--- /dev/null
+;; @(#) xml.el --- XML parser
+
+;; Copyright (C) 2000 Free Software Foundation, Inc.
+
+;; Author: Emmanuel Briot <briot@gnat.com>
+;; Maintainer: Emmanuel Briot <briot@gnat.com>
+;; Keywords: xml
+
+;; This file is part of GNU Emacs.
+
+;; GNU Emacs is free software; you can redistribute it and/or modify
+;; it under the terms of the GNU General Public License as published by
+;; the Free Software Foundation; either version 2, or (at your option)
+;; any later version.
+
+;; GNU Emacs is distributed in the hope that it will be useful,
+;; but WITHOUT ANY WARRANTY; without even the implied warranty of
+;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+;; GNU General Public License for more details.
+
+;; You should have received a copy of the GNU General Public License
+;; along with GNU Emacs; see the file COPYING. If not, write to the
+;; Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+;; Boston, MA 02111-1307, USA.
+
+;;; Commentary:
+
+;; This file contains a full XML parser. It parses a file, and returns a list
+;; that can be used internally by any other lisp file.
+;; See some example in todo.el
+
+;;; FILE FORMAT
+
+;; It does not parse the DTD, if present in the XML file, but knows how to
+;; ignore it. The XML file is assumed to be well-formed. In case of error, the
+;; parsing stops and the XML file is shown where the parsing stopped.
+;;
+;; It also knows how to ignore comments, as well as the special ?xml? tag
+;; in the XML file.
+;;
+;; The XML file should have the following format:
+;; <node1 attr1="name1" attr2="name2" ...> value
+;; <node2 attr3="name3" attr4="name4"> value2 </node2>
+;; <node3 attr5="name5" attr6="name6"> value3 </node3>
+;; </node1>
+;; Of course, the name of the nodes and attributes can be anything. There can
+;; be any number of attributes (or none), as well as any number of children
+;; below the nodes.
+;;
+;; There can be only top level node, but with any number of children below.
+
+;;; LIST FORMAT
+
+;; The functions `xml-parse-file' and `xml-parse-tag' return a list with
+;; the following format:
+;;
+;; xml-list ::= (node node ...)
+;; node ::= (tag_name attribute-list . child_node_list)
+;; child_node_list ::= child_node child_node ...
+;; child_node ::= node | string
+;; tag_name ::= string
+;; attribute_list ::= (("attribute" . "value") ("attribute" . "value") ...)
+;; | nil
+;; string ::= "..."
+;;
+;; Since XML is case insensitive, tag_name is always converted to lower-cases.
+;; tag_name is then converted to a symbol (this is not a string, so that the
+;; list takes less space in memory and is faster to traverse).
+;;
+;; Some macros are provided to ease the parsing of this list
+
+;;; Code:
+
+;;*******************************************************************
+;;**
+;;** Macros to parse the list
+;;**
+;;*******************************************************************
+
+(defmacro xml-node-name (node)
+ "Return the tag associated with NODE.
+The tag is a lower-case symbol."
+ (list 'car node))
+
+(defmacro xml-node-attributes (node)
+ "Return the list of attributes of NODE.
+The list can be nil."
+ (list 'nth 1 node))
+
+(defmacro xml-node-children (node)
+ "Return the list of children of NODE.
+This is a list of nodes, and it can be nil."
+ (list 'cddr node))
+
+(defun xml-get-children (node child-name)
+ "Return the children of NODE whose tag is CHILD-NAME.
+CHILD-NAME should be a lower case symbol."
+ (let ((children (xml-node-children node))
+ match)
+ (while children
+ (if (car children)
+ (if (equal (xml-node-name (car children)) child-name)
+ (set 'match (append match (list (car children))))))
+ (set 'children (cdr children)))
+ match))
+
+(defun xml-get-attribute (node attribute)
+ "Get from NODE the value of ATTRIBUTE.
+An empty string is returned if the attribute was not found."
+ (if (xml-node-attributes node)
+ (let ((value (assoc attribute (xml-node-attributes node))))
+ (if value
+ (cdr value)
+ ""))
+ ""))
+
+;;*******************************************************************
+;;**
+;;** Creating the list
+;;**
+;;*******************************************************************
+
+(defun xml-parse-file (file &optional parse-dtd)
+ "Parse the well-formed XML FILE.
+Returns the top node with all its children.
+If PARSE-DTD is non-nil, the DTD is parsed rather than skipped."
