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502 lines
16 KiB
EmacsLisp
502 lines
16 KiB
EmacsLisp
;;; xml.el --- XML parser
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;; Copyright (C) 2000, 2001 Free Software Foundation, Inc.
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;; Author: Emmanuel Briot <briot@gnat.com>
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;; Maintainer: Emmanuel Briot <briot@gnat.com>
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;; Keywords: xml
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;; This file is part of GNU Emacs.
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;; GNU Emacs is free software; you can redistribute it and/or modify
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;; it under the terms of the GNU General Public License as published by
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;; the Free Software Foundation; either version 2, or (at your option)
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;; any later version.
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;; GNU Emacs is distributed in the hope that it will be useful,
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;; but WITHOUT ANY WARRANTY; without even the implied warranty of
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;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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;; GNU General Public License for more details.
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;; You should have received a copy of the GNU General Public License
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;; along with GNU Emacs; see the file COPYING. If not, write to the
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;; Free Software Foundation, Inc., 59 Temple Place - Suite 330,
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;; Boston, MA 02111-1307, USA.
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;;; Commentary:
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;; This file contains a full XML parser. It parses a file, and returns a list
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;; that can be used internally by any other lisp file.
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;; See some example in todo.el
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;;; FILE FORMAT
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;; It does not parse the DTD, if present in the XML file, but knows how to
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;; ignore it. The XML file is assumed to be well-formed. In case of error, the
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;; parsing stops and the XML file is shown where the parsing stopped.
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;;
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;; It also knows how to ignore comments, as well as the special ?xml? tag
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;; in the XML file.
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;;
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;; The XML file should have the following format:
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;; <node1 attr1="name1" attr2="name2" ...>value
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;; <node2 attr3="name3" attr4="name4">value2</node2>
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;; <node3 attr5="name5" attr6="name6">value3</node3>
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;; </node1>
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;; Of course, the name of the nodes and attributes can be anything. There can
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;; be any number of attributes (or none), as well as any number of children
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;; below the nodes.
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;;
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;; There can be only top level node, but with any number of children below.
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;;; LIST FORMAT
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;; The functions `xml-parse-file' and `xml-parse-tag' return a list with
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;; the following format:
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;;
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;; xml-list ::= (node node ...)
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;; node ::= (tag_name attribute-list . child_node_list)
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;; child_node_list ::= child_node child_node ...
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;; child_node ::= node | string
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;; tag_name ::= string
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;; attribute_list ::= (("attribute" . "value") ("attribute" . "value") ...)
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;; | nil
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;; string ::= "..."
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;;
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;; Some macros are provided to ease the parsing of this list
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;;; Code:
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;;*******************************************************************
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;;**
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;;** Macros to parse the list
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;;**
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;;*******************************************************************
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(defsubst xml-node-name (node)
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"Return the tag associated with NODE.
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The tag is a lower-case symbol."
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(car node))
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(defsubst xml-node-attributes (node)
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"Return the list of attributes of NODE.
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The list can be nil."
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(nth 1 node))
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(defsubst xml-node-children (node)
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"Return the list of children of NODE.
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This is a list of nodes, and it can be nil."
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(cddr node))
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(defun xml-get-children (node child-name)
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"Return the children of NODE whose tag is CHILD-NAME.
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CHILD-NAME should be a lower case symbol."
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(let ((match ()))
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(dolist (child (xml-node-children node))
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(if child
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(if (equal (xml-node-name child) child-name)
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(push child match))))
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(nreverse match)))
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(defun xml-get-attribute (node attribute)
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"Get from NODE the value of ATTRIBUTE.
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An empty string is returned if the attribute was not found."
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(if (xml-node-attributes node)
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(let ((value (assoc attribute (xml-node-attributes node))))
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(if value
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(cdr value)
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""))
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""))
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;;*******************************************************************
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;;**
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;;** Creating the list
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;;**
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;;*******************************************************************
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(defun xml-parse-file (file &optional parse-dtd)
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"Parse the well-formed XML FILE.
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If FILE is already edited, this will keep the buffer alive.
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Returns the top node with all its children.
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If PARSE-DTD is non-nil, the DTD is parsed rather than skipped."
