and &#xHEX; formats,
+  destructively modifying string, which is also returned,
+  destructively modifying entity, incorrect entity formats result in errors"
+  (declare (type (vector character) entity))
+  (loop
+   (let ((char (read-char stream nil #\Null)))
+     (declare (type character char))
+     (cond ((char= char #\Null) (error (parser-error "encountered eof before end of entity")))
+	   ((char= #\; char) (return))
+	   (t (vector-push-extend char entity)))))
+  (if (char= (char entity 0) #\#)
+      (let ((code (if (char= (char entity 1) #\x)
+		      (parse-integer entity :start 2 :radix 16 :junk-allowed t)
+		    (parse-integer entity :start 1 :radix 10 :junk-allowed t))))
+	(when (null code)
+          (error (parser-error "encountered incorrect entity &~s;" (list entity) stream)))
+	(vector-push-extend (code-char code) extendable-string))
+    (let ((value (gethash entity entities)))
+      (if value
+	  (loop :for char :across value
+                :do (vector-push-extend char extendable-string))
+	(error (parser-error "encountered unknown entity &~s;" (list entity) stream)))))
+  extendable-string)
+
+;;; namespace support
+
+(defclass xml-namespace ()
+  ((uri :documentation "The URI used to identify this namespace"
+        :accessor get-uri
+        :initarg :uri)
+   (prefix :documentation "The preferred prefix assigned to this namespace"
+           :accessor get-prefix
+           :initarg :prefix
+           :initform nil)
+   (package :documentation "The Common Lisp package where this namespace's symbols are interned"
+            :accessor get-package
+            :initarg :package
+            :initform nil))
+  (:documentation "Describes an XML namespace and how it is handled"))
+
+(setf (documentation 'get-uri 'function)
+      "The URI used to identify this namespace"
+      (documentation 'get-prefix 'function)
+      "The preferred prefix assigned to this namespace"
+      (documentation 'get-package 'function)
+      "The Common Lisp package where this namespace's symbols are interned")
+
+(defmethod print-object ((object xml-namespace) stream)
+  (print-unreadable-object (object stream :type t :identity t)
+    (format stream "~A - ~A" (get-prefix object) (get-uri object))))
+
+(defvar *local-namespace* (make-instance 'xml-namespace
+                                         :uri "local"
+                                         :prefix ""
+                                         :package (find-package :keyword))
+  "The local (global default) XML namespace")
+
+(defvar *xml-namespace* (make-instance 'xml-namespace
+                                       :uri "http://www.w3.org/XML/1998/namespace"
+                                       :prefix "xml"
+                                       :package (or (find-package :xml)
+                                                    (make-package :xml :nicknames '("XML"))))
+  "REC-xml-names-19990114 says the prefix xml is bound to the namespace http://www.w3.org/XML/1998/namespace.")
+
+(defvar *known-namespaces* (list *local-namespace* *xml-namespace*)
+  "The list of known/defined namespaces")
+
+(defvar *namespaces* `(("xml" . ,*xml-namespace*) ("" . ,*local-namespace*))
+  "Ordered list of (prefix . XML-namespace) bindings currently in effect - special variable")
+
+(defun find-namespace (uri)
+  "Find a registered XML namespace identified by uri"
+  (find uri *known-namespaces* :key #'get-uri :test #'string-equal))
+
+(defun register-namespace (uri prefix package)
+  "Register a new or redefine an existing XML namespace defined by uri with prefix and package"
+  (let ((namespace (find-namespace uri)))
+    (if namespace
+        (setf (get-prefix namespace) prefix
+              (get-package namespace) (find-package package))
+      (push (setf namespace (make-instance 'xml-namespace
+                                           :uri uri
+                                           :prefix prefix
+                                           :package (find-package package)))
+            *known-namespaces*))
+    namespace))
+
+(defun find-namespace-binding (prefix namespaces)
+  "Find the XML namespace currently bound to prefix in the namespaces bindings"
+  (cdr (assoc prefix namespaces :test #'string-equal)))
+
+(defun split-identifier (identifier)
+  "Split an identifier 'prefix:name' and return (values prefix name)"
+  (when (symbolp identifier)
+    (setf identifier (symbol-name identifier)))
+  (let ((colon-position (position #\: identifier :test #'char=)))