+ (find-file file)
+ (let ((xml (xml-parse-region (point-min)
+ (point-max)
+ (current-buffer)
+ parse-dtd)))
+ (kill-buffer (current-buffer))
+ xml))
+
+(defun xml-parse-region (beg end &optional buffer parse-dtd)
+ "Parse the region from BEG to END in BUFFER.
+If BUFFER is nil, it defaults to the current buffer.
+Returns the XML list for the region, or raises an error if the region
+is not a well-formed XML file.
+If PARSE-DTD is non-nil, the DTD is parsed rather than skipped,
+and returned as the first element of the list"
+ (let (xml result dtd)
+ (save-excursion
+ (if buffer
+ (set-buffer buffer))
+ (goto-char beg)
+ (while (< (point) end)
+ (if (search-forward "<" end t)
+ (progn
+ (forward-char -1)
+ (if (null xml)
+ (progn
+ (set 'result (xml-parse-tag end parse-dtd))
+ (cond
+ ((listp (car result))
+ (set 'dtd (car result))
+ (add-to-list 'xml (cdr result)))
+ (t
+ (add-to-list 'xml result))))
+
+ ;; translation of rule [1] of XML specifications
+ (error "XML files can have only one toplevel tag.")))
+ (goto-char end)))
+ (if parse-dtd
+ (cons dtd (reverse xml))
+ (reverse xml)))))
+
+
+(defun xml-parse-tag (end &optional parse-dtd)
+ "Parse the tag that is just in front of point.
+The end tag must be found before the position END in the current buffer.
+If PARSE-DTD is non-nil, the DTD of the document, if any, is parsed and
+returned as the first element in the list.
+Returns one of:
+ - a list : the matching node
+ - nil : the point is not looking at a tag.
+ - a cons cell: the first element is the DTD, the second is the node"
+ (cond
+ ;; Processing instructions (like the <?xml version="1.0"?> tag at the
+ ;; beginning of a document)
+ ((looking-at "<\\?")
+ (search-forward "?>" end)
+ (skip-chars-forward " \t\n")
+ (xml-parse-tag end))
+ ;; Character data (CDATA) sections, in which no tag should be interpreted
+ ((looking-at "<!\\[CDATA\\[")
+ (let ((pos (match-end 0)))
+ (unless (search-forward "]]>" end t)
+ (error "CDATA section does not end anywhere in the document"))
+ (buffer-substring-no-properties pos (match-beginning 0))))
+ ;; DTD for the document
+ ((looking-at "<!DOCTYPE")
+ (let (dtd)
+ (if parse-dtd
+ (set 'dtd (xml-parse-dtd end))
+ (xml-skip-dtd end))
+ (skip-chars-forward " \t\n")
+ (if dtd
+ (cons dtd (xml-parse-tag end))
+ (xml-parse-tag end))))
+ ;; skip comments
+ ((looking-at "<!--")
+ (search-forward "-->" end)
+ (skip-chars-forward " \t\n")
+ (xml-parse-tag end))
+ ;; end tag
+ ((looking-at "</")
+ '())
+ ;; opening tag
+ ((looking-at "<\\([^/> \t]+\\)")
+ (let* ((node-name (match-string 1))
+ (children (list (intern (downcase node-name))))
+ pos)
+ (goto-char (match-end 1))
+
+ ;; parses the attribute list
+ (set 'children (append children (list (xml-parse-attlist end))))
+
+ ;; is this an empty element ?
+ (if (looking-at "/>")
+ (progn
+ (forward-char 2)
+ (skip-chars-forward " \t\n")
+ (append children '("")))
+
+ ;; is this a valid start tag ?
+ (if (= (char-after) ?>)
+ (progn
+ (forward-char 1)
+ (skip-chars-forward " \t\n")
+ (while (not (looking-at (concat "</" node-name ">")))
+ (cond
+ ((looking-at "</")
+ (error (concat
+ "XML: invalid syntax -- invalid end tag (expecting "
+ node-name
+ ")")))
+ ((= (char-after) ?<)
+ (set 'children (append children (list (xml-parse-tag end)))))
+ (t
+ (set 'pos (point))
+ (search-forward "<" end)
+ (forward-char -1)
+ (let ((string (buffer-substring-no-properties pos (point)))
+ (pos 0))
+
+ ;; Clean up the string (no newline characters)
+ ;; Not done, since as per XML specifications, the XML processor
+ ;; should always pass the whole string to the application.