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(let ((keep))
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(if (get-file-buffer file)
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(progn
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(set-buffer (get-file-buffer file))
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(setq keep (point)))
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(find-file file))
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(let ((xml (xml-parse-region (point-min)
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(point-max)
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(current-buffer)
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parse-dtd)))
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(if keep
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(goto-char keep)
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(kill-buffer (current-buffer)))
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xml)))
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(defun xml-parse-region (beg end &optional buffer parse-dtd)
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"Parse the region from BEG to END in BUFFER.
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If BUFFER is nil, it defaults to the current buffer.
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Returns the XML list for the region, or raises an error if the region
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is not a well-formed XML file.
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If PARSE-DTD is non-nil, the DTD is parsed rather than skipped,
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and returned as the first element of the list"
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(let (xml result dtd)
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(save-excursion
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(if buffer
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(set-buffer buffer))
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(goto-char beg)
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(while (< (point) end)
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(if (search-forward "<" end t)
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(progn
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(forward-char -1)
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(if (null xml)
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(progn
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(setq result (xml-parse-tag end parse-dtd))
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(cond
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((null result))
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((listp (car result))
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(setq dtd (car result))
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(add-to-list 'xml (cdr result)))
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(t
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(add-to-list 'xml result))))
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;; translation of rule [1] of XML specifications
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(error "XML files can have only one toplevel tag")))
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(goto-char end)))
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(if parse-dtd
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(cons dtd (reverse xml))
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(reverse xml)))))
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(defun xml-parse-tag (end &optional parse-dtd)
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"Parse the tag that is just in front of point.
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The end tag must be found before the position END in the current buffer.
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If PARSE-DTD is non-nil, the DTD of the document, if any, is parsed and
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returned as the first element in the list.
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Returns one of:
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- a list : the matching node
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- nil : the point is not looking at a tag.
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- a cons cell: the first element is the DTD, the second is the node"
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(cond
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;; Processing instructions (like the <?xml version="1.0"?> tag at the
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;; beginning of a document)
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((looking-at "<\\?")
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(search-forward "?>" end)
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(skip-chars-forward " \t\n")
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(xml-parse-tag end))
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;; Character data (CDATA) sections, in which no tag should be interpreted
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((looking-at "<!\\[CDATA\\[")
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(let ((pos (match-end 0)))
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(unless (search-forward "]]>" end t)
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(error "CDATA section does not end anywhere in the document"))
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(buffer-substring-no-properties pos (match-beginning 0))))
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;; DTD for the document
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((looking-at "<!DOCTYPE")
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(let (dtd)
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(if parse-dtd
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(setq dtd (xml-parse-dtd end))
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(xml-skip-dtd end))
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(skip-chars-forward " \t\n")
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(if dtd
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(cons dtd (xml-parse-tag end))
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(xml-parse-tag end))))
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;; skip comments
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((looking-at "<!--")
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(search-forward "-->" end)
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nil)
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;; end tag
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((looking-at "</")
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'())
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;; opening tag
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((looking-at "<\\([^/> \t\n]+\\)")
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(goto-char (match-end 1))
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(let* ((case-fold-search nil) ;; XML is case-sensitive.
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(node-name (match-string 1))
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;; Parse the attribute list.
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(children (list (xml-parse-attlist end) (intern node-name)))
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pos)
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;; is this an empty element ?
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(if (looking-at "/>")
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(progn
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(forward-char 2)
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(nreverse (cons '("") children)))
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;; is this a valid start tag ?
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(if (eq (char-after) ?>)
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(progn
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(forward-char 1)
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;; Now check that we have the right end-tag. Note that this
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;; one might contain spaces after the tag name
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(while (not (looking-at (concat "</" node-name "[ \t\n]*>")))
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(cond
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((looking-at "</")
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(error (concat
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"XML: invalid syntax -- invalid end tag (expecting "
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node-name
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") at pos " (number-to-string (point)))))
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((= (char-after) ?<)
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(let ((tag (xml-parse-tag end)))
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(when tag
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(push tag children))))
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(t
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(setq pos (point))
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(search-forward "<" end)
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(forward-char -1)
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(let ((string (buffer-substring-no-properties pos (point)))
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(pos 0))
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;; Clean up the string (no newline characters)
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;; Not done, since as per XML specifications, the XML processor
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;; should always pass the whole string to the application.