+    (if colon-position
+        (values (subseq identifier 0 colon-position)
+                (subseq identifier (1+ colon-position)))
+      (values nil identifier))))
+
+(defvar *require-existing-symbols* nil
+  "If t, each XML identifier must exist as symbol already")
+
+(defvar *auto-export-symbols* t
+  "If t, export newly interned symbols form their packages")
+
+(defun resolve-identifier (identifier namespaces &optional as-attribute)
+  "Resolve the string identifier in the list of namespace bindings"
+  (if *ignore-namespaces*
+      (intern identifier :keyword)
+    (flet ((intern-symbol (string package) ; intern string as a symbol in package
+             (if *require-existing-symbols*
+                 (let ((symbol (find-symbol string package)))
+                   (or symbol
+                       (error "Symbol ~s does not exist in ~s" string package)))
+               (let ((symbol (intern string package)))
+                 (when (and *auto-export-symbols*
+                            (not (eql package (find-package :keyword))))
+                   (export symbol package))
+                 symbol))))
+      (multiple-value-bind (prefix name)
+          (split-identifier identifier)
+        (if (or (null prefix) (string= prefix "xmlns"))
+            (if as-attribute
+                (intern (if (string= prefix "xmlns") identifier name) (get-package *local-namespace*))
+              (let ((default-namespace (find-namespace-binding "" namespaces)))
+                (intern-symbol name (get-package default-namespace))))
+          (let ((namespace (find-namespace-binding prefix namespaces)))
+            (if namespace
+                (intern-symbol name (get-package namespace))
+              (error "namespace not found for prefix ~s" prefix))))))))
+
+(defvar *auto-create-namespace-packages* t
+  "If t, new packages will be created for namespaces, if needed, named by the prefix")
+
+(defun new-namespace (uri &optional prefix)
+  "Register a new namespace for uri and prefix, creating a package if necessary"
+  (if prefix
+      (register-namespace uri
+                          prefix
+                          (or (find-package prefix)
+                              (if *auto-create-namespace-packages*
+                                  (make-package prefix :nicknames `(,(string-upcase prefix)))
+                                (error "Cannot find or create package ~s" prefix))))
+    (let ((unique-name (loop :for i :upfrom 0
+                             :do (let ((name (format nil "ns-~d" i)))
+                                   (when (not (find-package name))
+                                     (return name))))))
+      (register-namespace uri
+                          unique-name
+                          (if *auto-create-namespace-packages*
+                              (make-package (string-upcase unique-name) :nicknames `(,unique-name))
+                            (error "Cannot create package ~s" unique-name))))))
+
+(defun extend-namespaces (attributes namespaces)
+  "Given possible 'xmlns[:prefix]' attributes, extend the namespaces bindings"
+  (unless *ignore-namespaces*
+    (let (default-namespace-uri)
+      (loop :for (key . value) :in attributes
+            :do (if (string= key "xmlns")
+                    (setf default-namespace-uri value)
+                  (multiple-value-bind (prefix name)
+                      (split-identifier key)
+                    (when (string= prefix "xmlns")
+                      (let* ((uri value)
+                             (prefix name)
+                             (namespace (find-namespace uri)))
+                        (unless namespace
+                          (setf namespace (new-namespace uri prefix)))
+                        (push `(,prefix . ,namespace) namespaces))))))
+      (when default-namespace-uri
+        (let ((namespace (find-namespace default-namespace-uri)))
+          (unless namespace
+            (setf namespace (new-namespace default-namespace-uri)))
+          (push `("" . ,namespace) namespaces)))))
+  namespaces)
+
+(defun print-identifier (identifier stream &optional as-attribute)
+  "Print identifier on stream using namespace conventions"
+  (declare (ignore as-attribute) (special *namespaces*))
+  (if *ignore-namespaces*
+      (princ identifier stream)
+    (if (symbolp identifier)
+        (let ((package (symbol-package identifier))
+              (name (symbol-name identifier)))