+ ;; (while (string-match "\\s +" string pos)
+ ;; (set 'string (replace-match " " t t string))
+ ;; (set 'pos (1+ (match-beginning 0))))
+
+ (set 'children (append children
+ (list (xml-substitute-special string))))))))
+ (goto-char (match-end 0))
+ (skip-chars-forward " \t\n")
+ (if (> (point) end)
+ (error "XML: End tag for %s not found before end of region."
+ node-name))
+ children
+ )
+
+ ;; This was an invalid start tag
+ (error "XML: Invalid attribute list")
+ ))))
+ ))
+
+(defun xml-parse-attlist (end)
+ "Return the attribute-list that point is looking at.
+The search for attributes end at the position END in the current buffer.
+Leaves the point on the first non-blank character after the tag."
+ (let ((attlist '())
+ name)
+ (skip-chars-forward " \t\n")
+ (while (looking-at "\\([a-zA-Z_:][a-zA-Z0-9.-_:]*\\)[ \t\n]*=[ \t\n]*")
+ (set 'name (intern (downcase (match-string 1))))
+ (goto-char (match-end 0))
+
+ ;; Do we have a string between quotes (or double-quotes),
+ ;; or a simple word ?
+ (unless (looking-at "\"\\([^\"]+\\)\"")
+ (unless (looking-at "'\\([^\"]+\\)'")
+ (error "XML: Attribute values must be given between quotes.")))
+
+ ;; Each attribute must be unique within a given element
+ (if (assoc name attlist)
+ (error "XML: each attribute must be unique within an element."))
+
+ (set 'attlist (append attlist
+ (list (cons name (match-string 1)))))
+ (goto-char (match-end 0))
+ (skip-chars-forward " \t\n")
+ (if (> (point) end)
+ (error "XML: end of attribute list not found before end of region."))
+ )
+ attlist
+ ))
+
+;;*******************************************************************
+;;**
+;;** The DTD (document type declaration)
+;;** The following functions know how to skip or parse the DTD of
+;;** a document
+;;**
+;;*******************************************************************
+
+(defun xml-skip-dtd (end)
+ "Skip the DTD that point is looking at.
+The DTD must end before the position END in the current buffer.
+The point must be just before the starting tag of the DTD.
+This follows the rule [28] in the XML specifications."
+ (forward-char (length "<!DOCTYPE"))
+ (if (looking-at "[ \t\n]*>")
+ (error "XML: invalid DTD (excepting name of the document)"))
+ (condition-case nil
+ (progn
+ (forward-word 1) ;; name of the document
+ (skip-chars-forward " \t\n")
+ (if (looking-at "\\[")
+ (re-search-forward "\\][ \t\n]*>" end)
+ (search-forward ">" end)))
+ (error (error "XML: No end to the DTD"))))
+
+(defun xml-parse-dtd (end)
+ "Parse the DTD that point is looking at.
+The DTD must end before the position END in the current buffer."
+ (let (dtd type element end-pos)
+ (forward-char (length "<!DOCTYPE"))
+ (skip-chars-forward " \t\n")
+ (if (looking-at ">")
+ (error "XML: invalid DTD (excepting name of the document)"))
+
+ ;; Get the name of the document
+ (looking-at "\\sw+")
+ (set 'dtd (list 'dtd (match-string-no-properties 0)))
+ (goto-char (match-end 0))
+
+ (skip-chars-forward " \t\n")
+
+ ;; External DTDs => don't know how to handle them yet
+ (if (looking-at "SYSTEM")
+ (error "XML: Don't know how to handle external DTDs."))
+
+ (if (not (= (char-after) ?\[))
+ (error "XML: Unknown declaration in the DTD."))
+
+ ;; Parse the rest of the DTD
+ (forward-char 1)
+ (while (and (not (looking-at "[ \t\n]*\\]"))
+ (<= (point) end))
+ (cond
+
+ ;; Translation of rule [45] of XML specifications
+ ((looking-at
+ "[\t \n]*<!ELEMENT[ \t\n]+\\([a-zA-Z0-9.%;]+\\)[ \t\n]+\\([^>]+\\)>")
+
+ (setq element (intern (downcase (match-string-no-properties 1)))
+ type (match-string-no-properties 2))
+ (set 'end-pos (match-end 0))
+
+ ;; Translation of rule [46] of XML specifications
+ (cond
+ ((string-match "^EMPTY[ \t\n]*$" type) ;; empty declaration
+ (set 'type 'empty))
+ ((string-match "^ANY[ \t\n]*$" type) ;; any type of contents
+ (set 'type 'any))
+ ((string-match "^(\\(.*\\))[ \t\n]*$" type) ;; children ([47])
+ (set 'type (xml-parse-elem-type (match-string-no-properties 1 type))))
+ ((string-match "^%[^;]+;[ \t\n]*$" type) ;; substitution
+ nil)
+ (t
+ (error "XML: Invalid element type in the DTD")))
+
+ ;; rule [45]: the element declaration must be unique
+ (if (assoc element dtd)
+ (error "XML: elements declaration must be unique in a DTD (<%s>)."