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;; (while (string-match "\\s +" string pos)
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;; (setq string (replace-match " " t t string))
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;; (setq pos (1+ (match-beginning 0))))
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(setq string (xml-substitute-special string))
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(setq children
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(if (stringp (car children))
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;; The two strings were separated by a comment.
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(cons (concat (car children) string)
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(cdr children))
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(cons string children)))))))
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(goto-char (match-end 0))
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(if (> (point) end)
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(error "XML: End tag for %s not found before end of region"
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node-name))
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(nreverse children))
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;; This was an invalid start tag
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(error "XML: Invalid attribute list")
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))))
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(t ;; This is not a tag.
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(error "XML: Invalid character"))
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))
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(defun xml-parse-attlist (end)
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"Return the attribute-list that point is looking at.
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The search for attributes end at the position END in the current buffer.
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Leaves the point on the first non-blank character after the tag."
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(let ((attlist ())
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name)
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(skip-chars-forward " \t\n")
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(while (looking-at "\\([a-zA-Z_:][-a-zA-Z0-9._:]*\\)[ \t\n]*=[ \t\n]*")
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(setq name (intern (match-string 1)))
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(goto-char (match-end 0))
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;; Do we have a string between quotes (or double-quotes),
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;; or a simple word ?
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(unless (looking-at "\"\\([^\"]*\\)\"")
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(unless (looking-at "'\\([^']*\\)'")
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(error "XML: Attribute values must be given between quotes")))
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;; Each attribute must be unique within a given element
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(if (assoc name attlist)
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(error "XML: each attribute must be unique within an element"))
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(push (cons name (match-string-no-properties 1)) attlist)
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(goto-char (match-end 0))
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(skip-chars-forward " \t\n")
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(if (> (point) end)
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(error "XML: end of attribute list not found before end of region"))
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)
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(nreverse attlist)))
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;;*******************************************************************
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;;**
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;;** The DTD (document type declaration)
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;;** The following functions know how to skip or parse the DTD of
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;;** a document
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;;**
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;;*******************************************************************
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(defun xml-skip-dtd (end)
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"Skip the DTD that point is looking at.
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The DTD must end before the position END in the current buffer.
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The point must be just before the starting tag of the DTD.
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This follows the rule [28] in the XML specifications."
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(forward-char (length "<!DOCTYPE"))
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(if (looking-at "[ \t\n]*>")
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(error "XML: invalid DTD (excepting name of the document)"))
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(condition-case nil
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(progn
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(forward-word 1) ;; name of the document
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(skip-chars-forward " \t\n")
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(if (looking-at "\\[")
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(re-search-forward "\\][ \t\n]*>" end)
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(search-forward ">" end)))
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(error (error "XML: No end to the DTD"))))
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(defun xml-parse-dtd (end)
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"Parse the DTD that point is looking at.
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The DTD must end before the position END in the current buffer."