+          (let* ((namespace (find package *known-namespaces* :key #'get-package))
+                 (prefix (or (car (find namespace *namespaces* :key #'cdr))
+                             (get-prefix namespace))))
+            (if (string= prefix "")
+                (princ name stream)
+              (format stream "~a:~a" prefix name))))
+      (princ identifier stream))))
+
+;;; the parser state
+
+(defclass xml-parser-state ()
+  ((entities :documentation "A hashtable mapping XML entity names to their replacement stings"
+	     :accessor get-entities
+	     :initarg :entities
+	     :initform (make-standard-entities))
+   (seed :documentation "The user seed object"
+	 :accessor get-seed
+	 :initarg :seed
+	 :initform nil)
+   (buffer :documentation "The main reusable character buffer"
+	   :accessor get-buffer
+	   :initform (make-extendable-string))
+   (mini-buffer :documentation "The secondary, smaller reusable character buffer"
+		:accessor get-mini-buffer
+		:initform (make-extendable-string))
+   (new-element-hook :documentation "Called when new element starts"
+		     ;; Handle the start of a new xml element with name and attributes,
+		     ;; receiving seed from previous element (sibling or parent)
+		     ;; return seed to be used for first child (content)
+                     ;; or directly to finish-element-hook
+		     :accessor get-new-element-hook
+		     :initarg :new-element-hook
+		     :initform #'(lambda (name attributes seed)
+				   (declare (ignore name attributes))
+                                   seed))
+   (finish-element-hook :documentation "Called when element ends"
+			;; Handle the end of an xml element with name and attributes,
+			;; receiving parent-seed, the seed passed to us when this element started,
+                        ;; i.e. passed to our corresponding new-element-hook
+			;; and receiving seed from last child (content)
+                        ;; or directly from new-element-hook
+			;; return final seed for this element to next element (sibling or parent)
+			:accessor get-finish-element-hook
+			:initarg :finish-element-hook
+			:initform #'(lambda (name attributes parent-seed seed)
+				      (declare (ignore name attributes parent-seed))
+                                      seed))
+   (text-hook :documentation "Called when text is found"
+	      ;; Handle text in string, found as contents,
+	      ;; receiving seed from previous element (sibling or parent),
+              ;; return final seed for this element to next element (sibling or parent)
+	      :accessor get-text-hook
+	      :initarg :text-hook
+	      :initform #'(lambda (string seed)
+			    (declare (ignore string))
+                            seed)))
+  (:documentation "The XML parser state passed along all code making up the parser"))
+
+(setf (documentation 'get-seed 'function)
+      "Get the initial user seed of an XML parser state"
+      (documentation 'get-entities 'function)
+      "Get the entities hashtable of an XML parser state"
+      (documentation 'get-new-element-hook 'function)
+      "Get the new element hook of an XML parser state"
+      (documentation 'get-finish-element-hook 'function)
+      "Get the finish element hook of an XML parser state"
+      (documentation 'get-text-hook 'function)
+      "Get the text hook of an XML parser state")
+
+#-allegro
+(setf (documentation '(setf get-seed) 'function)
+      "Set the initial user seed of an XML parser state"
+      (documentation '(setf get-entities) 'function)
+      "Set the entities hashtable of an XML parser state"
+      (documentation '(setf get-new-element-hook) 'function)
+      "Set the new element hook of an XML parser state"
+      (documentation '(setf get-finish-element-hook) 'function)
+      "Set the finish element hook of an XML parser state"
+      (documentation '(setf get-text-hook) 'function)
+      "Set the text hook of an XML parser state")
+
+(defmethod get-mini-buffer :after ((state xml-parser-state))
+  "Reset and return the reusable mini buffer"
+  (with-slots (mini-buffer) state
+    (setf (fill-pointer mini-buffer) 0)))
+
+(defmethod get-buffer :after ((state xml-parser-state))
+  "Reset and return the main reusable buffer"
+  (with-slots (buffer) state
+    (setf (fill-pointer buffer) 0)))
+
+;;; parser support
+
+(defun parse-whitespace (stream extendable-string)
+  "Read and collect XML whitespace from stream in string which is
+  destructively modified, return first non-whitespace character which