+ (symbol-name element)))
+
+ ;; Store the element in the DTD
+ (set 'dtd (append dtd (list (list element type))))
+ (goto-char end-pos)
+ )
+
+
+ (t
+ (error "XML: Invalid DTD item"))
+ )
+ )
+
+ ;; Skip the end of the DTD
+ (search-forward ">" end)
+ dtd
+ ))
+
+
+(defun xml-parse-elem-type (string)
+ "Convert a STRING for an element type into an elisp structure."
+
+ (let (elem modifier)
+ (if (string-match "(\\([^)]+\\))\\([+*?]?\\)" string)
+ (progn
+ (setq elem (match-string 1 string)
+ modifier (match-string 2 string))
+ (if (string-match "|" elem)
+ (set 'elem (append '(choice)
+ (mapcar 'xml-parse-elem-type
+ (split-string elem "|"))))
+ (if (string-match "," elem)
+ (set 'elem (append '(seq)
+ (mapcar 'xml-parse-elem-type
+ (split-string elem ","))))
+ )))
+ (if (string-match "[ \t\n]*\\([^+*?]+\\)\\([+*?]?\\)" string)
+ (setq elem (match-string 1 string)
+ modifier (match-string 2 string))))
+
+ (if (and (stringp elem)
+ (string= elem "#PCDATA"))
+ (set 'elem 'pcdata))
+
+ (cond
+ ((string= modifier "+")
+ (list '+ elem))
+ ((string= modifier "*")
+ (list '* elem))
+ ((string= modifier "?")
+ (list '? elem))
+ (t
+ elem))))
+
+
+;;*******************************************************************
+;;**
+;;** Substituting special XML sequences
+;;**
+;;*******************************************************************
+
+(defun xml-substitute-special (string)
+ "Return STRING, after subsituting special XML sequences."
+ (while (string-match "&" string)
+ (set 'string (replace-match "&" t nil string)))
+ (while (string-match "<" string)
+ (set 'string (replace-match "<" t nil string)))
+ (while (string-match ">" string)
+ (set 'string (replace-match ">" t nil string)))
+ (while (string-match "'" string)
+ (set 'string (replace-match "'" t nil string)))
+ (while (string-match """ string)
+ (set 'string (replace-match "\"" t nil string)))
+ string)
+
+;;*******************************************************************
+;;**
+;;** Printing a tree.
+;;** This function is intended mainly for debugging purposes.
+;;**
+;;*******************************************************************
+
+(defun xml-debug-print (xml)
+ (while xml
+ (xml-debug-print-internal (car xml) "")
+ (set 'xml (cdr xml)))
+ )
+
+(defun xml-debug-print-internal (xml &optional indent-string)
+ "Outputs the XML tree in the current buffer.
+The first line indented with INDENT-STRING."
+ (let ((tree xml)
+ attlist)
+ (unless indent-string
+ (set 'indent-string ""))
+
+ (insert indent-string "<" (symbol-name (xml-node-name tree)))
+
+ ;; output the attribute list
+ (set 'attlist (xml-node-attributes tree))
+ (while attlist
+ (insert " ")
+ (insert (symbol-name (caar attlist)) "=\"" (cdar attlist) "\"")
+ (set 'attlist (cdr attlist)))
+
+ (insert ">")
+
+ (set 'tree (xml-node-children tree))
+
+ ;; output the children
+ (while tree
+ (cond
+ ((listp (car tree))
+ (insert "\n")
+ (xml-debug-print-internal (car tree) (concat indent-string " "))
+ )
+ ((stringp (car tree))
+ (insert (car tree))
+ )
+ (t
+ (error "Invalid XML tree")))
+ (set 'tree (cdr tree))
+ )
+
+ (insert "\n" indent-string
+ "</" (symbol-name (xml-node-name xml)) ">")
+ ))
+
+(provide 'xml)
+
+;;; xml.el ends here
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