1#
2# ElementTree
3# $Id: ElementInclude.py 3375 2008-02-13 08:05:08Z fredrik $
4#
5# limited xinclude support for element trees
6#
7# history:
8# 2003-08-15 fl   created
9# 2003-11-14 fl   fixed default loader
10#
11# Copyright (c) 2003-2004 by Fredrik Lundh.  All rights reserved.
12#
13# fredrik@pythonware.com
14# http://www.pythonware.com
15#
16# --------------------------------------------------------------------
17# The ElementTree toolkit is
18#
19# Copyright (c) 1999-2008 by Fredrik Lundh
20#
21# By obtaining, using, and/or copying this software and/or its
22# associated documentation, you agree that you have read, understood,
23# and will comply with the following terms and conditions:
24#
25# Permission to use, copy, modify, and distribute this software and
26# its associated documentation for any purpose and without fee is
27# hereby granted, provided that the above copyright notice appears in
28# all copies, and that both that copyright notice and this permission
29# notice appear in supporting documentation, and that the name of
30# Secret Labs AB or the author not be used in advertising or publicity
31# pertaining to distribution of the software without specific, written
32# prior permission.
33#
34# SECRET LABS AB AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH REGARD
35# TO THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANT-
36# ABILITY AND FITNESS.  IN NO EVENT SHALL SECRET LABS AB OR THE AUTHOR
37# BE LIABLE FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY
38# DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS,
39# WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
40# ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE
41# OF THIS SOFTWARE.
42# --------------------------------------------------------------------
43
44# Licensed to PSF under a Contributor Agreement.
45# See http://www.python.org/psf/license for licensing details.
46
47##
48# Limited XInclude support for the ElementTree package.
49##
50
51import copy
52from . import ElementTree
53
54XINCLUDE = "{http://www.w3.org/2001/XInclude}"
55
56XINCLUDE_INCLUDE = XINCLUDE + "include"
57XINCLUDE_FALLBACK = XINCLUDE + "fallback"
58
59##
60# Fatal include error.
61
62class FatalIncludeError(SyntaxError):
63    pass
64
65##
66# Default loader.  This loader reads an included resource from disk.
67#
68# @param href Resource reference.
69# @param parse Parse mode.  Either "xml" or "text".
70# @param encoding Optional text encoding.
71# @return The expanded resource.  If the parse mode is "xml", this
72#    is an ElementTree instance.  If the parse mode is "text", this
73#    is a Unicode string.  If the loader fails, it can return None
74#    or raise an IOError exception.
75# @throws IOError If the loader fails to load the resource.
76
77def default_loader(href, parse, encoding=None):
78    with open(href) as file:
79        if parse == "xml":
80            data = ElementTree.parse(file).getroot()
81        else:
82            data = file.read()
83            if encoding:
84                data = data.decode(encoding)
85    return data
86
87##
88# Expand XInclude directives.
89#
90# @param elem Root element.
91# @param loader Optional resource loader.  If omitted, it defaults
92#     to {@link default_loader}.  If given, it should be a callable
93#     that implements the same interface as <b>default_loader</b>.
94# @throws FatalIncludeError If the function fails to include a given
95#     resource, or if the tree contains malformed XInclude elements.
96# @throws IOError If the function fails to load a given resource.
97
98def include(elem, loader=None):
99    if loader is None:
100        loader = default_loader
101    # look for xinclude elements
102    i = 0
103    while i < len(elem):
104        e = elem[i]
105        if e.tag == XINCLUDE_INCLUDE:
106            # process xinclude directive
107            href = e.get("href")
108            parse = e.get("parse", "xml")
109            if parse == "xml":
110                node = loader(href, parse)
111                if node is None:
112                    raise FatalIncludeError(
113                        "cannot load %r as %r" % (href, parse)
114                        )
115                node = copy.copy(node)
116                if e.tail:
117                    node.tail = (node.tail or "") + e.tail
118                elem[i] = node
119            elif parse == "text":
120                text = loader(href, parse, e.get("encoding"))
121                if text is None:
122                    raise FatalIncludeError(
123                        "cannot load %r as %r" % (href, parse)
124                        )
125                if i:
126                    node = elem[i-1]
127                    node.tail = (node.tail or "") + text + (e.tail or "")
128                else:
129                    elem.text = (elem.text or "") + text + (e.tail or "")
130                del elem[i]
131                continue
132            else:
133                raise FatalIncludeError(
134                    "unknown parse type in xi:include tag (%r)" % parse
135                )
136        elif e.tag == XINCLUDE_FALLBACK:
137            raise FatalIncludeError(
138                "xi:fallback tag must be child of xi:include (%r)" % e.tag
139                )
140        else:
141            include(e, loader)
142        i = i + 1
143