+  was peeked but not read, return #\Null on eof"
+  (declare (type (vector character) extendable-string))
+  (loop
+   (let ((char (peek-char nil stream nil #\Null)))
+     (declare (type character char))
+     (if (whitespace-char-p char)
+	 (vector-push-extend (read-char stream) extendable-string)
+       (return char)))))
+
+(defun parse-string (stream state string)
+  "Read and return an XML string from stream, delimited by either
+  single or double quotes, the stream is expected to be on the opening
+  delimiter, at the end the closing delimiter is also read, entities
+  are resolved, eof before end of string is an error"
+  (declare (type (vector character) string))
+  (let ((delimiter (read-char stream nil #\Null))
+	(char #\Null))
+    (declare (type character delimiter char))
+    (unless (or (char= delimiter #\') (char= delimiter #\"))
+      (error (parser-error "expected string delimiter" nil stream)))
+    (loop
+     (setf char (read-char stream nil #\Null))
+     (cond ((char= char #\Null) (error (parser-error "encountered eof before end of string")))
+	   ((char= char delimiter) (return))
+	   ((char= char #\&) (resolve-entity stream string (get-entities state) (get-mini-buffer state)))
+	   (t (vector-push-extend char string))))
+    string))
+
+(defun parse-text (stream state extendable-string)
+  "Read and collect XML text from stream in string which is
+  destructively modified, the text ends with a '<', which is peeked and
+  returned, entities are resolved, eof is considered an error"
+  (declare (type (vector character) extendable-string))
+  (let ((char #\Null))
+    (declare (type character char))
+    (loop
+     (setf char (peek-char nil stream nil #\Null))
+     (when (char= char #\Null) (error (parser-error "encountered unexpected eof in text")))
+     (when (char= char #\<) (return))
+     (read-char stream)
+     (if (char= char #\&)
+	 (resolve-entity stream extendable-string (get-entities state) (get-mini-buffer state))
+       (vector-push-extend char extendable-string)))
+    char))
+
+(defun parse-identifier (stream identifier)
+  "Read and returns an XML identifier from stream, positioned at the
+  start of the identifier, ending with the first non-identifier
+  character, which is peeked, the identifier is written destructively
+  into identifier which is also returned"
+  (declare (type (vector character) identifier))
+  (loop
+   (let ((char (read-char stream nil #\Null)))
+     (declare (type character char))
+     (cond ((identifier-char-p char)
+	    (vector-push-extend char identifier))
+	   (t
+            (when (char/= char #\Null) (unread-char char stream))
+	    (return identifier))))))
+
+(defun skip-comment (stream)
+  "Skip an XML comment in stream, positioned after the opening '<!--',
+  consumes the closing '-->' sequence, unexpected eof or a malformed
+  closing sequence result in a error"
+  (let ((dashes-to-read 2))
+    (loop
+     (if (zerop dashes-to-read) (return))
+     (let ((char (read-char stream nil #\Null)))
+       (declare (type character char))
+       (if (char= char #\Null)
+	   (error (parser-error "encountered unexpected eof for comment")))
+       (if (char= char #\-)
+	   (decf dashes-to-read)
+	 (setf dashes-to-read 2)))))
+  (if (char/= (read-char stream nil #\Null) #\>)
+      (error (parser-error "expected > ending comment" nil stream))))
+
+(defun read-cdata (stream state string)
+  "Reads in the CDATA and calls the callback for CDATA if it exists"
+  ;; we already read the <![CDATA[ stuff
+  ;; continue to read until we hit ]]>
+  (let ((char #\space)
+	(last-3-characters (list #\[ #\A #\T))
+	(pattern (list #\> #\] #\])))
+    (declare (type character char))
+    (loop
+     (setf char (read-char stream nil #\Null))
+     (when (char= char #\Null) (error (parser-error "encountered unexpected eof in text")))
+     (push char last-3-characters)
+     (setf (cdddr last-3-characters) nil)
+     (cond
+       ((equal last-3-characters
+	       pattern)
+	(setf (fill-pointer string)
+	      (- (fill-pointer string) 2))
+	(setf (get-seed state)
+	      (funcall (get-text-hook state)
+		       (copy-seq string)
+		       (get-seed state)))
+	(return-from read-cdata))
+       (t
+	(vector-push-extend char string))))))
+
+(defun skip-special-tag (stream state)
+  "Skip an XML special tag (comments and processing instructions) in
+  stream, positioned after the opening '<', unexpected eof is an error"
+  ;; opening < has been read, consume ? or !