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(forward-char (length "<!DOCTYPE"))
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(skip-chars-forward " \t\n")
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(if (looking-at ">")
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(error "XML: invalid DTD (excepting name of the document)"))
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;; Get the name of the document
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(looking-at "\\sw+")
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(let ((dtd (list (match-string-no-properties 0) 'dtd))
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type element end-pos)
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(goto-char (match-end 0))
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(skip-chars-forward " \t\n")
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;; External DTDs => don't know how to handle them yet
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(if (looking-at "SYSTEM")
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(error "XML: Don't know how to handle external DTDs"))
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(if (not (= (char-after) ?\[))
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(error "XML: Unknown declaration in the DTD"))
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;; Parse the rest of the DTD
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(forward-char 1)
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(while (and (not (looking-at "[ \t\n]*\\]"))
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(<= (point) end))
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(cond
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;; Translation of rule [45] of XML specifications
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((looking-at
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"[\t \n]*<!ELEMENT[ \t\n]+\\([a-zA-Z0-9.%;]+\\)[ \t\n]+\\([^>]+\\)>")
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(setq element (intern (match-string-no-properties 1))
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type (match-string-no-properties 2))
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(setq end-pos (match-end 0))
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;; Translation of rule [46] of XML specifications
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(cond
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((string-match "^EMPTY[ \t\n]*$" type) ;; empty declaration
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(setq type 'empty))
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((string-match "^ANY[ \t\n]*$" type) ;; any type of contents
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(setq type 'any))
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((string-match "^(\\(.*\\))[ \t\n]*$" type) ;; children ([47])
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(setq type (xml-parse-elem-type (match-string-no-properties 1 type))))
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((string-match "^%[^;]+;[ \t\n]*$" type) ;; substitution
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nil)
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(t
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(error "XML: Invalid element type in the DTD")))
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;; rule [45]: the element declaration must be unique
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(if (assoc element dtd)
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(error "XML: elements declaration must be unique in a DTD (<%s>)"
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(symbol-name element)))
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;; Store the element in the DTD
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(push (list element type) dtd)
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(goto-char end-pos))
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(t
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(error "XML: Invalid DTD item"))
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)
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)
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;; Skip the end of the DTD
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(search-forward ">" end)
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(nreverse dtd)))
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(defun xml-parse-elem-type (string)
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"Convert a STRING for an element type into an elisp structure."
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(let (elem modifier)
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(if (string-match "(\\([^)]+\\))\\([+*?]?\\)" string)
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(progn
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(setq elem (match-string 1 string)
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modifier (match-string 2 string))
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(if (string-match "|" elem)
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(setq elem (cons 'choice
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(mapcar 'xml-parse-elem-type
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(split-string elem "|"))))
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(if (string-match "," elem)
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(setq elem (cons 'seq
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(mapcar 'xml-parse-elem-type
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(split-string elem ","))))
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)))
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(if (string-match "[ \t\n]*\\([^+*?]+\\)\\([+*?]?\\)" string)
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(setq elem (match-string 1 string)
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modifier (match-string 2 string))))
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(if (and (stringp elem) (string= elem "#PCDATA"))
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(setq elem 'pcdata))
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(cond
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((string= modifier "+")
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(list '+ elem))
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((string= modifier "*")
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(list '* elem))
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((string= modifier "?")
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(list '? elem))
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(t
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elem))))
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;;*******************************************************************
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;;**
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;;** Substituting special XML sequences
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;;**
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;;*******************************************************************
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(defun xml-substitute-special (string)
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"Return STRING, after subsituting special XML sequences."
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(while (string-match "&" string)
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(setq string (replace-match "&" t nil string)))
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(while (string-match "<" string)
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(setq string (replace-match "<" t nil string)))
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(while (string-match ">" string)
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(setq string (replace-match ">" t nil string)))
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(while (string-match "'" string)
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(setq string (replace-match "'" t nil string)))
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(while (string-match """ string)
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(setq string (replace-match "\"" t nil string)))
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string)
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;;*******************************************************************
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;;**
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;;** Printing a tree.
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;;** This function is intended mainly for debugging purposes.
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;;**
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;;*******************************************************************
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(defun xml-debug-print (xml)
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(dolist (node xml)
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(xml-debug-print-internal node "")))
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(defun xml-debug-print-internal (xml indent-string)
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"Outputs the XML tree in the current buffer.
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The first line indented with INDENT-STRING."
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(let ((tree xml)
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attlist)
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(insert indent-string "<" (symbol-name (xml-node-name tree)))
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;; output the attribute list
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(setq attlist (xml-node-attributes tree))
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(while attlist
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(insert " ")
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(insert (symbol-name (caar attlist)) "=\"" (cdar attlist) "\"")
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(setq attlist (cdr attlist)))
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(insert ">")
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(setq tree (xml-node-children tree))
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;; output the children
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(dolist (node tree)
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(cond
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((listp node)
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(insert "\n")
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(xml-debug-print-internal node (concat indent-string " ")))
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((stringp node) (insert node))
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(t
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(error "Invalid XML tree"))))
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(insert "\n" indent-string
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"</" (symbol-name (xml-node-name xml)) ">")))
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(provide 'xml)
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;;; xml.el ends here
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