+  (read-char stream)
+  (let ((char (read-char stream nil #\Null)))
+    (declare (type character char))
+    ;; see if we are dealing with a comment
+    (when (char= char #\-)
+      (setf char (read-char stream nil #\Null))
+      (when (char= char #\-)
+	(skip-comment stream)
+	(return-from skip-special-tag)))
+    ;; maybe we are dealing with CDATA?
+    (when (and (char= char #\[)
+	       (loop :for pattern :across "CDATA["
+		     :for char = (read-char stream nil #\Null)
+		     :when (char= char #\Null) :do
+		     (error (parser-error "encountered unexpected eof in cdata"))
+		     :always (char= char pattern)))
+      (read-cdata stream state (get-buffer state))
+      (return-from skip-special-tag))
+    ;; loop over chars, dealing with strings (skipping their content)
+    ;; and counting opening and closing < and > chars
+    (let ((taglevel 1)
+	  (string-delimiter #\Null))
+      (declare (type character string-delimiter))
+      (loop
+       (when (zerop taglevel) (return))
+       (setf char (read-char stream nil #\Null))
+       (when (char= char #\Null)
+	 (error (parser-error "encountered unexpected eof for special (! or ?) tag" nil stream)))
+       (if (char/= string-delimiter #\Null)
+	   ;; inside a string we only look for a closing string delimiter
+	   (when (char= char string-delimiter)
+	     (setf string-delimiter #\Null))
+	 ;; outside a string we count < and > and watch out for strings
+	 (cond ((or (char= char #\') (char= char #\")) (setf string-delimiter char))
+	       ((char= char #\<) (incf taglevel))
+	       ((char= char #\>) (decf taglevel))))))))
+
+;;; the XML parser proper
+
+(defun parse-xml-element-attributes (stream state)
+  "Parse XML element attributes from stream positioned after the tag
+  identifier, returning the attributes as an assoc list, ending at
+  either a '>' or a '/' which is peeked and also returned"
+  (declare (special *namespaces*))
+  (let ((char #\Null) attributes)
+    (declare (type character char))
+    (loop
+     ;; skip whitespace separating items
+     (setf char (skip-whitespace stream))
+     ;; start tag attributes ends with > or />
+     (when (or (char= char #\>) (char= char #\/)) (return))
+     ;; read the attribute key
+     (let ((key (let ((string (parse-identifier stream (get-mini-buffer state))))
+                  (if *ignore-namespaces*
+                      (funcall *attribute-name-parser* string)
+                      (copy-seq string)))))
+       ;; skip separating whitespace
+       (setf char (skip-whitespace stream))
+       ;; require = sign (and consume it if present)
+       (if (char= char #\=)
+	   (read-char stream)
+	 (error (parser-error "expected =" nil stream)))
+       ;; skip separating whitespace
+       (skip-whitespace stream)
+       ;; read the attribute value as a string
+       (push (cons key (let ((string (parse-string stream state (get-buffer state))))
+                         (if *ignore-namespaces*
+                             (funcall *attribute-value-parser* key string)
+                             (copy-seq string))))
+	     attributes)))
+    ;; return attributes peek char ending loop
+    (values attributes char)))
+
+(defun parse-xml-element (stream state)
+  "Parse and return an XML element from stream, positioned after the opening '<'"
+  (declare (special *namespaces*))
+  ;; opening < has been read
+  (when (char= (peek-char nil stream nil #\Null) #\!)
+    (skip-special-tag stream state)
+    (return-from parse-xml-element))
+  (let ((char #\Null) buffer open-tag parent-seed has-children)
+    (declare (type character char))
+    (setf parent-seed (get-seed state))
+    ;; read tag name (no whitespace between < and name ?)
+    (setf open-tag (copy-seq (parse-identifier stream (get-mini-buffer state))))
+    ;; tag has been read, read attributes if any
+    (multiple-value-bind (attributes peeked-char)
+	(parse-xml-element-attributes stream state)
+      (let ((*namespaces* (extend-namespaces attributes *namespaces*)))
+        (setf open-tag (resolve-identifier open-tag *namespaces*))
+        (unless *ignore-namespaces*
+          (dolist (attribute attributes)
+            (setf (car attribute) (funcall *attribute-name-parser* (car attribute))
+                  (cdr attribute) (funcall *attribute-value-parser* (car attribute) (cdr attribute)))))
+        (setf (get-seed state) (funcall (get-new-element-hook state)
+                                        open-tag attributes (get-seed state)))
+        (setf char peeked-char)
+        (when (char= char #\/)
+          ;; handle solitary tag of the form <tag .. />
+          (read-char stream)
+          (setf char (read-char stream nil #\Null))
+          (if (char= #\> char)
+              (progn
+                (setf (get-seed state) (funcall (get-finish-element-hook state)
+                                                open-tag attributes parent-seed (get-seed state)))
+                (return-from parse-xml-element))
+            (error (parser-error "expected >" nil stream))))
+        ;; consume >
+        (read-char stream)
+        (loop
+         (setf buffer (get-buffer state))
+         ;; read whitespace into buffer
+         (setf char (parse-whitespace stream buffer))
+         ;; see what ended the whitespace scan
+         (cond ((char= char #\Null) (error (parser-error "encountered unexpected eof handling ~a"
+                                                         (list open-tag))))
+               ((char= char #\<)
+                ;; consume the <
+                (read-char stream)
+                (if (char= (peek-char nil stream nil #\Null) #\/)
+                    (progn
+                      ;; handle the matching closing tag </tag> and done
+                      ;; if we read whitespace as this (leaf) element's contents, it is significant
+                      (when (and (not has-children) (plusp (length buffer)))
+                        (setf (get-seed state) (funcall (get-text-hook state)
+                                                        (copy-seq buffer) (get-seed state))))
+                      (read-char stream)
+                      (let ((close-tag (resolve-identifier (parse-identifier stream (get-mini-buffer state))
+                                                           *namespaces*)))
+                        (unless (eq open-tag close-tag)
+                          (error (parser-error "found <~a> not matched by </~a> but by <~a>"
+                                               (list open-tag open-tag close-tag) stream)))
+                        (unless (char= (read-char stream nil #\Null) #\>)
+                          (error (parser-error "expected >" nil stream)))
+                        (setf (get-seed state) (funcall (get-finish-element-hook state)
+                                                        open-tag attributes parent-seed (get-seed state))))
+                      (return))
+                  ;; handle child tag and loop, no hooks to call here
+                  ;; whitespace between child elements is skipped
+                  (progn
+                    (setf has-children t)
+                    (parse-xml-element stream state))))
+               (t
+                ;; no child tag, concatenate text to whitespace in buffer
+                ;; handle text content and loop
+                (setf char (parse-text stream state buffer))
+                (setf (get-seed state) (funcall (get-text-hook state)
+                                                (copy-seq buffer) (get-seed state))))))))))
+
+(defun start-parse-xml (stream &optional (state (make-instance 'xml-parser-state)))
+  "Parse and return a toplevel XML element from stream, using parser state"
+  (loop
+   (let ((char (skip-whitespace stream)))
+     (when (char= char #\Null) (return-from start-parse-xml))
+     ;; skip whitespace until start tag
+     (unless (char= char #\<)
+       (error (parser-error "expected <" nil stream)))
+     (read-char stream)			; consume peeked char
+     (setf char (peek-char nil stream nil #\Null))
+     (if (or (char= char #\!) (char= char #\?))
+	 ;; deal with special tags
+	 (skip-special-tag stream state)
+       (progn
+	 ;; read the main element
+	 (parse-xml-element stream state)
+	 (return-from start-parse-xml (get-seed state)))))))
+
+;;;; eof